Liver shunt and health news from America
Recently I spoke to an Dutch Irish Wolfhound breeder who had imported a puppy from Germany. It turned out that this puppy had just been tested for liver shunt. Since I was told at the time that this test was not available in Germany, I inquired further.
The German Irish breeder had just had blood drawn from his puppies at his own vet and he did sent it to Laboklin. The next day the breeder had the results.
So if you want to get a puppy from Germany, the breeder can have it tested for liver shunt via Laboklin, insist on this, it can save you a lot of misery!
In the Claymore, the club magazine of the Scottish Deerhound Club of America, the Health and Genetics chapter appears in every issue. Always very interesting! In the latest edition (September/October 2021), Dr. Michael H. Court, researcher at the Pharmacogenomics Laboratory in the College of Veterinary Medicine at Washington State University, updates on the progress of studies on slow anesthesia recovery, perianesthetic stress hyperthermia (a stress-induced, life-threatening temperature elevation) and delayed postoperative bleeding. Below is an abbreviated version of his presentation at the National Specialty.
Slow anesthesia recovery
“The slow recovery of anesthesia after surgery or examination is a well-known phenomenon in Greyhounds and also occurs in other greyhounds. Usually it is after injected anesthetics such as thiopental and propofol (the latter to a lesser extent). This is related. with the low body fat content that greyhounds have.Normally the injected anesthetic passes out of the blood and into the body fat fairly quickly, allowing the dog to recover quickly, but due to the little body fat a greyhound has, a lot of anesthetic remains in the blood. , if first this blood is purified by the liver and that takes several hours. But there seems to be another factor involved and that is that the liver of greyhounds metabolize anesthetics more slowly than in other (non greyhound) breeds. There are two different mutations found in two different genes encoding enzymes crucial for the metabolism of pr opofol (CYP2B11-H3 and POR-H3). These mutations are most often found in Greyhounds and Deerhounds. Lab studies have shown that these mutations drastically reduce the metabolizing of propofol. The result of the latest study comparing Greyhounds with these mutations and Greyhounds without these mutations is still pending.
Perianesthetic stress hyperthermia
Another condition that has been studied is ‘stress hyperthermia’ which occurs in both Deerhounds and Greyhounds. Usually this is seen in conjunction with the anesthesia procedure before surgery. Signs are a very rapid temperature increase to above 41 C°, panting and deep red mucous membranes. Treatment consists of rapid cooling and the administration of sedatives and fluids. Stress hyperthermia can be prevented by judicious use of sedatives before an exhilarating experience (e.g. a vet visit) as well as taking steps to reduce stress.
Although stress hyperthermia is very serious and life-threatening, there have been no reports of fatal cases in the Deerhound. This is different from the malignant hyperthermia which is invariably fatal.
Since not all Greyhounds and Deerhounds are sensitive to stress hyperthermia, it is thought to be a genetic predisposition. With the support of the SDCA, we identified a mutation in the RYR1 gene in dogs with a history of stress hyperthermia. This mutation appears to be a milder form than the mutation of the gene that causes malignant hyperthermia. Since we have only studied 8 Deerhounds and 1 Greyhound, the usefulness of the clinical trial for this mutation is unclear. Therefore, we continue to recruit cases to see if the RYR1 mutation can explain all cases. Please contact courtlab@vetmed.wsu.edu if you have a dog that has suffered from hyperthermia and would like to donate DNA.
Delayed postoperative bleeding
Finally, we worked on a problem initially identified in Greyhounds, delayed post-operative bleeding. The clinical picture of this condition concerns dogs that have undergone major orthopedic or abdominal surgery (castration/sterilisation). Although no bleeding occurred during surgery, bleeding was noted within the next 24 to 48 hours. Symptoms range from bruising around the surgical site to overt bleeding from the wound. For abdominal surgery, internal bleeding may go undetected until the dog is seriously ill. Treatment consists of blood transfusions and intravenous administration of anti-fibrinolytic medication (Amicar). These bleedings can also be prevented by administering these agents before the operation and for 5 days after the operation.
We have conducted several studies (funded in part by the SDCA) implying that a mutation of the SERPINF2 gene is the cause of the delayed bleeding. SERPINF2 stands for alpha-2 antiplasmin, which is essential for protecting against the premature breakdown of blood clots (hyperfibrinolysis).
A case-control study was conducted using information gathered from the SDCA health survey and DNA samples from bleeding and dead dogs. We found 7 dogs that had postoperative bleeding after surgery and 55 dogs that had surgery without postoperative bleeding. All dogs were genotyped for the SERPINF2 mutation. The result indicates that the risk for delayed bleeding is 40 times higher in dogs that have at least one copy of the mutation and 500 times higher in dogs that have two copies, compared to dogs without a mutation. Important; all affected dogs had this mutation while none of the dogs that did not have the mutation had delayed bleeding.
In another study in healthy Greyhounds, we showed that dogs with two copies of the SERPINF2 mutation had significantly lower levels of antiplasmin in their blood than dogs with one or no copies of the mutation.
Taken together, it shows that testing for the SERPINF2 mutation can be useful to identify dogs that may have an interest in prophylactically administering anti-fibrinolytic drugs (Amicar). And just as important; the test can also identify dogs that will not benefit from this medication.
The SERPINF2 test is available now (free of charge) by contacting courtlab@vertmed.wsu.edu and requesting a DNA sample pack.
Like all genetic testing, we realize that the post-operative bleeding test can and will be used by Deerhound breeders to inform themselves about breeding plans. The SDCA Health & Genetics Committee is preparing guidelines for breeders on how or how not to use the test .
In this regard, it is important to emphasize that breeders should not attempt to eliminate the SERPINF2 mutation from the breed or a particular breeding line, as the disease causing the mutation can be effectively prevented in dogs at risk.”