Dog Genetics

Question 1

Genetic Theory

Answer 1

• Same as with other animals
• Diploid number = 78 (chromosomes)
• 38 pairs of autosomes
• 1 pair of sex chromosomes
• Some things are speculative

Question 2

Coat Genetics

Answer 2

Controlled by 3 genes:
-Hairlessness (h) - probably homozygous lethal
-Wiry Hair
* Incompletely dominant - heterozygote is somewhere in between

-Pigments (2)
* Melanin (gray, black)
* Pheomelanin (red, orange yellow)

Question 3

Bedlington terrier

Answer 3

Hair gets lighter over time - starts black, turns gray

Question 4

Merle - want to produce heterozygotes

Answer 4

MM - white or almost white, other problems
* Often blind
* Eyes may be small, malformed
* Often deaf
* Pups often die or must be destroyed
* Homozygous semi-lethal

Mm - irregular patches of black on blue or tan (desired color)
mm - non-merle

Question 5

Spotting genes (Piebald series)

Answer 5

Extreme Piebald - almost all white

Question 6

Ticking

Answer 6

Colored areas have little patches of white in it, white areas have little patches of color
T - spots of color ticking in white areas
t - no ticking, clear white areas

Question 7

Pleiotropy

Answer 7

One gene affects multiple traits

Question 8

Dalmatians

Answer 8

Health situations
* Deafness - common
* Uric acid production - bladder stones in dalmatians must often be removed surgically

Question 9

Hip Dysplasia

Answer 9

• Fairly common problem in some breeds
• Hip joint breaks down - ball and socket, ball is too flat, hips move out of socket
• Very painful to walk - too much movement can cause arthritis
• Can be diagnosed by X-ray
• PFA certification
• Afflicted should not be used as breeders

Question 10

Collie eye anomaly

Answer 10

Collies have been selected to have really long, narrow muzzle - eventually changed shape of skull
* Causes problems with eyes - detached retinas, pressure on nerves of eyes

Question 11

Respiratory problems

Answer 11

Dogs that were bred for short muzzle (ex. pug)

Question 12

Back problems - dachshunds, boxers

Answer 12

Dachshunds - select for long body
Boxers - select for tight and muscled body

Question 13

Skin problems

Answer 13

Dogs bred for wrinkly skin - make sure it is cleaned

Question 14

Other Breed-Related Issues

Answer 14

• Nearly every breed has some specific problems that have been found in that breed
• Check into these when deciding on a breed, and then discuss with breeder
• Some genetic tests being developed now

Question 15

Inbreeding

Answer 15

Increases homozygosity
* Advantage: increases predictability, “purity” - sometimes necessary
* Disadvantage: can increase incidence of deleterious (“bad”) recessive traits

To be used properly, must be willing to remove problems from the gene pool
Potential usefulness of inbreeding
* Breed formation (linebreeding)

Question 16

GOAL: To produce a Dalmatian that does not produce uric acid

Answer 16

1.Cross Dalmatian with a Pointer
First generation:
* All will be heterozygous, likely none will produce uric acid

2.Backcross to dalmatian
* Take out of gene pool any that produce uric acid

3.Backcross to dalmatian again
* Again, eliminate from gene pool any that produce uric acid
…
After 6 generations of backcrossing (including first cross), pups should be 98% Dalmatian