Overview of Bruising and Bleeding in Dogs
Abnormal bruising and bleeding arises with disorders of hemostasis (clotting) in dogs. Clotting abnormalities are also called coagulopathies, because they reflect the inability of the blood to coagulate or clot. Bleeding from clotting disturbances may occur into the skin, the mucous membranes, and various internal organs, tissues, and body cavities. When the bleeding occurs into the skin, the membranes of the mouth, nose, eyes and external genitalia it may become visible to the owner. Bleeding into the intestinal tract may appear as hematochezia (fresh blood in the stools) or melena (dark, tarry stools). Bleeding into the urinary tract may be detected as blood in the urine (hematuria).
The impact of such bleeding on the affected individual may be mild or severe depending on the degree of blood loss. Unexpected or unexplained bruising warrants examination of the animal by your veterinarian in order to determine if a clotting abnormality exists. Many clotting abnormalities are serious because they may predispose the animal to a life-threatening episode of bleeding.
Causes of Abnormal Bleeding and/or Bruising in Dogs
The causes of bruising and bleeding can be classified as platelet disorders, vessel wall disorders, or clotting factor disorders. Platelets are small particles in the blood that begin the formation of a blood clot by clumping together at the site of any break in the blood vessel wall. Clotting factors are proteins in the blood that are responsible for further development of a clot after the platelets have initiated the process.
Platelet disorders can arise when platelet numbers are decreased, or platelets fail to function properly. Platelet numbers are decreased when they are not produced adequately in the bone marrow, when they are destroyed, or when they are prematurely removed from the circulation. Dysfunction of platelets can occur as an inherited, congenital disorder, or may develop as an acquired condition later in life.
These disorders cause a decrease in the production of platelets:
These disorders result in increased platelet destruction:
These disorders cause increased removal of platelets from the circulation:
Disorders that affect the function of platelets include the following:
Vascular disorders usually result in abnormal bleeding by weakening the walls of the blood vessels. In some instances the underlying disease may also increase blood pressure, which aggravates any bleeding tendency. Disorders that increase the fragility of blood vessel walls include the following:
Clotting Factor Disorders
What to Watch For
Diagnosis of Bruising and Bleeding in Dogs
There are many tests that may be recommended for the patient with abnormal bruising or bleeding. The following is a list of the tests that are often performed initially: