Von-What Disease? If you've ever heard of Von Willebrand's Disease, the first breed you think of is a Doberman Pinscher. But did you know other breeds are affected, and humans can also be diagnosed with this disease?
Von Willebrand’s disease (vWD) is the most common inherited bleeding disorder of both man and animals. It is caused by a deficiency in the amount of a protein needed to help platelets (a blood cell used in clotting) seal broken blood vessels. The deficient protein is called von Willebrand factor antigen. It takes its name from Dr. Erik von Willebrand, who first described the condition in 1926.
Which breeds are most commonly affected by VWD?
About 30 different breeds are known to be affected but the Doberman Pinscher is the breed most commonly associated with this disease. Of 15,000 Dobermans screened, more than 70% were found to be carriers of the disease. Fortunately, most of these are not clinically affected (i.e., we see no evidence of bleeding). However, the number of Dobermans with a history of bleeding appears to be on the rise. Although Dobermans are commonly affected, they usually have the mildest form of the disease. The average at diagnosis for this breed is about four years of age.
One study showed that 30% of Scotties and 28% of Shelties had abnormally low concentrations of von Willebrand factor. Chesapeake Bay Retrievers and Scotties are affected with the most severe form of the disease.
As many of you may know, I recently adopted Lena, a 6mth old Doberman Pinscher, from Gulf Coast Doberman Rescue. I have always wanted a Doberman, and she was the perfect puppy and fit into the family. Lena (formerly Ridley from GCDR) was found as a stray on Grand Isle. A stray?! I know! No one ever claimed her and thus went into a foster home before I adopted her. Lena was too young to be spayed when I adopted her, so we waited a few months. In the mean time, I had her tested for VWD prior to her spay. Unfortunately, Lena came back as a heterozygous VWD Type 1 Carrier with an abnormal 45% Von Willebrand Factor (normal range is 70% to 180%). Because of this, it was suggested that Lena be spayed laparoscopically with a plasma transfusion prior to surgery. A plasma transfusion given prior to surgery provided Lena with enough Von Willebrand Factor (vWF) that she needed in order for her blood to clot efficiently.
What are some of the signs of VWD?
Many dogs with VWD never show outward evidence of having the disease. Others may hemorrhage from the nose, vagina, or urinary bladder or oral mucous membranes; prolonged bleeding after trauma or surgery is common. Females may bleed excessively after giving birth. In affected dogs with uncontrolled hemorrhage, death may occur.
How is VWD diagnosed?
A screening test, called the buccal mucosal screening time, may be performed in the veterinarian’s office. Prolonged bleeding on this test can raise the suspicion of the disease, especially in breeds known to be at risk. Occasionally, BMBT's and clotting profiles (PT/PTT) are normal and a dog can still not have enough vWF. This was the case for Lena, as both were normal. For owners who wish to confirm the diagnosis, it is possible to determine the exact amount of von Willebrand protein present in the blood.
Recently, a DNA test by VetGen gives a more accurate answer that will categorize vWD into clear, carrier, and affected. Test results will come back as "clear," "carrier," or "affected." Clear means both vWf genes are normal, carrier means one is normal and one is defective, and affected means both genes are defective. It is important to realize that this DNA test is very different from the old protein-based factor assay. The DNA test is definitive and final, a lifelong, permanent determination of the vWD status of each dog tested as contrasted to the factor assay, in which the levels could change drastically over time. We can now say in hindsight that the old test probably correctly identified some affected Dobermans (values under 20), but it is completely unreliable for carrier detection.
Owners of Dobermans often report that the pet has undergone routine spay, castration, ear cropping, and tail docking as a pup. An uncomplicated recovery from such procedures does not eliminate the possibility that a dog may be affected; some dogs do not become obvious “bleeders” until later in life which is why its very important when owning a breed pre-disposed to vWD you have them tested.
Are there any situations which pose an increased risk if my dog is affected?
The avoidance of certain medications is critical for the dog with VWD as some drugs that may precipitate a bleeding crisis in a dog with vWD. Emotional stress is thought to precipitate bleeding in humans with the disease. The subjective nature of such a finding makes it difficult to know if there may be a similar association in dogs, although this remains a possibility.
Should I breed my dog if they've tested as carrier or affected for VWD? VWD is NOT a desired trait and can be passed down to offspring. While I am a strong advocate of rescue and spay/neuter, if you choose to breed your Dobermans or breed predisposed to VWD, having them tested prior to producing any offspring is HIGHLY recommended. The Doberman breeder and owner should view vWD as a significant health risk, and a fault, and strive to get rid of the mutated gene.
The problem facing the Doberman breeder is that it appears that only 15 to 20% of Dobermans are clear of the vWD gene. If one breeds mostly clear to clear, it narrows the breeding pool so much that there is risk of losing some of the Doberman's genetic heritage, i.e., some of the genes determining valuable positive characteristics of the Doberman might be lost, or highly diluted. Therefore, as a first priority, we advise breeding clear to clear and clear to carrier, at least for the next two or three generations. Over time, as the frequency of clear dogs increases, it should be possible to breed mostly clear to clear, and to eventually eliminate the mutant vWD gene. As a second priority, we suggest that it is reasonable to breed carrier to carrier, if an acceptable clear dog is not available for breeding. This type of mating will produce 25% clear, 50% carrier, and 25% affected, on average. The puppies should be tested and the affected puppies not used for breeding.
Breeding carrier to affected and affected to affected should be avoided if at all possible. The first breeding produces 50% affected on average, and the second produces 100% affected animals. In my opinion, there should be two initial objectives of the Doberman vWD breeding program. One objective should be to produce as few affected animals as possible, because each is a health risk. That doesn't mean we believe affected Doberman puppies should be put down. Most of them can live normal lives. If possible, we believe it would be a good idea to neuter affected animals. The second objective of the breeding program should be to gradually reduce the gene and disease frequency. The kinds of breedings involving the mating of an affected, as listed at the first of this paragraph, tend to increase the disease gene frequency, whereas clear to clear and clear to carrier breedings tend to decrease frequency. This information is provided by VetGen.
What can be done to treat dogs with VWD?
In an emergency situation, transfusion of blood or fresh frozen plasma may stabilize the patient. The dog donating blood may be treated with a drug called DDAVP prior to blood collection; this will raise the level of von Willebrand factor in the donor’s blood, an obvious benefit for the dog with VWD.
Some dogs with VWD are able to increase the amount of protein in circulation after the administration of DDAVP, although the response is variable. At this time, it is not recommended to use this drug on a regular basis. The drug is expensive, and not all dogs will respond to it.
If I own a Doberman or a breed predisposed to VWD that has always been healthy, should I do something?
Since many Dobermans or predisposed breeds will never have bleeding problems, any recommendation to do routine testing is debatable. However, identification of dogs that have abnormal bleeding times can be very valuable if surgery is planned. Additionally, knowing that your dog is a carrier of VWD can be very important if an injury occurs or emergency surgery is needed.
For more information on VWD, speak to your veterinarian! I'll be happy to answer any questions you may have regarding VWD to the best of my ability. Lena is doing well post spay. She also had a gastropexy done at the same time- stay tuned for my next blog on what a gastropexy is and the benefits!
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