Any donkey of 20 years of age or older is considered to be geriatric. While companion animals will form the mainstay of geriatric donkey patients, it is not uncommon to experience aged working donkeys overseas and the following comments may be equally applicable.
Conditions of geriatric donkeys are frequently overlooked not receive regular, thorough inspection. Veterinarians may be called upon in an emergency situation, or, ideally, annual veterinary checks may be in place as part of routine vaccination protocols. It is important that any associated paraprofessionals are also aware of care of the geriatric donkey, as farriers and dental technicians can play a vital role in alerting owners to any potential health problems.
Stoic in nature, the donkey’s inherent behavioural response is to avoid displaying pain, thus the true extent of a pathological condition may be easily missed; it is vital that a thorough clinical examination of the whole donkey takes place at every veterinary visit. Beneath the thick coat may lie an underweight or obese animal, or advanced skin disease. Respiratory and musculoskeletal conditions of the non-athletic donkey may not be apparent at rest until an advanced stage has been reached. Research from The Donkey Sanctuary has identified a high proportion of advanced dental disease and poor to no routine dental care in relinquished geriatric donkeys (unpublished data). Heavy endo- and ectoparasite burdens have been seen in geriatric donkeys at The Donkey Sanctuary.
Chronic laminitis is highly prevalent but frequently overlooked by owners. Classic weight shifting is less reported in donkeys, with subtle changes in gait the more frequent indicator; depressed demeanour, muscle wastage over the shoulders and a reluctance to walk, alongside external hoof changes, should all trigger a check for laminitis. Hoof radiography is strongly advised to aid diagnosis and assist with remedial farriery.
Testing for pituitary pars intermedia dysfunction (PPID) is advised in cases of chronic laminitis, particularly where changes in demeanour, muscle wastage, recurrent infections and high faecal worm egg counts are seen. The classic hirsutism and hyperhidrosis seen in horses is not commonly identified in the donkey. Presently, measurement of basal adrenocorticotropic hormone (ACTH) is advised as a diagnostic test. Use of the thyrotropin-releasing hormone (TRH) stimulation test may be advisable in equivocal cases, although donkey-specific reference ranges have not been validated. If PPID is diagnosed, therapeutic management with pergolide mesylate at standard equine doses is valid, although owners should be cautioned as to the potential for inappetence and secondary hyperlipaemia.
Osteoarthritis of the axial and appendicular skeleton is very common. Owners may notice little more than a reduction in ambulation of the donkey and deterioration in temperament on handling. An onset of reluctance to raise the limb for foot care may indicate pain of the limb joints. Farriers should be advised to keep the limb as low as possible during foot trimming sessions. A donkey that rarely lies down or rolls or has sores over the carpi or hocks is also a cause for concern. Management of the arthritic patient should involve careful weight control, access to flat pastures where possible, routine farriery, consideration of appropriate bedding material, and adequate analgesia. Appropriate analgesics include phenylbutazone 2.2 mg/kg bwt orally twice a day or carprofen 0.7–1.3 mg/kg bwt orally once a day. Firocoxib has been used, but to this author’s knowledge there are no published data relating to its use in donkeys. Paracetamol 20 mg/kg bwt orally twice a day has been used as short-term adjunctive analgesia in acute-on-chronic presentations of both osteoarthritis and laminitis. While gastric ulceration has been seen at postmortem examination, there have been no studies linking its occurrence with long-term NSAID administration in donkeys.
Weight loss is a common presentation of the geriatric donkey. Diagnostic work-up should follow the same principles as for other equines. Liver disease appears to be relatively prevalent in the geriatric weight loss case, with liver fibrosis not infrequently seen at post-mortem examination. A thorough dental examination is paramount in weight loss cases; significant and painful dental disease is often identified.
Conversely, obese geriatric companion donkeys are also frequently seen and pose a particular hyperlipaemia risk. The diet of the geriatric donkey should be adjusted to account for desired weight, seasonality, underlying health concerns and dental disease. Short-chop forage products may replace straw for donkeys with poor dental function. Poor dental function and failure to provide access to warm drinking water in colder months have been significantly associated with an increased incidence of impaction colic in geriatric donkeys [1]. Balancer products should be fed to reduce vitamin and mineral deficiencies.
Ocular lesions are often identified during routine clinical examinations of the geriatric donkey. Advanced cases of uveitis, non-ulcerative keratitis and glaucoma may be present despite little indication of pain, while cataract formation is seen regularly. Ocular conditions should be treated and monitored as for other equines, with particular emphasis to owners on the subtle clinical signs of pain in the donkey.
Interstitial pulmonary fibrosis appears relatively prevalent amongst geriatric donkeys presenting with respiratory disease. Disease is rarely recognised until advanced, and/or secondary bacterial pneumonia has increased the severity of clinical signs. The disease is invariably fatal, although over wideranging time periods. Ultrasonographic imaging and thoracic radiography can aid the diagnosis where the clinical signs raise suspicion of disease. Equine herpesvirus-5 has been isolated from bronchoalveolar lavage samples taken from donkeys with confirmed pulmonary fibrosis, and asinine herpes viruses have been detected in donkeys with interstitial pneumonia; however, the precise role of herpesviruses in donkey pulmonary fibrosis has not been definitively established [2,3].
Tracheal collapse has been identified in a high number of geriatric donkeys at post-mortem examination, such that age-related degeneration of the tracheal rings is thought to be common. Clinical signs are rarely seen unless advanced stenosis is present; the presence of concurrent respiratory disease may severely exacerbate clinical signs [4].
Quality of life assessments can play a vital role in monitoring geriatric donkeys with chronic conditions. Informal discussions will likely form a mainstay of regular consultations, while more formal recording sheets can assist owners to identify any decline in their donkey’s condition or highlight issues in the case of working donkeys.
Discussing and defining ‘end-of-life’ points is a critical part of this process. Awareness of pain scoring systems, including facial pain recognition scales, can provide useful information relating to the efficacy of analgesia and true severity of any chronic disease processes. Euthanasia of the donkey follows the same basic principles as for other equines. In the UK, Somulose® is the most commonly employed agent. It is essential to have a calm and experienced handler to assist with euthanasia. Due to the small size of the average donkey found in the UK, i.v. agents are frequently given off the needle, but use of an i.v. catheter is down to personal preference. Certain anatomical differences, namely, thicker skin and a prominent cutaneous colli muscle, can make jugular venepuncture more difficult than in horses. It is vital that any companion is allowed access to the deceased donkey until they lose interest in the body; this can take from minutes to hours. Owners should be advised to monitor closely the companion, as bereavement stress has been known to elicit hyperlipaemia. Further information can be found in The Clinical Companion of the Donkey [5].
References
- R. Cox, C. J. Proudman, A. F. Trawford, F. A. Burden. (2007) Epidemiology of impaction colic in donkeys in the UK. BMC Veterinary Research 3, 1-11.
- S. B. Kleiboeker, S. K. Schommer, P. J. Johnson, B. Ehlers, S. E. Turnquist, M. Boucher, J. M. Kreeger. (2002) Association of two newly recognized herpesviruses with interstitial pneumonia in donkeys (Equus asinus). Journal of Veterinary Diagnostic Investigation 14, 273-280.
- A. K. Thiemann. (2012) Respiratory disease in the donkey. Equine Veterinary Journal 24, 469-478.
- R. J. Powell, N. Du Toit, F. A. Burden, P. M. Dixon. (2010) Morphological study of tracheal shape in donkeys with and without tracheal obstruction. Equine Veterinary Journal 42, 136-141.
- L. Evans, M. Crane. (2018) Euthanasia and the post-mortem examination. In: Clinical Companion of the Donkey, 1st edition, Troubador Publishing Ltd, Leicestershire. p 196.