Why Might My Dog Or Cat’s APTT Time Be Delayed? Activated Partial Thromboplastin Time

Why Might My Dog Or Cat’s aPTT Time Be Delayed Or Shortened?

Your Pet’s Activated Partial Thromboplastin Time (aka aPTT, partial thromboplastin time (PTT)

Ron Hines DVM PhD

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The Causes Of Most Abnormal Blood  & Urine Tests

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When your veterinarian is suspicious that your dog or cat has a blood-clotting problem that is leading to internal or external bleeding or , perhaps, unexplained anemia; one of the most sensitive examination to detecting a blood-clotting defects is the aPTT test.

Because the clotting of blood is such a complex process ( the coagulation cascade) with many different stages or steps and the interplay of many chemicals and cells; a series of tests on your dog or cat may be required to determine exactly what is wrong. The other tests are its thrombocyte count,  its prothrombin time (PT), partial thromboplastin time (PTT),  fibrinogen level , the d-dimer test and thrombin clot time (TCT).

Problems That Can Cause Abnormally Long aPTT Times In Your Dog Or Cat:

Shock-induced coagulation (=DIC),  liver failure , certain rodent poisons, and hemophilia in dogs or cats can be the underlying cause.  In dogs, babesiosis & ehrlichiosis,   leptospirosis and bacterial septicemias have been known to slow the blood clotting process. Extended aPPT times have also been documented in some Bernese Mountain Dogs due to genetic problems still to be defined.

In cats  FeLV,   FIP,   FIV and panleukopenia   can also have that effect on aPTT time. 

Problems That Can Shorten aPTT Times In Your Dog And Cat:

Inflammation anywhere in your pet’s body has been known to shorten aPPT time. But that is unpredictable as the opposite effect  has also been noted.


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