Disturbances of Repro in EQUINE

Question 1

Describe the most common ovarian tumor in mares

Answer 1

Granulosa (Theca) Cell Tumor (GTC/CTCT)
- benign, slow-growing masses
- typically unilateral: 1 enlarged (honeycomb appearance), 1 inactive (anestrus-like)
- hx: behavioral changes (behaves like a stallion, acts like she’s in estrus)
- dx: hormone analysis (P4 low b/c not cycling/not going into diestrus; 50% have incr. Testosterone, 90% have incr. Inihibin, 98% have incr. anti-mullerian hormone)
- cure = sx removal

Anti-Mullerian Hormone (AMH) is produced by granulosa cells in the equine ovary and in normal mares this level is very low (usually less than 1.0 ng/mL). AMH levels in normal mares do not significantly change during oestrus or pregnancy, unlike Inhibin, and this makes it clinically more useful in these cases.

Question 2

Mare presents for colic. No significant findings during PE except for pain on palpation. You perform an ultrasound and visualize an enlarged ovary. What is your diagnosis? What will you treat with?

Answer 2

Dx = Ovarian hematoma
Tx = Prostaglandin (once it luteinizes)

painful b/c putting pressure on broad ligament

Question 3

Tx for persistent CL

Answer 3

Prostaglandin

• CL continues to produce progesterone- if not treated, the CL will eventually lyse in 2-3 months. Not ideal for a mare one is trying to breed, so tx usually performed.

Question 4

You have a performance mare with behavioral issues. The owner wants to maintain a steady production of progesterone in this mare to aid with them. How will you go about this?

Answer 4

Want to induce a persistent CL / prevent lysis and prolong diestrus stage -> administer oxytocin, which prevents prostaglandin production in uterine endometrium

alternative to giving altrenogest (regumate) daily

Question 5

You are having issues with breeding a mare. Even though you have AI the mare severa times, she keeps failing to ovulate, over and over. What is your diagnosis?

Answer 5

Hemorrhagic Anovulatory Follicles (HAF)
- a breeding issue (a $$ loss)
- follicle develops normally, go though estrus normally, but NEVER OVULATES
- after failing to ovulate, follicle develops hemorrhagic speckles from bleeding into the follicle
- solution: most luteinize then respond to PGF; some do not luteinize but regress spontaneously
- increased risk w/ age & previous HAF

Question 6

Urine pooling
- etiologies
- consequences

Answer 6

Etiologies:
1. nerve damage
2. aged mares
3. poor conformation of cervix/vagina

Urine backflowing into vagina leads to inflammation -> fibrosis/scarring -> more difficult to become pregnant

Left = normal, Right = abnormal conformation.

Question 7

A healthy mare has a history of foaling trauma // tearing of her cervix. The owner wants to breed her again, but is unsure if she is able to due to this history. What length must the mare’s cervix be in order to successfully maintain another pregnancy?

Answer 7

Greater than 50% of original length
- her cervix must be able to stay tightly closed/protect the uterus/fetus from the external environment

sx repair -> scarring/adhesions are not as strong as original tissue

Question 8

When examining a mare for a foaling trauma laceration to her cervix, why should you perform a digital palpation when she is in diestrus?

Answer 8

Diestrus: cervix = longer & firm, so no need to distinguish between a normal anatomical fold versus actual laceration (unlike during proestus/estrus when the cervix is soft)

Question 9

Rectovaginal fistula

Answer 9

A foaling trauma (laceration) of the vagina: Hoof penetrates through floor of rectum and exits the mare thru the anus. Surgical repair of this laceration is performed after 6 weeks in order to allow for granulation tisue to form, + soften her manure to protect the sutures during recovery

Question 10

Endometritis
- predisposing factors (5)
- etiologies (infectious versus non-infectious)
- diagnostic methods (6)
- treatment options (5)

Answer 10

Endometritis = inflammation of uterine lining

1. Predisposing factors:
- Degenerative uterine changes (weakend uterine defence mechanisms- post-breeding contractions)
- Older mares; PPID
- Repeated foaling
- Poor vuvlar conformation
- Abnormal cervix (age-related firbosis; scarring)

2. Etiologies:
- Infectious contamination (Strep. equi zooepidemicus, E. coli, Pseudomonas aeruginosa, Klebsiella): inadequate seals, improperly cleaned stallion / mare
- Non-Infectious contamination (Semen, air, urine): post-mating endometritis (abnormal inflammatory response, delayed uterine clearance), uterine irritants (air, urine)

3. Diagnosis
- Hx + uterine cytology + culture

4. Treatment
- Correct vulvar conformation
- Uterine lavage (sterile fluids)
- Contraction inducers: Oxytocin (strong & short); Cloprostenol, PGF (weak & prolonged)
- Uterine infusors (mucolytics, chelators)
- Systemic versus Intra-uterine ABXs

Post-mating endometr. will recur each cycle

Question 11

Endometrial Cysts in the breeding mare
- definition
- how do they affect fertility (3)
- how to differentiate from embryo
- treatment

Answer 11

Dilated endometrial glands in areas of fibrosis - older mares
- more/larger cysts = higher chance of infertility (impair MROP, mvmt. of embryo, fluid clearance)
- Appear similar to an embryo (both are round) -> differentiate via change in size from breeding to pregnancy check (embryo grows, cyst will not)
- tx = laser ablation

Question 12

A mare presents for copious amounts of grey vulvar discharge. This condition has a carrier status in which the organism inhabits the clitoral sinus (mare) and the urethral fossa (stallion). What is the name of this condition, inciting organism, and its transmission? Why is it reportable?

Answer 12

Bacterial Venereal Disease = Contagious Equine Metritis (CEM)
- Taylorella equigenitalis
- Transmission = breeding (or fomite)
- Reportable b/c NOT endemic the United States

Question 13

What organisms are opportunistic pathogens(2) and cause veneral disease? How do stallions serve as source of these diseases?

Answer 13

Bacterial Venereal Diseases
1. Klebsiella pneumoniae
2. Pseudomonas aeruginosa
- Improperly managed stallion: normal flora on penis disrupted during breeding prep (cleaned with soap INSTEAD OF JUST WATER) + overgrowth of pathogenic flora -> spread via semen to mare -> endometritis
- Several mares bred to same stallion are unable to become pregnant b/c of that one
- NOT common

Question 14

Name the condition: Respiratory virus that can cause abortion in mares & carriers in stallions. Is it reportable?

Answer 14

Viral Venereal Disease = Equine Arteritis Virus
- Equine viral arteritis
- Reportable in some states
- other CS: fever, resp. disease, edema

Question 15

Name the condition: Painful vesicles/pustules/ulcerations on vulva or penis

Answer 15

Viral Venereal Disease = Equine Coital Exanthema (EHV-3)
- resolve on own w/ time

Question 16

Name the condition + inciting organism: Mucopurulent vaginal discharge + “silver dollar plaques” (edematous patches on skin). Is it reportable?

Answer 16

Protozoal Venereal Disease = Dourine
- Trypanasoma equiperidum
- HIGH MORTALITY RATE
- REPORTABLE

Question 17

How are most twins produced in mares?

Answer 17

Double ovulation (and not cleavage of embryo)

Question 18

Why are twins bad for mares? How to diagnose?

Answer 18

• 60-80% abort (14% of foals born alive survive > 1 week)
• Dx = 2 large follicles during estrus; 2 ebryos @ preg. check

Day 14

Question 19

Treatment options for reducing twins in mare: Pre- (4) and Post-day 45 (2) options

Answer 19

PRE DAY 45
1. Natural reduction to singleton (single fetus) BEFORE day 40 - will occur naturally for 85% of cases (fixed on same horn) but < 5% for opposite horns
2. Terminate pregnancy prior to day 35 (endometrial cups start forming), but mare will likely double ovulate again on next cycle
3. Manual Reduction via u/s probe to crush embryo (@ 13-16 days, >90% single foal born; @ 17-30 days, 75% single foal born)
4. Transvaginal u/s-guided apsiration (@ 16-45 days - increased risk if unilateral embryos)

POST DAY 45
5. Cervical dislocation (@ 60-120 days) - 60% single foal born
6. Transcutaneous u/s-guided injection of KCl in fetal heart/body (@ 110-130+ days) - 50% single foal born

If you terminate pregnancy after day 35, the endometrial cups will begin forming and once they do, the mare will NOT cycle again until 120 days, which will make it too late in the breeding season.

Endometrial cups in horses are outgrowths appearing in the uterine wall of the pregnant horn between approximately 38 days and 150 of gestation. The cups are structures which vary in shape from oval to irregular and have distinct raised edges, showing an ulcer-like form

Question 20

Consequences to twin foals being born alive? (5)

Answer 20

1. Difficult labor (poss. hypoxic schemic encephalopthy in foal)
2. Smaller-than-normal foals
3. FPT (foals too small/weak to reach udder)
4. Incomplete ossification of C/T bones (develop arthritis, painful)
5. Varus & valgus abnormalities (uterine position; number 4)

“Valgus” = force that pushes in toward the center of your body. “Varus” = pushing out, away from the center of your body. It’s the opposite of valgus.