Equine Reproduction Flashcards
By when are testes adult size?
5 months
When does the Gubernaculum shorten and the testes regress in size?
8.5 months
What do the cranial, middle and caudal Gubernaculum become?
Cranial: proper ligament of testes
Middle: ligament of tail of epididymis
Caudal: scrotal ligament
Why might you castrate a horse?
Prevent breeding
Modify behaviour
Neoplasia/ inguinal hernia
Why should you palpate the testes before castration?
Check both testes are palpable
Check for hernias
What are the 2 anaesthesia options for castration?
Standing sedation
GA
Field anaesthesia vs GA under theatre conditions (field is safer for horse)
How would you sedate a horse for a castration?
Alpha-2 agonist (eg detomidine) plus an opiate (eg butorphanol)
Describe a standing castration
Sedation (alpha 2 agonist plus opiate) Bandage the tail NSAIDs and antibiotics Aseptic preparation of scrotum (Chlorhexidine) LA (10-15ml) Repeat scrub of scrotum Incise close to median raphe (most dependent site) Bold incision away from you Ensure good drainage
How should a horse be positioned for a field castration?
Lateral recumbency
Elevate upper HL/pull forwards out of the way
Castrate lower testicle first
What induction agent would you use for a horse castration?
Ketamine
Are open or closed castrations generally performed on horses?
Open
What might make you decide to do a closed castration instead of open?
Older horse
History of herniation/swelling
Where should you tie a suture when castrating a horse with a history of scrotal/inguinal hernia?
Around vaginal tunic +/- suture superficial inguinal ring
What aftercare should you do after castration?
Check tetanus status Antibiotics NSAIDS Box rest for 24 hours followed by controlled exercise Keep away from mares
When should you advise an owner to contact the practice after castration?
Blood dripping from incision persisting >4 hours, or steady stream of haemorrhage
Evidence of tissue hanging from incision
Marked swelling of scrotum/stiffness that persists >3 days
Depression/inappetence/colic
Give some complications following castration
Swelling Haemorrhage Omental prolapse Evisceration Septic funiculitis Clostridial infection Septic peritonitis Penile damage Hydrocele (fluid accumulation around testis) Continued masculine behaviour (learned behaviour or incomplete castration) Incomplete cryptorchid castration
What is cryptorchidism?
Retention of one or both testes along normal path of descent
How do you diagnose cryptorchidism?
History (behaviour, previous surgery)
Thorough external palpation (sedate, castration scars? Palpable testicular structures?)
Hormone analysis (donkeys and horses <2 yo: hCG stimulation test) (horses >3 yo: oestrone sulphate assay) (anti-Mullerian hormone test)
Ultrasound
Rectal exam
Give some miscellaneous diseases of the testes
Anorchidism
Torsion of spermatic cord
Testicular neoplasia
What are the 2 types of inguinal herniation?
Direct and indirect
Direct occurs through a tear in the body wall (lies outside the vaginal tunic)
Indirect occurs via vaginal ring (lies inside the vaginal tunic)
How do you diagnose inguinal herniation?
Palpation
Ultrasound
What is the most common neoplasia of the penis?
Squamous cell carcinoma
Affects glans of penis
Squamous papillomas are pre-neoplastic
What other neoplasias can occur on the penis sheath?
Melanomas and Sarcoids
How do you treat penile squamous cell carcinoma?
Local excision/ cryotherapy/ topical chemotherapeutic agents
Surgery (distal phallectomy/remove glans/ segmental posthetomy/en bloc resection-resection of as much penis as possible plus lymph nodes, create a new urethral orifice)
What is the prognosis like for penis surgery in response to squamous cell carcinoma?
Good if treated early and appropriately
How can you prevent penile disease?
Clean sheath regularly (owner education)
Examine penis as part of yearly routine check up in older patients
How would you treat a case of penile trauma?
Ice packs/ cold hosing
NSAIDs and antibiotics
+/- referral
Penile support to reduce oedema (penile sling)
What might you see in a horse with penile trauma?
Severe swelling
Haematoma/ haemorrhage
What is priapism?
Persistent erection without sexual excitement
Why should you not give ACP to a breeding stallion?
Can cause priapism (persistent erection)
How do you treat priapism (persistent erection)?
B2 agonist
Lavage corpus cavernosum with heparin under GA (and remove blood)
What is paraphimosis?
Inability to retract penis into prepuce
Prolonged -> permanent
Pudendal nerve injury
Give GA, roll on back, gently put penis in sheath, purse-string suture across preputial orifice
What is phimosis?
Inability to protrude the penis
What is pyospermia?
What may cause it?
High no of WBCs in sperm
External infection
Cystitis, epididymitis, seminal vesiculitis
What is haemospermia?
Blood in ejaculate caused by high pressure in corpus spongiosum caused by external infection/ external injury/ urethral injury
What is urospermia?
Urine in ejaculate caused by external infection/ neurological dysfunction/ external injury/ urethral injury
When do the testes pass into the inguinal canal?
270-300 days
Give some complications following dystocia/parturition
Uterine prolapse Uterine rupture Uterine haemorrhage Invagination/ retroflexion of the uterine horn Retained foetal membranes Cervical tears Perineal lacerations/ recto-vaginal tears Intestinal complications
What orientation should the vestibular opening of the mare be?
Vertical
Horizontal -> contamination
What are the anatomical barriers of the mare repro tract?
Vulva, vestibule/vestibulo-vaginal fold, cervix
What happens if the anatomical barriers of the mare repro tract are compromised?
Contamination, reduced fertility
Why may a mare have poor confirmation of the vestibular opening?
Injury, age, parity, body condition
Give some conformation problems in the mare and how you’d correct them
Pneumovagina (Caslick’s, perineal reconstruction)
Urovagina (urethral extension)
Cervical incompetency (cervical repair)
Delayed uterine clearance (uterine suspension)
Oviduct blockage (oviduct lavage, prostagladin)
Give some advantages of AI
Semen can be transported- spreading genetic material
Semen can be stored– even after a stallions death
Ejaculates can be divided into smaller doses– more matings
Reduces risk of venereal disease
Reduces post mating endometritis
Semen can be examined readily
Give some disadvantages of AI
Specialist skills needed to collect, process and inseminate semen Conception rates may not equal natural service
Expensive
Labour intensive
Venereal infection still possible
Not acceptable for Thoroughbred authorities (must be natural matings)
Why may some over-large mares develop ventral oedema during pregnancy?
Is treatment required?
Compression of lymphatic drainage by foal
If mare is well and oedema is uniform and non-painful, no treatment is required (will resolve post-foaling)
Why does pre-pubic tendon rupture occur in some mares?
Due to weight of foetus (more common in older mares)
What clinical signs may you see in a pregnant mare with pre-pubic tendon rupture?
Large plaque of painful oedema, continuous with udder
May be bloody discharge in milk (rupture of blood supply to the mammary gland)
Often colic signs
Mare often spends more time recumbent
How do you treat pre-pubic tendon rupture in a pregnant mare?
Bute analgesia
Will need assistance with foaling, maybe C-section
Will resolve if mare nursed through to foaling, however often progressively becomes more painful- euthanasia
Don’t breed from mare again
What is hyrops amnion/hydrops allantois?
What are the clinical signs?
Pregnant mare with excessive fluid in allantoic/amniotic space
Colic, dyspnoea, recumbency, circulatory collapse
Foals usually deformed
Heritable?
How do you diagnose hydrops amnion/allantois?
Rectal exam-huge fluid-filled uterus but foal out of reach
How do you treat hydrops amnion/ allantois?
Induce foaling or abortion
Dilate cervix, drain fluid off slowly
Manually remove foal
IV fluids to maintain systemic blood pressure?
What may cause placentitis in the pregnant mare?
Strep spp, E.coli, Aspergillus,
Ascending infection from cervix -> abortion