Cat resting on the carpet.

Bleeding Disorders

Whenever an injury or illness compromises a blood vessel and leads to bleeding out of that vessel, a remarkable mechanism or chain reaction begins within the body in an effort to stop the leakage of blood from the damaged vessel and prevent the individual from bleeding to death.

This mechanism is known as hemostasis. When a blood vessel is compromised, the first reaction that occurs is constriction of the vessel to help slow blood loss. Following this, special blood cells called platelets begin to adhere to the injured vessel wall, forming a temporary plug.

At the same time, a coagulation (clotting) pathway is activated within the body, involving a complex interaction of blood and tissue components, as well as calcium and vitamin K. The end result of this pathway is the formation of a more permanent clot at the site of injury.

Bleeding disorders can occur whenever any part of the clotting mechanism is interfered with. Diseases or substances such as toxins, drugs, cancers, autoimmune hemolytic anemia, and infectious agents, such as Ehrlichia canis, can interfere with platelet numbers or function.

In addition, kidney disease and certain inherited defects can also lead to poor platelet function and secondary bleeding. Any disruptions of the coagulation pathway also spell trouble for hemostasis.

For instance, most rodent poisons contain substances that interfere with the vitamin K component of the coagulation pathway. If a dog or cat accidentally ingests these, its coagulation pathway will be effectively disrupted.

Also, inherited defects in the coagulation pathway can cause bleeding disorders known as hemophilia and von Willebrand’s disease. Serious diseases or injuries such as heartworm disease, viral diseases, and massive trauma (such as that caused by a car) can lead to a secondary condition known as disseminated intravascular coagulation (DIC).

In DIC, tiny blood clots form throughout the body. Not only are these clots detrimental to the health of the animal, but DIC also leads to a depletion of the body’s clotting components. This, in turn, predisposes the pet to a bleeding disorder.

DIC is invariably fatal to a pet unless rapid supportive treatment is instituted. Clinical signs of a bleeding disorder usually include noticeable bruising of the skin and mucous membranes. Blood in the urine or feces, nosebleeds, joint pain, abdominal pain, and breathing difficulties might be seen as well.

Because of the variety of potential causes, a veterinarian will need to run a series of tests to determine the exact cause and to formulate a proper treatment regimen. Initial treatment for any bleeding disorder entails blood transfusions until the exact cause is discerned.

If rodenticide poisoning is suspected, vitamin K injections, followed by oral vitamin K tablets, will help reverse the effects of certain rodenticides. These tablets should be given daily for a minimum of 4 weeks, since the ingested poison could linger within the body and exert its effects for this length of time.

Finally, for autoimmune clotting defects, steroid therapy can be used to help control the disease and subsequent bleeding.