Low platelet count is termed, “thrombocytopenia” and refers to a level of circulating platelet counts below 200,000 µL (microliter). Like all cellular blood components, platelets are made inside the bone marrow and circulate the body for about a week before they are absorbed and replaced with new platelets. Since platelets are formed inside the bone marrow, disease, cancer, infections, drugs, and toxins that target the bone marrow can cause a low platelet count in cats. Thrombocytopenia in cats can be caused by a variety of underlying conditions and is not a condition that is known to cause noticeable symptoms, which is why veterinary evaluation is an absolute must.

If your cat has a tendency to bruise easily or is prone to nosebleeds (epistaxis), your feline could be suffering from a low platelet count. Platelets are disc-shaped cell fragments present in blood plasma that circulate in the body through the bloodstream. When a cat injures herself, these platelets, or thrombocytes, pile up on each, glued together with a special protein called the von Willebrand's factor and form a clot to prevent the cat from bleeding out. When a cat’s platelet count becomes too low, however, there are not enough circulating cell fragments to form a proper clot and there is nothing to prevent the blood from leaving the body.

Symptoms of a low platelet count in cats can be difficult to detect and some felines may not have any symptoms at all if the platelet count is not severely low. The first sign a cat owner may notice is increased bleeding from a scratch or cut. The owner may apply pressure to the cut, but the time it takes for the wound to stop bleeding will seem excessive and is a reason to be concerned. A veterinarian may also note a similar sign of thrombocytopenia before or during surgery. Additional symptoms of a low platelet count in cats includes:

Disseminated intravascular coagulation is a condition in which the body uses more platelets than it can make. DIC causes the blood to clot, blocking the vascular system and using all the available circulating platelets before new ones can be made, resulting in a low platelet count.

Splenomegaly is the term used to describe an enlarged spleen. The healthy spleen stores approximately 40% of the body’s platelets, but when the spleen grows in size, more and more platelets are taken from the body to be put into storage, causing the circulating platelet levels to drop. 

Immune-Mediated Thrombocytopenia is an autoimmune disorder in which the cat’s immune system not only kills infections, but also targets platelets as harmful invaders to the body. 

Leukemia is bone marrow and blood cancer, in which cancer cells outnumber megakaryocytes (the cells in the bone marrow that make platelets) and few platelets will be made. Chemotherapy drugs used in cancer treatment can also cause a low platelet count due to the destruction of cancer and healthy cells. 

Feline leukemia virus (FeLV), feline panleukopenia (FPV), feline infectious peritonitis (FIP), and feline immunodeficiency virus (FIV) are known to affect blood platelet counts.

A low platelet count in cats can also occur for idiopathic, or unknown, reasons, as well as a secondary, adverse effect of the feline panleukopenia vaccine.  

Your veterinarian will begin diagnosis of a low platelet count in your cat with a review of her medical history and a physical examination. The veterinarian will ask you what symptoms you have noticed your cat displaying at home, her current medications and the possibility of exposure to poison. A complete blood cell count (CBC) is likely to be the doctor’s next diagnostic test, as a CBC will measure the amount of platelets in a sample of blood. The vet will then carry out other diagnostic tests based on his findings and what he suspects to by the underlying cause of the conditions. 

Treatment of a low platelet count in cats focuses primarily on treating the underlying disease or condition. However, if a great deal of blood has been lost due to a low platelet count, your veterinarian may advise a blood transfusion to take place. Talk to your veterinarian about an appropriate treatment plan for a low platelet count in your cat. 

After treatment, pet owners will be asked to follow-up with the veterinarian on a regular basis. Cats with a history of a low platelet count condition may be advised to remain an indoor cat in order to prevent fights with other cats or accidents that could cause excessive bleeding. Pet owners should also remember that cats diagnosed with severe thrombocytopenia cannot undergo certain surgical procedures and new veterinarians should always be reminded of this to avoid unfortunate situations.