Your pet’s immune system is designed to keep him healthy by detecting a wide range of foreign invaders, ranging from bacterial organisms to fungi and parasites, and then dealing with these threats appropriately.
We’ve talked before about what can happen when the immune system is overactive and inappropriately targets normal, healthy cells. Today we’ll discuss immunodeficiency, the condition in which the immune system is less active than it should be, leaving pets susceptible to serious (and sometimes life-threatening) infections.
Immunodeficiency can occur for genetic reasons, and in these cases, immunodeficiency is considered a primary problem. Most of the time, however, immunodeficiency in pets is present because of another underlying medical condition, and in these cases, immunodeficiency is considered a secondary problem.
Primary immunodeficiency in pets is rare, but it does occur. Specific examples include:
- Selective IgA deficiency in German Shepherd Dogs, Shar-Peis and Beagles
- Weimeraner immunodeficiency syndrome
- Canine Leukocyte Adhesion Deficiency in Irish Setters
Secondary immunodeficiency is much more common in pets. Sometimes immunodeficiency occurs in neonatal pets because, for one reason or another, they are deprived of their mother’s antibody rich colostrum. In adults, nutritional reasons may be to blame, especially in the face of severe protein or calorie restriction, vitamin A or zinc deficiencies, or lead toxicosis.
More commonly, however, immunodeficiency is secondary to other infections or medical conditions, like:
- Systemic disease—Hyperadrenocorticism (Cushing’s Syndrome), diabetes, cancer
- Viral—Feline immunodeficiency virus (FIV), feline leukemia, canine distemper
- Non-viral—Demodex infestation, Ehrlichiosis, Bartonellosis
And finally, secondary immunodeficiency can also occur for iatrogenic reasons, or those we cause, either on purpose or accidentally. Good examples include cytotoxic agents, like chemotherapy, some anti-fungal medications, and the use of some steroidal medications.
Common manifestations of immunodeficiency are growth retardation and ill thrift in neonates (fading puppies/kittens), respiratory disease, pyoderma (skin infections), vomiting and diarrhea, and gastrointestinal infections. Often, we see recurrent or chronic infections with opportunistic or unusual organisms. Pets with immunodeficiencies may also have a delayed response to antibiotics and adverse reactions to a specific type of vaccine called a modified live vaccine.
Immunodeficiencies may be suspected in pets with chronic or recurrent infections, and a thorough physical exam and blood work will support the diagnosis. However, a definitive diagnosis can be achieved only with specific immunologic tests.
There is no practical treatment for primary immunodeficiencies in pets yet. The use of appropriate medications to treat even mild infections or infestations is the immunocompromised pet’s best chance at fighting off foreign invaders. Additionally, pets with known immunodeficiencies should avoid modified live vaccines or be monitored closely after being given a modified live vaccine.
If your pet is immunocompromised, talk to your vet about ways to minimize her health risks on a day to day basis.