breeder’s genetic pattern

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Adam Christman, DVM, MBA: Share with me a few examples that you would like to share with your audience.

Jenna Dockweiler, MS, DVM, DACT, CCRT, CVAT: This is actually a really cool case for me as a zoogeneticist, and this goes back to a situation where we couldn’t read a swab for whatever reason. We have a little husky. She was about 17 months old when her owner asked her to be tested for the first time, and essentially, her genotyping ended up failing three times. If there is a sample from another dog in the DNA sample, just as there is a duplicate sample, it will be contaminated by the other dog and the machine will not be able to read it. So after the third time, we looked into it more deeply. We found that there were actually two different DNA signatures in the sample, one with an XX karyotype and therefore a female, and one with an XY karyotype and therefore a male.

Looking back at this patient, she has what I would consider a puppy look, like a broad skull, is larger in stature than her litter sister, and has never been in heat, even though her litter sister has been on her bike twice . So she is most likely a XXXY chimera. Chimerism is when two tiny embryos stick together very early in a few cell stages of development and then develop into a dog. For dogs, this is not so clear. The condition is uncommon, but there are no known health complications associated with mosaicism other than reproductive consequences.

Unfortunately for this little girl, her owners are seeking DNA testing as part of a responsible breeding program, which of course may not be her ultimate fate. But at least we have an answer to why she doesn’t ride a bike. So we probably saved her a rather expensive initial anastomosis exam.

Adam Christman, DVM, MBA: Wow, this is so fascinating. Wow, this is really crazy.

Lindsay Coker, DVM: I think this raises an interesting point. We’ve talked about educating clients about outcomes in the exam room and at observations, and depending on who you’re talking to, right, I think the outcomes may be more immediate for pets that have been neutered. But if you have a breeder coming in and want to see the results, I think the first thing I would do is change the 15 minute appointment to a 30 minute appointment because, to go through Punnett Square, take a little biology class and go through the genetics The basic knowledge of and its significance is very important for our breeding customers. This can be said, especially for varieties where there may be fewer varieties to choose from.

When something goes wrong or there’s a mutation in the DNA, it doesn’t necessarily mean they’re not suitable for breeding, but it does mean they may need some help interpreting those results and making some informed breeding decisions. Of the more in-depth cases that come out, I think these are really fun to complete but also take a little more time.

Adam Christman, DVM, MBA: Actually, let’s talk about this more with the breeders because I think it’s a great discussion that we’re having. Where are we with breeders and DNA testing? Because I know DNA testing wasn’t around a long time ago, so where are we in this day and age?

Jenna Dockweiler, MS, DVM, DACT, CCRT, CVAT: In fact, breeders may have been using DNA testing longer than pet owners. Two parts of genetic screening, if you will, is testing groups at risk for disease to see who is likely to pass on those disease alleles to the next offspring. Therefore, breeders have been using the latter half of the definition for some time.

As Dr. Coker says, if your dog does have a genetic risk, that doesn’t necessarily mean you can’t use your dog in a breeding program. It just means we have to pair wisely to avoid producing risky puppies. In fact, my own dog is an example of this. She is a Factor VII carrier, so it is a recessive disease, meaning she needs two copies to be at risk for excessive bleeding. She only has one copy, but I can’t mate her with my boyfriend who has one or two copies because doing so might produce risky puppies. As a responsible breeder, I would be reluctant to do this. You just have to be smarter about who you mate with.

Adam Christman, DVM, MBA: When you as the veterinarian are communicating the results back to the breeder, what is the conversation like when you look at the results? What’s next?

Jenna Dockweiler, MS, DVM, DACT, CCRT, CVAT: I would say most breeders are pretty well versed in genetics. Most good breeders are pretty well versed in genetics, but again, make it clear at the outset that this doesn’t mean your dog can’t breed. Even dogs at risk for genetic disease can sometimes be bred responsibly under certain circumstances, as long as they are properly matched and the breeding is not expected to exacerbate their condition. Of course, because they are our primary patients and not potential litter. I think the point of putting this in the beginning is because some breeders will be very upset even if they turn out to be carriers, but saying hey this doesn’t remove your dog from the breeding pool, we just have to be smart about it.

Adam Christman, DVM, MBA: When you hear about understanding genetics and working with breeders to breed more responsibly, how important is that to you?

Lindsay Coker, DVM: I’ve found that for every breed of dog or cat, today we’re not talking about cats, but cats, that breed has a unique language. I think the really interesting thing is I always start the conversation by saying, “Tell me about your breeding program.

Breeders also love to talk about physical traits, and honestly, as a veterinarian, it’s sometimes hard to keep my focus on the genetics of those physical traits. Coat color can be very complex, but breeders have a complete and realistic knowledge of what it means. I think the best conversations and the best relationships are when I can listen to them walk into the exam room and talk about their experiences, talk about what they’ve seen firsthand, and talk about this from an actual genetics science perspective, right? That’s when we can meet in the middle, and we can have this conversation: Yes, I know this genetic variation is an ongoing concern in your breed. This might be a little scary to you, but let’s look at the science of how heredity works and how it works, this is a genetic recessive trait, right? It does not mean that your dog is at risk for this clinical disease, it just means that we must choose the right companion for the dog. As a partner, it makes a huge impact on the success and care of these animals.

Adam Christman, DVM, MBA: Yes, a true partnership.