What is von Willebrand’s disease?
Von Willebrand’s disease is an inherited bleeding disorder. It is very rare in cats, although it is a relatively common bleeding disorder in dogs. Von Willebrand’s disease can be seen in both males and females.
Cats with von Willebrand’s disease lack a blood protein known as von Willebrand’s factor. This protein is responsible for helping platelets adhere to sites where blood vessels have been injured. Although affected cats have normal platelets, they experience clotting difficulties because their platelets are unable to properly attach to injury sites.
What are the clinical signs of von Willebrand’s disease?
The clinical signs of von Willebrand’s disease are similar to the clinical signs of all clotting disorders – abnormal or unexpected bleeding.
Affected cats often bleed from their mucous membranes (e.g., mouth and nose). You may notice that they intermittently sneeze blood, or there may be visible blood in the saliva (bleeding gums). Blood may also be observed in the urine or feces.
Von Willebrand’s disease is often first suspected when a cat bleeds excessively after surgery or trauma (physical injuries, giving birth to kittens, etc.). Although some degree of bleeding is normal in these situations, a cat with von Willebrand’s disease will continue bleeding for an abnormally long period of time.
How is von Willebrand’s disease diagnosed?
Your veterinarian will first take a complete medical history and perform a thorough physical examination of your cat. This will help suggest possible causes of your cat’s difficulties, as well as ruling out other medical conditions.
Next, your veterinarian will perform laboratory tests. These tests will likely include a complete blood cell count (CBC), blood chemistry profile, and a urinalysis. In most cases, all of this bloodwork will be normal in cats with von Willebrand’s disease. In some cases, especially if a cat has experienced a recent bleeding event, the CBC may show anemia due to red blood cell loss.
Your veterinarian may also perform coagulation tests, to assess your cat’s blood clotting. Most of these coagulation tests are normal in cats with von Willebrand’s disease.
In order to diagnose von Willebrand’s disease, your veterinarian must run a specific test that assesses the concentration of von Willebrand’s factor in the bloodstream. Low levels of von Willebrand’s factor confirm a diagnosis of von Willebrand’s disease.
How will my veterinarian treat von Willebrand’s disease?
The only treatment for von Willebrand’s disease is to supplement or replace von Willebrand’s factor in the bloodstream. There is no treatment currently available that forces the body to create its own von Willebrand’s factor, so this supplementation must be repeated on an as-needed basis when cats are in crisis states or when bleeding is expected.
A blood transfusion may be performed, especially if your cat is experiencing severe anemia due to blood loss. In a blood transfusion, your cat receives all of the blood components found in the donor blood. This includes not only von Willebrand’s factor, but also other clotting factors and replacement red blood cells.
Other materials, such as fresh frozen plasma (cryoprecipitate), may also be used in the treatment of von Willebrand’s disease. With these products, only a portion of the donor’s blood is delivered to your pet. This allows your pet to receive von Willebrand’s factor and other clotting factors, without receiving additional red blood cells. These therapies are often used prior to surgery in a cat with known von Willebrand’s disease. Increasing the blood levels of von Willebrand’s factor will decrease the likelihood of abnormal bleeding during surgery and in the recovery period.
What is the prognosis for von Willebrand’s disease?
Most cats with mild to moderate von Willebrand’s disease will experience a good quality of life and require no medical treatment.
Some cats are more severely affected. These cats may require blood transfusions for excessive bleeding, which may occur spontaneously or following surgery. In these cats, physical activity may carry additional risks of injury, so their activity levels may need to be restricted.
Additionally, these cats will need to be closely monitored over the course of their lifespan. With proper care, however, even severely-affected cats are able to live relatively normal lives.
