Bleeding Disorders in Dogs

Overview of Canine Bleeding Disorders

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 in dogs. They include:

• 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

Symptoms of Bleeding Disorders in Dogs may include:

• 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
• Pale gums

Diagnosis of Bleeding Disorders in Dogs

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.

Treatment of Bleeding Disorders in Dogs

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.

Home Care

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.

Bleeding disorders can be either relatively minor problems or rapidly life threatening. The severity of the problem depends on both the amount of bleeding, and on the site of bleeding.

Bleeding may be obvious, as is the case with open cuts or nose bleeds, or it may be harder to detect. Bleeding into the stomach or intestines, for example, may be visible as dark, tarry stool that an owner may not notice. Likewise, bleeding under the skin, or into body cavities including the joints, abdomen (belly), or chest may be difficult or impossible for the owner to identify.

Any time an animal exhibits bleeding either with no known provoking injury, or excessive or prolonged bleeding after a known injury, a diagnostic investigation is warranted.

Causes

Bleeding disorders can result from a variety of different processes, and each process can result from several different diseases. Coagulation is the sum of all the events that allow blood to clot and thereby stop bleeding. Normal coagulation first requires that the blood vessel lining, or endothelium, provide signals that it has been torn. Next, adequate numbers of platelets must fill in the hole in the torn blood vessel and must stick to both the vessel lining and to each other. Finally, soluble factors in the liquid part of the blood must be activated to form a solid, sticky substance known as fibrin in the area where the platelets have covered the hole. Problems in any of these processes, be it the proper functioning of the vessel wall, inadequate numbers or function of platelets, or insufficient soluble coagulation factors, can result in excessive bleeding. Some of the more common causes of disorders in these processes include:

• Vasculitis. Vasculitis is an inflammation of the blood vessels. The vessels become damaged, and small holes in the vessels allow for tiny amounts of blood to leak from the vessel. This is often seen as pinpoint sized red spots (petechiae) on the gums or the whites of the eyes. Vasculitis may be caused by a variety of infectious diseases or by immune mediated disease where the body’s own immune system begins to attack the body instead of attacking germs.
• Thrombocytopenia. Thrombocytopenia is a decreased number of blood platelets, the bloods cells that stick to and plug holes in the vessel. The body has a great reserve of platelets. As a result, only those diseases that cause a tremendous decrease in platelet numbers will result in excessive bleeding. The most common examples include an immune system attack directed against the platelets instead of germs, as well as a few specific types of infectious diseases. Because platelets are made in the bone marrow, infection, cancers, drugs or toxins that damage the bone marrow may also cause severe thrombocytopenia.
• Thrombocytopathia. Thrombocytopathia is when the platelets don’t function as they should. This can be due to drugs like aspirin, diseases like kidney failure or certain infections, or hereditary conditions. When there is a combination of thrombocytopenia and thrombocytopathy – decreased numbers of poorly functioning platelets – the resultant bleeding may be more severe than with either condition alone.
• Von Willebrand’s disease. This process is caused by deficiency of a substance that enables the platelets to stick to the vessel walls and to each other. This hereditary disease varies in severity from extremely mild to extremely severe. Often, the animal is diagnosed because of excessive bleeding at the time of either surgery or minor trauma.
• Coagulation factor deficiency. There are a number of soluble coagulation factors in the liquid part of the blood or plasma. When properly activated, they proceed through a chain reaction to form a sticky substance known as fibrin. Fibrin serves to seal the platelets that have plugged the holes in a vessel into place until healing can occur. Several different diseases can be responsible for coagulation factor deficiencies. Hereditary coagulation factor deficiencies are known as hemophilia; the specific type of hemophilia reflects the specific factor that is missing. Because the liver is responsible for making most coagulation factors, liver failure can also result in deficiencies of coagulation factors.
• Coagulation factor defects. Several of the soluble coagulation factors need to be kept in an active form to work properly. Substances such as warfarin and related compounds found in rat poison or certain prescription drugs can inhibit the vitamin K-dependent maintenance of soluble coagulation factors in an active state.
• Disseminated intravascular coagulation (DIC). This syndrome is not a primary disease, but is the result of any one of several other severe diseases. In DIC, the blood becomes activated to clot when it should not. As a result, clots are formed throughout the body, and the body then works to break up the clots. In the process, both the factors necessary for proper clot formation, platelets and soluble coagulation factors, and the factors that break up the clot are used up, resulting in widespread bleeding.

Diagnosis In-depth

A variety of diagnostic tests may be indicated in any individual situation. The following are each considered essential for the diagnosis of the cause of abnormal bleeding:

• Complete history and physical examination. Your veterinarian will look for evidence of bleeding in the eyes and on the gums, as well as bruises on the skin.
• A complete blood count (CBC) is always indicated in a bleeding animal. In this test a small amount of blood is withdrawn from the pet, and the cells of each type in the blood are counted. 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.

Other test will likely be indicated as well. Which of these tests is appropriate for an individual animal will be determined after the veterinarian has completed the initial examination, and perhaps after results of the CBC become available.

• Abnormal bleeding can be due to abnormal coagulation, or alternatively, to local disease. For instance, nosebleeds may be due to abnormal coagulation or to disease of the nasal passages themselves. Expect your veterinarian to try to determine if all the bleeding is coming from one site. If so, they may order tests to examine that site, including radiographs (X-rays) or biopsies.
• If platelet numbers are low, titers for infectious diseases may be indicated. Certain types of infection are particularly likely to result in low platelet numbers. The veterinarian may take blood to measure antibodies to that infection. Antibodies are part of the immune response to germs, and their presence shows that the pet has been exposed to the germ in question.
• Unfortunately, there are no good tests for one of the most common causes of low platelets, immune-mediated thrombocytopenia. Immune-mediated thrombocytopenia results from an immune system attack on the blood platelets. There are a few tests that attempt to measure this attack, but none are perfect tests. In each, a small amount of blood is withdrawn and subjected to special assays in the laboratory.
• Bone marrow aspiration/biopsy may be indicated. The bone marrow is the soft red tissue found inside hard bones and is here that most blood cells are made by the body. If the platelet count is low, your veterinarian may perform a procedure in which a large needle is inserted through the hard bone into the soft center, and a small amount of marrow is removed for examination under the microscope. Both local anesthetic and sedation are usually administered to minimize discomfort during the procedure.
• A buccal mucosal bleeding time may be indicated to evaluate platelet function, especially if 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.
• In cases where the suspicion of von Willebrand’s disease is strong, a blood sample is sent off to a special laboratory for measurement of the von Willebrand’s factor.
• 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.
• If hemophilia is suspected, blood samples may be collected and sent off to a special lab to have the concentration of soluble coagulation factors measured.
• If DIC is suspected, fibrin degradation products may be measured. In this test, a small blood sample is withdrawn to quantify the byproducts of clot lysis.

Therapy In-depth

One or more of the diagnostic tests described above may be recommended by your veterinarian. In the meantime, treatment of the symptoms might be needed, especially if the problem is severe. The following nonspecific (symptomatic) treatments may be applicable to some pets with bleeding disorders. These treatments may reduce severity of symptoms or provide relief for your pet. However, nonspecific therapy is not a substitute for definite treatment of the underlying disease responsible for your pet’s condition.

• If ongoing blood loss from a single site can be stopped, it will be. For instance, the nose might need to be packed with gauze if nosebleed is severe.
• If your dog 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 regardless of the cause of bleeding. This requires administration of the transfused blood through an intravenous catheter while the pet is in the hospital.
• Transfusion of either plasma (the liquid portion of the blood) or fresh whole blood provides soluble clotting factors, and may be initiated before a definitive diagnosis is obtained.
• 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 begun while waiting for test results. The most common treatments are with corticosteroids like prednisone or dexamethasone) to suppress the immune system, or with antibiotics such as tetracycline) for the more important infectious causes of thrombocytopenia.
• If your dog is suspected of having von Willebrand’s disease, a condition in which a substance that helps the platelets stick together is deficient, the animal may be treated with a plasma transfusion, and possibly also with medication designed to increase release of the deficient factor.
• If your dog 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 an accompanying transfusion. Because bleeding after exposure to warfarin can be very severe, the veterinarian may choose to administer vitamin K before a definitive diagnosis has been reached.
• Other causes of coagulation factor deficiency, such as hemophilia or liver failure, may temporarily respond to plasma transfusion.
• Treatment of DIC depends on elimination of the underlying disease, plus the administration of transfusions and drugs like heparin designed to stop the vicious cycle of blood clotting and clots breaking up.

Optimal treatment for your pet requires a combination of home and professional veterinary care. Follow-up can be critical. Administer prescribed medication as directed, and be certain to alert your veterinarian if you are experiencing problems treating your pet. Optimal follow up veterinary care for bleeding disorders often involves the following:

• Repeat blood testing. It is critical that you present your dog for repeat blood testing at the intervals indicated by your veterinarian. The results of these blood tests can prove crucial to the proper adjustments in medications necessary to prevent your dog from future bleeding episodes.
• Confinement as indicated. If your dog is more susceptible to bleeding and bruising than normal, you should confine your pet to minimize the chances of trauma or injury. Avoid rambunctious play or overexertion.
• Careful observation. You will need to observe your dog for signs of further bleeding. For instance, watch the gums and the whites of the eyes for the pinpoint bleeding known as petechiae, and look at the belly for bruises. Check the stool to make sure it is not a tarry black color, which could indicate bleeding into the stomach or intestines.