Bleeding Disorders (Von Willebrand disease, Hemophilia, and Immune-mediated Thrombocytopenia) in Dogs

Normal blood clotting, called hemostasis, involves blood vessels narrowing to slow blood flow and deployment of platelets and clotting proteins (or clotting factors) to mend breaks in the blood vessels, which occur due to injury.

Bleeding disorders affect the ability of the vessels to constrict properly, drastically reduce the number of platelets and factors, or impair platelets to adhere to the walls of damaged vessels.

Some conditions are rarer than others. The most common disorders are Von Willebrand disease (vWD), hemophilia A, and immune-mediated thrombocytopenia (IMT).

Some disorders cause major blood losses and can be considered emergencies. Immediate medical care is often necessary as blood and plasma transfusions are needed.

Symptoms that warrant emergency care include sudden lethargy, pale gums, and collapse. Prognosis often depends on the underlying cause, severity, and how long disease was occurring before detection.

Major episodes of blood loss due to a bleeding disorder might cause other symptoms such as lethargy, and collapse.

The risk of developing a bleeding disorder depends on the specific form. Von Willebrand disease and hemophilia A are congenital, meaning they are present at birth. Inheritable congenital diseases are more likely to develop in offspring of breeding pairs where one or both parents are carriers.

Immune-mediated thrombocytopenia has no known cause, so risk factors are difficult to identify.

Other forms of acquired bleeding disorders in dogs can develop following cancer, exposure to infectious agents, and certain drugs and vaccinations.

There are many potential causes of bleeding disorders. They can either be present at birth (congenital) or acquired later in life.

Von Willebrand disease (vWD) is the most common congenital bleeding disorder in dogs and results from a deficiency in the clotting factor called Von Willebrand factor. Another commonly known congenital bleeding disorder is hemophilia A; another clotting factor deficiency.

Other disorders such as immune-mediated thrombocytopenia (IMT) occur when the body’s immune system targets and destroys platelets. IMT is idiopathic, meaning the cause is unable to be determined.

Bleeding disorders rarely present with outward symptoms in dogs.

Congenital bleeding disorders are often diagnosed in puppies after their first surgical intervention, such as spaying/neutering, as the bleeding during and following surgery is excessive and does not stop naturally.

In other cases, the diagnostic process begins with a thorough physical examination and medical history of the patient.

Bloodwork is used to test for the number of platelets and the ability of the blood to clot.

Additional testing includes the examination of a bone marrow sample and genetic screening tests.

Treatment largely depends on the specific bleeding disorder.

IMT can be treated with:

• Steroids
• Chemotherapy
• Blood or plasma transfusions
• Supportive care such as crate rest and exercise restriction

In cases of vWD, dogs sometimes respond well to a drug called desmopressin acetate which might increase the level of vW factors. In an emergency situation blood or plasma transfusions are necessary to stabilize the patient.

The prognosis varies according to the specific bleeding disorder.

Dogs affected with IMT have a good to guarded prognosis. 80% of patients respond well to treatment and make a full recovery with a possibility of relapse. 20% are either euthanized or die as a consequence of the disease.

For vWD, there is no known definitive treatment, and dogs that are stabilized when an injury occurs usually have a positive outcome.

Bleeding disorders are not contagious. Most conditions, including vWD and IMT, are either congenital or idiopathic and the only form of prevention is not breeding affected dogs.

Certain types of drugs and vaccines have been associated with some acquired bleeding disorders. Close monitoring of patients following vaccination and during treatments is advised.

Some bleeding disorders in dogs are much more common than others. The most common bleeding disorders in dogs are vWD and IMT.

• Steroids
• Supportive care
• Blood and plasma transfusion
• Medications
• Chemotherapy