Guide to donkey castration

The optimum age for castration of the donkey is 6-18 months.

10 November 2018

Introduction

The optimum age for castration of the donkey is 6-18 months. The following considerations relate specifically to castration surgery in the donkey:

If the donkey is less than two years old and both testicles have descended, closed castration using the scrotal approach should be used.
If the donkey is over four years old or over 150kg and the testicles large and well developed, the inguinal approach is strongly recommended in order to reduce post-operative complications. Inguinal castration is best performed in a dedicated equine operating environment.
If the donkey is between two and four years old and under 150kg, a decision should be made based on the size of the testicles. In most cases the scrotal approach will be appropriate.

Anaesthetic protocol

Accurate weight estimation is essential.

Please note that horse weigh tapes are not accurate in the donkey.

The donkey weight estimator has been produced by The Donkey Sanctuary and is available as a fact sheet.

	Theatre Protocol	Field Protocol
Pre Med	ACP 0.03mg/kg bwt IM (30 min’s prior) Pre Med Induction Maintenance Detomidine Butorphanol*	ACP 0.03mg/kg bwt IM ( 30 min’s prior) Detomidine 20μg (kg IV 5 min’s prior) Butorphanol 0.01 - 0.02mg/kg bwt IV*
Induction	Ketamine 2.2 - 2.8mg/kg bwt IV Diazepam 0.1mg/kg bwt IV	Ketamine 2.2 - 2.8mg/kg bwt IV Diazepam 0.1mg/kg bwt IV
Maintenance	Isoflourane, or Triple Drip IV** at 1-2ml/kg/hr, or Ketamine top ups Can top up every 10-15 min’s as necessary with 1/3 induction dose of ketamine and 1/3 dose xylazine up to a maximum of 90 min’s as cumulative Aim not to exceed the original ketamine dose for induction as this can lead to severe ataxia on recovery	Ketamine top ups Can top up every 10-15 min’s as necessary with 1/3 induction dose of ketamine and top up with 1/2 induction dose of detomidine at 30 min’s The use of butorphanol will prolong initial anaesthesia by up to 10 min’s, but care with respiratory depression

*Care with butorphanol administration in older donkeys as it can cause a deeper anaesthetic plane. It is best reserved for stressed donkeys or very painful procedures.

For Mules, increase the doses by 1/3 – 1/2

**The triple drip recipe* used in donkeys is different to that used in horses and ponies.

The recipe used by The Donkey Sanctuary can be found on a separate factsheet: Triple Drip Combination: Maintenance of Anaesthesia in Donkeys.

Clipping is necessary in many cases because the testicles are often covered in hair.
There is an increased risk of haemorrhage in the donkey and a ligature around the vaginal tunic, including the testicular artery is essential.

* The triple drip recipe is different in donkeys to that used in horses and ponies

The constrictor knot

Donkey Castration Constrictor Knot Diagram.

Place working end over cord.
Cross over the static end.
Go round the back and through again. This is now a Clove Hitch.
Take the working end and go over the first loop.
Then under towards the middle and pull up tight.

Analgesia

We routinely give Flunixin 1.1.mg/kg IV with the premed five minutes prior to GA. Flunixin is then continued at 1.1mg/kg BID PO for a maximum of 5 days followed by Phenylbutazone 2.2 - 4.4mg/ kg BID PO if necessary.

Antibiotics

We give these according to the situation and responsible practice.

Be aware of vaccination status – if unsure we advise administering tetanus antitoxin.

Post-operative care

Monitor the donkey for appetite and faeces as donkeys on NSAIDs may hide a developing colic.
Encourage movement to reduce any swelling; walk the donkey where possible.
Use a cold hose from the top of the scrotum to minimise post- op swelling where the donkey will allow this.

More information

If you need clinical and dental veterinary advice contact our veterinary team or telephone 01395 578222 and ask to be put through to the veterinary department.

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