Most dog breeds highly inbred
Study suggests inbreeding contributes to increase in disease and health
care costs

Date:
December 2, 2021
Source:
University of California - Davis
Summary:
The majority of dog breeds are highly inbred, contributing to an
increase in disease and health care costs throughout their lifespan,
according to new research.



FULL STORY ==========================================================================
Dog breeds are often recognized for distinctive traits -- the
short legs of a dachshund, wrinkled face of a pug, spotted coat of a
Dalmatian. Unfortunately, the genetics that give various breeds their particular attributes are often the result of inbreeding.


==========================================================================
In a recent study published in Canine Medicine and Genetics, an
international team of researchers led by University of California, Davis, veterinary geneticist Danika Bannasch show that the majority of canine
breeds are highly inbred, contributing to an increase in disease and
health care costs throughout their lifespan.

"It's amazing how inbreeding seems to matter to health," Bannasch
said. "While previous studies have shown that small dogs live longer than
large dogs, no one had previously reported on morbidity, or the presence
of disease. This study revealed that if dogs are of smaller size and not inbred, they are much healthier than larger dogs with high inbreeding." Inbreeding affects health The average inbreeding based on genetic analysis across 227 breeds was close to 25%, or the equivalent of sharing the same genetic material with a full sibling. These are levels considered well
above what would be safe for either humans or wild animal populations. In humans, high levels of inbreeding (3-6%) have been associated with
increased prevalence of complex diseases as well as other conditions.

"Data from other species, combined with strong breed predispositions
to complex diseases like cancer and autoimmune diseases, highlight the relevance of high inbreeding in dogs to their health," said Bannasch,
who also serves as the Maxine Adler Endowed Chair in Genetics at the UC
Davis School of Veterinary Medicine.



==========================================================================
The researchers partnered with Wisdom Health Genetics, a world leader
in pet genetics, to obtain the largest sample size possible for
analysis. Wisdom Health's database is the largest dog DNA database in
the world, helping researchers collect data from 49,378 dogs across 227
breeds -- primarily from European sources.

Some breeds more inbred So, what makes a dog breed more inbred than
others? Bannasch explained that it's often a combination of a small
founding population followed by strong selection for particular traits
in a breed -- often based on looks rather than purpose. While she has
always had an interest in the population structure of some of these
breeds, she became particularly interested in the Danish-Swedish farmdog several years ago. She fell in love with their compact size, disposition
and intelligence, and ended up importing one from Sweden.

Bannasch discovered that Danish-Swedish farmdogs have a low level
of inbreeding based on their history of a relatively large founding
population of 200, and being bred for function, rather than a strong
artificial selection for looks.

And according to the insurance health data on breeds collected from Agria Insurance Sweden and hosted online by the International Partnership for
Dogs, the farmdog is one of the healthiest breeds.

The study also revealed a significant difference in morbidity
between brachycephalic (short skull and snout) and non-brachycephalic
breeds. While that finding wasn't unexpected, the researchers removed brachycephalic breeds from the final analysis on effects of inbreeding
on health.



========================================================================== Preserving genetic diversity In the end, Bannasch said she isn't sure
there is a way out of inbred breeds.

People have recognized that creating matches based solely on pedigrees
is misleading. The inbreeding calculators don't go back far enough in a
dog's genetic line, and that method doesn't improve overall high levels
of population inbreeding.

There are other measures that can be taken to preserve the genetic
diversity and health of a breed, she said. They include careful management
of breeding populations to avoid additional loss of existing genetic
diversity, through breeder education and monitoring of inbreeding levels enabled by direct genotyping technologies.

Outcrosses are being proposed or have already been carried out for some
breeds and conditions as a measure to increase genetic diversity, but care
must be taken to consider if these will effectively increase overall breed diversity and therefore reduce inbreeding, Bannasch said. In particular,
in the few breeds with low inbreeding levels, every effort should be
made to maintain the genetic diversity that is present.

Other UC Davis authors include Thomas Famula, Kevin Batcher, Noa Safra,
Sara Thomasy and Robert Rebhun. Contributors from Wisdom Health Genetics include Jonas Donner, Heidi Anderson and Leena Honkanen.

This work was supported by the International Canine Health Award and
the Maxine Adler Endowed Chair Fund.

========================================================================== Story Source: Materials provided by
University_of_California_-_Davis. Original written by Trina Wood. Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. Danika Bannasch, Thomas Famula, Jonas Donner, Heidi Anderson, Leena
Honkanen, Kevin Batcher, Noa Safra, Sara Thomasy, Robert Rebhun. The
effect of inbreeding, body size and morphology on health in
dog breeds.

Canine Medicine and Genetics, 2021; 8 (1) DOI:
10.1186/s40575-021-00111-4 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/12/211202162148.htm

--- up 3 weeks, 2 hours, 55 minutes
* Origin: -=> Castle Rock BBS <=- Now Husky HPT Powered! (1:317/3)