Stallion/Colt Fertility Assessment Flashcards
What is the range of numbers of mares which a stallion may be expected to cover in a season?
1 – 200 mares
What steps are involved in assessing a stallions reproductive capacity?
History - general & reproductive
Physical exam (including MSK assessment)
Observation of sexual behaviour & mounting behaviours (in both natural + AI-directed stallions)
What pathology samples should be collected from a stallion during a reproductive exam?
Pre- & post-ejaculatory swabs for culture - urethra, penis, prepuce
Fluid samples - semen, accessory gland fluid
Blood/serum (for viral analysis - EIA, EVA, EHV-3)
What bacterial pathogens are common causes of stallion reproductive disease? How are these detected?
Pseudomonas aeruginosa Klebsiella pneumoniae Taylorella equigenitalis (CEM)
Dx = culture of swabs from reproductive organs
What viral pathogens are common causes of stallion reproductive disease? How are these transmitted & how are they detected?
Equine infectious anaemia (EIA)
Equine viral arteritis (EVA)
Equine herpesvirus-3 (EHV-3)
Tm = venereal Dx = serology
What is involved in a testicle exam in stallions?
Total scrotal width (TSW)
What is the average width & length of the stallion scrotum?
Avg width = 110 mm (range 50-150mm)
Avg length = 80-140 mm
Why is total scrotal width important? What does it measure?
TSW measures testicular size, TF sperm production/output
- healthy large testes = more sperm production
- beware pathological enlargement
Formula - Daily sperm output (DSO)
DSO (billions) = 0.2 x (total testicular V) – 1.26
How long is the sperm production cycle? Why is this important?
60 days
- insult to testicles/seminiferous epithelium > decreased sperm output for 60 days (TF rest the stallion)
What methods can be used to expose the penis for examination?
Expose the stallion to a mare
Sedate with xylazine/ACP
What structures should be examined during the external part of the physical exam of the penis?
Penis
Urethral process
Fossa glandis + diverticulum of fossa glandis
What structures should be examined during the internal part of the physical exam of the penis? How are they examined & what aspects are considered?
Pelvic urethra Body of the prostate Seminal vesicles (vesicular glands) Bulbo-urethral glands Ampullae
Exam by palpation + endoscopy
Look at size + consistency
What accessory sex glands are present in the stallion?
Ampullae (terminal ductus deferens)
Vesicular glands
Prostate gland
Bulbourethral glands
What methods are available to collect semen from a stallion?
Artificial vagina - using a dummy/surrogate mare
- requires good training & preparation
Never use electroejaculation in horses
How should the artificial vagina be prepared for semen collection?
Temp = 42-48 deg C
Pressure
Lubrication
Protect sample from cold shock & sunlight & contamination
What parameters are considered when examining a semen sample in-field?
Volume of ejaculate Colour Density Debris pH of sperm (7.2-7.9) Wave motion = rapid swirling
What parameters are considered when examining a semen sample in the lab?
Sperm count (automated) Sperm cell morphology Bacterial cultures (CEM, pseudomonas, klebseilla)
What could cause morphological abnormalities in sperm?
E.g.’s of sperm morphological abnormalities
Obstruction to sperm flow/stenosis of tubes
Sperm stasis
Proximal cytoplasmic droplet
Kinked tail
Head abnormalities
What is the most accurate test of stallion fertility?
Pregnancy rate per mare cycle (>75%)
What are some advantages of AI over natural service?
No stallion transport required = dec Tm of STIs + able to remotely serve
Breeding possible w incompatible stallion/mare (size, temperament etc.)
Minimum contamination breeding technique
Quality control/monitoring of stallion semen quality
