pharmacology

Review: pharmacology and therapeutics in donkeys

Therapeutics are often administered to donkeys based on dosage and intervals recommended for horses because very few drugs have donkey-specific label indications. Yet differences between donkeys and horses in drug distribution, metabolism and elimination have been noted for most therapeutic agents studied. These differences can be partially explained by the donkey's unique physiology. Since their ancestors evolved in a desert environment, the modern donkey exhibits qualities that allow them to tolerate dehydration better than the horse and recover more quickly from its effects. Fluid balance and body water compartment partitioning differ from the horse and may have implications regarding drug distribution. Since donkeys are preferential browsers, differences in diet may have influenced evolutionary differences in metabolic disposition of drugs. It is important to acknowledge these differences when designing dose regimes for donkeys based on horse protocols in order to avoid either lack of efficacy or toxicity.

Volume
23
Issue
10
Start page
523
End page
530
Publication date

Medication for donkeys

Alexandra K. Thiemann
Presentation date

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.

Country

Colic in the donkey

The donkey is a unique species of equine, with certain specific variations and adaptations that differ from its cousin the horse. The donkey is used by humans as a pack and draft animal in areas of the world where its ability to cope with low‚Äźquality fiber and harsh conditions have excluded the horse. This chapter highlights the differences in anatomy and particularly physiology that have enabled the donkey to fulfill these roles. One of the consequences of being equipped to survive in areas of food scarcity is the tendency to deposit adipose if conditions are reversed. This fact, combined with insulin resistance, leads donkeys rapidly to become metabolically compromised and develop hyperlipemia as a response to stress and sudden reduction in appetite. The consequence is that many donkeys with colic must also be treated for hyperlipemia, which may have a higher mortality rate than the primary condition. Pain behaviors in the donkey may be more subtle than those in the horse and therapeutically there are differences in drug metabolism between donkeys and horses. This chapter summarizes the types of colic that occur in the donkey in relation to anatomic location and as a consequence of management and environmental factors.

Chapter number
38
Start page
471
End page
487
Subscribe to pharmacology