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
Give some clinical signs of placentitis in the pregnant mare
Premature udder development and lactation +/- vaginal discharge
How do you diagnose placentitis?
Clinical signs
Ultrasound (placental thickening)
Cervical swab if discharging
What is a stallion?
Entire male horse >4 years old
<4yrs old = colt
When does puberty occur in male horses?
12-24 months
When does the decent of the testes occur?
Normally descended into scrotum at/shortly after birth, but may occur up to 24 months old
When is maximum sexual maturity reached in stallions?
4-5 years, retained until about 20 years
How long does spermatogenesis take in the male horse?
60 days
What factors affect semen quality?
Testicular size (bigger = more semen)
Testicular efficiency (% of testicle that is producing sperm)
Age (younger = less sperm)
Frequency of ejaculations (no of sperm halves after each ejaculation)
General health/injury
What number of motile sperm is a suitable dose for natural service?
What about AI?
Natural: 500 million
AI: 150-500 million
What are the suggested rates for matings per week?
15 (variable)
How should you examine a stallion for breeding soundness?
Physical exam of external genitalia Exam of internal genitalia Observation of libido and mating ability (any ortho problems that would stop him mounting?) Semen evaluation Testicular biopsy (tru cut)
Where would you swab a stallion for CEM?
Urethra, urethral fossa, penile sheath, pre-ejaculatory fluid if available
What is CEM?
Contagious equine metritis (can be transmitted by stallion)
Notifiable
What do you vaccinate a stallion against?
Equine viral arteritis (abortion)
Stallions become carriers
Notifiable in stallions
Blood test first to prove seronegative
Why should you take serious action if a stallion has systemic illness?
Pyrexia affects sperm production
How should you treat penile/scrotal injury?
Anti-inflammatories (NSAIDs, maybe corticosteroids) Cold therapy Massage Support Diuretics? Topical treatments
Why should you take extra care when rectalling stallions?
More excitable, more likely to struggle -> higher risk of rectal tears (also, narrower pelvis)
What should you check for when investigating colic in stallions?
Inguinal hernias, scrotal hernias, testicular torsions
Which neoplasias may stallions get on their penis?
Sarcoids, squamous cell carcinoma, melanoma, seminoma, other testicular tumours, papillomas
What is hydrocele?
Fluid around testicle from lymphatic drainage plexus
Give some other diseases of stallions
Haemospermia
Urospermia
Testicular degeneration
Hydrocele/varicocele (veins become enlarged inside scrotum)
Orthopaedic disease
Psychological dysfunction (eg frustration if not allowed out with other horses)
Cushings
By when should fresh semen be used?
Few hours
What are semen ‘extenders’?
Increase lifespan of sperm, may contain antibiotics
Often milk/egg-based products
How long can chilled semen last?
Up to 48 hours
Mixed with extenders then slowly cooled to 5 degrees
Frozen semen is separated into doses of what size?
0.25 - 5ml
Multiple straws used per mare
What is frozen semen treated with?
Extenders and cryoprotectants
How is frozen semen stored?
In liquid nitrogen flasks
How long does frozen semen last?
Forever (provided liquid nitrogen is topped up)
How are fresh and chilled semen inseminated into mare?
Through cervix, from a loaded syringe, via an insemination catheter
How is frozen semen inseminated into mare?
Straws warmed to 37oC in water bath, dried, unsealed and inseminated via insemination ‘gun’ either just through cervix or into uterine horn on side of ovulation (deep uterine insemination)
When in the mare’s oestrus cycle should you inseminate with fresh and chilled semen?
Same for natural service: up to 48 hours before ovulation
When in the mare’s oestrus cycle should you inseminate with frozen sperm?
Best done as close to ovulation as possible as survival time of sperm is not as long (up to 12 hours before or 6 hours after ovulation)
Give some pre-parturient colics in pregnant mares
‘Foal movement’ (mild-moderate, common, should respond with mild/moderate analgesia eg buscopan or phenylbutazone)
GI colic
Actually foaling or aborting (do vaginal exam)
Uterine torsion
Ischaemia/necrosis/rupture of caecum or colon (may result in endotoxaemic shock; due to weight of foal applying pressure to viscera/stretching visceral blood vessels)
How do you treat placentitis in the pregnant mare?
Bute
Potentiated sulphonamides
What is the most common cause of vaginal bleeding in the mare?
Is any treatment required for this cause?
Varicose veins
Not usually
What might you give to an older mare to reduce orthopaedic disease?
NSAIDs
What should you pack in your car when going to a dystocia?
Sedation (+ ketamine?) Clenbuterol/buscopan LA (epidural) Doxapram Foaling ropes Lubricant Hibiscrub Needles/syringes Waterproofs
What should you check when arriving to a dystocic mare?
Restrain mare (Sedate? Twitch? Clenbuterol?) Check mare not in shock/haemorrhaging Clean perineum/arms Ascertain presentation of foal Vaginal exam
Can you remove a foal per vaginum if it is presented with all 4 feet pointing forward?
No, must do a C-section
What may happen if there is a complete uterine rupture in a pregnant mare? What should you do?
Foal may fall into abdomen and not be palpable in birth canal
Mare may fatally haemorrhage, or may develop fulminating peritonitis and fatal endotoxaemia
Extract foal and consider mare euthanasia
How do you diagnose a uterine rupture/tear?
Clinical signs
Rectal/vaginal exam
Ultrasound
Peritoneal tap
How do you treat a uterine rupture/tear in a pregnant mare?
Medical tx as for peritonitis
Exploratory laparotomy and repair for full thickness tears
How should you treat perineal laceration in a mare after foaling?
May heal without intervention
Lacerations which disrupt perineal anatomy should be repaired, esp if will alter perineal conformation. Repair surgically 4-6 weeks later when granulation has set in. Repair required for mare to conceive again
Give antibiotics/NSAIDs/tetanus
Why should you not repair 3rd degree perineal lacerations immediately?
Will break down
Urovagina is usually seen in which kind of mares?
Old, pleuriparous mares, often with pneumovagina
How can you confirm urovagina?
Cytology
Rule out ectopic ureter in young fillies
Improve BCS if thin
How can you surgically manage urovagina in the mare?
Caudal relocation of transverse fold of vestibule
Urethral extension
Uterine suspension (shorten broad lig of uterus -> elevates whole repro tract into the anatomy of a younger mare -> re-orientates the urethral orifice
When are cervical injuries usually sustained?
During parturition
How and when should you surgically repair cervical lacerations?
Perform surgery during di-oestrus, > 3 weeks post-partum
Retract caudally, suture with 3-layer closure
What causes delayed uterine clearance?
Endometritis
Post-mating persistent endometritis
Uterine suspension
How do you surgically fix delayed uterine clearance?
Uterine suspension:
Restoration of normal horizontal orientation of uterine horns
Improves uterine clearance and perineal conformation, may reduce urine pooling
How can you fix a blocked oviduct?
Prostaglandin-relaxes smooth muscle of oviduct, modulates oviductal transport
When do perineal lacerations occur in the mare?
During foaling in primiparous mares
Describe a first degree perineal laceration
Mucosal damage
Caslick/no surgery required
Describe a 2nd degree perineal laceration
Mucosa, submucosa and perineal muscles affected
Caslicks procedure and reconstruction of perineal body required
Describe a 3rd degree perineal laceration
Complete disruption of recto-vestibular shelf, perineal body and anus
Requires surgical repair, delay repair for 4-6 weeks for granulamatous tissue to form
One or 2 stage procedures
How do recto-vestibular fistulas occur? How are they fixed?
Penetration of foal’s foot into rectum without progression to 3rd degree perineal laceration
Unsuccessful repair of 3rd degree perineal laceration
Repair surgically
What is the most common neoplastic disorder of the ovaries? Describe it
Granulosa cell tumour
Unilateral
Rarely metastasises
Good prognosis
What behaviour signs would you see in a mare with a granulosa cell tumour on her ovary?
Anoestrus/continuous oestrus
Stallion-like behaviour/aggression
How do you diagnose ovarian granulosa cell tumours?
Rectal exam (enlarged ovary) Ultrasound (honeycomb appearance of enlarged ovary) Endocrine tests (increased testosterone in 50%, increased inhibin in 85%, increased anti-mullerian hormone in 98%-this test is best!)
How do you treat ovarian granulosa cell tumours?
Ovariectomy, unilateral or bilateral
Can do laparoscopy (standing, GA), or laparotomy under GA, or colpotomy (incision through vagina)
How would you recognise a mare in dystocia?
Prolonged discomfort and straining
Straining without appearance of amnion
Appearance of amnion/head/limb but no further progress
How long should you give yourself to clinically examine a mare in dystocia?
15 mins
How should you clinically examine a mare in dystocia?
See what state mare is in (shock, haemorrhage) +/- sedation (xylazine) Bandage tail Clean perineum Wash hands/anus/gloves Lubricant
What are the 4 delivery options for a mare in dystocia?
Assisted vaginal delivery
Controlled vaginal delivery
C-section
Embryotomy
Describe an assisted vaginal delivery
Mare is conscious
Foal delivered using traction +/- ropes
Sedation and epidural if mare straining excessively
Describe a controlled vaginal delivery
Mare anaesthetised +/- HLs elevated (to allow foetus to move cranially into abdomen)
Foetus delivered per vaginum
Abdomen should be prepared for C-section at same time
When might you perform a terminal C-section?
Foal more important than saving mare
Chronic disease in mare
Deliver foal under anaesthetic then euthanise mare
When may uterine prolapse occur? How do you correct it?
Post dystocia/straining
Replacement under standing sedation/GA
When does uterine artery haemorrhage occur?
Give some clinical signs
Older mares
Colic and evidence of haemorrhagic shock
When may uterine torsion occur?
How do you diagnose?
How do you treat?
Rare, last 2 months gestation/at parturition
Colic/dystocia
Diagnose by rectal palpation-will feel 1 tight broad ligament
Correct surgically or non-surgically
When may uterine rupture occur?
Clinical signs evident 24-72 hours post-foaling
Treatment depends on size of tear
How do you correct uterine neoplasia?
Rare
Partial/total ovariohysterectomy
GA/standing laparoscopic techniques
How do you correct pyometra?
Rare
Drain uterine contents prior to surgery -> ovariohysterectomy (laparotomy +/- laparoscopy)
What mammary problems may occur in the mare?
Mastitis
Neoplasia
Which part of the mare repro tract does squamous cell carcinoma affect?
What is the prognosis?
Vulva and clitoris
Poor prognosis even with radical resection
When are varicosities worst in the mare?
Oestrus (increased blood flow)
When should the foetal membranes be passed after parturition?
Within 2 hours of parturition
Over 4 hours is considered abnormal
How do you treat retained foetal membranes?
Oxytocin
Broad-spectrum ABs, NSAIDs, flunixin for anti-endotoxic effects, tetanus cover
How do you treat metritis post-foaling?
ABs, NSAIDs, oxytocin, lavage
Give some clinical signs of hypocalcaemia post-foaling
How do you treat it?
Rare. Muscle fasiculations, recumbent, diaphragmatic flutter ‘thumps’
Tx: Give calcium diluted in saline
