How the Dog's Immune System Works

Updated on July 10, 2019
Bob Bamberg profile image

Bob has been in the pet supply business and writing about pets, livestock, and wildlife in a career that spans three decades.

When humans have allergies, they usually suffer upper respiratory symptoms while dogs usually suffer a maddening itch.
When humans have allergies, they usually suffer upper respiratory symptoms while dogs usually suffer a maddening itch. | Source

In pet supply stores, we see a huge assortment of dog foods and treats that claim to support the animal’s immune system. Overall, we tend to take a pretty simplistic view of that system.

The immune system usually, but not always, protects dogs from infections, allergies, and various pathogens.

On occasion, it fails to do its job. A dog may start scratching, rubbing, and gnawing, so we suspect that the immune system failed to fight off a certain food or environmental allergen.

We figure that the dog’s immune system needs support, so we buy certain foods or treats under the assumption that we’re helping out—and we are, some.

But it’s not that simple. The immune system is very complex and science still doesn’t know a lot about it.

Here's What We Do Know

There are two parts to the immune system. The default setting, if you will, is called the innate immune system. It’s made up of the skin, mucous, specialized cells in the saliva, stomach acid, and certain cells in the body called phagocytes.

You might remember from your conversational Greek classes that "phago" refers to eating. Phagocytes consume foreign matter, and they aren’t too particular about what they consume.

Together, these elements make up the innate immune system, otherwise known as the body’s first line of defense.

As it often happens, repeated exposure to a substance will allow the body to build up a resistance to that substance. The innate immune system has nothing to do with that, but it does do a pretty good job at what it was designed for: defense.

The Adaptive Immune System

The other half of this immune system duo is known as the adaptive immune system. Now that’s a system! It defends against specific foreign invaders by actually overreacting and setting off an impressive chain reaction that results in an allergic reaction.

In its toolbox, the adaptive immune system has a variety of features that enable it to do battle. If the invader simply needs a whack on the head to disable it, the adaptive immune system whips out its hammer. If it takes cutting off a germ’s legs to disable it, the system whips out its saw.

Not only does it recognize specific invaders and adapt to disable them, but it remembers them, too. If a pathogen tries to pull a fast one and re-enter an organism, the adaptive system responds with a swifter, more powerful tool.

Inhaling pollen, and building ones own antibodies, is an example of active immunity.
Inhaling pollen, and building ones own antibodies, is an example of active immunity. | Source

The Two Types of Immunity

Active immunity is when the body is exposed to a substance either by natural means such as inhalation or absorption, or by vaccination (inoculation).

Active immunity gives the animal’s body the opportunity to develop its own antibodies in most cases.

The second form of immunity is passive immunity, which is achieved by receiving another animal’s antibodies. Neither the animal nor its caretaker has anything to do with it.

Most of us are familiar with the term “maternal immunity.” This is the immunity received by the fetus from the placenta.

The newborn also receives some immunity from the colostrum, also know as mother’s milk, which is consumed in the hours immediately following birth.

A third example of passive immunity is that which is received from bone marrow transplants.

In the dog, maternal immunity wanes from shortly after birth, but is usually dissipated by the 12th week.

That’s why puppies aren’t immunized against rabies before 12 weeks. The maternal immunity can neutralize the vaccine.

When the Immune System Misfires

When the immune system misfires and mistakenly recognizes a part of the body as an enemy, it goes on the attack against the animal’s own body.

This is known as autoimmunity. The system can also overreact or it can fail to react at all, which can be fatal.

While human and animal immune systems basically function in the same manner, there’s still a lot that experts don't know (more so with animals).

That’s probably because funding for research in animal health is a lot harder to come by than funding for research into human health.

For years, the veterinary community has been trying to establish protocols for animal immunization. In 2001, the American Veterinary Medical Association’s (AVMA) Council on Biologic and Therapeutic Agents (COBTA) studied the issues surrounding vaccinations.

Professionals Gather to Establish Protocols

A task force of distinguished American professionals from four career groups, academia, regulation, industry, and veterinary practitioners, was assembled. The group also conducted extensive reviews of scientific literature.

Nonetheless, the group was unable to establish the protocols they sought. There just isn't enough knowledge of the immune system to enable scientists to draw conclusions.

While the body of knowledge is increasing, it hasn’t increased to the point where protocols can be definitive.

The council also alluded to excessive government regulations. I have to give the task force credit for diplomacy, because they worded their frustration as follows: "the strengths and limitations of the biologic regulatory approval process also complicate decisions required for best patient care.”


The council did conclude that there needs to be a customized approach to vaccine recommendations considering variations in individual animals, their lifestyles, and variations in the individual vaccine products currently approved for use in the U.S.

The group called for pet owners, who are able to provide detailed information about their animal, to take an active role in helping their veterinarian develop a customized vaccine recommendation.

As it stands now, veterinarians differ on the value and frequency of some vaccines. This is due in part to variations in individual training and experience.

Core Vaccines Are Universally Acknowledged

Although standardized vaccination protocols have yet to be established, there are vaccinations that are considered to be essential for dogs and cats. These are called core vaccinations, and they've been recognized as such for years.

Vaccines other than those designated as core vaccines are optional, and are known as non-core vaccines.

Professional organizations including the American Animal Hospital Association (AAHA), the American Association of Feline Practitioners (AAFP), the World Small Animal Veterinary Association (WSAVA), plus individuals from academia, industry, regulatory agencies, and private practices, established the core vaccines.

Core Vaccines for Dogs

  • Canine parvovirus (CPV)
  • Canine distemper virus (CDV)
  • Canine adenovirus (CAV)
  • Rabies.


Note that rabies vaccinations for dogs are required by law in all states, although some exemptions are allowed.

Non-Core Vaccines for Dogs

  • Canine parainfluenza virus (CPiV)
  • Canine influenza virus H3N8
  • Canine influenza virus H3N2 distemper-measles combination vaccine
  • Bordetella bronchiseptica, and Borrelia burgdorferi.

There are several other vaccines available for dogs, all of which are considered non-core and therefore optional.

Core Vaccines for Cats

  • feline herpesvirus 1 (FHV1)
  • feline calicivirus (FCV)
  • feline panleukopenia virus (FPV)
  • feline leukemia virus (FeLV)
  • rabies. As noted with the canine core vaccines, rabies vaccinations for cats are required by law in all states, but some exemptions are allowed.

Non-Core Vaccines for Cats

  • feline immunodeficiency virus
  • Chlamydia felis
  • Bordetella bronchiseptica

As with canine vaccines, there are several other vaccines available for cats that are considered non-core and therefore optional.

Which Non-Core Vaccines Are Appropriate for My Dog or Cat?

As to which non-core vaccines you should elect for your dog or cat, that is something that only you and your veterinarian can decide. Together, you'll consider the animal's state of health, age, lifestyle, exposure risk, and other factors that your veterinarian will evaluate.

Is There a Vaccine for Protection Against Food Allergies?

When dogs and cats have allergies, over 90% of the time it's due to an environmental allergen. When it is a food allergy, it's almost always to a protein, with chicken and beef being the top two allergens, and occasionally grain. And there are no vaccines against food allergies.

Food allergies are difficult and time-consuming to diagnose. Your veterinarian will likely suggest an elimination diet trial. There are three types of diets vets rely on.

Diets That Vets Recommend

  • novel protein diets
  • hydrolyzed protein diets
  • therapeutic diets.

Most people think of exotic meats such as kangaroo and bison as novel, but if your pet has had kangaroo or bison, they're not novel proteins for your pet. Conversely, if your pet has never had chicken or beef, those would be novel proteins for your pet.

When you think of all the proteins your pet has been exposed to, through pet food, people food and treats, you can begin to see the complexity of the undertaking.

Pet Foods Can Complicate the Issue

When I talk about complication, I'm thinking of a top quality pet food that has the silhouettes of six animals on the front of the bag and that boasts a Crude Protein value of 38% in its Guaranteed Analysis.

If your pet develops an allergy and the veterinarian suspects a food allergy, good luck with that one. The elimination diet could take up to a year and a half to complete.

I'm thinking of another top quality pet food that also boasts a Crude Protein value of 38% in its Guaranteed Analysis, but only utilizes three animal protein sources. The elimination diet trial would take only half as long as the other food's trial.

The point is, it doesn't necessarily matter how many animal protein sources the food sports. What matters is the Crude Protein value in the Guaranteed Analysis.

For that reason, I personally favor single-source protein formulations. They're much less complicated should the pet develop an allergy. If the veterinarian suspects that food is the cause, the owner can simply eliminate that protein source and try another.

This article is accurate and true to the best of the author’s knowledge. It is not meant to substitute for diagnosis, prognosis, treatment, prescription, or formal and individualized advice from a veterinary medical professional. Animals exhibiting signs and symptoms of distress should be seen by a veterinarian immediately.

Questions & Answers

    © 2017 Bob Bamberg


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      • Bob Bamberg profile imageAUTHOR

        Bob Bamberg 

        22 months ago from Southeastern Massachusetts

        Glad you liked it, Dianna, thanks for stopping by and commenting.

      • teaches12345 profile image

        Dianna Mendez 

        22 months ago

        Interesting fact on maternal immunization being the same with animals. Great reading on this topic.

      • Bob Bamberg profile imageAUTHOR

        Bob Bamberg 

        22 months ago from Southeastern Massachusetts

        Man, the scariest wildlife around here is the coyote...pretty lame compared to jaguars and anacondas. Are your living quarters a house or more like a camp? With those animals lurking about, I'd want a house with a mote and a 20 foot high wall. I wonder if Ajej's instincts are a bit messed up by the new environment. I'd guess drinking from a stream would be more natural than drinking from a bowl. It's good that you'll have the internet soon! I, too am an early riser...usually around 4:30, so I'm usually asleep by 9. Stay safe down there!

      • DrMark1961 profile image

        Dr Mark 

        22 months ago from The Atlantic Rain Forest, Brazil

        I hope to have internet soon, but I am up early and in bed by 8 or 9; quite a change from life on the beach. Jags dont usually come out until night, so although I hear them I have yet to see one. I have a creek through one of my fields, so everytime Ajej gets down to drink I worry about her getting her nose grabbed from an Anaconda. (I guess it takes better than water from the bowl!)

      • Bob Bamberg profile imageAUTHOR

        Bob Bamberg 

        22 months ago from Southeastern Massachusetts

        Great to hear from you, Doc, and thanks for the word on the possible immune system/cancer link.

        As active as you've been, doesn't it drive you crazy not to have internet access anymore? That's quite a drastic change in neighborhoods...sort of like moving from The Hamptons to Chicago. You gotta keep your eyes on your neighbors or else they'll eat you! I'll bet Ajej would give anything for a nice bowl of cow throat right now. I hope you get into town to use the internet more frequently, we miss you. I've just recently gotten active again here and noticed you didn't have much new stuff up. Great to have you stop by. Please keep in touch, and stay safe.

      • DrMark1961 profile image

        Dr Mark 

        22 months ago from The Atlantic Rain Forest, Brazil

        Interesting article. Many holistic vets are also convinced that a faulty immune system is responsible for cancer, so a lot of us are looking at ways to improve it. Cats claw is one herbal alternative.

        On a personal note, I am no longer living at the beach. I live in the jungle and do not have internet access anymore, just happpened to be in town today to buy supplies and was checking my email and saw your article. Hope all is going well up there. Ajej likes the move, and yesterday was playing with a baby anteater, and has been around lots of other beasts. So far we have avoided the jaguars and anacondas. My monkey avoids her--may have something to do with her carnivore face!

      • Bob Bamberg profile imageAUTHOR

        Bob Bamberg 

        22 months ago from Southeastern Massachusetts

        Most pet owners probably don't give a second thought to why the rabies shot isn't given until 12 weeks. Most probably just figure it's part of the schedule for puppies and kittens. Thanks for stopping by, FlourishAnyway, it's always nice to have you comment.

      • FlourishAnyway profile image


        22 months ago from USA

        It's sad that they get autoimmune conditions too. I was never quite sure why rabies vaccinations weren't required until 12 weeks, so thank you for the information.


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