Reproduction in Sheep & Goats Flashcards
What kind of estrous cycle do does and ewes have? How does the interestrus interval compare?
seasonally polyestrous, short-day breeders (August-March, peak at October-December)
- DOE = 20-21 days
- EWE = 16-17 days
- during transitional period or non-breeding season (luteal failure)
How long does estus last in does and ewes? What is their first ovulation like?
36 hours –> late in estrus, requires progesterone priming
silent estrus - due to no P4 priming
What is the ram/buck effect?
ewe/doe does not exhibit signs of estrus when the ram/buck is not present –> use teaser males prior to breeding season to stimulate cyclicity
How are teaser males used to induce cyclicity in does/ewes?
- no contact for 3-4 weeks prior
- induce fenceline contact with highly fertile or vasectomized males
- generally ovulation should occur within 6 days (silent)
When are does/ewes inseminated? What is considered the time of optimal insemination? What are 3 options?
behavioral signs of heat in the presence or with the odor of a buck/ram –> interest, tail flagging, vocalization, increased urination
mucous turns cloudy
- vaginal/cervical AI
- transcervical AI - NOT in sheep due to the folds in the cervix
- laparoscopic intrauterine AI - bypass vagina and cervix, able to use less semen
How long is gestation in goats/sheep? What is their placentation like?
5 months
synepitheliochorial, cotyledonary with concave caruncles
What is a normal breed difference in placentation? What 4 tests are used for pregnancy diagnosis?
caruncular melanosis –> black-faced sheep (Suffolk)
- interferon tau - day 13-15
- pregnancy-specfiic protein B - > day 25 in goats, day 30-70 in sheep
- estrone sulfate - >50 days (viable fetus)
- progesterone - >21 days in goats, >18 days in sheep (low in nonpregnant)
What are the sources of progesterone in does and ewes?
DOES - CL
EWES - CL until days 50-60, then placenta
What 3 types of imaging can be done to diagnose pregnancy in does/ewes?
- transrectal U/S - days 30-35, embryonic vesicle
- transabdominal U/S - days 45-70, embryonic vesicle, fetus, placentomes
- radiographs - >90 days, fetal skeletons
What is seen in this ultrasound of a goat’s uterus?
placentome
In what small ruminants is uterine prolapse most common? How is it treated?
sheep > goats –> genetic, do not use as breeding animals
- early/mild - only seen in recumbency, typically do not need treatment
- complete - clean exposed tissue, decrease size, and replace tissue gently, place paddle, harness, or modified Buhner suture
What is likely the cause of the odd appearance of this goat?
distended uterine lumen –> hydrometra (“cloudburst”
- pyometra would have some hyperechoic fibrin in the fluid
What are 3 signs of hydrometra? How is it treated?
- anestrus
- pregnancy-like - abdominal enlargement and elevated progesterone from persistent CL
- variable accumulation of fluid within uterus due to closed cervix
PGF2a - resume cycle and induce luteolysis
What are some possible causes of hydrometra?
- pseudopregnancy - cessation of luteolysis in absence of pregnancy
- early pregnancy loss
What are some noninfectious and infectious causes of infertility in female sheep and goats?
polled intersex syndrome, toxic Veratrum californicum
- Toxoplasmosis
- Q fever
- Chlamydiosis
- Campylobacteriosis (sheep > goats)
- Brucellosis
- Border disease
- Bluetongue virus
- Cache Valley disease
- Schmallenberg virus
What is polled intersex syndrome? What genetic predisposition is associated?
60, XX, SRY-, testicular DSD –> male pseudohermaphrodites (undescended testicles with female secondary genitalia)
dominant polled gene (no horns) is closely linked to recessive intersex gene/gene deletion
What phenotype is associated with polled intersex syndrome?
- polled goats
- female-like at birth
- intra-abdominal or partially descending testes
- always sterile
What toxic plant typically causes infertility in sheep? What signs are associated with the timing on ingestion?
Veratrum californicum –> teratogenic alkaloids
- 12th-14th day of gestation = cyclops, prolonged gestation associated with absence of pituitary gland
- after day 14 = shortened limbs, tracheal stenosis, increased embryonic loss
What causes Toxoplasmosis in goats and sheep? What signs are associated? What are the pathognomic lesions?
Toxoplasma gondi - shed in cat feces
- abortion
- mummification
- stillbirth
- birth of weak kids/lambs
pepperoni-like necorsis of cotyledons –> white to yellow focal areas of necrosis and calcification with normal inter-cotyledonary areas
How is Toxoplasmosis diagnosed? Managed?
stained smears of cotyledons + histopath
- limit exposure to infected cat feces
- coccidiostats
What causes Q fever? How is it transmitted?
Coxiella burnetii - G-, intracellular
inhalation or MM contact with aborted materials
What placental lesions are indicative of Q fever? How is it diagnosed? Treated?
- necrosis of cotyledons
- thickened intercotyledonary areas
large numbers of organisms in placental tissue
tetracyclines
What causes Chlamydiosis in small ruminants? What sign is associated?
Chlamydia abortus –> Enzootic Abortion of Ewes, more common in goats in the US
abortion within last 2-3 weeks of gestation
How is Chlamydiosis transmitted? What acts as reservoirs?
ingestion and inhalation from aborted materials and vaginal d/c –> sheep-to-sheep contact especially at lambing
pigeons and sparrows
What pathological changes are seen with Chlamydiosis? How is it treated?
nonspecific - generalized placentitis, stained placental smear with elementary bodies
Tetracyclines
What 2 species cause Campylobacteriosis in small ruminants? What sign is associated?
- Campylobacter fetus subsp fetus - large outbreaks
- C. jejuni - sporadic abortion
- most significant cause of abortion in sheep in the US (ewes are typically not sick)
late-gestation abortions and weak/stillborn lamb
How is Campylobacteriosis transmitted? What pathological changes are characteristic?
ingestion (unlike venerally transmitted in bovines)
- aborted lambs with grossly visible liver necrosis
- edematous placenta with necrosis of cotyledons
How is Campylobacteriosis treated?
- Tetracycline in feed or injection of long-acting
- vaccinate all pregnant ewes during outbreak
