Stallion Infertility Flashcards
Breeding Soundness Examination
Reasons
Pre – purchase examinations
Before the start of the breeding season Fertility problems
1. Signalment - age (PPID), breed
2. History – experience/vaccination status*
3. General physical examination-PPE MS pain, recent pyrexia?
4. Examination of external and internal reproductive organs
5. Semen collection and evaluation
Factors to Consider
Suitability for breeding - no genetic defects
Season - Testosterone reduced in winter
Age - overuse of young stallion
Testicular Factors:
Testis size:
- Directly related to number of sperm produced
- Measure width – callipers or ultrasound →calculate volume and sperm production
Tone:
- Degen evidence
Number of functional testicles
Frequency of Ejaculation
“Normal stallion”
100-500 million sperm for optimal fertility Artificial insemination – collect every other day
# mares bred= # of motile sperm per ejaculate/500 million
AI – can be calculated
Natural service – difficult as number of sperm per ejaculate unknown Maximum 1-2 times per day
Fertility Problems
5 points
- BehaviouralAbnormalities
- Ejaculatory Dysfunction
- Poor Semen Quality
- Infection
- Maremanagement
Natural service
Mare readiness
How determined? Teasing, vet exam?
Presentation for service
In hand, run with mares…
Check ejaculatory function – does he?
Artificial Insemination:
Observe semen collection technique and appraise Semen collection, equipment, security of footing
Semen processing and shipping
Quality of inseminators (vet/paraprofessional)
Behavioural Abnormalities
Normal - obtain an erection 1-2 minutes, maintain this, ejaculate within 1-2 mounts.
Unwilling to serve:
Low Libido
* Inexperience - patience
* Mismanagement
* Handler/location/type of AV
* Ill prepared mares
* Hormones
* Low testosterone +/- LH
* Administer GnRH
Inability to Serve:
* Pain
* Musculoskeletal
* Penile injury
* Treat underlying cause
* Also ejaculatory/erectile dysfunction
Non-Ejaculatory Coitus:
Psychogenic - overuse, poor handling, env
- behaviour mod - tease
Damaged dorsal nerve of penis
- stim smooth muscle contractility
- Imipramine - indice erection
- Xylazine - induce emission
Spermiostasis - blocked ducts
- vigorous massage of blocked ampullae and admin oxytocin before ejaculation
Urinary Incontinence During Ejaculation
Intermittent or continuously through ejaculation Normal otherwise
Semen→distinctive colour, odour, high urea/creatinine
Treat
Train to urinate before mating
Imipramine (100-500mg orally)→closes bladder neck during emission of semen
Poor Semen Quality:
Semen Collection and Evaluation
Collect 2 ejaculates 1 hour apart
Use an artificial vagina filled with hot water (temp 45-48) Plastic disposable liner
Clean the penis
Maintain semen at 34-37, protected from light, temperature extremes, chemicals and water
Assess – volume, total no. sperm, pH, motility
Scrotum Abnormalities
Inflammation increases temperature and adversely affects spermatogenesis
Takes approximately 2 months after resolution to produce normal ejaculate
Acquired
- Acute trauma
- Scrotal lacerations
- Hydrocele
- Herniation
Hydrocele:
➢Collection of serous fluid between visceral and parietal vaginal tunics
➢Trauma, ascites, local lymphoedema ➢Usually bilateral
➢Scrotum enlarged but NOT painful ➢Dx: Ultrasonography, FNA
➢Tx: underlying cause, exercise, remove affected testicle
Testis Abnormalities:
Cryptorchidism
Haematoma
Torsion
Neoplasia
- Seminoma most common tumour
- Cryptorchids → teratoma
Hypoplasia
Degeneration
Orchitis
Hypoplasia or Degeneration of Testes/Epidymes
Breed predisposition – Welsh
Usually congenital
Early→soft testes
Late→firm testes
Libido and semen volume normal BUT sperm count low
No treatment for congenital condition
Degeneration – Tx underlying cause
Orchitis
Hot, painful testes,testicular and scrotal oedema +/- fever
Traumatic
Bacterial
- Haematogenous spread of pathogens,
extension from peritonitis, penetrating
wound
Viral
- 2° to systemic viral infections causing
vascular lesions, EIA, EVA, Influenza
Automimmune
Parasites
Tx: Cryotherapy, NSAIDS, anti-microbials, sexual rest
Prepuce and Penis
- Paraphimosis
- Haematoma
- Traumatic
- Can lead to paraphimosis
- Coital Exanthema
- Squamous Cell Carcinoma
- Squamous Papilloma
Bacterial Infection
Topical infection→infertility by inducing infectious endometritis
After 1st Jan in the year of intended use (annually)
Taylorella equigenitalis = Contagious Equine Metritis Organism (CEMO) → NOTIFIABLE
Klebsiella pneumoniae
Pseudomonas aeruginosa
Infection - HBLB Guidelines
Swab set - Two sets of swabs at an interval of no less than 7 days (aerobic and microaerophilic &/or PCR)
- Urethra
- Urethral fossa
- Penile sheath
- Pre-ejaculatory fluid
Infection- Viral
Coital exanthema
Caused by Equine Herpesvirus 3 Pox-like lesions on penis
Venereally transmitted
Self-limiting
Complete resolution 3-5 weeks
Lesions can be painful→stallion reluctant to mate
Tx: Sexual rest, daily application of emollients
Equine Viral Arteritis (EVA)
- Notifiable disease EVA Order 1995
- Caused by Equine Arteritis Virus
- CS similar to other diseases
- Vaccination?
- HBLB recommends (Artervac)
- Serologically positive post-vaccine so must show negative pre-vaccine
Health test page of passport - Must be kept up once started
Dx: laboratory testing - VI by PCR or by antibody response demonstration
Equine Infectious Anaemia (EIA/Swamp Fever)
Notifiable disease
ELISA or Coggins Test – yearly testing pre-breeding season
* No vaccine
Mare Management
Stallion’s “book”
Establish number of mares that can be covered
Overuse early in breeding season
Depress libido
Ideal: Mare covered once per oestrus, less than 24 hours before ovulation Matings should be equally distributed throughout the day
Ideally 1-2/day→No more than 3
Artificial insemination – greatly increases number of mares that can be booked to a stallion
