Canine Breeding Management

Question 1

describe the canine estrous cycle

Answer 1

1. NOT seasonal breeders
2. inter-estrus interval average: 7 months
3. puberty = onset first proestrus (6-24 months); size and breed dependent
   -exceptions: only of anestrus length
4. cycle:
   -proestrus: 9 days
   -estrus: 9 days
   -diestrus/preg: 60d
   -anestrus: 90-150d

Question 2

describe estrogen’s role in the canine estrous cycle

Answer 2

1. increased estrogen causes increased capillary permeability and diapedesis of RBCs
2. increased estrogen also causes vaginal epithelium to become hyperplastic, causing superficial epithelial cells to cornify or become keratinized
3. vaginal epithelial cells throughout cycle
   -parabasal in diestrus
   -intermediate in proestrus
   -superficial nuclear then superficial anuclear in estrus
   (fried egg to cornflake)

Question 3

describe vaginal cytology

Answer 3

not just for breeding management!

-a cheap assessment of estrogen levels for hyper-estrogenism syndromes
(ovarian remnant in spayed females, GCTC, exposure to exogenous estrogen creams, can even work on prepuces to determine estrogen exposure)

Question 4

describe proestrus

Answer 4

1. average 9 days
2. increase in LH pulses at end of anestrus causes follicular growth which causes increased plasma estrogen
3. estrogen peaks at end of proestrus
4. physical exam: vulvar swelling, serosanguinous vulvar discharge (originates from uterus)
5. behavior: attracts males but won’t stand for mating
6. cytology: starts <10% cornified at onset then >90% cornified by end of proestrus
   -nondegenerate PMNS and many RBCs

Question 5

describe estrus

Answer 5

1. average 9 days
2. increasing progesterone throughout
   -unique! follicles start to luteinize PRIOR TO ovulation!!!
3. physical exam: less vulvar swelling, vulvar discharge more serous
4. behavior: attracts males AND stands for mating
5. cytology: >90% cornified, most anuclear, NO PMNS, fewer RBCs (thickest epithelium = hardest for WBCs to cross; if see them get concerned)

Question 6

describe diestrus

Answer 6

1. approx 60 days
   -same whether pregnant or not, no maternal recognition of pregnancy
2. Day 1: sharp decrease to <50% cornified
   -can use for retrospective calculation of fertile period;
   -usually ovulate 6d before day 1 diestrus
3. whelp 57 +/- 2 days from day 1 of diestrus
4. cytology: some nondegenerative PMNs, no RBCs, some metestrus

Question 7

describe anestrus

Answer 7

1. 90-150d
   -most variable stage in length, by breed and age
2. basal progesterone and estradiol
3. physical exam: no detectable changes
4. behavior: does not attract males or stand to be mated
5. cytology: parabasal cells, some neutrophils, no RBCs

Question 8

describe the first estrus

Answer 8

1. often irregular
2. may be split heat:
   -LH surge but no ovulation, then can come into heat 6-8 weeks later
   -looks like two heats back to back and concerns owners
3. shouldn’t breed on first heat!
   -lower fertility
   -potentially increased risk of dystocia bc baby (not 2 years of age and not skeletally mature)

Question 9

how are vets involved in breeding management?

Answer 9

pre-breeding consult and exams

1. client education
2. general PE
3. vaccinations (MUST be up to date)
4. parasite control- also must be up to date
5. genetic screening: breed specific
6. CERF, OFA exams
7. brucellosis testing: EVERY LITTER
8. CHV-1 serology

Question 10

describe the fertile period

Answer 10

depends on type of insemination!

-in general: want to breed AFTER ovulation
-DOGS do not ovulate mature oocytes! need 36-48 hours post ovulation to be mature enough for fertilization

Question 11

describe natural mating

Answer 11

-breed every 48 hours until go out of heat
-used when: male and female in same area, both dogs young and healthy, no history of infertility
fails when: poor timing (female not actually in estrus), dominant female, inexperience, size mismatch, vaginal strictures, spinal or hind limb pain

-diagnose and treat condition, AI

Question 12

describe breeding management

Answer 12

1. vaginal cytology and serum progesterone every 48 hours
2. determine date of LH peak and ovulation
   -testing LH: LH surge really is only one day, so if testing every other day might miss, so commonly use progesterone as surrogate for LH
   -progesterone is usually around 2ng/ml at LH peak! once increase past that, you know they’ve already had their LH peak and will expect to ovulate 2 days later
3. breeding date based on type of semen used and number of inseminations

Question 13

describe vaginal insemination with fresh semen

Answer 13

do because: inability to mate, overbooked males, or some male subfertility

use a long pipette, inseminate as far cranial as we can

Question 14

describe AI with cooled semen

Answer 14

1. ideally within 24-48 hours but most can last 5-7d
2. ideally breed twice, 48 hours apart
   -day 3 and 5 post LH
   -day 4 and 6 post LH
   -sometimes base timing on male semen quality
3. rule of 2s: LH peak at 2ng/ml progesterone, ovulate 2 days later, oocytes mature 2 days after that

Question 15

describe AI with frozen semen

Answer 15

1. often only one insemination dose, esp if using surgical insemination
   -day 5 or 6 post LH
2. MUST do intrauterine insemination (transcervical or surgical)
   -sperm doesn’t live as long after cryopreservation
   -get close to site of fertilization (want IN uterus if possible)
   -usually smaller total number of sperm

Question 16

describe pseudopregnancy clinical signs

Answer 16

1. behavioral changes:
   -nesting
   -aggression
   -variable appetite
2. mammary gland development: may lactate
3. often also see weight gain

Question 17

describe pseudopregnancy

Answer 17

1. in non-pregnant bitches during diestrus
2. a physiologic process (dogs don’t have recognition of pregnancy)
3. can also occur if spayed during late estrus/diestrus
4. progesterone withdrawal canuses prolactin increase which can trigger pseudopreg

Question 18

describe treatment of pseudopregnancy

Answer 18

first diagnose via clinical signs and non-pregnancy

1. no treatment needed, resolves with time!
2. if owners need something to do
   -cold and warm mammary compresses
   -food and water restriction
3. IF medical management needed
   -megesterol acetate (progestagen) for 8d is only approved treatment but may relapse once stop tx
   -mibolerone (androgen) for 5d
   -bromocriptine or cabergoline (D2 dopamine receptor agonists) for 5-10d
   -spay them, may not necessarily help tho