REPRODUCTION - Mare Fertility Flashcards by Emily Hunter

What is the only accurate indicator of fertility rate?

Pregnancy rate per cycle (PRPC)

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Which factors influence pregnancy rate per cycle (PRPC)?

Mare fertility
Stallion fertility
Management practices

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How can you categorise causes of infertility to help narrow down your differentials?

Mares that fail to cycle
Mares with an abnormal oestrous cycle
Normal mating but don’t conceive
Pregnancy failure
Behavioural problems related to reproduction

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What is embryonic loss?

Embryonic loss is pregnancy loss before 40 days of gestation

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What is the typical signalement for embryonic loss?

Older mares (over 12 years old)

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Which age-related factors have an affect on reproductive efficiency?

Reduced oocyte viability
Reduced embryo viability
Degenerative changes to the internal or external reproductive tract
Altered placenta development

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How do you diagnose embryonic loss?

When doing your transrectal ultrasound pregnancy tests, you may notice some embryonic abnormalities which could indicate embryonic loss

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What are some of the signs of an abnormal embryo?

Small vesicle
Continued mobility of the vesicle (beyond 16 days)
Abnormal appearance of conceptus
Fluid surrounding the vesicle
Endometrial oedema
No foetal heartbeat

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What should you do if you suspect embryonic loss?

If you suspect embryonic loss, do a recheck and if the embryo is not progressing as expected, abort the pregnancy

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How do you approach a mare breeding soundness examination?

Breeding history
Thorough clinical examination
Assess the perineum
Vaginal examination
Transrectal ultrasound and palpation
Hysteroscopy
Uterus sample collection

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Which tests can you do on uterine samples for a mare breeding soundness examination?

Histopathology
Culture
Cytology

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How do you sample for uterine culture in the mare?

Sterilly prep the area and use a double guarded swab (as you don’t want to sample commensal bacteria in the vagina) to sample the endometrium. Furthermore, you should do a low volume uterine lavage. Submit both of these samples for culture and sensitivity

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What is a potential limitation of using a swab to sample for uterine culture?

Using a swab for sampling could potentially miss a local infection

This is why you also do a uterine lavage sample

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How do you sample for uterine cytology in the mare?

Sterilly prep the area and use a double guarded swab (as you don’t want to sample commensal bacteria in the vagina) to sample the endometrium. Furthermore, you should do a low volume uterine lavage. Carry out cytological analysis on both of these samples

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What should you assess on cytological analysis of uterine samples?

When carrying out cytological assessment of uterine samples, assess for uterine epithelial cells, and evidence of inflammation and infection through looking for leukocytes and/or pathogens

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What is indicated if there is neither neutrophils or pathogens on uterine cytology?

Most likely there is no infection

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What is indicated if there is both neutrophils and pathogens on uterine cytology?

Most likely there is an infection

What is indicated if there are pathogens but no neutrophils on uterine cytology?

There is unlikely to be an infection and the sample was likely contaminated

What is indicated if there are neutrophils but no pathogens on uterine cytology?

Maybe inflammatory and non-infectious, or the pathogen was missed during sampling

What are the three anatomical seals which protect the reproductive tract in mares?

Vulvar seal
Vestibulovaginal seal
Cervix

What is the normal perineal conformation in the mare?

In the mare, the vulval lips should be evenly closed and vertically orientated, and two thirds of the vulva should be distal to the ischial arch

How can the perineal conformation change in older mares or mares in poor body condition?

Older mares can end up with anal recession and progressive tilting of their vulva until is it practically horizontal, reuslting in poor perineal conformation and contamination of the vulva with faecal material and aspiration of air into the vulval lips

What are mares with poor perineal conformation at increased risk of?

Endometritis

How can you correct poor perineal conformation in the mare?

Caslick’s surgery

How can endometrial cysts affect fertility?

Impede materal recognition of pregnancy Impede embryo fixation Make it challenging to determine pregnancy status

How can you try to differentiate endometrial cysts from an embryo?

Endometrial cysts tend to be irregular in shape whereas an embryo in mares in perfectly spherical. Furthermore, if you map out the location of the cysts and the embryo, you can recheck using transrectal ultrasound and the embryo should be growing at a set rate whereas the cysts will not

How can you treat endometrial cysts?

Cyst ablation

What is the typical history associated with endometritis?

Mares with endometritis typically have a history of infertility and shorter interoestrus periods

What are the potential clinical signs of endometritis in the mare?

The mare may have vaginal discharge

How do you diagnose endometritis in the mare?

Assess perineum Vaginal examination Transrectal ultrasound and palpation Endometrial cytology Endometrial culture Endometrial biopsy and histopathology

What is the gold standard test for diagnosing endometritis?

Endometrial biopsy and histopathology

What is the pathophysiology of post mating induced endometritis (PMIE)?

When the mare is inseminated, either via natural cover or artificial insemination, the uterus becomes contaminated with semen and bacteria *(remember the penis is not sterile)*. Normally, within 24 hours, between the mare's inflammatory response, uterine contractions and lymphatic drainage, there will be uterine clearance of this debris. However, mares with poor uterine contractions, lymphatuc drainage and/or poor perineal conformation *(resulting in continuous contamination)* can end up with post mating induced endometritis

How can you try to prevent post mating induced endometritis (PMIE)?

Minimise uterine contamination Hygiene during breeding Minimise number of matings Use semen extenders for artificial insemination

How can you treat post mating induced endometritis (PMIE)?

Oxytocin Uterine lavage ± Broad spectrum antibiotics

When can you carry out uterine lavage post breeding?

You can carry out uterine lavage at 6 hours post breeding as sperm should reach the oviducts by 4 hours post breeding

What can cause mares to fail to cycle?

Spring transition Pregnant Ovarian abnormalities Developmental abnormalities

What are the clinical signs of granulosa cell tumours in the mare?

Failing to cycle Stallion-like behaviour

How can you diagnose granulosa cell tumours in the mare?

Transrectal palpation of enlarged ovary Ultrasound Anti-Mullerian hormone (AMH) concentrations

How do you treat granulosa cell tumour?

Ovariectomy

What are anovulatory follicles in the mare?

Anovulatory follicles are follicles which reach preovulatory size but fail to ovulate and instead the antrum fills with blood and eventually luitenise and persist for subsequent cycles and disrupt the mare's cycle

What are the risk factors for anovulatory follicles in mares?

Older mares End of breeding season NSAIDs

How can you treat anovulatory follicles?

When the anovulatory follicles undergo luteinisation, you can stimulate luteolysis with low doses of prostaglandin