Genetics and dog breeding

Question 1

Most Popular Dog Breeds

Answer 1

 Labrador Retrievers (29 years in a row) – data from the American Kennel Club (AKC) so this means ONLY registered breeds and ignores popularity of designer breeds

-then german shepherd, then golden retriever…

Question 2

can mixed breeds register with AKC?

Answer 2

AKC has realized they were losing a huge clientele and you can now register your mutt (or designer breed or whatever) through the AKC Canine PartnersTM Program
 This allows “mutts” to participate in sporting events with their owners

Question 3

Reasons for Genetic Testing

Answer 3

 Paternity
 Disease testing
> Carrier (recessive traits)
> Affected
> Clear
 Trait testing, eg. coat colour testing eg. does this black Lab carry chocolate or yellow? (formerly pedigree analysis)

Question 4

peternity testing methods

Answer 4

 DNA“Fingerprinting”
 BloodTyping
 AKC requirements for Frequently Used Sires (FUS), frozen semen, etc.

Question 5

types of DNA tests for paternity

Answer 5

 Usemarkers
 The AKC used 10 now 14 with gender verification too (MMI)
 Other labs will perform this too
 Ask CKC about which lab results they will accept

Question 6

AKC DNA Data bank breadth

Answer 6

 As of Dec., 2012 the AKC collected over 653,000 DNA profiles from 228 breeds
 In 2017, the top 11 breeds AKC DNA Profiled
> Labrador Retriever; Yorkshire Terrier; German Shepherd Dog; Dachshund; Poodle; Chihuahua; Golden Retriever; Shih Tzu; Pomeranian; Beagle
> These are not the same as the most popular breed list

Question 7

AKC DNA Profile Program; how does it work and how extensive is it

Answer 7

 >709,000 samples have been submitted
voluntary basis and/or to satisfy AKC DNA requirements.
Frequently Used Sires (FUS) Requirement
 >45% of pups registered are from FUS
Some argue this is the biggest problem in purebred dogs

Question 8

What is the AKC multiple-sured litters requirement?

Answer 8

previously, if your bitch had been bred to more than one stud dog, AKC would refuse to register the litter
-often, owners wouldnt know about multiple sires
-test all puppies to determine sires
- now 14 markers and XX vs XY, no ‘unidentifiables’

Question 9

what is the AKC compliance audit program?

Answer 9

-AKC may show up and ask you for DNA samples from your dogs
-when program started, 11% of ‘purebreds’ were not actually
-identifies puppy parentage
-this program only in USA, not canada
>Expect at least 10% of puppies in Canada have wrongly identified parents

Question 10

how many inherited diseases described in dogs? usually caused by what kind of mutation?

Answer 10

350 to 600 inherited diseases described in dogs
precise mode of inheritance known in ~half
-85% caused by a single gene mutation (monogenic disorders)
- 70% single recessive
- 10% polygenic (eg. hip dysplasia)

Question 11

what can the canine health information center tell you?

Answer 11

CHIC site allows you to search by breed or disease - tells you what a breed should be tested for at minimum
>good for client info before they get a dog
>helps with breeding decisions
>open to public

Question 12

Influence of Single Sire on Genetic Diseases: common problem in doberman

Answer 12

Doberman Pinschers and von Willebrand’s Disease

Question 13

how has DNA testing allowed us to decreased affected animals

Answer 13

DNA testing has decreased affected animals by breeding clears to carriers
1997: 30% affected/51% carriers/19% clear 2008: 19% affected/46% carriers/35% clear

Question 14

Methods of Genetic Testing

Answer 14

 Phenotypic tests, eg. CAER (Companion Animal Eye Registry), PennHip, OFA hips, elbows, shoulder, BAER hearing test, etc.
 Metabolic screening eg. urine in MPS VI
 DNA (really only one to test for those diseases that are not apparent at a
young age and best for “carriers”)
 Parental tests with above

Question 15

classic example of a partially hereditary genetic condition

Answer 15

hip dysplasia

Question 16

difference between a horizontal and vertical pedigree

Answer 16

-horizontal only looks at parents, grandparents
- vertical looks at siblings as well, for all generations

> vertical tells you a lot more about what that animal may be carrying
issue is that we rarely have this much information about siblings

Question 17

OFA reccomendations for fair hips; when is a fair dig a good breeding prospect

Answer 17

Fair hips may be within normal limits
eg. Fair hips with a strong hip background and >75% of siblings normal is a good breeding prospect
eg. Excellent hips, but with a weak family background and <75% of its siblings normal is a poor breeding prospect

Question 18

OFA’s Recommended Breeding Principles for hip dysplasia

Answer 18

• Breed normals to normals
• Breed normals with normal ancestry
• Breed normals from litters (brothers/sisters) with a low incidence of HD
• Select a sire that produces a low incidence of HD
• Replace dogs with dogs that are better than the breed average

Question 19

how are hereditary diseases of purebred dogs tracked?

Answer 19

 Every breed has a list of diseases, constantly updated
 Breeders ‘know’ what these are and often what lines have them
 Every breed has internet sites with information

Question 20

World Small Animal Veterinary Association (WSAVA); what info does it give you?

Answer 20

 Web site searchable by breed, disease or laboratory
>Can be used to find nearest lab or best lab for testing for breed and also names, when known, the gene being tested

Question 21

Samples for DNA Testing

Answer 21

 Whole blood in EDTA (lavender top)
 Cheek (buccal) swab with brush
 Dried blood on filter paper

Question 22

what is a wisdom panel?

Answer 22

mixed breed analysis by Mars Veterinary
>tells you what breeds are in your dog
- only check EIC and MDR1 disease genes
-cheek swabs

Question 23

what test is available for mutt health?

Answer 23

Royal canin genetic health analysis (blood)
- performed by Mars
-

Question 24

limitatins of mutt genetic testing? uses and issues?

Answer 24

 Can’t “verify” it’s a purebred since can’t test for EVERY breed, but can be more sure
 Various claims, most ~90% accuracy
 Prices have come down, all use cheek swabs now
 Only two companies as there was an issue of patents
 Those performing both breed and DNA use blood rather than cheek swabs

Question 25

use of fecal DNA detection for dogs

Answer 25

-enforce stoop and poop laws

Question 26

should designer breeders (hybrid) do generic testing? do they often do this?

Answer 26

 Many do a lot of genetic testing of parents
 Web sites of those producing designer breeds RARELY say
they do genetic testing
 Counsel clients to do their homework before purchasing any dog
 MUST test parents for common genetic diseases PRIOR to breeding
 Use clear parents differently from carrier
 Use common sense, for example, bad heart worse than missing teeth!

Question 27

Types of DNA Tests for Disease

Answer 27

Single gene testing
>Clear or Carrier or Affected
ie. Rare false results unless > 1 gene causing same disease (PRA in Chinese Crested)

Linked-marker gene(s) testing
>A or B or C based on frequency of the marker in the population not linked and % recombination reported at the lab,
ie. Subject to Major interpretation!!

Question 28

Counseling Considerations for DNA test and conditions

Answer 28

 Type of DNA test used
 Dominant or recessive trait or X-linked
 Genetic pool for the breed
 Certainty of a genetic basis for the congenital/adult disease/condition
 Severity of disease/condition to health/quality of life of the individual
>eg. cryptorchidism vs PRA vs lysosomal storage disease

Question 29

most common veterinary species with genetic defects? what types?

Answer 29

canine
 Musculoskeletal most common followed by organs of special sense

Question 30

is a congenital defect always genetic?

Answer 30

Congenital defects are often genetic, BUT
Possible Teratogens: medicines, environmental exposures, vaccines, radiation, plants, nutrition, viruses, circulatory disturbance, mechanical factors, aged gametes, aged parents, and UNKNOWN
Karyotype abnormality – maybe hereditary (eg. Robertsonian Translocation) or aged gametes and parents

Question 31

what is the litter effect for generic disorders?

Answer 31

Rarely do all fetuses respond to the same degree
Fetal death, infertility, stillbirth, mummification, congenital defects, apparently normal neonates dying shortly after birth, totally normal puppies

Question 32

how do we approach a diagnosis for congenital disorders?

Answer 32

History (as available) of similar defects in related dogs
>Problem with teasing out environment from genetics in a “kennel”

Lists of common defects by breed are available
>Cleft palates in Bulldogs and other brachycephalic breeds

Compare defect with reports in other species, eg. humans, cattle
>Need to do complete gross and perhaps further post mortem or workup
>Karyotype analysis
>Internet

History during pregnancy eg. medicines, exposure to teratogens

When exposed eg. palate closes about 5 weeks of gestation

Exposure to other dogs eg. returning from shows or new arrivals

Question 33

what contributes to possible teratogenicity of drugs?

Answer 33

 Properties of the drug, eg. metabolism, lipid solubility  Concentration and duration of drug in dam and any
metabolism
 Access to fetuses
 Stage of development at exposure
 Fetal metabolism of drug
 Individual susceptibility
 “Litter effect” – fetuses will not all respond the same- death, resorption, mummification, congenital defects, stillbirth, normal