Equine Castration and Cryptorchids

Question 1

Why are horses routinely castrated?

Answer 1

Behaviour modification:
- Reduces aggression to horse and humans.
- Geldings are more docile so easier to handle, particularly for less experienced/competent people.
- Group turnout now possible.
- Inappropriate erection avoided e.g. at shows.
- Improves focus.
if behaviour already learnt, removing hormonal driver will not change this. 20% of geldings may express stallion like behaviour
Gene pool:
- Approved/licensed stallions have desired attributes – these become more valued.
- Allows focussed choice not to breed from those w/ poor conformation or heritable characteristics.
Medical:
- Orchitis.
- Neoplasia.
- Inguinal herniation.
- Trauma.

Question 2

1. Who can perform equine castration?
2. What should always be done before the castration procedure is started?

Answer 2

1. Vets only.
2. General health check.
   Palpate both testicles.

Question 3

When to castrate?

Answer 3

When both testicles are present.
Between 6-24m old.
- to allow “handling” training first.
- allows conformation of an entire horse.
- after raced as colt.
- after performance testing/grading.
Later the castrate, the larger the testicles and the more developed the blood vessels.
When good management is possible.
- avoid fly/mud season, although not statistically significant in research. May just increase vigilance and prophylaxis.

Question 4

Discussion w/ client in advance of the castration procedure.

Answer 4

What is expected.
- of and by you.
- consent form.
Facilities available.
- shelter.
- lights.
- CLEAN running water.
- table/surface?
- surface for GA?
- stable/turnout for recovery/rehab.
Tetanus vac status.
- full cover from 2w after primary course.
– signed informed consent if do w/ 2nd vac and antimicrobial cover (common).
- TAT.
Technique advised/desired.
- costs.
Restraint – GA/standing sedation.
Risks/complications.

Question 5

Approaches of equine castration.

Answer 5

Open:
- vaginal tunic incised and left open.
- use in all locations/positions.
- not in mature stallions (risk evisceration).
- not in donkeys / mules.
Semi-closed:
- vaginal tunic incised, contents checked then closed.
- only under GA.
- care w/ field use (sterility).
Closed:
- testicle removed in vaginal tunic which is ligated then removed.
- only under GA.
- Care w/ field use (sterility).

Question 6

1. Positioning of horse for castration.
2. Surgical methods of equine castration.

Answer 6

1. Standing:
   - sedation and LA.
   Dorsal or later recumbency:
   - GA +/- LA.
2. • Surgical kit.
     - Emasculators.
     - Henderson instrument.

Question 7

Standing field castration – emasculators.

Answer 7

• Emasculators have 2 blades:
  – cut –> zigzag.
  – crush –> grooves.
• Store them loosely done up.
  – tighten before use.
  – take the tool for this.
  – avoids warping.
• Practice how to assemble.
  – be familiar before you arrive.
  – disassemble/loosen to clean.
• Always use “nut to nut”.

Question 8

1. In what circumstances is closed castration used?
2. Benefits of closed castration?

Answer 8

1. • As a matter of preference.
     - Mature stallion.
     - Large inguinal rings.
     - Donkeys.
     - Mules.
2. Reduces risk of peritonitis, herniation and evisceration.

Question 9

Closed castration in the hospital.

Answer 9

Under GA.
Dorsal recumbency.
Full aseptic prep and drape.
Sterile lidocaine.
Incise skins and dartos only! (not too bold).
Strip skin and dartos from vaginal tunic, using blunt dissection (dry swab).
Palpate testicle inside vaginal tunic.
Either clamp and ligate x2 (anchored) then excise OR ligate and emasculate proximal to the testicle.
Can remove and ellipse of scrotal skin (ablation).
Absorbable subcuticular skin sutures.

Question 10

Semi-closed castrate in hospital.

Answer 10

GA.
Start as closed technique so strip tunic to exteriorise testicle in vaginal tunic.
Incise tunic to visualise.
- testicle in scrotum.
- no intestines herniated.
Then either:
- If large, apply emasculators to vasculature, release stump and then to tunic.
- OR if small, apply emasculators across all on abdominal side of incision.

Question 11

Scrotal healing options.

Answer 11

Primary closure:
- Closure or…
- ablation – remove ellipse.
- subcuticular.
– nothing to remove.
– no FB outside to track in bacteria.
- Box rest to allow primary healing.
Second intention.
- scrotal incisional stretching.
- ensure the incision is:
– at most ventral point.
– long enough to allow drainage.
- MUST get these moving.

Question 12

1. What is the Henderson device?
2. Advantages?
3. Disadvantages?

Answer 12

1. Device put onto a drill which rotates the testicle to remove it - start slow then speed up. Twists cord then breaks it.
   Approach the procedure as open castrate.
2. • Reduces post op haemorrhage.
     - Reduces scrotal swelling.
     - Reduces surgery time.
     - Reduces anaesthetic time.
3. • Requires GA.
     - Greater risk of herniation/evisceration:
     – GIT.
     – Connective tissue.

Question 13

What is a rig?

Answer 13

A cryptorchid horse.
Or any male that behaves like a stallion.

Question 14

1. Cryptorchidism incidence?
2. Breed dispositions?
3. Heritable?
4. Possible positions of the undescended testicle?
5. Incidence of unilateral cryptorchids w/in cryptorchid population?
6. Incidence of bilateral cryptorchids w/in cryptorchid population.

Answer 14

1. 1%.
2. • Percheron.
     - Quarter horses.
     - Saddle horses.
     - Ponies.
3. Yes.
4. • Abdominal.
     - Inguinal.
5. 90% – fertile.
6. 10% – sterile.
   – both usually in same position.
   – higher chance of abdominal compared to inguinal.

Question 15

1. Cryptorchids still hormonally active?
2. Normal testicular descent?

Answer 15

1. Yes.
   - Leydig cells create testosterone.
   - Stallion-like behaviour.
2. • Foetus, testicle develops close to caudal pole of kidney.
     - Gubernaculum (mesenchymal cord) from caudal pole of testicle to scrotum.
     - Testicle in abdomen hypertrophies @ ~5m and epididymis descends into vaginal process.
     - Testicle atrophies and gubernaculum get shorter and wider, expanding inguinal rings.
     - Testicle into vaginal process by 10m w/ large gubernaculum in scrotum.
     - At birth, testicle in inguinal canal w/ full descent by 2w.
     - Remnants of the gubernaculum are:
     – scrotal ligament / ligament of the tail of the epididymis / proper ligament.

Question 16

1. What is the inguinal canal made up of?
2. What happens to the inguinal rings when the horse grows and what are the consequences of this?

Answer 16

1. Internal inguinal ring.
   External inguinal ring.
2. They do not grow proportionately to the horse and the inguinal canal narrows relative to the rest of the horse.
   - If testes have passed through both rings, remain in scrotum.
   - If testes are inguinal, may descend at puberty (14-15m) and most often during the breeding season (Spring to summer).
   - If testes are abdominal, they may become trapped there.

Question 17

Cryptorchid Dx.

Answer 17

Hx.
Palpation.
- w/ sedation.
– relaxes cremaster muscle.
- for testicle OR scarring.
- percutaneously of scrotum and external inguinal ring.
- transrectally for internal inguinal ring.

Question 18

1. What might be palpated in the inguinal ring?
2. How can you determine the structure you are palpating?

Answer 18

1. • Gubernaculum.
     - Epididymis.
     - Testicle.
     - Fat.
     - Intestine.
2. Ultrasound.

Question 19

What if unable to palpate anything in either inguinal canal?

Answer 19

Hormone assay for anti-mullerian hormone (AMH).
- strongly expressed by foetal, neonatal, pre-pubertal and cryptorchids.
- At puberty, Sertoli cell maturation accompanied w/ reduced AMH.
- Short half-life (1.5d) so can use shortly after unilateral castration if unable to identify 2nd testicle on palpation/US and there is a suspicion it may have already been removed.

Question 20

What if unilateral scrotal testicle found?

Answer 20

Either:
- Palpate 2nd testicle and advise appropriate removal.
- OR if cannot locate 2nd testicle, US and identify 2nd testicle and advise appropriate removal OR if no other testicle identified, remove the single testicle and perform AMH test.

Question 21

What if neither testicle identified in the scrotum?

Answer 21

Test AMH:
- If positive, US and identify inguinal testicles and advise GA and inguinal castration, OR do not identify testicles w/ US and advise laparoscopic approach to locate and remove testicles.
- If negative, advise behavioural.

Question 22

1. Advantages of laparoscopic cryptorchid surgery.
2. Disadvantages of laparoscopic cryptorchid surgery.

Answer 22

1. • Definitive Dx and Tx.
     - May avoid GA if required.
     - Shorter recovery.
     - Cosmetic results are excellent.
     - Low incidence of complications.
2. • Cost.
     - Surgical experience required.
     - Only if quiet demeanour.
     - More challenging if inguinal.

Question 23

Approach for laparoscopic cryptorchid castration surgery.

Answer 23

• Standing sedation / GA.
• Starve 48hrs pre op.
• Insert canulae x 2-3.
• ID and grasp testis.
• Transect spermatic cord w/ Ligasure or staple/suture and cut/enlarge portal to exteriorise and emasculate.
• Exteriorise if not already done through portal.
• Close muscle, (subcutis) and skin.

Question 24

Approaches of cryptorchid castration under GA.

Answer 24

• Inguinal.
• Para-inguinal.
• Midline abdominal approach.
• Laparoscopic.

Question 25

Midline/para-inguinal approach.

Answer 25

- Enter abdomen away from inguinal ring. - Avoids inguinal ring dilation. - Identify testis by palpation. - Exteriorise testis. - Apply emasculators.

Question 26

Inguinal approach.

Answer 26

- 3-5cm incision over inguinal ring. - Blunt dissect through subcut. - ID inguinal extension of gubernaculum testis. - ID scar/stump if previous attempts. - Exteriorise testis in vaginal process. - Transfixing ligature. - Incise to ensure all present. - Emasculate.

Question 27

Possible characteristics of the excised cryptorchid testicle.

Answer 27

- Normal. - Hypoplastic. - Dysplastic. - Teratoma. Always visualise for removal to ensure entire testicle removed as usually have atrophied testicles and large epididymis.

Question 28

Equipment for open castration of a horse w/ standing sedation.

Answer 28

Chlorhexidine in spirit. Chlorhexidine in solution w/ cotton swabs/wool. Sedation -- detomidine and butorphanol. Phenylbutazone. Procaine penicillin. Lidocaine. Vaccination - FTB (if booster due). Emasculators in pack w/ spanner and sterile swabs. Sterile gloves. Some number 23 blades. Stethoscope and fob watch/timer.

Question 29

Preparation of the horse for open castration w/ standing sedation.

Answer 29

Ensure spotlessly clean first then a full 5 mins sterile prep w/ chlorhexidine diluted in warm water (improves penetration of chlorhexidine into skin and helps w/ horse compliance and relaxes cremaster muscle).

Question 30

LA for open castration w/ standing sedation.

Answer 30

Stand w/ feet in line w/ FL and facing the rear. Bend at the waist so head near stifle on outside of limb. Allows good visualisation for insertion of needle into testicle. Mark or score location of LA so know where to incise.

Question 31

Second prep of horse undergoing open castration w/ standing sedation.

Answer 31

2 mins then apply spirit and leave to dry and for local to diffuse whilst you scrub up and glove up.

Question 32

1. Incising the scrotum for open castration w/ standing sedation. 2. Exteriorising the testicle from the scrotum.

Answer 32

1. Hold testicle firmly in non dominant hand then incise away from hand aiming between 2 hindlimbs too. A bold cut through the skin. 2. Push the caudal pole of testis down through incision first. Now exteriorised, cut through dartos to expose vaginal tunic. Cut through vaginal tunic to expose the testicle. Push testicle through incision. Pull testicle down w/in vaginal tunic (it is still attached via ligament of tail of epididymis). Push finger through mesorchium above epididymis body to then separate pampiniform plexus from vaginal tunic.

Question 33

1. Preparing to apply the emasculators. 2. Applying the emasculators.

Answer 33

1. Grasp the testicle in such a way to have your hand proximally and in the way as to apply the emasculators to ensure all of the testicle is distal to the emasculators. 2. Apply the emasculators to the caudal vaginal tunic first, or tear the ligament of tail of epididymis (up to a yearling). Can now pull the testicle out further and apply the emasculators to the pampiniform plexus loosely and slide up and down until at comfortable level (high enough to remove as much tissue as possible, but low enough so no skin or subcutaneous tissue is caught in the emasculators, and so the stump is long enough to be grasped if required). Apply a little tighter and then support them in place for 3-5mins.

Question 34

1. Removing the emasculators. 2. Finishing up.

Answer 34

1. Hold the stump as you remove the emasculators, then watch for haemorrhage and release the stump only if it is not bleeding. 2. Pull the scrotum down to cover both stumps and release any blood which has pocketed here. Observe for level of bleeding. Ensure removed both testicles in their entirety (whole epididymis, tail, head, body, whole testicle and short length of deferent duct). Advise clients to keep mares and geldings separate for some time as remain fertile for up to weeks. Advise that testosterone driven behaviours may subside but if behaviours are learnt, likely to persist.

Question 35

List complications of castration in horses.

Answer 35

- Intestinal herniation through inguinal ring. - Persistent haemorrhage. - Oedema. - Omentum herniation. - Infection. - Inflammation.

Question 36

1. When is haemorrhage considered acute? 2. How to manage acute haemorrhage. 3. When is omentum herniation considered acute? 4. Managing omentum herniation?

Answer 36

1. <24hr post op. ok to see dripping blood. 2. Monitor closely if dripping. If flowing, clamp/pack/ligate. 3. <48hrs post op. 4. Resect.

Question 37

1. When is prolapsed tissue considered acute? 2. Managing prolapsed tissue. 3. When are respiratory signs considered acute? 4. Managing resp. signs?

Answer 37

1. <48hrs post op. 2. Resect. 3. <48hrs post op. 4. NSAIDs +/- ABX.

Question 38

1. When is fever considered acute? 2. Managing fever. 3. When is swelling considered acute? 4. Managing swelling?

Answer 38

1. <48hrs post op. 2. NSAIDs. 3. <1w post op. 4. Exercise, NSAIDs +/- ABX.

Question 39

1. When is seroma considered acute? 2. Managing seroma. 3. When is infection/abscess considered acute? 4. Managing infection. 5. Are all previously mentioned complications life threatening?

Answer 39

1. <2w post op. 2. Re-establish drainage, exercise, NSAIDs, +/- ABX. 3. <3w post op. 4. Re-establish drainage, exercise, NSAIDs +/- ABX. 5. No.

Question 40

List acute life threatening complications of equine castration.

Answer 40

- Arterial haemorrhage. - Evisceration. - GA associated risks e.g. cardiac event/fracture/myopathy.... - Penile damage / paraphimosis.

Question 41

1. When are all acute life threatening complications considered acute? 2. Managing arterial haemorrhage.

Answer 41

1. <24hrs post op. 2. ID artery which is source of bleeding and ligate. Likely need to re-sedate or GA. If unable to occlude then pack scrotum w/ swabs, count, suture closed and refer.

Question 42

1. Managing evisceration. 2. Managing GA associated risks e.g. cardiac event, fracture, myopathy etc...

Answer 42

1. Hold intestines up in towel to avoid self-trauma. Refer for GA, clean, replace into abdomen. Possible resection and anastomosis depending upon damage. 2. Euthanasia? Fluids if myopathy.

Question 43

Managing penile damage / paraphimosis.

Answer 43

Catheterise if difficulty urinating. Refer for repair of CCP. Intensive care for reduction.

Question 44

Septic funiculitis (chronic complication of equine castration). Treatment for this?

Answer 44

- Infected spermatic cord. - 2w-6m after castration. - Presents as hindlimb stiffness/reluctance. - More likely w/ open castration. - Find a small discharging sinus tract in scar. - Associated w/ sutures? - Streptococcus (champignon - "mushroom"), Staphylococcus (Schirrous cord). Requires surgical excision under GA. - collect swab. - leave a new shorter stump.

Question 45

Hydrocoele (chronic complication).

Answer 45

- Peritoneal lining produces fluid leaving a pocket in scrotum. - Appears as testicle. - Palpates as fluid. - US -- anechoic. - DDx -- inguinal herniation. - Clinically insignificant but cosmetic.