Approach to eq fertility

Pre-breeding exam in mare

·    General clinical examination

·    BCS

·    Look at feet

·    Look at udders

·    Look at perineum, assess vulval conformation

o  With age, muscle changes, anus shrinks and vulva moves caudally – gas can get in, increased risk of faecal contamination ® vaginitis, vestibulitis, cervitis, metritis, endometritis

·    Vaginal exam

·    Rectal exam

Venereal pathogens

·    Pathogens:

o  Bacterial:

§ Taylorella (CEMO)

§ Klebsiella pneumoniae (types 1, 2, 5)

§ Pseudomonas aeruginosa

o  Viral:

§ Equine viral arteritis – NOTIFIABLE

·    Screening – for bacterial venereal pathogens

o  Swab of clitoral fossa and sinus

·    If positive mare: stop covering, isolate and treat, don’t cover again until 3 negative swabs, each 2d apart

Investigating fertility

·    Uterine swabs

o  Indications: screening for bacterial venereal pathogens, in cases of endometritis (detection, determine appropriate abx)

o  Easier if taken during oestrus as cervix is open

·    Uterine U/S

o  Indications: confirmation of normality, confirmation of cyclicity and stage of cycle, confirmation of non-pregnancy, evidence of gross pathology

o  Uterine oedema = oestrus

o  Corpus haemorrhagum – bright white structure, blood filled cavity that proceeds the CL

§ Will luteinise, become more grey ® CL

·    Uterine endoscopy

o  Allows direct visualisation and detection of congenital or acquired abnormalities

o  Make sure mare is not pregnant dirst

·    Endometrial cytology

o  Looking for neutrophils – few = normal, massively increased = endometritis

§ Aseptic swab, stain with diff-quick

o  Streptococcus zooepidemicus commonly isolated – treat with pen-strep (not licensed)

·    Endometrial biopsy

o  Indications: barren mares, repeat breeder mares, early embryonic death/abortion, anoestrus, pyometra, pre-purchase fertility evaluation

o  Pathological changes detectable:

§ Acute inflammation – neutrophil and eosinophil infiltration

§ Chronic inflammation – mononuclear cells

§ Chronic degenerative changes – layers of fibrous tissue, dilated glands + lymphatics

o  Can then determine how likely mare is to get in foal (severe pathology = less likely)

Anatomical changes during oestrus cycle

·    Cervix

o  Progesterone ® closes cervix

o  Oestrogen ® opens cervix (soft, oedematous)

·    Structure of repro tract – via rectal palpation

o  Progesterone ® small, firm repro tract

o  Oestrogen ® large, soft repo tract

·    Uterus

o  Oestrus ® uterine oedema

Cyclicity in mares

·    Long day breeders

o  Winter = more melatonin ® down regulation ® don’t cycle

·    Manipulation of cyclicity

o  Influence seasonal breeding and transitional phase: light, progesterone then withdraw

§ Mare under lights = additional lights at night to extend day length

o  Hasten ovulation of mares in oestrus: short acting GnRH

·    Inducing return to oestrus: prostaglandin (> day 5), will return to oestrus in 4-6d

Optimum mating time

·    24-48h before ovulation

o  Egg is released fertile, but can only survive 12h – so need to breed before ovulation

·    Need to predict when ovulation will occur

o  Look for signs of oestrus

o  U/S – follicle size/softening, follicle wall thickening, follicle haemorrhage, follicle pointing, reduction in uterine oedema

·    Pregnant mare – breed at foal heat (5-10d post-partum)

Prolonged dioestrus

Causes:

·    Persistence of secondary CL in absence of pregnancy

o  Ovulation ® CL produces progesterone, no pregnancy ® CL regresses

o  If second follicle is growing during this time (rare) ® ovulates ® another CL

§ Wont be lysed by PG at same time as primary CL as too early to respond

o  Second CL can persist up to 3m as no further PG release to lyse it

o  Mare wont return to oestrus

Pregnancy diagnoses

·    Failure to return to oestrus – day 18-24

·    Transrectal U/S – day 15

o  Need to differentiate pregnancy from endometrial cyst – embryo more circular

§ Re-examine in 60 minutes – if moved = conceptus, if in same position = cyst

§ Re-examine next day – if bigger = conceptus

o  Conceptus is mobile until day 17

o  See heart beat from day 22

·    Transrectal palpation – day 21

·    Plasma eCG – day 60-120

·    Transrectal ballottement of foetus – day 80

Twin conceptuses

·    Need to crush one – use U/S transducer to crush or squeeze with hand

o  Risk of crushing both if close together

·    Mare cannot support 2 pregnancies – placenta SA is not large enough

Pregnancy loss

·    Consequence depends on when it occurs:

o  Before mineralisation at day 80 ® resorption

§ Endometrial cups form at day 35 – if looses pregnancy after this point, they will persist for 5 months (cannot re-breed during this time)

o  Between mineralisation and luteo-placental shift (day 80-150) ® mummification

o  After LP shift (>150d) ® expulsion

·    Pregnancy loss considered abortion after mineralisation of skeleton (day 80)

Persistent mating-induced endometritis

·    Causes: abnormal cervix, inadequate immune response, pus in uterus post-breeding, conformation changes with age (repro tract hangs below pelvis ® harder to expel fluid)

·    Treatment:

o  Remove fluid (scoop, aspirate, lavage)

o  Promote contractions – oxytocin, PG

o  Penicillin

o  Re-check daily and continue to treat until fluid gone (could be pregnant so want resolved asap)

Causes of embryonic death

·    Persistence of endometritis – bacteria/pus creates hostile environment

·    Chronic endometrial disease – abnormal uterus wont form normal placenta

·    Luteal insufficiency (low progesterone)

Granulosa cell tumours

·    Presenting signs: depends on tumour function

o  Producing oestrus ® persistent oestrus

o  Producing progesterone ® persistent anoestrus

o  Producing androgens ® virilsation

·    Diagnosis

o  Affected ovary will be enlarged, contra-lateral ovary will be small

o  Differentiate from CH – contralateral ovary will be normal sized

·    Treatment: unilateral ovariectomy, cyclic activity should resume in contralateral ovary next season

Pre-breeding screening

·    Swabs from urethra, urethral fossa, penile sheath and sample pre-ejaculatory fluid

·    If positive result: clean penis, remove any smegma, topical abx based on C+S, retest in future

EVA in stallions

·    Infected via respiratory secretions, can then pass onto mares venereally

·    Will be persistently infected – shed virus in semen for life (lives in accessory glands)

·    Prevention: vaccination (but then cant differentiate between vaccine and infection as serologically positive) – take blood sample before vaccine to prove negative, then vaccinate

Factors affecting sperm output

·    Age

·    Season of year

·    Frequency of ejaculation

·    Testicular size

Testicular U/S

·    Normal U/S appearance – echogenic capsule, hypoechogenic parenchyma, echogenic mediastinum

o  Reasons for changed appearance: haemorrhage, oedema, inflammation/infection, neoplasia, cysts, fibrosis

o   

Sheath lesions

·    Phimosis – failure of penile protrusion due to small preputial orifice, see urine dribbling

o  Treatment: surgery

·    Paraphimosis – failure to retract penis, dry surface, gravity oedema

o  Treatment: catheterise if unable to urinate, pressure bandage to reduce size, tie up penis to prevent gravity oedema

·    Priapism – penis remains outside of sheath, persistent enlargement in absence of sexual excitement (can see when sedated)

o  Treatment: manual replacement, clip/suture sheath

·    Sarcoid – nodular appearance

o  Treatment: topical cytotoxic drugs

·    Melanoma – large ulcerated lesions, bleeding

o  Treatment: oral cimetidine to control growth or tumour excision