The Canine Immune System

by Anne Jones RN, BSNE

The basis of good health is a sound immune system. It is also difficult to understand because it exists on the cellular level of development. You can’t see it or touch it or get an image to study; you can only imagine it as an invisible wrap that serves as protection from disease.

Obviously it is far more complex than that but this image may serve to establish in the owner’s mind just how valuable a good immune system is to all living things, animals and plants alike. To learn in depth about canine immunity, a good resource can be found on the Epilepsy Foundation site at

Prepared by W. Jean Dodds, DVM, you will find no better or more informative site. Dr. Dodds has long been considered by breeders and fellow veterinarians as an authority on immune diseases and immune health. This article can only be a primer for her lengthy and expert material that is available to anyone wanting or needing to become better informed.

The intent of this article is to offer a simplified summary of Immunity and the diseases of the immune system, some of which are autoimmune in nature. We should begin with some terminology that will appear here.

immunity – resistance to disease

autoimmunity – disease which occurs when the body’s immune defense turns against itself and which has a basis in genetic inheritance

immune mediated – refers to the body’s reaction to its own antigens

antigens – the protein substances that stimulate production of antibodies

antibodies – the body’s natural defense against invasion by foreign substances; specific to a particular antigen

immune suppressant – substances that block formation of antibodies to antigens (a term found in regard to specific medications used to treat disease)

lymphocytes – cells produced by the lymphatic organs

lymphatic organs – bone marrow, thymus, lymph nodes and spleen

There are many more words that need to be defined to fully describe immunity but these will be important to understand. Immunity is a complex topic and not easily defined in a brief article such as this. However you can begin to comprehend the importance of a healthy immune system and the negative aspects of immune mediated diseases.

Immunity is established in part by the genetic influence of ancestors of the dog but it can also be affected in either a positive or a negative way by environmental factors. So what would be an environmental factor? The environment has been described as the sum total of all the conditions and elements that surround an individual – herein referring to the dog as the individual affected. That is a huge picture which includes the air breathed, the surface walked upon, the diet consumed, the vaccines injected, the medications prescribed, the germs or contaminants exposed to. The list is endless! We will focus on but a few of these elements in the environment but your imagination can broaden the picture immensely. In other words, anything in our environment can have either a positive or negative effect on immunity. This is a broad statement but serves to establish that there is nothing that can be disregarded when immune mediated illness is discussed.

For the purpose here, we will focus on genetics, plus significant environmental factors. BFCA has tried to educate pet owners and potential buyers to know the health of any immediate ancestors. If you want a healthy dog, he has to have healthy parents. There is disease potential in any living thing but a healthy environment sometimes trumps disease. Therefore the basis for good health beyond genetics is to provide the best possible home environment to include healthy diet.

Immune health relies on lymphocytes produced by bone marrow and thymus organ (primary system) or lymph nodes and spleen (secondary system). Bone marrow produces B-cells and thymus produces T-cells. Hyperactive cells can be either acute (occur as reaction to disease or inflammation) or chronic (immune mediated or otherwise stimulated by the body itself).

Hypoactive cells refer to decreased levels of immunity and are more likely related to chronic infection, aging, poor diet, stress or toxic events including drugs. It is more complex than this but these are common causes of immune deficient or immune suppressant states. (The prefix hyper- refers to high and hypo- refers to low. These prefixes can be applied to health terminology as they are in day to day situations.)

Autoimmunity is the inability of the body to protect itself from itself. This sounds very strange unless you understand that the body can be susceptible to its own antigens and any assault from the environment may trigger a reaction that is known as autoimmune disease. There is usually a genetic predisposition to autoimmunity which then causes the body to react, usually aided by stress, infection and hormonal influence on the system. Stress can be poor nutrition, fatigue, previous illness, some drugs, certainly any recent vaccinations, chemicals that are used as parasite or pest control, the list is endless.

Thyroid disease can play an important part in weakening the immune defenses. The thyroid is a body regulator and imbalance of an over or under active thyroid can disrupt the endocrine functions of the body. Underactive is hypothyroid disease, for instance, and should be investigated when an autoimmune condition exists.

Recent research in the use of vaccines in canines has resulted in an adjustment of the use of boosters to provide sufficient immunity to disease. These studies continue and it is expected that there will be future changes in the recommended protocols for vaccine use. This much we know: some of the vaccines currently in use for dogs are not necessary in all dogs and some are not of any value in any dogs. From this better understanding, vaccines are now described as core (essential vaccines needed by all dogs) and non-core (vaccines that may or may not have any value). Before having annual boosters, you need to determine through your own research and discussion with your veterinarian which your dog will need and how often they are to be given. The recommended protocol at this time is every three years for core vaccines but that will continue to be changed so you MUST make a determination each year about which you will and which you will not give.

Vaccines serve to stimulate antibody production. To have a better understanding of how these can eventually harm your dog if overdone, you will want to read articles by Dr. Dodds and other prominent and respected researchers. In a recent health survey completed by BFCA club members, the majority of those who have reduced the use of boosters in their dogs also have reported longer life spans for most of them. Other more scientific data supports this finding among these Bichon breeders and their own dogs. Survey results are found on line at

Why would vaccines affect the immune system enough to permit dogs to live longer (and healthier) lives? To answer this question, one has to understand how vaccinating an animal works. It would take more space than provided for this article to give a full explanation. The short form answer is that injecting viruses/antigens (or bits of virus material) into the body creates a reaction in the immune system to stimulate production of antibodies. The injected material can be modified live virus (MLV) or killed (previously inactivated) virus suspended in a carrying agent. The methodology for preparing either of these products need not be covered here.

The result of these injections is to stimulate antibody production and the dosage is the same for all breeds and sizes of dogs on the presumption that they contain the same body cellular makeup with teeny tiny cells in small/toy breeds and bigger cells in large breeds. Picture the Chihuahua next to the Irish Wolfhound and pack the cells into the different sized bodies and shapes for an image of what is happening. Today there is some question as to the assumption that both toy and giant breeds are equal. Also in question is whether packing all antigen material into one dose of product (vaccine) is wise. This debate has been going on for some years and no satisfactory resolution has been achieved.

Further debate is based on the assumption that there needs to be a booster every one to three or more years, even as to the need to boost production of antibodies at all once initial immunity has been created. Is this an added stress? Does the repeated stress to the immune system create a weakened immunity? Does the healthy dog, with no stress in his life, react the same way as does the one that is on the show or agility trial circuit? What about the dog recently relocated from a home in the east to live in the western desert? Is his system too stressed to be subjected to injections? Is there a latent illness or has the dog had recent surgery? had puppies? been treated for internal parasites or had antibiotics for illness? All of these are questions that are currently debated as a determination is being made about future vaccine regimens for our dogs and cats. Stress affects immunity – how much is too much stress?

Diet is a crucial part of building a healthy immune system. There are possibly a hundred available brands of dog food with several stages of feeding recommendations among all those brands (puppy to senior, disease specific diets, etc.). Home cooked diets are currently popular due to recent dog food contaminant illnesses. Raw diet versus cooked diet is debated. The most important lesson to be taken here is that a cheap dog food is NOT desirable, that healthy ingredients in prepared foods are equal to the properly prepared and balanced home made diet but that it is critical to good health that the ingredients of either consist of human grade quality, of correct balance of nutrients and without extremes. Consistency is also critical, meaning that only those pet owners who are truly dedicated to study of nutrition and to proper and safe production of the home diet will be successful. This is not a do it today and forget it tomorrow kind of approach to nutrition. It takes proportionately as much time to get home prepared dog food to the food bowl as to properly feed a family. Junk food for your dog is detrimental to his health just as it is to your toddler or your teen.

Cancer and immunity is still under investigation in both humans and canines but there is no question that immune mediated diseases will include cancers. On our website we have an asterisk on titles of autoimmune diseases seen with some frequency in Bichons. There are many others listed on the above web site (address on page 1, paragraph 2). Diseases of the endocrine system are autoimmune designated, as are diseases of the skin, the thyroid, the circulatory system. The list is long and every body system is either strengthened by healthy immunity or weakened when the immune level is low.

The most common disease in the Bichon Frise is allegy/atopy which is entirely related to the immune health of the animal. First and foremost this goes back to healthy parents and other ancestors who have had allergic reactivity from mild to horrific but have been used for breeding. Mild allergy can be tolerated but emails come to the Ask Us inquiry base on our web site about dogs that are miserable, owners that cannot deal with the existing problems, those with financial concerns about treatments. The worse are those reports of dogs that are chewing on themselves or scratching 24/7 or even those who have had to be euthanized due to the depth of misery from allergic illness. These dogs are truly allergic to themselves! The reports are heart breaking, each and every one.

What can the pet owner do? First read this material and other material available on the web or in books about canine health and immune mediated conditions. If you cannot read about it in dogs, read about it in humans. But come to an understanding that your dog will be far healthier if you do all you can to boost immunity. This applies to the dog with mild allergy as well because a mild allergy is the precursor of other immune mediated conditions that MAY (not always) occur. The time to prevent a crisis is always BEFORE the crisis occurs. Feed a GOOD diet, not just some bag of tummy filling stuff. Have an understanding with your veterinarian that you will discuss current vaccine protocols and that you will NOT give boosters each year which are not warranted. When signs of immune issues appear, have the screening needed for thyroid disease or any appropriate testing. Give drugs and medications only when they are needed and not “just because”. This includes the preventives for fleas and ticks when a good brushing can do the job without those chemicals (poisons) being ingested or applied to your dog. Heartworm preventive is important. The others are conveniences. If your current veterinarian is obstinate about annual boosters, you may need to locate one who is up to date on research and the recommended protocols.

YOU are your dog’s best advocate! Knowledge is power! Education today is free with the internet. Learn and you and your dog will benefit – and your family as well, I suspect.

This article is derived from the Epilepsy Foundation web site mentioned above and from other medical and veterinary dictionaries and texts, with acknowledgment to W. Jean Dodds DVM