Genetics of conformation in dogs

Question 1

giant dog breed characteristics

Answer 1

-~100lbs, 22-42 inches at withers
-bred for protection and work that require great strength
-grow rapidly
-common problems: hip dysplasia, arthritis

Question 2

giant breed genes

Answer 2

-issues with the pituitary gland and somatatrophin
-IRS4-insulin receptor substrate 4-deletion
-IGSF1-immunoglobin superfamily 1- homozygous mutation
-ACSL4-acyl-coA synthetase long-chain family member 4

Question 3

small and miniature breeds

Answer 3

-proportional size decreases
-8-12 inches at the withers
-bred to decrease size
-PWD size range from 25-75lbs
-smaller PWDs had an identical piece of DNA on dog chromosome 15

Question 4

small size genetics

Answer 4

-IGF1 (insulin like growth factor 1) assoceated with small sized dogs (chromosome 15)

Question 5

issues with minimization

Answer 5

-hydrocephalus
-protruding eyes, prone to problems
-bite problems
-bite problems
-cryptorchidsm
-luxating patella

Question 6

dwarf breedds

Answer 6

-have shortened limbs but normal torso and head
-fibroblast growth factor 4 (FGF4) retrogene
-recessive- two copies of retrogene found in genome

Question 7

skull types

Answer 7

-dolichocephalic
-mesaticephalic
-brachycephalic

Question 8

characteristics with dolichocephalic

Answer 8

-long muzzle
-narrow base
-shifts canter of gravity
-allows greater speed

Question 9

characteristics with mesaticephalic

Answer 9

-moderate head shape
-allows strength to the jaw

Question 10

characteristics with brachycephalic

Answer 10

-strength to the jaw
-breeds developed to fight

Question 11

dog skull gene

Answer 11

variation of BMP3 contributes to dog breed skull diversity

Question 12

variation in ears

Answer 12

-inheritance is not a simple mendelian trait
-floppy ears found in foxes selected for tameness
-possible mutation involved in cartilage enzyme methionine sulfoxide reductase B3 (MSRB3)

Question 13

what are floppy ears prone to

Answer 13

infections and mites

Question 14

ear cropping

Answer 14

-cropping is controversial
-banning in some countries now- no federal laws banning ear cropping (just provincial laws)
-cropping involves surgical removal of a section of ear about 9-12 weeks of age
-ears must be bandaged with splint for weeks after
-was done in guard dogs to prevent injury with fighting
-cosmetic procedure

Question 15

tail docking

Answer 15

-docking is becoming controversial
-cut at 2 days with out anesthetic
-some European countries do not allow docked dogs in showring
-usually in dogs bred for hunting and herding

Question 16

natural bob tails

Answer 16

-T-box transcription factor T (TBXT) mutation present in most dogs with naturally bob tails
-nucleotide change—> amino acid change
-mutation found in 18 of 24 breeds studied
-homozygous lethal mutation