Holweit Perm Reg'd
Bred with Care, Raised with Love and Shown with Pride
Go to http://scwtca.org for latest information regarding Genetic Testing
Last year, after years of research supported by hundreds of Wheatens and their owners and breeders, Dr. Meryl Littman and Dr. Paula Henthorn identified mutations associated with PLN in two genes.
As a result, there is now a test using a non-invasive cheek swab, which an owner can take and submit to the University of Pennsylvania School of Veterinary Medicine for interpretation; no blood test, no complicated shipping, no trip to the vet!
This is going to help you understand our brand new DNA test that is available for our breeders to use to continue to improve the health of our breed. Every breed, every hybrid, every mixed breed has health problems of one sort or another. Cancer is the most prevalent cause of death in all dogs. In Wheatens, our health concentration has been on the protein-losing diseases, protein losing nephropathy (PLN) and protein losing enteropathy (PLE).
One of the most exciting things that has happened in the last year is the development of a DNA test for PLN. Reputable breeders are testing their breeding animals. If the breeder you are talking to about a puppy is not testing, do NOT buy a puppy from them. Expect to be given a copy of an email from Dr. Meryl Littman that will tell you the DNA status of the sire and the dam of the litter. You may even be given an email about the DNA test results on your specific puppy.
In the email Dr. Littman relays the results of the DNA test to the breeder. The results may be homozygous normal, heterozygous, or homozygous positive. The homozygous normal dogs carry no markers of the variant genes. The heterozygous dogs carry one marker and the homozygous positive carry two markers of the variant genes. We started testing our dogs in May of 2012. Currently our dogs (over 600 tested) are showing that 1/2 of the dogs are heterozygous, 1/3 are homozygous negative, and 1/6 are homozygous positive.
As breeders our first goal is to stop producing homozygous positive dogs, or dogs with two markers. This is now the norm at Holweit and has been since 2001. Our second goal is to keep enough genetic diversity in the breed so we don’t produce more health problems. We will do this by keeping heterozygotes and in our breeding programs but breeding them without producing more homozygous positive or two marker dogs. We may on occasion use a stud that is homozygous positive to keep other qualities that are desired in the Wheaten without producing any homozygous positive puppies. Our third goal will be to end up with all homozygous normal dogs. This will take a long time, probably 5-10 years.
I know, I know, you want to know what it means if your pup is a heterozygote and that’s what is coming next…but the truly important thing to remember is that cancer is the number one killer of dogs.
Please remember the incidence of PLN in our breed is between 5% and 15% and stop panicking.
You may have a puppy who is homozygous normal (therefore has no markers). He is the pup that is least likely to get PLN, but even without a marker he can still get PLN because there are non-genetic forms of PLN. And isn’t that just the pits? But that’s the way it is.
Your puppy may be a heterozygote (therefore has one marker). This pup is at intermediate risk of inheriting PLN. He might get it; but don’t hold your breath and worry about it. Remember that half the Wheatens tested so far have one marker but only 5% to 15% of the breed historically have developed the disease.
If you purchase a Wheaten from HOLWEIT your puppy will NOT have two markers.
Enjoy your new pup and don’t spend your life worrying about his or her DNA results. Do the appropriate testing, play with your dog and have fun!
So the test results are back and you want to know what to do if your dog is:
1) a HOMOZYGOUS NORMAL dog (with no copies of the predisposing alleles associated with PLN) - This dog will be very popular for breeding! If it has other great qualities you want to perpetuate, go for it! However, realize that we don’t have genetic tests yet for allergies, inflammatory bowel disease, PLE, Addison’s, renal dysplasia, etc, so breed carefully away from these problems. We recommend annual screening (blood and urine tests) for all Wheatens. If this dog shows proteinuria, we need to get that feedback from you, and we will want to study these dogs more to find out why they have proteinuria despite not having the predisposing alleles that affect the structure of the slit diaphragm.
2) a HETEROZYGOTE dog (with 1 copy of the predisposing alleles) - This dog is at intermediate risk for developing PLN. It is at much lower risk than a dog with 2 copies, but it is at somewhat higher risk than a dog with no copies. Realize that the Wheagles at NCSU were not all normal, and they had 1 copy of the predisposing alleles. It’s possible that having other genetic problems such as allergies or environmental infections or inflammatory disease can provoke these dogs to get sick with PLN. It is also possible that some dogs have modifier genes that protect them, because many heterozygote dogs lived into their geriatric years. A heterozygote dog should be monitored carefully throughout its life for proteinuria, and have annual screening tests done (blood and urine).
3) a HOMOZYGOUS POSITIVE dog (with 2 copies of the predisposing alleles) – Not a possibility at HOLWEIT. This dog has the highest risk for developing PLN itself. It should be monitored closely all its life for proteinuria (some people would test the urine 2-3 times per year beginning at age 4 years or so) in addition to the annual screening tests (blood and urine). Early intervention and treatment for proteinuria and any other problems such as allergies, infections, and inflammatory diseases may help these dogs live good quality lives for years. They may even live into their geriatric years, and we want to know about them! It’s possible that some dogs have modifier genes that protect them from getting sick.
