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Founder: Dr E.D. Svendsen MBE
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Chief Executive: David Cook
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Director of Veterinary Services: Mr A. Trawford
A charity registered with the Charity Commission for England & Wales Number: 264818
Castration
Castration in the donkey is complicated by the small size of the patient necessitating general
anaesthetic, and the need for ligation of the spermatic cord. In addition, a wide range of ages
may be presented for castration. At the Donkey Sanctuary the range can be from six months to
29 years. There are also a number of donkey owners who request castration of foals only a
few days old. In theory, castration of the very young donkey can easily be done under sedation
and local anaesthetic, with an assistant holding the foal. In practice, one must bear in mind the
stress of the procedure, and perform a full work-up including measurement of IgG before
attempting castration.
Unless the conditions are very clean there is the risk of the foal
succumbing to neonatal sepsis after surgery.
Castration of the adult donkey can be complicated by the presence of excess fat within the
scrotum and inguinal region. Surgery at this late age is unlikely to remove behavioural
problems associated with stallion-like tendencies.
Ideally castration should be performed somewhere between 10-18 months old and at a time of
year avoiding major fly worry. Tetanus anti-toxin should be administered if there is any doubt
about the tetanus vaccination history.
Cryptorchidism occurs in donkeys as in horses. A good examination of the inguinal region
should be performed prior to surgery and if in doubt a rig test should be carried out. This
involves injection of 6000iu human chorionic gonadotrophin and sampling before and between
30-120 minutes after the injection.
There are three methods of castration used: closed, semi-closed using a scrotal approach, and
semi-closed using a cranial inguinal approach.
Each method has advantages and
disadvantages, and the decision on which method to use is based on surgical experience and
size/age of patient.
Castration by the closed technique
This is the method most commonly used in immature and young, slim, adult donkeys. It may
not be the best method for mature individuals with significant fat deposits, or sexually active
donkeys.
The term ‘closed castration’ refers to the fact that the parietal tunica vaginalis is not opened,
and there is, therefore, no direct access to the abdominal cavity.
The surgery is performed under general anaesthesia in the field or in theatre. It is essential
that the surgeon is adequately assisted with administering the anaesthetic. The surgery will be
longer than that for a simple open castration and can be fiddly for those not used to performing
it. In addition donkeys tend to require top-up doses of anaesthetic agents and may wake too
quickly if a simple alpha-agonist/ketamine combination is used.
For in-field castration we
recommend placement of an intravenous catheter and having available top-up doses of a
suitable anaesthetic eg alpha-agonist/ketamine, triple drip, or thiopentone bolus.
Antiinflammatory medication is included in the initial induction protocol and antibiotics, if used, may
best be administered pre-operatively. Once the donkey is recumbent he is positioned in lateral
recumbency with the uppermost hind leg tied to expose the surgical area. After cleaning the
site local anaesthetic (3-10mls) is injected into each testicle. This will reduce the depth of
anaesthesia needed and ensure better exposure of the cord, as the donkey is less likely to
retract the testicle if it is anaesthetised.
The lowest testicle is operated on first to ensure good visualisation. The skin is incised, but the
incision is not carried through the tunica vaginalis communis. A dry swab and blunt finger
dissection is the best way to strip the tissue away and expose the spermatic cord and cremaster
muscle. It is best to remove fat deposits at this stage, as if left in place they may protrude
through the scrotal wound and wick infection into the wound. If the donkey is retracting the
testicle an assistant may be useful to hold it and allow good ligature placement. It is important
that the assistant does not pull excessively and apply undue tension when the ligatures are
tightened. For ligation, two doubled 5 metric absorbable sutures are placed around the cord
and tightened slowly and firmly to prevent retraction of the vessels within. Where the sutures
are anchored in the cremaster muscle or tunic, a transfixing ligature may be used instead. (It is
wise to apply tissue forceps to the proximal cord before emasculating. This allows one to check
for haemorrhage after emasculation. A standard emasculator is applied 2cms distal to the
ligature and left in place for 2 minutes.
This procedure is repeated on the upper testicle. The incisions are left open to drain and heal
by second intention.
Post-operatively the donkey must be exercised to prevent swelling and, if necessary, antiinflammatory drugs should be continued for 3-5 days.
Skin incision
Expose spermatic cord
and cremaster muscle
Ligation around vaginal tunic
Emasculate distal to ligature
Castration by the semi-closed technique
In mature individuals with well-developed testes or large fat deposits in the scrotum there is
more risk that ligatures may not adequately crush the structures within the cord if applied in a
closed technique. For this reason one of the semi-closed methods may be chosen. This
involves incising through the parietal vaginal tunic and ligation of the contents. There is a
greater possibility of introducing infection by this method, and if it is chosen, a high degree of
asepsis is required, preferably in a hospital environment.
Semi-closed castration via the scrotal approach
This technique is suitable for quiet, mature jacks where a simple closed technique may not
provide adequate haemostasis. A strict standard of asepsis is required.
The donkey is prepared as in the closed castration technique. The tunica vaginalis communis is
opened by incision and the neurovascular cord is ligated with 3 metric absorbable sutures,
checked for haemorrhage and allowed to retract into the vaginal process. The remaining
vaginal process is ligated as before and the distal portion is emasculated. It is important to
perform this procedure as proximal as possible and to remove all spare fat and fascia that may
act as a focus for infection. In mature donkeys there is a good blood supply to the scrotum,
and care must be taken with the many vessels in the area, using diathermy or ligation if
necessary. While in theory the skin could be closed the amount of swelling is usually
unacceptable without ventral drainage.
Semi-closed castration via the inguinal approach
As it is time-consuming, this technique is only suitable if hospital facilities are available. For a
full description see: Du Preeze, PM (1999) Castration-update on techniques. Proceedings of
the Annual Conference of the British Equine Veterinary Association, Newmarket, .pp 137-138,
or Green, P (2001) Castration techniques in the horse. In Practice volume 23, 5, pp 250-261.
It is the most suitable method for large sexually active donkeys as there is less risk of infection.
We have had experience with large mature jacks post castration continuing to be sexually active
and forcing further lengths of vaginal process down the inguinal canal leading to post-operative
infection. In the semi-closed technique via the inguinal approach this is less likely.
The operation is performed with the donkey in dorsal recumbency. An incision is made over
the external inguinal ring and the spermatic cord is located and withdrawn. Using gentle but
firm traction the testicle is withdrawn through the incision, thus everting the scrotum. The
scrotal ligament is divided, freeing the testicle. The cremaster muscle is separated and ligated,
the vaginal tunic is incised and the contents ligated as in the previously described technique.
The testicle is then removed and the stump of the vaginal process pushed back in the inguinal
ring. The skin can be closed with absorbable sutures. The donkey needs two days of box rest
followed by five days of hand walking twice daily
In our experience this method can result in unacceptable swelling as donkeys are not always
easy to hand walk and tend to be very immobile if box rested. If this method is used a good
exercise regime must be implemented.
Complications of castration
It is good practice to be aware of the complications that can occur following castration, and
discuss with the owner of the donkey what to look out for in the period following the operation.
It is also sensible, if one is operating in the field, to have sufficient equipment and anaesthetics
available for correction of haemorrhage should it occur, for example, a spare sterile kit, long
artery forceps, sterile packing material, and fluids.
Haemorrhage is the most immediate complication and can be life-threatening. If pressure from
sterile packing is not controlling the flow the donkey may need to be rapidly re-anaesthetised to
locate the source of the haemorrhage. The blood may be from the large scrotal vessels,
external pudenda vessels or from the testicular artery. The scrotal wound must be cleaned and
the cut ends of the testicular artery located and re-ligated if necessary. The risk of infection
occurring after such an emergency is high, and antibiotics will be needed. The donkey must be
assessed for blood loss and haemorrhagic shock and treated accordingly.
Post castration infection
Eventration is unlikely following a closed castration. However, small pieces of fat and fascia
may prolapse out of the wound.
Every effort should be made to trim these away during
surgery, if they are found hanging from the wound they can act to draw infection into the wound.
Small pieces of tissue may be cut away under sedation if they are fresh; larger pieces may
require removal under anaesthetic to ensure asepsis.
Excessive swelling may be a problem in donkeys due to their sedentary nature, especially in
older animals. Every effort must be made to encourage exercise and use non-steroidal antiinflammatory drugs. Hosing the wound can cause water logging of the tissues and is not
recommended. Uncontrolled swelling can lead to secondary paraphimosis which may be slow
to resolve.
Infection can be superficial and easily dealt with, or deeper, leading to involvement of the
vaginal tunic and scirrhous cord. Any suspicion of infection should be promptly investigated
under sedation using a gloved hand. Local superficial infection is best dealt with by enlarging
the incision sites to improve drainage, combined with cleaning with povidine–iodine and a
course of antibiotic treatment. If infection is within the vaginal tunic repeat surgery is required
to resect all affected tissue and this may need to be combined with scrotal ablation if the scrotal
tissue is also oedematous and infected.
© The Donkey Sanctuary 2006