RuffCoast & Meliora

At Iris’s reproductive consultation appointment, we decided to perform a Buccal Mucosal Bleeding Time (BMBT) test to confirm that she is non-symptomatic for any bleeding disorders. Sure enough, her results were completely normal.

While we had no concerns, since she is only a vWD1 carrier, it was an inexpensive and easy screening test. It was only $50 – and that’s in Southern California veterinary prices! – and took less than 5 minutes. So we felt it would be an interesting data point to add to the conversation surrounding vWD1 in the breed. If you are interested in learning more about why, read on!

Background

Von Willebrand’s Disease Type 1 is a bleeding disorder characterized by mild to moderate increases in bleeding times (due to increased clotting times) compared to non-affected individuals. There is a genetic marker identified for vWD1, but its expression (i.e., its ability to predict which individuals may be symptomatic) can vary significantly by breed.

At the time of this writing, there have been no scientific studies on vWD1 expression in Drents, but based on anecdotal experiences, most in the breed believe it to be an autosomal recessive gene with incomplete penetrance. What this means is that only dogs with two copies of the mutated vWD1 gene (one from each parent) might develop bleeding symptoms, but not all dogs with two copies will be symptomatic. In fact, in Drents, it seems that among those with two copies of the gene, symptomatic individuals are exceptionally rare.

However, it’s known in some other breeds from scientific study that vWD1 is expressed in those breeds as autosomal dominant with incomplete penetrance. Where this is the case, even carriers – individuals with only one copy of the mutated gene – are possibly at risk of increased bleeding caused by symptomatic vWD1.

The Buccal Mucosal Bleeding Time (BMBT) test is a functional screening test that evaluates clotting/bleeding time. A small cut is made in the upper lip of the dog, and time is measured until the bleeding stops. A normal result (bleeding stops in under 4-5 minutes) proves the dog is healthy – an abnormal result (bleeding does not stop in under 4-5 minutes) means the dog may need extra care during surgery or trauma to prevent too much blood loss.

Why Perform a BMBT?

Given what we know (and don’t know) about vWD1 expression in Drentsche Patrijshonden, it was no surprise to us that Iris, being only a carrier, had a completely normal result to the BMBT test. However, we have been involved in many conversations with other Drent owners, breeders, and enthusiasts based almost exclusively on what-if theory and anecdotes regarding vWD1 – and we believe it will be important for the future of the breed to focus on collecting and making decisions based on actual data specific to the Drent.

While it is our perspective at Meliora that vWD1 is one of the least significant health concerns in the breed given the rarity of its expression and the generally mild severity compared to issues such as epilepsy and joint dysplasia, we encourage others to get their Drents genetically tested for vWD1 and, if they are a single-copy carrier or two-copy “at risk”, to ask their vet to perform a BMBT test and record the results in their medical history.

If the BMBT test is returned as abnormal, you and your vet will be able to better prepare in case your dog needs surgery or medical care. It’s worth noting, however, that there are multiple genetic blood disorders and/or environmental reasons a BMBT test result may be abnormal – vWD1 is only one of them!

However, if a Drent with two copies of the mutated vWD1 marker gene has normal BMBT results, it may suggest that that individual has other genetic factors involved that counteract the effects of the mutated vWD1 genes. For a female, this may allow for her to be bred without increased risk of bleeding during the whelp – and for either gender, a normal BMBT test may open up more options for breeding, as offspring would likely be at less risk of symptomatic vWD1 than offspring from individuals with abnormal BMBT results.

Regardless of the result of the genetic test, BMBT test, and intentions or lack thereof of breeding, gathering more information will help the Drent community better understand the occurrence of bleeding disorders in the breed, and perhaps start to connect the dots between vWD1 genetic status and symptomatic expression. More data means a clearer picture, and a clearer picture means that breeders can make more informed decisions in the preservation of the Drent long-term.