Drug manufacturers consider the donkey to be a minor species, despite the millions that work to sustain livelihoods globally, through draught power, milk and meat. Unfortunately, this means that very few drugs are licensed for use in the donkey and we rely upon the work of a select few researchers to know about drug metabolism. The Donkey Sanctuary has a non-invasive research policy and so is unable to work in this field.
In most instances, it is sensible to start with using recommended horse dosages but with knowledge of some fundamental differences between the species to aid in correct prescribing.
Donkeys can range in size from miniature to mammoth and accurate weighing is best practice. Donkey foals may be only 10- 15kg when born.
Many donkeys are obese and this can affect the distribution of drugs. Conversely, a thick winter coat can hide an emaciated frame. It is helpful to determine Body condition Score BCS, when considering medication and this requires hands on palpation of the donkey.
The donkey evolved to be more desert adapted than the horse, and are reported to tolerate dehydration with fewer and later clinical and haematological signs. The normal haematology and biochemistry values are different from horse: red cell numbers are lower with a larger mean cell volume. They have a different volume of distribution of drugs. Their liver metabolises drugs in a slightly different manner from the horse- usually more rapidly with some exceptions.
Donkeys are stoical and good at masking disease. Routine haematology and biochemistry samples are advisable before starting treatment especially with potentially nephrotoxic or protein bound drugs. Good assessment of pain is useful in monitoring the effectiveness of analgesia, we use a donkey composite and facial pain score.
Donkeys working overseas are often dehydrated and may need rehydrating before full doses of drugs such as NSAIDs are used.
It is always good practice to base prescribing on a full clinical examination and the results of any test results including bacteriology culture and sensitivity. However due to the fact that donkeys often present late with clinical signs, and many are geriatric and immunosuppressed, antibiotic therapy may need to be based on empirical knowledge and using best practice guidelines available to protect critically important antibiotics.
This presentation will cover recommendations for prescribing in donkeys for the following areas:
- Sedation
- Anaesthesia/Analgesia
- Maintenance of anaesthesia with top ups
- Maintenance of anaesthesia with triple drip
- Antibiotics
- Anthelmintics.
References
Grosenbaugh et al, (2001) Pharmacology and therapeutics in donkeys. Equine Veterinary Education 23 (10) 523-530.
N. S. Matthews et al, (1997b) Anaesthesia of donkeys and mules. Equine Veterinary Education 9, 198-202.
F. A. Burden, A. K. Thiemann, A K (2015) Donkeys are different. Journal of Equine Veterinary Science 35 (5) 376-382.