Von Willebrand disease in dogs – Pet tip 138
You may be familiar with the human inherited blood disorder Hemophilia A, in which affected individuals suffer from prolonged, spontaneous bleeding due to a missing clotting factor in their blood. What you may not know, is that a very similar condition exists in our canine companions. Von Willebrand’s Disease (vWD) is a genetically inherited bleeding disorder that affects some of the most popular dog breeds, including the German Shepherd, Shetland Sheepdog, Golden Retriever, Standard Poodle, and most notably, the Doberman Pinscher.
As in human hemophilia, dogs with vWD lack a factor which is essential to the clotting process. Normally, when a blood vessel sustains an injury and bleeding occurs, cell fragments called platelets clump together at the site of the tear to effectively ‘plug’ the hole. While these platelets temporarily stop the bleeding, a cascade of clotting factors leads to the formation of a more permanent seal made of a material called fibrin. In vWD the deficient clotting factor severely disrupts both platelet function and the formation of the fibrin clot. As a result, dogs affected with vWD experience prolonged bleeding following injury.
Due to the fact that the major symptom of this disease often does not appear until an injury has taken place, many owners are completely unaware that anything is even wrong with their dog. Commonly, the first bleeding episode will occur following a dog’s neuter or spay surgery. In some cases, owners may first notice blood in their dog’s stool or urine. Other times, dogs will develop nose bleeds or bleeding from the gums that prompt their owners to seek veterinary care. Without this care, a dog with vWD has the potential to bleed to death even from injuries which might seem only minor.
If you or your veterinarian suspects that your dog might be suffering from vWD, it is possible to make a definitive diagnosis. The most primitive form of testing involves making a tiny cut on the inside of the animal’s mouth prior to surgery. This is normally done once the dog is already under anaesthetic, and the test simply involves measuring the amount of time it takes for a clot to form naturally (this should take under four minutes). This test, while a good way to screen patients at the time of surgery, cannot specifically point to vWD as the cause of clotting problems. A better test involves taking a blood sample from the dog in question, and measuring the levels of the von Willebrand clotting factor. Abnormally low levels are indicative of vWD. This test is extremely useful, but not the most sensitive. In some cases, several samples must be tested before a confident diagnosis can be made. The ideal way to diagnose vWD is through DNA testing. This involves taking a swab of fluid from inside the dog’s mouth and submitting it to a veterinary genetics laboratory. As of yet, only certain forms of vWD can be detected through genetic testing, but the number of tests available is growing.
Currently, there is no cure available for dogs with vWD, and treatment involves managing bleeding episodes as they occur. A hemorrhaging animal should be treated with an infusion of a blood product containing the necessary clotting factor. This product can also be administered proactively, in anticipation of surgery or any other procedure with an associated risk of injury. There is also a newer drug available called desmopressin, which has been shown to help induce clotting in some vWD patients. In some dogs, the disease is associated with hypothyroidism, and so thyroid hormone supplements can help to alleviate the disease somewhat as well.
It is important to recognize that a dog with vWD has the potential to live a long and happy life. In order to do so, however, owners must take special precautions to help prevent injuries in their pets. This might mean limiting the amount of ‘rough-housing’ they let their pet partake in, and feeding them soft or canned food to prevent any cuts from forming in their mouths. There are also certain medications that affected dogs should avoid, including aspirin (which will further decrease blood clotting). Finally, because this disease is genetically inherited, it is critical that dogs with vWD are not bred. With no cure available to dogs suffering from vWD, we must turn to responsible breeding to prevent the occurrence of the disease in the first place.
By Alison Norwich – Pets.ca writer