The Functional Breeding Podcast

What is the coefficient of inbreeding (COI) and why does it matter?

This week you get just me (Jessica Perry Hekman) talking at you! I'm talking about the coefficient of inbreeding (COI), a measurement of genetic diversity that's commonly mentioned in discussions of individual and breed health. I talk about what it is, how to interpret it, how to get the measurement done for your own dog(s), why we care about it, and give the take-home messages from some papers with evidence for its importance in dog specifically. COI is not the only thing you should be breeding for, and it's rarely even the most important thing - but it's something we should keep in mind when we are working in closed gene pools.

NOTE: Oops, I said in the episode that the MDR1 mutation is recessive. It's not - it's incompletely dominant, meaning that dogs can be affected even with only one copy of the mutant allele. I apologize - please note the mistake as the correct information is important here.

• I mention some previous podcast episodes with related material - you can find them here:
  Alison Skipper, PhD on the history of breed registries: https://functionalbreeding.podbean.com/e/alison-skipper-phd-the-history-of-breed-registries/
• Mary Peaslee, MD, MPH, on breeding for population health: https://functionalbreeding.org/breeding-for-population-health/

The papers:

• https://functionalbreeding.org/the-impact-of-inbreeding-on-litter-size/ - Chu ET, Simpson MJ, Diehl K, Page RL, Sams AJ, Boyko AR. Inbreeding depression causes reduced fecundity in Golden Retrievers. Mammalian Genome. 2019 Jun 1;30(5):166-72. - "The least inbred dogs had an average litter size of 8 puppies, while the most inbred dogs had an average litter size of 6-7 puppies. On average, with each 10% increase in inbreeding, the litter size decreased by one puppy."
• https://functionalbreeding.org/inbreeding-depression-and-lifespan/ - Yordy J, Kraus C, Hayward JJ, White ME, Shannon LM, Creevy KE, Promislow DEL, Boyko AR. Body size, inbreeding, and lifespan in domestic dogs. Conserv Genet. 2020 Feb;21(1):137-148. - mixed breed live on average 1.2 years longer than size matched purebreds
• https://www.sciencedirect.com/science/article/abs/pii/S1090023313004486 - O'Neill DG, Church DB, McGreevy PD, Thomson PC, Brodbelt DC. Longevity and mortality of owned dogs in England. Vet J. 2013 Dec;198(3):638-43. doi: 10.1016/j.tvjl.2013.09.020 - again, mixed breed live on average 1.2 years longer than size matched purebreds
• https://link.springer.com/article/10.1186/s40575-020-00086-8 - Urfer SR, Kaeberlein M, Promislow DEL, Creevy KE. Lifespan of companion dogs seen in three independent primary care veterinary clinics in the United States. Canine Med Genet. 2020 Jun 16;7:7. -   breeds with lower COI have 3-6 month longer expected lifespans
• https://functionalbreeding.org/size-genetic-diversity-lifespan/ - Kraus C, Snyder-Mackler N, Promislow DEL. How size and genetic diversity shape lifespan across breeds of purebred dogs. Geroscience. 2023 Apr;45(2):627-643. - + 1% heterozygosity -> + 31 days of life
• https://functionalbreeding.org/the-effect-of-inbreeding-body-size-and-morphology-on-health-in-dog-breeds/ - Bannasch, D., Famula, T., Donner, J. et al. The effect of inbreeding, body size and morphology on health in dog breeds. Canine Genet Epidemiol 8, 12 (2021). - 30kg dog: 0->40% COI -> 10% increase in veterinary care visits; 5kg or 60kg: 37% increase
• https://journals.plos.org/plosgenetics/article?id=10.1371/journal.pgen.1007361 - Donner, Jonas, et al. "Frequency and distribution of 152 genetic disease variants in over 100,000 mixed breed and purebred dogs." PLoS genetics 14.4 (2018): e1007361. - purebred more likely to be affected, mutts to be just carriers

REPLAY: Jane Lindquist: Puppy Culture

I will have new content for you all soon - but for now, enjoy one from the archives!

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Jane Lindquist is the founder and owner of Puppy Culture, a widely used educational resource for raising and socializing puppies. She herself breeds and competes with bull terriers. As it turns out, she is very thoughtful when it comes to how to apply science to the raising of puppies. We had a wide ranging conversation, at times nerdy, at times philosophical. You can learn more about Puppy Culture at www.puppyculture.com, and more about Jane's breeding program, Madcap Bull Terriers, at www.madcapbullterriers.com.

Find this episode's transcript at functionalbreeding.org/jane-lindquist-puppy-culture/

Mary Peaslee, MD, MPH: Breeding for Population Health

This episode I welcome back Mary Peaslee, MD, MPH, to talk about a breeder's perspective on all the advice Dr Dan O'Neill gave us in his recent episode on how to approach disorder testing. Mary works in population health and brings that perspective to her breeding practice. So what does all this stuff look like in the real world? How can breeders focus on the future health of the dog population they work with? What are some challenges they'll encounter? Mary has some great advice and perspective that I hope will help people think through their breeding goals and approaches.

You can learn more about Mary's breeding program here: https://englishshepherds.net and you can find her on Facebook at https://www.facebook.com/mary.peaslee.9

 

Detailed summary: https://functionalbreeding.org/breeding-for-population-health/

 

Jessica Hekman, DVM, PhD, on "Lifetime Prevalence of Owner-Reported Medical Conditions"

We have a flipped episode this week with Sarah Stremming of Cog Dog Radio interviewing me. We're talking about the new paper out of the Dog Aging Project, "Lifetime Prevalence of Owner-Reported Medical Conditions in the 25 Most Common Dog Breeds in the Dog Aging Project Pack." There's been a lot of buzz on social media about this paper and we wanted to dig in to its findings. For those who saw our live Q&A about the paper, this interview covers very similar ground, although we go into some more detail. I'll include links to this study and others below, and if you want to ask questions about the paper, the Functional Breeding Facebook group is a great place to do it!

 

Forsyth, Kiersten K, et al. “Lifetime Prevalence of Owner-Reported Medical Conditions in the 25 Most Common Dog Breeds in the Dog Aging Project Pack.” Frontiers in Veterinary Science, vol. 10, 3 Nov. 2023.

• Original: https://doi.org/10.3389/fvets.2023.1140417
• FDC summary: https://functionalbreeding.org/common-conditions-seen-in-primary-care-visits/ 

 

Do purebreds live longer?

• Yordy, J, et al. “Body size, inbreeding, and lifespan in domestic dogs”. Conserv. Genet. 21 (2020): 137-148. - https://functionalbreeding.org/inbreeding-depression-and-lifespan/ - “For a given body size category, mixed breed dogs lived on average 1.2 years longer than purebred ones.”
• Urfer, Silvan R., et al. "Lifespan of companion dogs seen in three independent primary care veterinary clinics in the United States." Canine medicine and genetics 7 (2020): 1-14. - https://link.springer.com/article/10.1186/s40575-020-00086-8 - DAP authors before DAP started - “We did not find significant differences in lifespan between purebred and mixed breed dogs; however, breeds with larger effective population sizes and/or lower inbreeding coefficients had median survival times 3–6 months longer than breeds with smaller effective population sizes or higher inbreeding coefficients”
• Mata, Fernando, and Andreia Mata. "Investigating the relationship between inbreeding and life expectancy in dogs: mongrels live longer than pure breeds." PeerJ 11 (2023): e15718. - https://peerj.com/articles/15718/?f...gzQO4ualQE4De4iuO6RmqokNKNTRYdxORkaYEMBwDx_0I - VetCompass data - “mongrel dogs had the highest life expectancy, followed by cross-bred dogs with only one purebred ancestor and purebred dogs had the lowest life expectancy”

Increased inbreeding correlates to decreased lifespan

• Kraus C, et al. “How size and genetic diversity shape lifespan across breeds of purebred dogs”. GeroScience (2022). - https://functionalbreeding.org/size-genetic-diversity-lifespan/
• Bannasch, D., Famula, T., Donner, J. et al. The effect of inbreeding, body size and morphology on health in dog breeds. Canine Genet Epidemiol 8, 12 (2021). - https://functionalbreeding.org/the-effect-of-inbreeding-body-size-and-morphology-on-health-in-dog-breeds/

Are there specific disorders of concern that are more common in purebreds?

• Bellumori, Thomas P., et al. "Prevalence of inherited disorders among mixed-breed and purebred dogs: 27,254 cases (1995–2010)." Journal of the American Veterinary Medical Association 242.11 (2013): 1549-1555. - https://avmajournals.avma.org/view/journals/javma/242/11/javma.242.11.1549.xml - UC Davis, 24 heritable (genetic) disorders - “Purebred dogs were more likely to have 10 genetic disorders, including dilated cardiomyopathy, elbow dysplasia, cataracts, and hypothyroidism. Mixed-breed dogs had a greater probability of ruptured cranial cruciate ligament.”
• Donner, Jonas, et al. "Frequency and distribution of 152 genetic disease variants in over 100,000 mixed breed and purebred dogs." PLoS genetics 14.4 (2018): e1007361. - https://journals.plos.org/plosgenetics/article?id=10.1371/journal.pgen.1007361 - “Mixed breed dogs were more likely to carry a common recessive disease, whereas purebreds were more likely to be genetically affected with one, providing DNA-based evidence for hybrid vigor.” (i.e. it isn’t a problem if you don’t inbreed on it)

What's up with FDC and the podcast

There's a lot going on behind the scenes of the Functional Dog Collaborative and I have a lot of plans for upcoming podcast episodes. I also have had a bunch of people say they can't record this summer and so it may be a few weeks until I get the next episode out. So here's some stuff to tide you over - explanation of what's going on and what episode topics I have coming up! (If you want to suggest episode topics, or get a chance to have your questions asked during an interview, head over to join our Patreon at https://www.patreon.com/functionalbreeding.)

Dan O'Neill, MVB, PhD, FRCVS: Disorder Testing

Last episode I talked with Dr. Dan O'Neill, a veterinary epidemiologist who studies canine disorders that have an inherited component - what the rest of us might call "genetic diseases." During that interview he mentioned that he didn't think disorder testing - what most of us call health testing - has been workinig to improve canine health. I cut that section because I felt we needed to go into a lot more detail on it to understand what he meant by that, since I knew he didn't mean we should entirely stop health testing - I mean disorder testing. So here is the followup interview. I want to emphasize that he isn't saying disorder testing shouldn't be done as an aid to choosing how to breed dogs. He IS saying that the way we approach choosing and interpreting tests could use a revamp. I hope you enjoy this conversation as much as I did!

Dan O'Neill, MVB, PhD, FRCVS: VetCompass and Inherited Disease

Dan O'Neill, MVB, PhD, FRCVS is a veterinary epidemiologist who studies canine disorders that have an inherited component - what the rest of us might call "genetic diseases." He is the author of more than 95 papers, mostly on the prevalence and risk factors of disorders in dogs based on data drawn from VetCompass, the large scale veterinary database and research tool that he co-leads. Dan was awarded the Kennel Club Charitable Trust "International Canine Health Award" in 2021, and is passionate both about the health of purebred dogs and about saving breeds.

Danika Bannasch, DVM, PhD: The Dalmatian Outcross Project

Danika Bannasch, DVM, PhD returns to the podcast to talk about the Dalmatian Outcross Project. Danika's laboratory found the genetic mutation that was targeted in this outcross, and she had a front row seat to the project's path to acceptance by the AKC and the Dalmatian Club of America. She is also herself a past breeder of Dalmatians. Danika walks us through the genetic, social, and practical implications of high uric acid in Dalmatians, why the outcross was necessary, how it worked, and which populations with different mutations could be helped today by a similar approach (spoiler - one of them is the population of dogs in breeds with high frequency of the chondrodystrophy mutation that we discussed in the previous episode).

Danika Bannasch, DVM, PhD: Chondrodystrophy

Danika Bannasch, DVM, PhD is the owner of Pint, the famous UC Davis football tee retrieving dog. She also happens to run a genetics lab, also at UC Davis, where she studies the genetics of inherited diseases in dogs and other animals. She is known for her work associating genetic variants with a variety of traits including coat color and skull shape. On this episode we're talking about a genetic mutation that she discovered - known to genetic testing companies as CDDY - for a trait she feels passionately about, chondrodystrophy. Most of the dog world knows this mutation as "that risk gene that makes your dog more likely to get IVDD," but in this episode, Danika talks us through the difference between disc herniation and IVDD (intervertebral disc disease), noting that all dogs with CDDY have IVDD, and therefore disc degeneration, whether or not they actually herniate. I hope you learn as much from this discussion as I did.

 

Find this episode's transcript here.

Lisa Gunter, PhD, CBCC-KA: Shelter Dog Welfare

Lisa Gunter, PhD, CBCC-KA is an Assistant Professor at Virginia Tech in the School of Animal Sciences and directs the Laboratory for Animal Behavior and Welfare. Lisa’s research explores the behavior and welfare of companion animals, specifically our interactions with them, as it relates to animal sheltering, behavioral issues, and training. Lisa combines a love of research with hands-on dog training skills. I wanted to have someone from the shelter world on the podcast because, depending on what you mean by "source," shelters are a source of dogs. Lisa and I talked about how shelters can best help dogs cope with the shelter experience and what the future of sheltering might look like.

For those interested in the Applied Animal Behavior and Welfare online MS program at Virginia Tech, where Lisa and Jessica both teach, check it out at https://www.cals.vt.edu/academic-programs/online/omals-program-virginia-tech.html.