Signs & Symptoms of Blood Clots in Dogs

Blood clots can be fatal if not quickly addressed.
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Blood clots in dogs occur most often in the lungs, heart and limbs, forming when blood cells clump together. You dog may develop a blood clot if he has an underlying medical problem, such as cancer, heart disease, heartworms, a blood infection or a liver or intestinal disease. A clot that grows large enough can lodge in a narrow artery, impacting blood flow. The condition requires immediate medical treatment.

Blood Clot Symptoms

A dog with a lung blood clot may experience difficulty breathing and may even spit up blood. He may be unable to get comfortable, and will cough and show signs of lethargy. His gums may become pale or blue, and he may have trouble moving. A heart blood clot will present many of the same symptoms as a lung blood clot, in which the dog has difficulty breathing and moving, and may have a faint or irregular pulse. He may become disoriented and may pass out. A clot that travels to the heart could be fatal. Your dog can develop blood clots in his limbs if he remains in one position for too long. He may be unable to move the affected limb, and it may be cold to the touch.

Blood Clot Diagnosis

Your vet may use an X-ray to diagnose your dog and will likely order urine analysis and blood tests, including a prothrombin time analysis to measure blood clotting. Arterial blood gases will be taken to check for low oxygen in the blood, and your vet may do a heartworm test as well. A coagulation profile may be performed to measure clotting rate, and your vet will ask about your dog’s health history to help him make an accurate diagnosis. If your dog’s clot is in the heart or lungs, your vet may perform an electrocardiogram to get a more detailed analysis of the situation.


Your vet will likely prescribe blood thinners for your dog to help break down the clot, as well as supply fluid therapy if renal function is compromised. Your pup will need close supervision to ensure he doesn’t injure himself, as even a mild cut or abrasion can bleed profusely when a dog is on blood-thinning medication. Your dog may be given oxygen therapy as well, particularly if the clot was in his heart or lungs.


Unfortunately, blood clots are often fatal in dogs. If they survive, they may experience a recurrence. Regular home monitoring and vet visits are essential to preserving your dog’s health. He may remain on blood-thinning medications and be prescribed limited activity or specific therapeutic-type exercise to improve blood flow.