Bruising and Bleeding in Cats


Overview of Feline Bruising and Bleeding

Abnormal bruising and bleeding arises with disorders of hemostasis (clotting). Clotting abnormalities are also called coagulopathies, because they reflect the inability of the blood to coagulate or clot. In cats, 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 Bruising and Bleeding in Cats

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. Fortunately, clotting abnormalities of all three types are uncommon in the cat.

Platelet Disorders

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:

  • Drugs toxic to the bone marrow
  • Infection of the bone marrow with certain bacteria and viruses
  • Immune mediated destruction of the bone marrow (rare in the cat)        
  • Cancer of the bone marrow
  • Myelophthisis and myelofibrosis, which are scarring and disappearance of bone marrow cells

    These disorders result in increased platelet destruction:

  • Immune-mediated destruction of platelets (rare in the cat)
  • Certain drugs
  • Certain viral infections

    These disorders cause increased removal of platelets from the circulation:

  • Vasculitis
  • Certain parasites
  • Certain disorders of the spleen

    Disorders that affect the function of platelets include the following:


  • Congenital platelet function disorders (Chediak-Higashi syndrome in cats)
  • Certain drugs
  • Some infections
  • Kidney failure
  • Liver failure
  • Certain leukemias
  • Vascular Disorders

    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:

  • Vasculitis – inflammation of blood vessels
  • Hyperadrenocorticism – a disease where the adrenal glands produce too much cortisone hormone in the body (rare in the cat)
  • Diabetes mellitus – sugar diabetes
  • Uremia – an increase in waste products not cleared by diseased kidneys
  • Clotting Factor Disorders

  • Inherited deficiencies of clotting factors that result in hemophilia (rare in cats)        
  • Toxicity with warfarin or warfarin-like products that antagonize Vitamin K. This is the most common cause of bleeding problems in cats. It often arises when cats hunt and eat rodents that have been poisoned with warfarin type products. It may also arise when cats directly ingest bate containing warfarin or similar toxins.
  • Liver disease that prevents the manufacture of clotting factors
  • Disseminated intravascular coagulation (DIC), which is widespread bleeding due to the consumption of platelets and clotting factors
  • What to Watch For

  • Blood in the urine or stool
  • Nose bleed (epistaxis)
  • Bruises or swelling on or under the skin
  • Pin point or blotchy hemorrhages on the gums of the mouth
  • Pinpoint hemorrhages on the whites of the eyes or the inside of the eyelids
  • Bleeding into the front chamber of the eye
  • Difficulty breathing with bleeding into the lungs or chest cavity
  • Abdominal distension with bleeding into the abdomen
  • Weakness, depression
  • Pale gums from anemia
  • Excessive or unrelenting bleeding from a cut or wound
  • Diagnosis of Bruises and Bleeding in Cats

    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:

  • Complete blood count (CBC)
  • Platelet count
  • Biochemical profile
  • Urinalysis
  • Thoracic (chest) and abdominal radiographs (x-rays)
  • Fecal tests
  • Coagulation studies that measure how long it takes for the blood to clot
  • Serologic tests for infectious diseases that can affect clotting
  • Abdominal ultrasonography
  • Bone marrow aspiration and cytology
  • Assays of clotting factors
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