Why Is My Dog Or Cat’s Coagulation Time Increased? = Slow To Clot

Ron Hines DVM PhD

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

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

To see how tests are grouped, go here

For an extensive list of health problems that can delay blood clotting in your pet, go here

Your Pet’s Blood Coagulation Time – Also Called Clotting Time or Buccal Mucosal Bleeding Time

When your pet is bleeding more than would be expected from a skin wound, one of its body openings or blood is appearing in its stool, you vet will want to know the status of its blood clotting mechanism (hemostasis). Your vet will have the same questions when your pet is anemic and the cause is not readily apparent (alternatively, your vet might time how long it takes a drop of your pet’s blood placed on a glass slide to coagulate. Read about that test here.

Most veterinarians now request a prothrombin time (PT) or activated partial thromboplastin time (APTT) test to determine that; but the older, coagulation or clotting time tests, when performed by pricking your pets inner lip, (Buccal mucosal bleeding time) or by short clipping a toenail provides useful information as well. The links to the more current tests are at the bottom of this page.

Reasons Your Pet’s Clotting Time Might Be Increased (Slowed):

Low blood platelet (thrombocyte) counts (thrombocytopenias). Too high a dose or a sensitivity to aspirin and other NSAID anti-arthritic and pain-relieving medications, Exposure to certain rat and mouse poisons, Disseminated Intravascular Coagulation (DIC), Inherited bleeding disorders (hemophilias), low blood fibrinogen levels, Chediak-Higashi syndrome in cats

Blood coagulation/clotting time can also increased in liver failure   due to reduced clotting factor production. (ref) and in a specialized form of liver disease, portosystemic shunts. ( read here

Reasons Your Pet’s Coagulation Time May Be Shortened (Too Rapid)

Dogs with obstructions the the flow of bile from their liver to their intestine have more rapid than normal blood clotting (hypercoagulability) (ref)  

Complementary Tests:

Platelet count, fibrinogen level, prothrombin time (PT) or activated partial thromboplastin time (APTT), von Willebrand factor


You are on the Vetspace animal health website