Why Is My Dog Or Cat’s ANA Test Positive?

Ron Hines DVM PhD

To see what normal blood and urine values are for your pet, go here

For an explanation of causes of most abnormal blood and urine tests go here 

To see how tests are often grouped, go here

Anti-nuclear Antibody = ANF, ANA

This test measures factors similar to the Coombs test – evidence that your dog or cat is producing antibodies against its own tissue (In this case, antibodies against components of the nuclei of its cells). This is called an autoimmune reaction. In humans, many of the conditions that produce it are lumped together as forms of “Lupus”.

As pets and humans age, the number of these blood antibodies increase moderately in all of us (mine are high).

Health Problems That Might Increase ANA Levels In Your Pet:

The ANA test is sensitive; but it is not specific for any one disease. It is only used as one factor your vet will consider in making a diagnosis. ANA is often elevated in:
Systemic lupus erythematosis (SLE), autoimmune polyarthritis, pemphigus vulgaris and autoimmune thrombocytopenia. Titer can also be increased in many chronic inflammatory and infectious diseases that are not auto-immune in nature (such as ehrlichiosis, bartonellosis and babesiosis) and a few dogs and cats have an increase in ANA without underlying autoimmune disease – particularly older dogs and cats. Can occurs post-vaccination – particularly after vaccines containing leptospirosis antigens or due to a natural case of lepto. (ref

The Diagnostic Laboratory of the University of Georgia Veterinary School puts little faith in the value of the ANA test in animals. Quoting their website: ” There is no consensus as to what is a significant ANA titer in animals. Many investigators feel that titers >10 are significant while others feel that titers > 40 are significant. A negative result does not rule out systemic lupus erythematous or other immune-mediated diseases as these conditions can occur without detectable antinuclear antibodies”.


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