The post was shared in a couple of Facebook groups dedicated to Hovawarts and quickly went "viral" - or, as viral as a post about Hovawarts can possibly go.
DM, Degenerative Myleopathy, is a disease of the spinal cord. The membrane that protects the nerves degenerates, and eventually the nerves themselves become affected. The disease progresses slowly, and symptoms start with dragging of the rear legs, until it progresses into paralysis of the rear legs, incontinence, breathing-problems, and finally complete paralysis when also the front-legs are affected. After this there is also a final stage with more complications like organ failure, but this is rare, as most dogs are humanly euthanized before reaching this stage.
To see a Hovawart like Carmen's Sammy suffer from DM is heartbreaking when you can see the cruel core of this disease. It will inevitably end in Carmen having to take that dreaded decision of euthanasia for a Hovawart who is fresh, lively, happy, in no pain and clear in spirit, but with a body that can function no more. How do you say goodbye to such a dog? You simply can't. That's the cruelty of DM. It will force you to make a decision based on quality of life alone, while you look into a pair of eyes which are far from ready to let go.
Carmen's post reminded me of my friend Thomas and his Hovawart Cliff, who also suffered from DM and sadly passed shortly after they shared their story on this blog some years ago.
Back then I followed up with two posts about DM and how Dr. Elisabeth Dietschi, Phd, and prof. Tosso Leeb, from the University of Bern, Institute of Genetics, presented their first result from the Research project of the Hovawart, to participants and breed clubs worldwide:
"From the samples of 1,200 Hovawarts we investigated, the DNA test for the SOD1 mutation, a gene believed to be a major factor in DM, showed 45% are free from the mutation, 45% are carriers, and 10% are affected."
The news hit like a bomb shell back then and the clubs and breeders scattered in all directions. I wondered, what had happened since that meeting in 2012, now almost five years ago, by looking at what the German RZV, "Rassezuchtverein für Hovawart-Hunde", the largest and, through the IHF, the "International Hovawart Federation", the most influential club world-wide, has done since.
The RZV initially questioned the SOD1 mutation to be the actual cause of DM for the Hovawart. They launched their own research, the so-called "Pfeiffer" report which tried to debunk the link between the SOD1-mutation and DM. The RZV embraced the results of this report which are dodgy to say at least, and chose to ignore new evidence from Dr. Elisabeth Dietschi, who on a much larger sample than the "Pfeiffer" report, could confirm a certain correlation between the SOD1 mutation and DM.
Why would the RZV ignore this? This becomes clear on September 2016 when they publish an article about DM in their club magazine. In short, the RZV worries that excluding a significant number of dogs - the carriers and affected dogs - from the breeding population will shrink the gene pool significantly and will only lead to new genetic disorders that are unknown today.
They are absolutely right.
Because we breed in a closed gene pool there can be dozens or more of disease-causing mutations in every dog and therefore there will always be the next disease waiting on the doorstep. Selecting dogs based on genetic tests for each new disease we encounter will only accelerate that process. The population becomes more inbred and homozygous, severely cutting the sustainability of the Hovawart breed short.
But I don't agree with the conclusion of the RZV, to continue breeding with untested dogs. Let me explain.
I am afraid it is too late at this point to do nothing about DM. The majority of dogs are already affected or at risk. If breeding continues like we do now with untested dogs, simple probability mathematics can predict with absolute certainty the whole population will be affected in time. More and more dogs will suffer from DM, and it will also become more and more difficult to solve, if not completely impossible to solve.
It seems like a choice between pest and cholera. But don't despair, something can be done though.
The key is to avoid new disease-causing mutations and continue with the dogs that are not affected by DM by changing the way we breed today and adopt new breeding strategies. Carol Beuchat, PhD, from the Institute of Canine Biology identifies three key strategies to reduce genetic disorders in dogs, to ensure no new genetic disorders will occur if we would continue breeding with dogs not affected by DM:
1. Increase the number of breeding animals.For the RZV, I believe the breeding population to be a couple of hundred individuals give or take. The number of breedings per individual can be limited and more dogs could be used, without an increase in the number of puppies. An important note here is not all DM carriers necessarily need to be excluded if only we would breed them with DM free dogs and keep tracking them.
2. Eliminate popular siresPopular sires can sire multiple litters and are an important threat to diversity, somewhere down the line their offspring meets and those recessive genes like SOD1 kick in and voila, we have a new disease. Popular sires are a main cause of new genetic disorders.
3. Use strategic outcrossing to reduce inbreedingThere are genetically distinct sub-populations of Hovawarts. They might represent standard versus working lines, geographic areas like the Hovawarts who originate from the former West- or East-Germany, or some other factor (dare I mention clubs?). Because they carry genes that will be less common in other groups, they can be used to reduce the level of inbreeding in a litter of puppies. Homozygosity will be reduced, and therefore the risk of forming a recessive mutation will be less. An outcross every now and then can be sufficient to reset the inbreeding to a healthier level.
Following these strategies ensure we can stop DM - we must - without exchanging it with the next genetic disease as the RZV fears. We can do something about it. Get rid of DM and ensure it will not just lead to new problems.
Or we can do nothing, and watch the Hovawart in a wheelchair join the long line of dog breeds in the next episode of Pedigree Dogs Exposed.
|Remembering Cliff, 2003 - 2013|