Bleeding Disorders in Dogs
Dr. Leah Cohn
Bleeding disorders are diseases in which the blood does not clot normally, causing a tendency to bleed abnormally or excessively after minor bumps or cuts. There are a variety of causes of bleeding disorders: Decreased numbers of blood platelets (thrombocytopenia). Platelets are the blood cells that fill in the defects in torn blood vessels. If there are not enough platelets in the bloodstream, blood does not clot and defects or tears in the blood vessel walls cannot be rapidly plugged up by platelets, allowing blood to ooze out of the torn vessel.
Poorly functioning platelets (thrombocytopathy). Platelets aren't sticky enough, and when the platelet cells plug up defects in the vessel wall, they need to sick to the vessel and to each other. If this fails, the defect in the vessel is not plugged.
Soluble coagulation factors. These are found in the liquid part of the blood (plasma). When activated by chemicals released from torn blood vessels, they produce a substance called fibrin that holds the clump of platelets on top of the tear in the blood vessel. Decreased concentrations of the soluble coagulation factors cause bleeding because the clump of platelets washes off the torn vessel, allowing blood to leak out of the holes.
The effects of bleeding disorders on your pet are related to how much blood is lost and where the bleeding occurs. If the pet loses a lot of blood, he will become anemic, which means he has decreased numbers of oxygen-carrying red blood cells. Anemia makes the gums look pale instead of pink, and makes the animal easily exhausted.
Many signs are related to the site of the bleeding, which can occur almost anywhere in the body. Sometimes the site of bleeding is obvious, as when there are nosebleeds (epistaxis), bruising related to bleeding under the skin, or bleeding into the urinary tract resulting in discolored urine.
Sometimes the bleeding can be evident to a professional but to an owner, as in instances when bleeding occurs in the back of the eye or into the gastrointestinal tract resulting in tarry black or bloody stools.
Sometimes the bleeding is not obvious, as when bleeding occurs into a body cavity like the abdomen or chest, resulting in abdominal distention or difficulty breathing, respectively. Bleeding into the brain or the spinal cord may result in seizures, loss of consciousness, or paralysis.
What to Watch For
Obvious bleeding without an apparent cause
Bruises in the absence of trauma
Tiny pin-point red spots on the gums or the whites of the eyes
Blood in the urine or stool
A variety of diagnostic tests may be indicated in any individual situation. These include:
Complete history. Be prepared to answer questions about your animal's previous health and any medication he receives, including over-the-counter remedies like aspirin or herbal supplements. Describe the symptoms you have observed, when they were first noticed, and how they have changed. Also, be prepared to answer any questions about exposure to potential toxins such as rat poison.
Complete physical examination. Your veterinarian will look for evidence of bleeding in the eyes, on the gums, and bruises on the skin. They will also feel for enlargement of the abdomen or organs in the abdomen, and will listen to the heart and lungs.
A complete blood count is always indicated in a bleeding animal. Not only does it allow quantification of the number of platelets, the cells that allow the blood to clot, but it also shows how serious the blood loss has been by revealing how many red blood cells are left.
A buccal mucosal bleeding time may be indicated to evaluate platelet function or whether Von Willebrand's disease is suspected. A small cut is made on the gums, and the time required for a clot to form is measured.
Effective coagulation factor concentration may be measured by performing one of several tests. Examples include activated coagulation time (ACT), activated partial thromboplastin time (aPTT), one stage prothrombin time (OSPT). In each of these tests, a small amount of blood is collected in a special tube, blood clotting is activated artificially, and the time required for the blood to clot is measured.
Whenever possible, treatment is aimed at the underlying disorder causing the bleeding, with supportive care administered to maintain the animal while specific therapy is given time to work.
If the animal has lost a lot of blood, a transfusion of either red blood cells, or whole blood (red blood cells plus the liquid plasma) may be indicated.
If ongoing blood loss from a single site can be stopped, it will be addressed. For instance, the nose might need to be packed with gauze if nosebleed is severe.
If there are not enough blood platelets, treatment will be geared to likely causes. Unfortunately, transfusion of platelets themselves is not particularly effective. Because immune mediated disease and certain infectious diseases are frequent causes of a severe decrease in platelet numbers, treatment may be initiated with corticosteroids to suppress the immune system or with antibiotics for the more important infectious causes of thrombocytopenia.
If the animal is suspected of having Von Willebrand's disease, a condition with a deficiency in the substance that helps the platelets stick together, the animal may be treated with a plasma transfusion.
If the animal is suspected of having ingested a toxin that interferes with the ability of the coagulation factors to work, such as warfarin-related rat poison, the animal may receive vitamin K either with or without also receiving a transfusion.
Other causes of coagulation factor deficiency, such as hemophilia or liver failure, may respond temporarily to plasma transfusion.
If you notice that your pet is bleeding profusely, attempt to staunch the flow of blood and seek veterinary care immediately.
If you notice even small amounts of bleeding when there has been no trauma or injury to provoke bleeding, or bruising in the absence of injury, seek veterinary care as soon as possible.