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Clinical audit results on donkey castrations

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01 September 2011, at 12:00am

GRAHAM DUNCANSON shares some findings on his experiences with donkey castrations in the hope that they will be of interest and help to other practitioners

WHEN I was in my final year at Langford in 1965-66, we were told that the testicular vessels should be ligated as well as applying an emasculator when castrating donkeys. I followed this instruction for 40 years so that by 2005 I had carried out a thousand equine castrations. This series included 78 donkeys and two mules. I gave a talk on my findings to a BEVA regional meeting at Rossdales in Newmarket. My findings showed that none of the horses, mules or donkeys had suffered from any post-op haemorrhage, other than to a minor extent. During question time, Hannah Kelly thanked me for the talk but suggested that ligaturing donkeys was unnecessary. The policy in her practice, which carried out frequent donkey castrations, was only to apply an emasculator. We then had a show of hands: 24 of the audience of 58 claimed, like Hannah, that they never ligated donkey castrations. The other two thirds, like me, had always been told of the dangers and had ligated all their donkey patients.

Other authorities

Responses from the Donkey Sanctuary at Sidmouth were very helpful. The charity obviously castrates a considerable number of donkeys; however it has very good facilities and a policy of providing “Rolls Royce” surgery for its donkeys. It not only gives the donkeys a GA, like myself, but also entubates them to give gaseous anaesthesia. This gives a longer anaesthetic window so there is ample time to carry out a careful closed castration (Sprayson and Thiemann, 2007). These authors concluded that the donkey was a special case because of the following considerations:

  • the larger than normal vessels in the donkey require ligation, which can lead to an increased risk of infection and foreign body reaction;
  • donkeys are often presented at an older age for castration with increased size of testes, increased quantities of scrotal and inquinal fat together with established sexual behaviour, all of which can cause post-operative complications;
  • the short height of most donkeys precludes standing surgery, necessitating general anaesthesia and extra assistance during surgery to monitor the animal;
  • owners of miniature donkeys occasionally request castration at a very young age (sometimes only a matter of days);
  • post-operative care in some unhandled animals can prove difficult; 
  • the stoic nature of donkeys can result in post-operative problems not being noticed early enough. All these considerations are valid and to some extent provide the reasoning behind my ligation of all donkey and mule castrations prior to 2005.

My series

Since 2005 I have castrated 325 normal equines (I have also castrated 18 rigs but they have been removed from the series). The animals were divided into 25 donkeys, 190 ponies and 110 horses. Their ages were recorded. The ages of the donkeys ranged from four months of age to eight years of age; the mean was 27 months. The ages of the ponies ranged from three months of age to five years; the mean was 28 months. The ages of the horses ranged from five months of age to four years of age; the mean was 15 months. In my series, the donkey patients
were not on average older than their horse and pony counterparts; however, there were some older donkeys presented. My series did include two miniature donkeys but neither was under four months of age. They were all given a short-acting anaesthetic of a combination of romifidine 1ml/100kg intravenously followed in four minutes by ketamine
at 2.2ml/100kg intravenously. Castration was carried out on the
ground using an open method with a Sierra emasculator. No ligatures were applied. The animals received antibiotic, NSAIDs and tetanus antitoxin. Any complications were recorded. 

Post-operative complications 

One donkey and three horses were seen to haemorrhage more than normal but not sufficient for further action to be taken. One horse suffered from a prolapse of 0.75cm of omentum 24 hours after castration (see picture). This was reanaesthetised with the same anaesthetic protocol. The omentum was removed and the scrotum sutured. Further doses of antibiotic and NSAIDs were administered for five days. The horse made an uneventful recovery. Eighteen horses had problems with post-castration sepsis. These were treated with oral antibiotics and made uneventful recoveries.

Discussion

A direct comparison of my two series would not be valid as there were other variables, e.g. type of anaesthesia, ambient temperature (the first series included animals in Africa and Australia), method used (some of the horses were castrated with a semiclosed method) and antibiotic usage. If, however, we compare the postoperative complications suffered by the
donkeys in each series, we get a much fairer comparison. In the first series, all the 78 donkeys were ligatured at the time of castration. None suffered any marked haemorrhage. In the second series, one donkey suffered haemorrhage which was not deemed to require further intervention. This is noteworthy but hardly warrants ligation of all donkeys. In the first series, six horses suffered post-operative haemorrhage (0.6%) and in the second series three horses (1%). None of the horses suffered severe enough haemorrhage to warrant further intervention. I doubt if any authority is going to suggest that all horses should be ligatured on the strength of those results. In the first series there were 42 animals which suffered post-operative sepsis: nine of these animals were donkeys; 3.3% of horses in this series
suffered sepsis compared to 12% of donkeys. The inference is that the ligatures were a predisposing cause of the sepsis.
In the second series there were 18 horses (6%) which suffered from postcastration sepsis. None of the donkeys suffered from sepsis. If donkeys which had not been ligated were the same as
horses, one would have expected to have at least one donkey suffering from sepsis. If the donkeys were more prone to sepsis regardless of ligatures, one would have expected 12% of 25
donkeys, i.e. three donkeys.

Conclusion

Donkeys do not require ligation at the time of castration when performed under general anaesthesia in the UK. It is a myth that they are more likely to suffer haemorrhage. If donkeys are ligated at the time of castration it would be prudent to perform the castration in a closed manner with a full aseptic protocol as advised by the Donkey Sanctuary. If this is not possible, then antibiotics should be given for a longer period to donkeys which have been ligatured. The workers at the Donkey sanctuary are correct that donkeys are more stoical than horses and so it is
important to have a correct examination protocol for donkeys
post-castration so that any signs of sepsis are treated early. There is no comparison of post-