Equine Reproduction

Dr. Jack Sales, DVM

LESSON FOUR

Broodmare Management

In this lesson we continue to discuss the broodmare and examine some of the modern techniques used on the breeding farm to make for a more efficient program.

Assignment: Read Chapter 4 – Breeding Soundness Examination in the mare.

The following outline will help you follow your reading assignment and also contains pertinent information regarding the proper management of the broodmare.

I. Internal Reproductive Exam

A. Rectal Palpation

1. Palpate ovary size, shape, and function (follicles, CL).

2. Palpation of both uterus and cervix.

a. Tone of uterus, pregnancy status (18 – 22 days is earliest), size.

b. Cervix – open or closed?

B. Utrasonography

1. Rectal exam with ultrasound probe in palpating hand.

2. Can examine ovaries, uterus, cervix, early pregnancy(14 to 16 days).

C. Vaginal speculum exam

1. Status of the cervix.

a. Open, relaxed, edematous (swollen), and moist – estrus.

b. Closed and dry – Pregnancy or diestrus or anestrus.

2. Determination of Urine pooling in vaginal vault

a. Usually in older mares.

b. Some urine is not excreted to the outside, but splashes back and pools in the vagina (responsible for infertility).

c. Candidates for surgical correction to prevent problem.

3. Uterine fiberoptic exam

a. Not routine. Only done for examinations of the internal structures of the uterus for diagnostic purposes.

4. Uterine Biopsy

a. Use of a biopsy instrument to get a small sample of uterine tissue.

b. Microscopic exam of this tissue by a pathologist.

c. Biopsy classified in 3 basic categories:

1. Kenney type 1 –Normal. Should not have a problem getting pregnant or carrying a foal to term.

2. Kenney type 2 –Evidence of mild infection or inflammation that should be able to be cleared up with correct therapy, and mare would be considered to be able to get in foal and carry to term.

3. Kenney type 3 – Evidence of scar tissue damage to uterus and previous damage to tissues that would make it difficult for this mare to conceive or carry to term (less than 10% chance of being fertile).

5. Uterine culture and sensitivity (refer to picture under speculum exam).

a. Use of a sterile swab that is introduced into the uterus and a swab sample is taken from the uterus.

1. Sent to laboratory to attempt to grow microorganism (bacteria) on gel agar plates, identify the microorganisms, and determine susceptibility to antibiotics.

2. Common Pathogenic bacteria isolated:

a. E. coli

b. Beta-hemolytic streptococcus

c. Klebsiella

d. Pseudomonas

Practical Farm Practices with Broodmare Management

I. Pregnant Mares

A. Carry through foaling and determine status at foal heat for rebreeding.

1. Foal heat is 9 days post foaling

a. If uterine involution is good at this stage, the mare is healthy, consider breeding.

b. Heat after 9 day heat is 28 -30 days from foaling. Conception rates are higher if mare is bred at this time.

II. Barren mares (did not conceive or aborted last breeding season)

D. Begin in the latter fall to examine these mares and clear up any infections, urine pooling, poor vulvar conformation (caslicks) or other problems.

Figure 1a Vulva of a mare with good vulval conformation

Figure 1b Vulva of a mare with poor vulval conformation

1. Consider putting these mares under lights (16 hours of light per day from the first part of December through February.

II. Maiden mares

A. Examine at the beginning of breeding season for normality of reproductive tract.

1. Open hymen if necessary.

2. Open caslicks if necessary.

3. Use light to go through transition phase of cycle on these mares as well (same as barren mares).

III. Management concerns in the broodmare during the breeding season (this includes all mares to be bred and undergoing an estrous cycle).

A. Irregular Cycles

1. Mares going through the transition phase (were not put under lights).

a. Put on REGUMATE for 14 days. When they are taken off, some may begin cycling normally.

b. Transition phase mares can be very difficult. May just have to wait out the transition phase.

2. Persistent heat

a. Normally caused by transition phase.

b. An excessively long fertile heat can be ended by using Human Corionic gonadotropin (HCG) 2500 units. (2 ½ cc of a 10 cc vial) This will normally cause ovulation within 24 to 48 hours.

3. Prolonged diestrus (persistent corpus leteum)

a. The CL continues to produce progesterone and possibly the prostaglandin level of the mare is not high enough to cause luteolysis.

b. Injection of prostaglandin product (lutalyse) will destroy the CL and the mare will show estrus within 2 to 3 days. This will be a fertile heat.

c. Early embryonic death may cause a prolonged diestrus. Prostaglandin would also be used in this case.

d. BE SURE THE MARE IS NOT PREGNANT BEFORE ADMINISTERING PROSTAGLANDIN

4. Silent Heat

a. Detected when records indicate the mare should be in heat (9-day heat, or 16 to 18 days since last heat and mare is not pregnant.

1. Palpation to determine if mare is showing physical evidence of heat (estrus) is pregnant or possibly has a persistent CL.

2. Silent heat normally seen in mares with first foals and over protective dams.

3. Rectal palpation to determine breedability, follicle, artificial insemination, or tranquilization and live cover. Allow mare to visualize foal during the breeding process. Take extra time to tease and reassure the mare and her foal will be okay.

5. Anestrus during breeding season (mare stops cycling)

a. MAKE SURE IT IS NOT PREGNANCY THAT IS CAUSING ANESTRUS.

b. The occasional mare that foals will stop cycling for no reason. These mares appear to be every other year mares. They usually continue to show this characteristic throughout their lifetime.

c. Early embryonic death in mares cause many to fail to come back into regular cycling. Prostaglandin will usually work to bring them back in if it is not more than 45 days since the mare was bred.

6. Stallion like behavior in the mare

a. Normally caused by granulosa cell tumor on the ovary.

IV. Granulosa cell tumors produce testosterone. These mares are infertile until the tumorous ovary is removed. Can normally be diagnosed by behavior signs and palpation of ovary (these tumorous ovaries can become very large).

1. Endometritis - (uterine infections). This subject is covered

under fertility in the mare.

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