NAVLE Theriogenology and Reproductive Medicine — Questions and Answers
Question 1: A 5-year-old Holstein cow has not shown estrus 60 days postpartum. Rectal palpation reveals a corpus luteum (CL) on one ovary with no other abnormalities. Which treatment protocol is most appropriate to initiate cyclicity?
- Administer GnRH to stimulate follicle-stimulating hormone release
- Administer prostaglandin F2α (PGF2α) to lyse the CL and allow return to estrus (Correct answer)
- Begin a progesterone-releasing intravaginal device (PRID) for 14 days
- Administer estradiol cypionate to induce a standing heat
Correct answer: Administer prostaglandin F2α (PGF2α) to lyse the CL and allow return to estrus
A persistent CL causing anestrus is treated with prostaglandin F2α (dinoprost or cloprostenol), which causes luteolysis — regression of the CL, progesterone levels drop, and the cow returns to estrus within 2–5 days. GnRH induces ovulation of the dominant follicle but does not address a persistent CL. PRIDs are used for synchronization, not CL regression.
Question 2: During a routine equine breeding soundness evaluation (BSE) in a 4-year-old Thoroughbred stallion, semen evaluation reveals: total motility 65%, progressive motility 45%, morphology 55% normal sperm. Per AAEP guidelines, how should this stallion be classified?
- Satisfactory potential breeder
- Questionable potential breeder (Correct answer)
- Unsatisfactory potential breeder
- Deferred — repeat evaluation in 30 days
Correct answer: Questionable potential breeder
AAEP minimum standards for a satisfactory equine BSE are: total motility ≥60%, progressive motility ≥60%, normal morphology ≥60%. This stallion fails progressive motility (45% vs. ≥60% required) and morphology (55% vs. ≥60% required), placing him in the 'questionable' category — not outright unsatisfactory, which requires multiple parameters clearly below threshold.
Question 3: A primiparous Labrador Retriever bitch delivered 6 puppies 18 hours ago. She is now febrile (40.5°C), depressed, and has a malodorous dark vaginal discharge. Abdominal palpation reveals uterine discomfort. The most likely diagnosis and first-line treatment are:
- Subinvolution of placental sites — supportive care and monitoring
- Acute metritis — broad-spectrum antibiotics (amoxicillin-clavulanate), oxytocin, and supportive care (Correct answer)
- Mastitis — hot-pack mammary glands and oxytocin to promote drainage
- Eclampsia — IV calcium gluconate 10% slowly to effect
Correct answer: Acute metritis — broad-spectrum antibiotics (amoxicillin-clavulanate), oxytocin, and supportive care
Acute postpartum metritis presents with fever, depression, malodorous uterine discharge, and uterine pain within the first week after delivery. Treatment includes broad-spectrum antibiotics (covering gram-negative organisms and anaerobes), oxytocin or PGF2α to promote uterine evacuation, and IV fluid support. Eclampsia presents with tetany/seizures, not discharge.
Question 4: A 7-year-old mare is presented for evaluation of repeat breeding failure. Uterine culture yields a pure growth of Streptococcus equi subsp. zooepidemicus. Cytology shows >2 neutrophils per low-power field. The most appropriate initial treatment is:
- Systemic enrofloxacin for 14 days
- Uterine lavage with large-volume saline followed by intrauterine infusion of appropriate antibiotic after culture and sensitivity (Correct answer)
- Intrauterine oxytocin to promote drainage without antibiotics
- Systemic penicillin G IM for 10 days only
Correct answer: Uterine lavage with large-volume saline followed by intrauterine infusion of appropriate antibiotic after culture and sensitivity
Equine endometritis caused by Streptococcus zooepidemicus is best treated with uterine lavage (to remove exudate and biofilm) followed by culture-guided intrauterine antibiotic infusion (typically penicillin or amikacin). Systemic antibiotics alone achieve poor uterine concentrations. Lavage without antibiotics is insufficient for established infection.
Question 5: A beef cow has been in second-stage labor for 90 minutes with no calf produced. Vaginal examination reveals a calf in dorsal longitudinal presentation with both forelimbs retained. Which corrective manipulation should be performed?
- Apply traction immediately to the visible head to deliver the calf
- Repel the head, extend and cup each forelimb in turn, then reposition in anterior presentation before applying traction (Correct answer)
- Perform fetotomy of the head to relieve obstruction
- Administer oxytocin 20 IU IV to increase uterine contractions
Correct answer: Repel the head, extend and cup each forelimb in turn, then reposition in anterior presentation before applying traction
Retained forelimbs (head-only presentation) must be corrected before traction to avoid traumatic brachial plexus injury and uterine laceration. The calf is repelled cranially (pushed back into the uterus) to create space, each forelimb is cupped and brought into extension one at a time, then traction is applied with the calf in normal anterior presentation. Traction on the head alone risks elbow lock and maternal injury.
Question 6: Which statement correctly describes the feline estrous cycle?
- Queens are spontaneous ovulators with a 21-day cycle similar to dogs
- Queens are induced ovulators; without mating or coital stimulation, they undergo repeated estrous cycles during the breeding season (Correct answer)
- Queens are seasonally polyestrous induced ovulators with luteal phase length of 2–3 weeks after infertile mating
- Queens ovulate spontaneously mid-estrus and develop a functional CL regardless of mating
Correct answer: Queens are induced ovulators; without mating or coital stimulation, they undergo repeated estrous cycles during the breeding season
Cats are seasonally polyestrous (long-day breeders) and induced ovulators — ovulation requires coital stimulation of the vagina/cervix causing a neuroendocrine GnRH surge. Without mating, queens cycle repeatedly through estrus (lasting 4–7 days) and interestrus periods throughout the breeding season without forming a CL. If mating occurs but does not result in pregnancy, a pseudopregnancy of ~35–40 days follows.
NAVLE Theriogenology and Reproductive Medicine
A 5-year-old Holstein cow has not shown estrus 60 days postpartum.
Rectal palpation reveals a corpus luteum (CL) on one ovary with no other abnormalities.
Which treatment protocol is most appropriate to initiate cyclicity?