I am Your Dog’s Salivary Glands

 

You might have never given your dog’s salivary glands much thought, but these structures have likely proven to you many times that they’re working, and quite efficiently too! Whether your dog drools because he’s hungry or because he’s getting a bit queasy during a car ride, that’s proof that his salivary glands are doing their job. As with many other structures of a dog’s body, the salivary glands carry out several functions and can also be prone to several problems. So today, let’s discover more about a dog’s salivary glands, the roles they play and conditions that affect them.

salivary-gland-in-dogs-anatomyIntroducing Your Dog’s Salivary Glands

Hello, it’s your dog’s salivary glands talking! We’re talking plural here because there are several of us populating your dog’s body, more specifically, we’re mostly located by your dog’s upper and lower jaw.

We are found in matching pairs, meaning that there are two of us of each side of your dog’s face and we consist of the following: 2 zygomatic glands, by the cheek bone near the dog’s eyes, 2 parotid glands where the head meets the neck,  2 sublingual glands right under the dog’s tongue and 2 mandibular glands, by the dog’s lower jaw.

We are exocrine glands meaning that we release fluids through special ducts. The special fluid we release, as our name implies, is saliva which is delivered from each of our ducts straight to your dog’s mouth.

idea tipDid you know? As Russian physiologist Ivan Pavlov demonstrated, higher centers of the dog’s brain are capable of eliciting the parasympathetic response of drooling in anticipation of food.

We Help With Moisturedog drooling

We help keep your dog’s mouth nice and moist. A dry mouth can mean trouble when it comes to the proliferation of harmful bacteria. A moist mouth instead is the perfect recipe for a healthy mouth. Indeed, the saliva we produce is quite rich in antibacterial substances that helps keep the number of bacteria down.

You might not be aware of this, but here’s a little hint: the level of moisture of your dog’s mouth can help you assess your dog’s level of hydration. A healthy dog who is well-hydrated will have gums that feel nicely moist, while a dog who is dehydrated will have gums that feel sticky, tacky and dry.

The saliva we produce also helps lubricate the passage of  chewed-up food from the mouth through the esophagus and then all the way down to the dog’s stomach. The blob of chewed up food is known as “bolus” and the more slippery it is, the easier it will slide down without causing damage.

idea tipDid you know? A 20 kilogram dog (around 44 pounds) is capable of producing  anywhere between a half a liter up to 1 liter of saliva a day! The amount is usually higher in dogs who are fed dry foods.

dog eatingWe Aid Digestion

Have you ever heard the saying “the digestive process starts in the mouth?” This applies to dogs too. Indeed, we start the digestion process by breaking down some components found in your dog’s food. As dogs chew, saliva indeed helps break down starch into individual sugar molecules, explains veterinarian Race Foster.

Not all of us though produce the same type of saliva. According to Dukes’ Physiology of Domestic Animals, secretions from us may vary from watery to a thicker, mucoid-like consistency.

The parotid glands, for instance, produce a watery saliva rich in amylase, which is what helps dog digest starch.

The sublingual glands, on the other hand, produce a mucus-type of saliva rich in mucin, which helps the bolus travel from the mouth to the stomach.

idea tipDid you know? Your dog’s salivary glands also increase salivation when there are irritating substances in the mouth and when your dog is anxious.

 

We Provide Evaporative Cooling 

dog panting tongue

Dogs do not cool down primarily through their skin like humans do, but their main way of cooling off is by panting. You might not know this, but we can play a role in helping dogs cool down too. The saliva we produce indeed, can help Rover cool down when those temperatures soar in the dog days of summer.

You see, when your dog has his mouth open and breaths quickly after romping in the yard on a warm summer day,  the moist surfaces of his mouth and tongue help cool him down by increasing evaporation.

If you take a close look at a dog panting after a long run, you will get a better picture how the saliva we produce help him cool down.

When Things Go Wrong

As with other structures of your dog’s body, we are prone to problems, which sometimes can be even quite urgent. We can become inflamed, we can be subject to injuries and we can also be affected by cancer sometimes, although not commonly. Here is a brief rundown of several salivary gland problems in dogs.

Ranula in dog mouth.
Ranula in dog mouth.

Salivary Mucocele in Dogs

If our duct happens to get damaged and rupture, we may develop what’s known as a salivary mucocele. When this happens, the saliva must drain somewhere and this often leads to soft (and often quite large!) swellings seen by the dog’s neck and face. We may also cause presence of blood in the dog’s saliva, trouble swallowing and sometimes eye pain or trouble breathing.

Mucocele in dogs can be caused by infections, tumors or a foreign bodies stuck in the duct (sialolithiasis). Depending on which one of us are affected, the mucocele may be given different names.

A Zygomatic mucocele affects the zygomatic salivary glands and saliva in this case tends to collects around the eye area. If the area swells too much, it can trigger exophthalmos, a protrusion of the dog’s eyeball. Surgical removal of these glands may be more complicated due to the presence of ocular glands nearby and is best done by a specialist.

A Cervical mucocele tends to form a swelling by the upper area of the dog’s neck and/or under the jaw. These should not be confused with reactive lymph glands or lymphoma, cancer of the dog’s lymph glands.

A Pharyngeal mucocele may form by the dog’s pharynx causing swelling that may impair a dog’s ability to breath and can therefore require urgent veterinary care.

A Sublingual mucocele forms under the dog’s tongue, When a dog’s lingual glands are injured, a swelling in the floor of the dog’s mouth, right under the tongue, forms. A mucocele under the dog’s tongue is commonlhy called a ranula.

Mucocele are often treated by draining and removing the affected glands. Drainage alone is not resolutive considering that mucocele tend to re-occur several weeks or months later. How much does surgery to remove us cost? Cost tends to vary from one place and another and is also based on the location of the swollen gland and how enlarged it is. Prices for salivary gland removal in dogs may therefore range between 500 and 1,500 dollars.

Did you know? The copious salivation seen in rabid animals is not due to the overproduction of saliva, but the paralysis of the dog’s pharynx, causing excess saliva to build up. Source: Colorado State University.

Other Conditionsveterinary

On top of mucocele and ranula, we may be affected from several other conditions such as salivary gland fistula, sialadenitis, (the inflammation of the salivary gland with the zygomatic gland most commonly affected) and sialadenosis, (a non-inflammatory swelling of the salivary glands.)

While cancer of the salivary glands is not very common, when it occurs, the dog’s submandibular and parotid glands tend to be the most likely affected.

The Bottom Line

Figuring out whether we are swollen because of a mucocele, fistula, tumor or other cause, is not always straightforward. Bloodwork doesn’t  typically show any high white blood cell unless there is a major infection going on.

Diagnosis is most often obtained through the dog’s medical history and results from aspirating the fluid within us though a fine needle aspirate. For instance, mucocele aspirates are often typically characterized by thick, ropy fluid that may have blood or a yellowish tint. A correct diagnosis is crucial because right where we are located, are also found a dog’s submandibular lymph nodes which may swell when a dog has lymphoma, explains veterinarian Dr. Andy. So make sure you see your vet if you notice any problems with us. Your dog and us will thank you!

Yours Truly,

Your Dog’s Salivary GlandsDog Pawprint

Disclaimer: this article is not meant to be used as a substitute for professional veterinary advice. If your dog is sick, has a lump or bump, or is acting abnormally, please see your vet at once.

 

References:

  • Colorado State University, Salivary Glands and Saliva, retrieved from the web on October 17th, 2016
  • The Merck Veterinary Manual, Salivary Disorders in Small Animals, retrieved from the web on October 17th, 2016
  • Dukes’ Physiology of Domestic Animals, edited by William O. Reece, Comstock Publishing Associates; 12 edition (July 29, 2004)
  • Best Pet Home Remedies, Salivary Infections in dogs,  retrieved from the web on October 17th, 2016

 

Photo Credits:

Wikipedia, Ranula in a dog, by Uwe GilleOwn work, Ranula in a dog CC BY-SA 3.0

 

I am Your Dog’s Nails

 

You may not pay attention to your dog’s nails much until they start clicking on the floor, reminding you that perhaps it’s now time for another nail trim. Whether your dog likes them or not, those “nail trim pedicures” are very important, so it’s ultimately time well invested working on making them a more pleasant activity. Your dog’s nails are more than just protrusions extending from him paws, dog nails play several important functions and paying close attention to them is important as they are also predisposed to problems. So today, let’s discover more about a dog’s nails, their function and possible signs of trouble.

dog-nailsIntroducing Your Dog’s Nails!

We are long and sharp, make a clicking sound and come in different colors, who are we? You guessed it, your dog’s nails! We are that curvy part that you find at the end of your dog’s toes, and just like your nails, we are made of keratin – a special protein made of dead cells, but wait, don’t let the word “dead” fool you, we are actually well alive!

We have several nerves and blood vessels within us, which compose your dog’s “quick,” that area that makes your dog startle and yelp in pain if you accidentally happen clip through it during a nail trim. While humans also have a “quick,” in humans the quick stops at the finger tips while in dogs the quick extends into the nail which makes it particularly vulnerable to being accidentally clipped.

Variety is the Spice of Life!dog-nails-colors

There are no general rules of “thumb” when it comes to our numbers and colors. Normally, each toe has one nail. Humans typically have five fingers and five toes (if you’re wondering, that makes you pentadactyl, by the way), whereas, the average dog has only four toes in both the front and back paws.  This means there are four of us in the front paws and four of us in the back paws respectively.

Dogs who have extra digits though, like the amazing Norwegian ludenhund have more of us compared to the average dog.

And when it comes to colors, we often reflect the color of the surrounding skin. In dogs with white fur, we may therefore be white, whereas in dogs with dark fur, we tend to be black (which makes it more challenging to identify the quick) and in some cases, we can even be multi-colored as seen in the picture.

idea tipDid you know? Fossil evidence shows that animals that have a reduced number of digits are mostly cursorial animals who were required to maintain high speeds for long distances, explains John Buckwalter, Emeritus of Biology at Alfred State College. Cursorial animals are known for having long limbs, shortened digits and reduced number of toes. Dogs for example have four toes instead of five as in humans, and horses (cursorial grazers) have only one (the hoof is simply the distal phalanx of the 3rd digit)

agility dewclawWe Provide Traction…

What’s our purpose in a dog’s life? We have several functions. Mother Nature really crafted us with dogs living in a natural setting in mind. She probably never expected that dogs would end up living in people’s homes with all their modern features.

Indeed, if you take a close look at your dog’s nails, you may notice that they’re shaped like cleats purposely crafted to dig into earthen terrains. “When was the last time you saw a dog slipping around while playing on dirt or grass?”questions veterinarian Dr. Julie Buzby. So it’s not surprising if dogs nowadays as domesticated companions have a hard time “getting a grip” on totally unnatural surfaces such as tiles, linoleum and hardwood floors.

  And Torque..

dog dewclaw

Yes, providing traction when running over uneven surfaces is what we are there for, but there’s more. Even those dewclaw nails that many people think have no function at all, actually have a function.  If  you are planning on having a puppy that will later on compete in the sport of agility or the perfect working dog you have always dreamed of, you may want to give chopping off those dewclaws a second thought.

Dewclaws help support Rover’s lower legs, and when he makes those swift tight turns as seen in the sport of agility, it’s thanks to his dewclaws that torque is prevented and the dog’s leg is saved from twisting and sustaining other injuries, explains veterinarian and rehabilitation specialist of performance-related injuries,  Dr.Christine Zink.

 

dog-diggingWe Help in Digging Up Treasures…

Mother Nature also provided us so to help dogs unearth certain “treasures.” Whether your dog is digging to uncover roots from your favorite plants, an old, hidden bone or the hiding spot of some sort of critter living underground, for sure us nails help accomplish these determined canine’s goals!

We may have been particularly useful to certain dogs breeds with a history as “diggers” such as the terriers and doxies, the digging dogs par excellence. For instance, in dachshunds, we have been crafted to grow particularly strong and quite fast so to compensate for the wear and tear associated with this dog breed’s predisposition for digging, explains Stephanie Cimmarusti, in the book “Everything You Need To Know About Your New Mini Dachshund Puppy.

And We Also Provide A Grip!

bone dog

Some dogs are particularly “pawsy”compared to others, using their paws do perform several actions, but all dogs at some point or another in their lives may find a use for us when handling items or putting their paws to “good use.”

Whether your dog is holding down a bone, trying to open a door or pawing to get a toy from under the couch, let’s face it, we come extra handy in helping dogs “get a grip”and reaching their objective. Dogs are quite determined pooches and it’s quite comical when we see them put us to use.

When Things Go Wrong

veterinary

We may seem strong and tough, but we are also prone to several problems. Annoying bacterial and fungal nail infections may affect dogs too. Bacteria may affect us when we get injured, so if you notice a broken nail or some other type of injury, make sure to keep us clean and well disinfected, or in complicated cases, ask your vet to take care of us to prevent annoying infections.

You may also want to make sure we heal well, considering that when a dog’s nail is chronically infected, it may lead to permanent defective nail growth, explains veterinary dermatologist Dr. Patrick Hensel.

Sometimes can also become affected by cancer, in particular squamous cell carcinoma, mast cell tumors and malignant melanoma of the toe. If you notice any changes in our appearance, such as a damaged nail or a toe nail falling off a swollen toe, consider that this can be one of the first signs of trouble, according to the Veterinary Cancer Place. Sp when in doubt, see your vet at once.

On a brighter side, consider that  fungal nail infections are less common in dogs than in humans. When we are infected by fungus, you’ll likely know pretty soon, as we’ll often exhibit a brown-red discoloration with a waxy brown-red seepage. I know, yuck! And sometimes, dog owners are quite baffled when they see their dogs growing what looks like an “extra nail.” No, we don’t grow out of no where,  in reality, this often turns out being a cutaneous horn, which is caused by a papillomavirus.

 

As seen, we are are quite important to your dog! However, let’s face it, dogs are often not walked as much as they should, they rarely are allowed to dig to their heart’s content and they live indoors for the most time walking on soft carpets and grassy areas. This gives us little opportunity to wear down. Long nails are not a cosmetic issue, but rather a health one. If we are allowed to grown too long, your dog’s gait will be thrown off badly which can ultimately affect his joints in the long run, and we may even  break, split or even curl and embed in your dog’s paws, ouch! So please take good care of us, and don’t forget to teach your dog to like having his feet handled!

Yours dearly,

Your Dog’s NailsDog Pawprint

Disclaimer: this article is not meant to be used as a substitute for professional veterinary advice. If your dog’s nails appear abnormal or are bleeding, seeping pus or showing other worrisome signs, please see your vet.

 

References:

  • DVM360, Nail Diseases, by Patrick Hensel, retrieved from the web on July 8th, 2016
  • Puppy’s First Steps: The Whole-dog Approach to Raising a Happy, Healthy …By Nicholas H. Dodman, Lawrence Lindner, Houghton Mifflin Harcourt (April 18, 2007)
  • Saint Bernard’s Animal Medical Center, The Quick and the Dead: Nail Trims, retrieved from the web on July 8th, 2016
  • Toe Grips, Frequently asked questions about Dr. Buzby’s ToeGrips: the traction aid to help stop dog slipping, retrieved from the web on July 8th, 2016

Photo Credits:

  • Letter “D” in the image indicates the dewclaw on this dog’s front paw. Letter “E” is the carpal pad. Amos T Fairchildown work (photo and GIMP modifications) CC BY-SA 3.0
  • jaimekay16, agility163,  Flickr creative commons (CC BY 2.0)
  • Wonderlane Rose, a puppy, chewing on a bone, south U District near the Montlake Cut, Seattle, Washington, USA,  Flickr creative commons CC BY 2.0
  • Flickr Creative Commons, John Collins, DSC_3594 (CC BY 2.0)

 

I am Your Dog’s Skull

 

Your dog’s skull is there for a great reason: to encase and protect your dog’s brain. A dog’s skull is compose of several bones, some of them surround the brain, others are just part of your dog’s facial structure. Since dogs come in different sizes, their skulls may vary accordingly. Learning more about your dog’s skull is not only interesting but also helpful, so you can recognizes signs of trouble. Let’s therefore discover some information about a dog’s skull, it’s anatomy and functions and problems this body part may be involved with.

dog-skull-anatomyIntroducing Your Dog’s Skull

Hello, it’s your dog’s skull talking! You might not be aware of how I look like exactly, but you may stumble on some resemblance of me when you visit a museum that houses skulls of wolves. However,  when it comes to canine skulls, imagine a scaled-down version considering that the overall size of a dog’s brain is nearly 30 percent smaller than the brain of wolves (Coppinger and Schneider 1995; Zeder 2012).

There is belief that domestication may have contributed to the shrinkage of some areas of the wolf’s brain, (the dog’s ancestor) with the limbic system in particular being affected, an area integral for the fight of flight response.

This shrinkage has been further noticed in the Farm Fox Experiment, where domesticated foxes in Novosibirsk, Russia, also showed changes in the dimensions of their skulls, a trait that has been associated with tameness (Trut 1999; Zeder 2012).

dog brachycephalic breedAs mentioned, I can come in different sizes. In brachycephalic breeds, such as bulldogs, pugs, and Boston terriers, I am quite compact, with  a “short head” while in dolichocephalic breeds such as Afghan hounds, Salukis and collies, I feature a long head with long, narrow snouts and orbits that are less forward set, so to enhance  a sighthound’s ability to scan the horizon (Miller and Murphy 1995; McGreevy et al. 2004) so they can effectively spot prey. And then you have the average skull shape as seen in mesaticephalic dogs.

I am composed of several bones , but you can technically divide me into two parts, the neurocranium, which encases the dog’a brain, and the facial skeleton, which makes up the skeleton of your dog’s face. However, if you’re a nerd, here is a partial list of bones I am composed of, just for your entertainment: the occipital bone, the sphenoid bone, the temporal bone, the frontal bone, the parietal bone, the ethmoid bone, the nasal bone, the lacrimal bone and the zygomathic bone, the incisive bone, the palatine bone, the vomer, the pterygoid bone, the maxilla and the mandible and the auditory ossicles .

idea tipDid you know? Those small holes in a skull are called foramina and are basically tiny passageways to allow the passage of nerves and blood vessels to the the face. The largest hole though is located where the vertebral column joins the base of the skull. It is known as foramen magnum and is meant to allow the passage of vertebral arteries and the spinal cord.

I Protect the Braindog concussion

Has your dog ever bumped his head against a table making a loud noises that had you wondering whether he got hurt? If so, you must thank me if your dog shakes his head once or perhaps twice, and then just walks away as if nothing ever happened.

I am quite thick, making your dog quite “hard-headed,” so to say. I am surrounded by  cerebrospinal fluid CSF providing both nutrients and protection to the brain. My main job is therefore to protect your dog’s brain and central nervous system. Quite an important task no?

idea tipDid you know? Those lines between the bones of the skull are called sutures.

 

veterinary

When Things Go Wrong

While I have a protective role and provide structure to your dog’s facial features., sometimes I may be subjected to problems, and some of them may need immediate attention! Please play it safe and report to your vet immediately if you notice problems associated with me.

Head Trauma

Even though I am quite tough, I can still be predisposed to head trauma. Bumping me against a table may not be enough to cause major problems, but being hit by car or kicked by a horse, can cause me enough trauma that I no longer may be able to protect the brain, and therefore, alterations to the brain’s physiology may occur.

This can lead to several complications such as abnormal glucose levels, electrolyte imbalances and acid-base disturbances, and even blindness if the ocular nerves are affected. Dogs suffering from head trauma may exhibit an altered state of consciousness, pupils of unequal sizes, stiff or flaccid legs, staggering gait, abnormal eye movements, tilted head, blood loss from ear canal or from the nose and breathing changes. Sometimes dogs may also develop vomiting following a severe blow to the head.

idea tipDid You know? According to a study, it was found that dogs who sustained a head trauma had a higher chance for developing seizures, especially in the immediate or early post-traumatic period.

“Fortunately dogs tend to have quite a thick skull that makes them less likely to suffer from major damage when hitting their head against a table or chair, explains veterinarian.”~ Dr. Fiona.

Chiari-Like Malformation

Remember when we talked about me having a big hole called the foramen magnum that’s meant to allow the passage of vertebral arteries and the spinal cord? Well, in some dogs, I am too small to accommodate all of the brain’s cerebellum, so part of the brain may descend out of me, with the end result of obstructing the normal flow of cerebrospinal fluid (CSF).  This condition is quite widespread in the Cavalier King Charles Spaniel (it’s estimated that 50 percent of them are affected) and the Brussels Griffon. Affected dogs develop syringomyelia (SM) where fluid-filled cavities develop within the spinal cord due to the variable pressure created by the abnormal flow of cerebrospinal fluid. Affected dogs develop pain and of the earliest signs is a hypersensitivity in the neck area, causing them to insistently scratch the neck area.

HydrocephalusApple head chihuahua

As in babies, some puppies are born with a soft spot in their skulls, also known as fontanel or molera. Why do I have such soft spot? This lack of complete closure of my bone plates is actually meant to allow an easier passage of the pups through mother dog’s birth canal. This soft spot is more common in certain dog breeds such as apple head Cihhuahuas,  Pomeranians and shih tzu and several toy breed dogs. Once the puppies are born though, my plates will eventually harden and the soft spot should disappear.

However, sometimes things may go wrong and dogs may have what’s known as hydrocephalus. In hydrocephalus, a dog’s cerebrospinal fluid (CSF) accumulates inside me because it doesn’t drain from the central nervous system as it should. Affected puppies may have seizures, be blind, have a dome-shaped and an unusual gait. Not all open fontanels though are connected with hydrocephalus.

 Tumors and Cancer

As with other bones, I can be prone to developing benign and malignant cancers. An osteoma is a benign growth, where a piece of bone grows on me, while a fibrosarcoma or osteosarcoma are malignant bones masses.  How can a veterinarian tell them apart? According to Critical Care Vet, an x-ray is not diagnostic, so a biopsy is needed.

As seen, I am very important! Just imagine for a moment how life would be without me. Your dog’s Jello-like brain would be getting traumatized every time your dog would move! I hope this article has helped you understand me better!

Your Dog’s SkullDog Pawprint

Disclaimer: this article is not meant to be used as a substitute for professional veterinary advice.  Please see your vet immediately if your dog sustained any type of injury or your dog is acting abnormally.

 

References:

  • The Genetics of Canine Skull Shape Variation, Jeffrey J. Schoenebeck, Elaine A. Ostrander 
  • Coppinger R.,Schneider R. 1995 Evolution of working dogs, pp. 21–50 in The Domestic Dog. Cambridge University Press, Cambridge, UK.
  • Trut L. N. 1999Early canid domestication: the Farm-Fox Experiment: foxes bred for tamability in a 40-year experiment exhibit remarkable transformations that suggest an interplay between behavioral genetics an development. Am. Sci. 87: 160169
  • Miller P. E. Murphy C. J. 1995 Vision in dogs. J. Am. Vet. Med. Assoc. 207: 16231634.
    MedlineWeb of Science Google Scholar
  • Coppinger R.,Schneider R. 1995 Evolution of working dogs, pp. 21–50 in The Domestic Dog. Cambridge University Press, Cambridge, UK.
  • Wikivet, Skull and Facial Muscles – Anatomy & Physiology retrieved from the web on October 3rd, 2016
  • Introduction to Veterinary Anatomy and Physiology Textbook, By Victoria Aspinall, Melanie Cappello, retrieved from the web on October 3rd, 2016

Photo Credits:

Wikipedia, Skull of a dog, Naturgeschichte für Bürgerschulen. Dr. Karl Rothe, Ferdinand Frank, Josef Steigl. I. Wien 1895, Verlag von A. Pichler’s Witwe & Sohn.{{PD-US}}

 

Fascinating Functions of Dog Teeth

 

Most dogs are blessed with 42 teeth, but do you know how dogs use their teeth? Sure, we know that dogs use their teeth for eating their chow, chewing bones and toys, and sometimes they also use them for grooming, but not all those doggy teeth are created equal. Indeed, every type of teeth dogs have are purposely crafted to accomplish specific tasks. So today, let’s discover what those dog teeth were built for, how dogs use them and some interesting facts about dog teeth you might not know.

A Look At Dog Teethdog-teeth-lower-jaw

Puppies have 28 teeth, which just as in humans, are deciduous meaning that they will eventually fall out. However, not always everything goes smoothly, and sometimes puppies may end up having retained baby teeth, basically baby teeth that are reluctant to fall out leaving little room for the permanent teeth to grow.

This can lead to problems, such as abnormal bites (malocclusions,)and therefore, retained baby teeth sometimes need to be pulled out.

When all goes well though, the dog’s 28 baby teeth are replaced by 42 adult permanent teeth, usually by the age of 7-8 months old. These permanent teeth consist of 20 teeth housed in the dog’s upper jaw and 22 teeth housed in the dog’s lower jaw. More precisely, there should be 6 incisors, 2 canines, 8 pre-molars and 4 molars in the upper jaw, and 6 incisors, 2 canines, 8 pre-molars and 6 molars in the lower jaw.

idea tipDid you know? Dogs are considered diphyodont, which means that they get two successive sets of teeth, the “deciduous” set, and afterward, the “permanent” set.

Dog incisors
Dog incisors

What are a Dog’s Incisors Used For?

Dogs have a total of 12 incisors in their mouths consisting of six incisors in their upper jaw and six incisors in the lower jaw.

There are two central incisors, two intermediate incisors, and two lateral ones.

What are dog incisors used for? These single-rooted teeth have several functions. If you watch your dog chew on a bone, you’ll likely notice that he doesn’t seem to use his incisors much, but if you give your dog a bone with some meat attached, you may notice that he’ll use this front teeth to rip and scrape the meat off the bone. For sake of comparison, the action is similar to when we remove kernels of corn on a cob.

On top of being used to scrape bones, those incisors also come handy for removing burrs from the coat and carrying objects around.

What are a Dog’s Canine Teeth Used For?

Dog canine teeth
Dog canine teeth

Right next to the incisors are a dog’s canine teeth. Dogs have four canine teeth, two in the top and two in the bottom.

When the dog’s mouth closes, these canine teeth should intersect nicely when they meet in a scissor bite. Canines are those sharp and pointy single-rooted teeth that are common in meat-eating animals.

What are dog canine teeth used for? A dog’s canine teeth were very important for survival purposes, as they allowed dogs to inflict several stabbing wounds to their prey. They also helped in catching and holding prey and tearing carcasses apart.

idea tipDid you know? Canine teeth also help dogs keep their tongue in place and therefore act as a “cradle for the tongue.” Indeed, when the lower canine teeth fall out or are removed, the tongue may be more likely to hang out of the mouth.

dog premolar teethWhat are a Dog’s Premolars Used For?

A dog’s premolars win the contest as the most numerous teeth in a dog’s mouth, if such a contest ever existed.

Dogs have a total of 16 premolars, eight in the upper jaw and eight in the lower one.

They are located behind the dog’s canine teeth. Also known as cheek teeth, some of the farthest premolars are only seen when a dog’s lips are pulled back.

What are these premolars used for? If you watch your dog chew on a toy or bone, you’ll likely see him tilt his head to side so that he can use his premolars. In the wild these teeth are use to rip meat away from bones. The arrangement of these teeth somewhat resembles shears with a serrated blade, an arrangement that helps dogs break food into smaller pieces, courtesy of these teeth’s sharp edges.

What are a Dog’s Molars Used For?

Molars live in the shadow, as they are tucked deeply inside a dog’s mouth, out of sight and often out of mind. There are four molars in the dog’s top jaw and six molars in the lower jaw. Often people become aware of their existence only when the vet mentions that one or more of these teeth need extracted.

What are a dog’s molars used for? We can get a clue from these teeth’s flat surfaces. Dog molars are  crafted so to allow dogs to grind foods like their kibble and crush bones. Mother dogs also rely on their molars to snip off the pups’ umbilical cord, explains Dr. Katherine A. Houpt in the book “Domestic Animal Behavior for Veterinarians and Animal Scientists.”

idea tipDid you know? Since puppies rely on milk for their first weeks of life, they aren’t equipped with molars.

How Are Dog Teeth Counted?cam00649

Dog teeth are counted by using a method known as the Modified Triadan System. Basically, imagine having your dog’s jaws split into four parts with a vertical line and a horizontal one.

You are therefore left with the dog’s mouth split into four parts: the right upper arch, the left upper arch, the right lower arch and the left lower arch. Each of these arches are given a numeric range.

The right upper arch is the 100 numeric series, the left upper arch is the 200 numeric series, the left lower arch is the 300 numeric series and the right lower arch is the 400 numeric series.

So for sake of an example, the dog’s first incisor on the right upper arch is tooth number 101, the second 102, the third 103 and the canine tooth is 104.

References:

Clinical Anatomy and Physiology for Veterinary Technicians, By Thomas P. Colville, Joanna M. Bassert, Mosby; 2 edition (December 21, 2007)

Dental Vet, Dental Anatomy, retrieved from the web onm Sept 30th, 2016

Photo Credit:

Wolf mandible diagram showing the names and positions of the teeth., William Harris Desktop publishing software – The base-image came from work that is publicly available, CC BY-SA 4.0

 

I am Your Dog’s Vomiting Center

 

Many dog owners may find it surprising that dogs have a vomiting center in their brain, perhaps even more surprisingly, humans have one too! When dogs vomit, it’s often assumed that it’s some sort of coordinated effort between the stomach contractions and expulsion of the contents out of the mouth, but it all actually starts in the dog’s vomiting center located in the brain. So today we discover more about this center, how it works, what it does and what role it plays in a dog’s life. All interesting stuff!

dog-vomiting-centerIntroducing Your Dog’s Vomiting Center 

Hello, I am your dog’s vomiting center! I am also known as the emetic center, just so you know. I am basically located by the medulla oblungata, a cone-shaped mass that’s responsible for  several involuntary functions such as sneezing and vomiting. Special receptors, cells whose main job is transmit a signal to a sensory nerve, communicate with me courtesy of several sympathetic nerves. Trigger these receptors and their signals will reach me quickly and soon your dog will soon start salivating, get a bout of nausea, and possibly, vomit.

While many nerves are located throughout your dog’s digestive tract, some may be located elsewhere.  For example, if your dog is prone to getting car sick, the vestibular system in his inner ear (your dog’s balance system) has special motion receptors that will alert me and trigger Rover to drool, and possibly, loose his meal all over your car seats. Since many nerves that lead to me are located mostly in the upper portions of your dog’s digestive tract, when your dog eats something that doesn’t agree with him, the nervous system around your dog’s gut will transmit signals to me via the vagus nerve, so that food can be brought back up. The nerves that travel to me are also sensitive to stretching. This means that if your dog devours a whole lot of food at once, I may be triggering the vomiting reflex.

Did you know? Dogs have quite a powerful vomiting center compared to other animals, possibly because of their history as scavenging animals. According to board-certified veterinarian David Twedt, from an evolutionary standpoint, vomiting is a defense mechanism for getting rid of rancid food or toxic substances that stimulate the  dog’s chemoreceptor trigger zone.

sick dog
A nauseous dog

I Save Lives

Vomiting may seem like a bothersome condition, but if you think about it, in many cases, it can be a life saving event for both you and your dog. When special chemoreceptors detect chemical abnormalities and poisons throughout your dog’s body, I am activated so that these substances quickly leave your dog’s system preventing him from absorbing toxins that could potentially kill him.

“Adjacent to the emetic center is a special clusters of receptors that constantly monitor the blood and the cerebrospinal fluid for chemicals that can stimulate vomiting. This specialized clusters of receptors is called the chemoreceptor trigger zone, CRTZ or CTZ. ~Robert L. Bill

Did you know? The most effective drugs against nausea and vomiting are those that act at both the vomiting center and the chemoreceptor trigger zone, says board-certified veterinarian  Todd R. Tams.

I Signal Trouble

I often act like a warning light that pops up on your dog’s health dashboard. Because I receive several inputs from inflamed or injured vital organs such as the dog’s kidneys or liver, I may trigger vomiting. This vomiting is the body’s way to get rid of  build-up of wastes from the dog’s blood coming from malfunctioning organs. This vomiting is often what triggers dog owners to bring their companion to the vet and provides an important puzzle piece that instigates investigation, especially in elderly dogs.

As seen, I am quite important! Think about it, life without me would spell disaster! Your dog would not be able to get rid of toxic substances from the body, and therefore, without me a dog would die very quickly. Horse lovers know very well how unfortunate it is that horses aren’t equipped with the ability to vomit as dogs, so next time you see your dog vomit, think about me helping your dog feel better, but don’t take me for granted. While I may do a good job in removing things that don’t agree with your dog’s body, I can only do so much. It’s ultimately your job is to ensure your dog is kept safe and doesn’t eat harmful things in the first place. It never hurts to be extra cautious! I hope this article has helped you understand me better!

Best regards,

Your Dog’s Vomiting Center Dog Pawprint

Disclaimer: this article is not to be used as a substitute for professional veterinary advice. If your dog is vomiting, please see your vet for diagnosis and treatment.

Photo Credits:

Flickr Creative Commons, Dale, PJ’s a sick girl, She’s suffering from Irritable bowel syndrome. We have an appointment with a new vet, hoping he can do something to help her out. CCBY2.0

 

I am Your Dog’s Sinuses

I am Your Dog’s Spleen

 

The spleen is one of those organs in dogs that lives in the shadow. Many people are not even aware that their dogs have a spleen, and unfortunately some get a scary, wake-up call of its presence when complications with this organ arise. Because a dog’s spleen is on the mushy side, it cannot be surgically repaired as other body parts and therefore it must often be removed when it starts bleeding. Yet, a dog’s spleen carries out many important functions. So today, let’s learn more about a dog’s spleen, what it does, where it’s located and the problematic complications that arise when a dog’s spleen is in trouble.

spleenIntroducing Your Dog’s Spleen

Hello, it’s your dog’s spleen talking! I am a vascular organ which means I carry lots of vessels, and since I am sort of spongy, I can easily store lots of blood  I am not that great looking, being a red, mushy blob, but looks aren’t really important after all when you are tucked away, out of sight. I am located in the left side of your dog’s body in an area well protected from his ribs. Your dog’s stomach is my neighbor to which I attach courtesy of the“gastrosplenic ligament.”  I might be small in size, but I do quite a whole lot!

Did you know? In ancient times the spleen was thought to be the physical source of hot temper, hence the reason for the saying “”venting spleen” meaning to let out anger.”

I Act as a Filtermaze

I work as a filter, removing old blood cells your dog’s body no longer needs. Yes, blood cells get old too after a while, so I filter all those worn-out or damaged red and white blood cells, and platelets from your dog’s blood. You may find my quality control process quite interesting, here’s an example of how I sort them out: I have all the blood cells pass through a maze of narrow passages. The healthy blood cells that pass through the maze with no problems are sent to the dog’s bloodstream, while those who can’t pass the test will be broken down. It’s survival of the fittest at best! Not everything that doesn’t pass my test is to toss though. I sort through the old and damaged red blood cells and recycle the iron so new healthy red blood cells can be made and I can dispose of the rest as waste. How’s that for an economical solution?

I Help with Immunity

It might not seem like it, but I play a role in helping your dog’s immune system. You see, I am on the “front line” and when I detect the presence of a foreign invader, such as a virus, bacteria or parasite, I make special lymphocytes and send them out to fight them.

I Act as a Reservoir

Remember when I said I am spongy and store lots of blood? Well, there’s a good reason why I do that. Generosity, is my second name. I keep a reservoir of blood that can be used in case of emergencies. Yup, I can provide a quick “transfusion” before going through the hassle of finding a donor with the correct blood type. But that’s not all, I also store platelets which helps your dog’s blood clot which comes handy when there is too much blood loss.

dog pain goes away at the vetWhen Things Go Wrong

Sadly, I am prone to some problems and some can be quite serious! I am prone to developing tumors, and the worst one is a nasty malignant cancer that goes by the name of hemangiosarcoma. This malignant cancer can quickly spread to other organs such as the heart, lungs or liver, and, remember when I said that I am vascular? Well, that means I am prone to bleeding easily, and as such, I can cause a dog to become quickly weak and anemic and I can even cause a dog to bleed to death too.

In the best case scenario, I may have a benign tumor known as a hemangioma. The only way to tell whether I am affected by a nasty cancer or not is by taking a needle biopsy to be sent out to a pathologist which can can be done while doing an ultrasound.  While having a hemangioma may sound like good news, the problem with this type of tumor is that it can cause me to rupture and bleed. Yes, imagine it as being “blood blister” on your dog’s spleen.  When this happens, you won’t see any bleeding as it’s internal, but affected dogs may become weak, lethargic, thirsty, they may develop pale gums, fluid in the belly and may even collapse. If it is more gradual, you might see just weakness and wobbliness, with an increase in drinking. So in this case, surgery is warranted, but the the best part is that surgery is in most cases curative. 

As other internal organs, I can be prone to injury as it can happen with car accidents, a kick from a horse or a bite wound. If the injury causes laceration to my major splenic vessels things can get life threatening, as I can hemorrhage profusely.

Did you know? Yunnan Paiyo, also known as Yunnan Baiyao, is a supplement that is getting more and more popular these days for spleen problems in dogs. This herbal product comes in capsule form and can help to stop bleeding, explains veterinarian Dr. Fiona.

As seen, I am quite important! While I may be an important organ that plays some important functions, I want to be honest: dogs and people can live without me. They sure may be missing out a helpful organ that helps fight infections, but they can still do well without me. I hope you now know more about me, best regards,

Your dog’s spleen Dog Pawprint

Disclaimer: this article is not meant to be used as a substitute for professional veterinary advice. If your dog is sick, please see your vet for proper diagnosis and treatment.

 

References:

DVM360, Surgery of the spleen (Proceedings), retrieved from the web on September 12th, 2016

 

 

 

I am Your Dog’s Bones

 

Whether your dog is chasing squirrels or romping around the yard with a ball in his mouth, his bones are always there to support him. Movement is the well-orchestrated effort of nerves, muscles and bones working together and making it all happen. A dog’s skeleton is composed of a variety of bones of different shapes and sizes meant to provide structural framework and general support for his whole body. So today, let’s discover more about dog bones, the various tasks they carry out throughout a dog’s life and potential problems a dog’s bones may encounter.

dog bonesIntroducing Your Dog’s Bones

Hello, it’s your dog’s bones talking today! Yes, there are many of us! Wondering how many bones dogs have? Dogs have over 300 bones, but if you want exact figures, we are closer to give or take 319, depending on how many bones are in a dog’s tail. If you’re looking for a comparison between the number of dog and human bones, consider that humans have about 206, so yes, dogs definitely win in the bone quantity department– if there was ever a contest for that!

Let’s start off by looking a bit at our composition. We are mostly made of minerals, primarily calcium and phosphorus and are somewhat, like onions, that is, we’re composed of many layers. Most of us are covered by a protective layer known as periosteum that’s responsible for delivering blood and nutrients to us. Periosteum also contains cells that help us grow and repair. If you’re wondering what periosteum looks like, imagine that white thin layer that lies between an egg and its shell. Yes, that pretty much looks like us.  Right under the layer of periosteum is compact bone, the smooth and very hard bone people are most familiar with when they think about us. Under the compact bone is what’s known as cancellous bone, also known as spongy or trabecular bone. As the name implies, this is the spongy part that is often found at the ends of the dog’s bones and joints. Finally, comes the innermost part of us, the bone marrow that carries important functions. Put together all these parts, and you get an idea of our composition. Now, let’s get a rundown of what we do.

idea tipDid you know? Despite their significant differences in size, Chihuahuas and Great Danes have approximately the same number of bones.
Illu long bone

We Provide Protection

We do our best job to protect your dog from getting hurt. If you look at your dog’s ribs, you will notice how we are arranged like a shield meant to protect your dog’s important internal organs such as the heart and lungs. Your dog’s thick skull is also there to protect that brain from dangerous concussions. Yup, being thick-headed is good thing for dogs!

Fun Fact:  The bones of the dog’s ears are there for neither protection nor support, but rather their primarily role is sound transmission, allowing dogs to use their sense of hearing, explains veterinarian Race Foster.

dog locomotion bonesWe Allow Movement

As mentioned, it is thanks to the teamwork between nerves, muscles and bones that your dog is capable of romping around. Many of us fit together like jig-saw puzzles connecting to their neighboring bones. Areas where we join one another are called joints which play a great role in locomotion. We interlock together in different ways, for example, the dog’s hip is an example of a ball and socket joint while the dog’s elbows are hinge joints.

We Produce Cells

When people think about us, they often get a mental picture of bones seen in a museum or those big  knuckle bones fed to their dogs, and this makes sense, as most likely those are the only types of bones people will ever see. But we are far from the dead, dry bones seen at museum exhibits. When we are still in the body of a live person, animal or dog, we are well alive, so much so that we grow, repair and even create blood cells. You see, in our bone marrow, that dark tissue found in hollow bones, special stem cells work hard to produce red and white blood cells.

We Store Minerals

Not many people think of bones as a warehouse for important substances the body needs. We store fat and several important minerals and keep them ready for when dogs need them. These minerals are constantly moved around, being deposited and taken out as needed. All this is coordinated by the parathyroid gland which produces a special hormone which tells us to release calcium into the bloodstream as needed.

When Things Go Wrongdog pain goes away at the vet

Many things can go wrong with us as we’re not indestructible. One of the most common problems affecting us are fractures, which can happen to many of us. We also may be subjected to issues when puppies grow if owners are not attentive enough to care for us. We may also get infections and problems associated with low calcium levels in the blood. Here’s a brief rundown of several problems we may encounter. This is not a complete list, but just a few problems that may affect us.

Dog Bone Fractures

When we are subjected to high impact accidents as when hit by car, we can dislocate and/or break and cause significant pain. Some types of fractures (like to toe fractures) may just need a splint, but others may require expensive and complex surgical repair. Sometimes we also can break due to an underlying condition that weakens us.

Dog Bone Cancer

When cancer affects us, dogs may suffer from what’s called a “pathological fracture” as we are destroyed from the inside out. While this fracture can affect any bones, the dog’s bones of the leg are most susceptible. What happens it that, as bone is destroyed, it’s replaced in part by tumorous bone, but this is not as strong as real bone and therefore the leg becomes prone to fracturing. Unfortunately, there’s no way to repair this type of fracture surgically.

Dog Bone Infection

Yes, we can sometimes get infected too. Osteomyelitis is the medical term for infection of the bone or bone marrow and it can be caused by bacteria or a fungal infection. In the case of bacteria, an infection in the body may spread to us, or the infection may be more localized. Bacteria may enter from bites, wounds or injuries or even complications from a surgery affecting the bone. Fungal infections affecting us include coccidiomycosis, blastomycosis, and cryptococcosis. Dogs affected by fungal infections that involve the bones usually develop pain, a fever and swelling.

Problems With Growth Plates

When puppies are born, they are equipped with all the bones they need, but as they grow, their bones need to increase in length. You see, us bones tend to grow from areas of immature, soft bone that are called growth plates which are located by the ends of the puppy’s bones. These growth plates are weak and can be prone to injury or even fractures, explains veterinarian Dr. Race Foster. It’s important therefore not to overexercise puppies such as jogging them on hard surfaces. As the puppy grows, we grow and finally harden with calcium and minerals, a process that is known as “closing the growth plates.“Generally, by one year of age the puppy’s growth plates close and significant bone growth ends.

“Vitamin D deficiency is characterized by an inadequate mineralization
of the bone and growth plates, also know as rickets.” Dr. Sally Perea

puppies nursingEffects of Low Calcium

As mentioned, we store minerals and this includes calcium. When dogs give birth and have a large litter, sometimes they may lose too much calcium at once which may cause what’s known as hypocalcemia (low calcium), milk fever or eclampsia. What basically happens in dog eclampsia is that mother dog’s body cannot keep up with the increase demands for calcium associated with nursing. When this happens, blood levels of this mineral become suddenly depleted and her parathyroid gland is not fast enough to start removing it from the bone. With not enough levels of calcium circulating in the body, affected dogs develop a stiff gait, fever and rapid breathing and death can occur if no treatment is given. While well-meaning dog owners may supplement calcium during a dog’s pregnancy, doing so is not recommended, explains Dr. Race Foster. Wrong amounts of  supplementation during pregnancy and inappropriate calcium to phosphorous ratios can actually trigger eclampsia  in the first place.

warning cautionDid you know? Too much of a good thing applies to calcium as well. While breeders and dog fanciers may advocate giving puppies calcium supplements, this is risky business. Too much calcium in puppies is detrimental to their development and can cause skeletal deformation, warns veterinary nutritionist Dr. Jennifer Larsen.

Aging Bones in Dogs

After years and years of providing locomotion, protection and support, sadly we start feeling the effects of time. As time goes by, the cartilage that cushions joints starts to wear down. Without this protection, us bones are left rubbing against each other, which causes friction and damage to us over time. Large dogs are mostly affected, and the weight-bearing joints such as hips, elbows and knees are particularly vulnerable.  Bones spurs may also appear. While there is no cure for old age, there are supplements and medications that can fortunately reduce inflammation and pain.

As seen, us bones do a whole lot, but we are also prone to problems! Make sure you keep us in good shape and report to your vet immediately as soon as you notice problems. I hoped this helped you discover more about us! Best regards,

Your dog’s bones Dog Pawprint

Disclaimer: this article is not meant to be used as a substitute for professional veterinary advice. If your dog is having health problems, please see your vet for proper diagnosis and treatment.

 

References:

  • Pet Education, Skeletal Anatomy: Bones, Joints and Muscles in Dogs, retrieved from the web on September 5th, 2016
  • Pet Education, Eclampsia (Puerperal Tetany, Milk Fever, Hypocalcemia) in Dogs, retrieved from the web on September 5th, 2016
  • Focus on Nutrition, Feeding Large Breed Puppies, retrieved from the web on September 5th, 2016
  • Nutrient Requirements of Dogs and Cats. National Research Council of the National Academies. The National Academies Press, Washington, DC, 2006

Photo credits:

Lateral view of a dog skeleton, Wilhelm Ellenberger and Hermann BaumUniversity of Wisconsin Digital Collections Public Domain

Fuelbottle~commonswiki Public domain

The Mystery Behind Those Ridges On the Roof of Dog’s Mouth

 

If you ever looked inside your dog’s mouth while he was yawning or perhaps panting, you may have noticed several ridges on the roof of his mouth. If you have been wondering what those ridges are, consider that you’re in good company; several dog owners have been wondering about those mysterious ridges too. As with most body parts in dogs, Mother Nature didn’t place those ridges on the roof of the dog’s mouth just for decoration; turns out, those ridges carry out several important functions.

dog mouth ridgesA Lesson in Anatomy

Dogs aren’t the only animals to have ridges on the top of their mouth. Humans actually have them too! If you feel the roof of your mouth with your finger or tongue, just a bit behind your front teeth, you may feel the presence of those ridges too. Those ridges are mostly located by the front part of the roof of the mouth (hard palate) while the back part is relatively smooth and soft as it’s made of tissues (soft palate). In dogs, those ridges in the mouth start just after the incisive papilla and they are quite prominent, which is possibly why they gain so much interest.

For those wondering, those ridges also have a name. They’re called rugae palatinae, or more simply palatal rugae. The term rugae simply means “ridges” while palatinae  simply means regarding the palate. According to  the McCurnin’s Clinical Textbook for Veterinary Technicians, the numbers of these rugae in dogs may vary generally ranging between 8 and 10.

Did you know? In brachycephalic dogs, these ridges are closely positioned rather than spaced out causing hair, debris and bacteria to accumulate there. (The CUSP, April 2005)

Interesting Functionsridges dog mouth

Also known as transverse palatine folds, those ridges in a dog’s mouth as mentioned aren’t there just for decoration; rather, they carry out some important functions. According to a study conducted by Crompton AW and Musinsky C., when dogs drink, it’s thanks to these ridges that water is prevented from falling out of the dog’s mouth as the dog’s tongue is protruded. Basically, what happens is that a tight contact between the tongue’s surface and the ridges helps trap the liquid ingested from the previous lapping cycle. On top of helping a dog lap up water without spilling out, those ridges are also helpful when dogs are eating. According to M. Lynne Kesel author of Veterinary Dentistry for the Small Animal Technician those ridges apparently also aid in swallowing

“X-ray videos of dog lapping reveal the dexterity with which their tongues trap previously lapped aliquots between the rugae on the roof of their mouths and the dorsal surface of the protruding tongue, in order to access the next aliquot without losing the previously ingested one.”~The Royal Society

CLEFT PALATE PUPPY
Puppy with cleft palate

The Importance of Fusion

Since the roof of the mouth ( palate) separates the mouth from the nasal cavities, it’s important that it’s nicely sealed. During infancy, the right and left sides of the dog’s palate are fused together so to prevent problems. However, in some cases, these parts may not fuse together correctly and newborn puppies present with what is called as a “cleft palate.” A cleft palate in puppies is life threatening because these puppies are not able to nurse properly and fluids can easily up into their nasal passages and airways causing aspiration pneumonia.

Did you know? The rugae of the palate are quite unique. Indeed, in humans, they can be used as a reliable guide in forensic identification when fingerprints are not available.

 

References:

  • McCurnin’s Clinical Textbook for Veterinary Technicians, By Joanna M. Bassert, John Thomas, Saunders; 8 edition (April 19, 2013)
  • How dogs lap: ingestion and intraoral transport in Canis familiarisBiol Lett. 2011 Dec 23;7(6):882-4. doi: 10.1098/rsbl.2011.0336. Epub 2011 May 25
  • Thexton A. J.McGarrick J. D. 1988 Tongue movement of the cat during lapping. Arch. Oral Biol. 33, 331339.doi:10.1016/0003-9969(88)90066-0 (doi:10.1016/0003-9969(88)90066-0)

Photo Credits:

British Veterinary Journal, Volume 61, January 1, 1905

Wikipedia, Cleft lip in a Boxer by Joel MillsOwn work, Cleft lip in a six week old Boxer puppy. CC BY-SA 3.0

 

I Am Your Dog’s Hippocampus

 

Among the many structures of the dog’s brain, the hippocampus plays several important roles. If your dog sits when you ask him to or he comes running to you when he hears you calling him, you must thank this tiny organ which stores tons of long-term memories. This structure also helps your dog navigate so he can find his way through the doggy door and it helps your dog form emotional reactions along with several other important cognitive functions. So today, let’s discover more about a dog’s hippocampus by listening to his story.

dog hippocampusIntroducing Your Dog’s Hippocampus

Hello, it’s your dog’s hippocampus talking! Yes, I am tiny, but don’t underestimate me based on size, I do a whole lot! My name derives from the Greek word “hippo,” which means horse and “kampos” which means sea. Put those two words together and you get “seahorse.” I am called this way because people think I am shaped like a sea horse, do you notice any resemblance in the picture on the right?

I am part of the limbic system and am surrounded by important neighbors such as the amygdala and the pineal gland.  People often think of me as a single structure, but in reality I am found in the left and right sides of your dog’s brain. Like other brain structures, I am known for being quite plastic.  I am just like a muscle, enlarging when used and shrinking when not in use.

”  It may even be possible to assess training efficacy by seeing how large the hippocampus becomes after a few weeks of the right type of training or how severely affected fear centers are when punitive training is employed (there is already evidence that even mild/unpleasant electric shock has long lasting (like forever) detrimental effects on these centers in rodents .  ” ~Dr. Nicholas Dodman

I Form Memoriesdog sit

When an event takes place in your dog’s life, his brain determines whether information about this event is worthy of saving. If the brain determines that the information is important, it will be saved in your dog’s “memory storage files.” I therefore play an important role when it comes to the consolidation of information from short-term memory to long-term memory. Yes, feel free to call me the storage and reception area for your dog’s memories!

Did you know? According to a study, it takes about 3 to 4 years for London taxi drivers to memorize all the route maps of the city. When the brains of these taxi drivers were scanned with an MRI, their memory center, the hippocampus, showed an increase in size. When the taxi drivers though retired, the hippocampus then shrunk back to its normal size.

dog fearI Encode Contexts

Since I often store memories that are important for survival purposes, when your dog is exposed to something that he has associated with a traumatic event, I encode such context and send an alert to my neighbor, the amygdala, the critical initiator of fear, which responds to threats triggering the dog to react. When the amygdala and I work together, through our teamwork, we can identify threatening contexts and “flag them” while discarding those contexts that aren’t threatening.

“One of the jobs of the hippocampus is to encode contexts. Those London cab drivers with oversized hippocampuses have countless contexts encoded to represent many different locations around London. The hippocampus of the puppy who had a tough time at playgroup encoded the room where playgroup happened as a context.” ~Jessica Perry Hekman, DVM, MS

I Help With Navigation dog navigation

If your dog knows how to navigate through your home, it’s thanks to me too. I help with spatial memory and navigation. Interestingly, according to data collected from Brian Hare and Vanessa Woods at Duke University, male and female dogs employed different navigational skills when it came to finding food hidden under a bowl. Female dogs were found to be more successful by using their hippocampus in what’s known as :”allocentric navigation“a  landmark-based strategy similar to forming a mental map; whereas, male dogs were found to use their basal ganglia in what’s known as “egocentric navigation.”

When Things go Wrong

I am a structure that may suffer the effects from aging. When dogs develop Canine Cognitive Dysfunction as they age, I am known to deteriorate and shrink, possibly playing a role when dogs start to forget important things such as learned obedience behaviors or how to navigate through the house to reach the doggy door. As it happens with humans, the more extensive the atrophy, the more pronounced the cognitive deficits. (Tapp et al., 2004a; Rofina et al., 2006).

I also can be damaged by certain medical conditions and I also can suffer from the effect of stress. According to veterinary behaviorist Karen Overall, stress increases cortisol and cortisol adversely affects my plasticity and my ability to learn. Medications meant to reduce stress, can take the edge off and help dogs gain back their ability to cognitively function.

As seen, I do a whole lot! The famous saying “If you don’t use it you lose it” can apply to me since I increase or shrink accordingly based on how much I am used. So keep your dog health, happy and mentally stimulated!

Best regards,

Your dog’s hippocampusDog Pawprint

 

References:

  • Dog Star Daily, “Inside a dog’s brain it’s too dark to read” … no more., Dr. Nicholas H. Dodman, retrieved from the web on August 29th, 2016
  • Current Biology, Acquiring “the Knowledge” of London’s Layout Drives Structural Brain Changes, Katherine Woollet, Eleanor A. Maguire,Volume 21, Issue 24, p2109–2114, 20 December 2011
  • Tapp, P. D., Siwak, C. T., Head, E., Cotman, C. W., Murphey, H., Muggenburg, B. A., et al. (2004b). Concept abstraction in the aging dog: development of a protocol using successive discrimination and size concept tasks. Behav. Brain Res. 153, 199–210. doi: 10.1016/j.bbr.2003.12.003
  • Rofina, J. E., van Ederen, A. M., Toussaint, M. J., Secreve, M., van der Spek, A., van der Meer, I., et al. (2006). Cognitive disturbances in old dogs suffering from the canine counterpart of Alzheimer’s disease. Brain Res. 1069, 216–226. doi: 10.1016/j.brainres.2005.11.021
  • Live Science, Female Dogs Are Better Navigators, By Brian Hare and Vanessa Woods, Duke University, 

Photo Credits:

The human hippocampus and fornix compared with a seahorse (preparation by László Seress in 1980), Hippocampus_and_seahorse.JPG: Professor Laszlo Seress derivative work: Anthonyhcole (talk) Hippocampus_and_seahorse.JPG, CC BY-SA 3.0

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