Selected common conditions of donkeys

Transcription

1 Vet Times The website for the veterinary profession Selected common conditions of donkeys Author : ALEX THIEMANN Categories : Vets Date : January 21, 2008 THIS article gives an overview of some common conditions encountered in the UK donkey population. Hoof conditions have been covered in a separate article. For more information about specific conditions, the veterinary department at The Donkey Sanctuary is happy to give advice and support. Obesity The donkey evolved in semiarid conditions with limited food resources. It has adapted to be an efficient digester of poorquality roughage feeds. Recent studies by The Donkey Sanctuary have shown that donkeys require far less dry matter intake (DMI) for maintenance than horses. Comparable figures for the donkey are 1.3 per cent DMI in summer to 1.7 per cent DMI winter, versus two per cent and 2.5 per cent for the horse. The vast majority of donkeys are overfed, with the result that obesity readily develops (Figure 1). In many cases, owners worry that the substantial fat deposits in the neck may be a tumour and, therefore, reassurance is necessary. These neck fat deposits can cause difficulties when trying to place a microchip for identification purposes. Obesity contributes to a number of problems, many of which are interconnected. An increase in the risk of developing laminitis may be due to a combination of diet, weight and obesity-related or metabolic syndromes. The resting triglycerides are higher in obese individuals, increasing the risk of hyperlipaemia. Large fat deposits are found under the skin, around the internal organs and under the linea alba. The Donkey Sanctuary has measured up to 14cm of fat in the ventral midline - this can make obtaining a peritoneal tap in cases of colic and abdominal disease very difficult (Figure 2). Excess fat deposits can make surgery more complicated and fat may prolapse out of scrotal castration wounds - increasing the risk of postoperative infections. Fat itself is relatively poorly vascularised in the subcutaneous areas, and injury to the fat pads can be notoriously difficult to heal. In cases where traditional wound management techniques have failed, the sanctuary has had success using sterile maggots to debride areas of necrotic fat1,2 (Figure 3). Where weight is lost, fat deposits can appear to mineralise, leading to hard, firm, painless avascular areas. Obesity inevitably puts more strain on organs and joints - if osteoarthritis is present, the extra weight can be sufficient to destroy a donkey s quality of life. 1 / 19

2 Dieting an obese individual is not an easy task, but should be encouraged and supported. It is advisable to take a resting blood sample at the start of the diet and at regular intervals throughout to assess resting triglycerides and organ function. The Donkey Sanctuary will run all donkey blood samples for routine haematology and biochemistry free of charge. The donkey should be regularly measured using weight or heart-girth measurements. A dental check is sensible at the outset, as reducing the quality or quantity of feed if the teeth are poor can be dangerous. The sanctuary recommends that owners learn to weigh portions of hay or straw and chopped fibre products, and feed only an appropriate, measured amount of these. Cubed or pelleted feeds should be chosen in obese individuals with poor teeth. In all cases, increased exercise is very useful - but this can be hard to achieve in non-ridden donkeys. Geriatric donkeys Many companion donkeys will live into their 30s and even 40s. The average age at death of animals at The Donkey Sanctuary is approximately 28 years. Owners are often committed to these donkeys and are keen to maximise their animals remaining quality of life. A number of problems are being seen with increased frequency, some of which are discussed below. Dental disease. Years of dental neglect may become apparent and it is common to see severe weight loss associated with this (Figures 4 and 5). It may be inappropriate to achieve full correction with geriatric donkey mouths and a carefully considered plan of work should be instituted. The sanctuary recommends pre-dental blood samples, and good use of peri and postoperative analgesia and antibiotics as necessary. Clients should pay particular attention to the donkey s diet after the procedure and ensure it is eating well. Organ failure. Older animals have an increased likelihood of developing renal and hepatic failure (Figures 6 and 7). In many cases, this takes the form of weight loss and general dullness. Annual geriatric blood screens, as are becoming more common in small animal medicine, should be used to monitor the condition of older donkeys. Usually, dietary and medical management are appropriate until the donkey s appetite fails - at which point, euthanasia is recommended. Neoplasia. The incidence of neoplasia appears to be different in donkeys in comparison to horses. The sanctuary does not come across cases of melanomas in grey donkeys or squamous cell carcinomas of the external genitalia. However, if the animal is more than 20 years of age, increases in incidences of internal neoplasias affecting all organs, especially the liver, kidney and respiratory system, can start to be seen (Figures 8 and 9). This is an important differential diagnosis in the examination of sick geriatric donkeys. In many cases that are unresponsive to straightforward medical management, attempts should be made to look for underlying neoplastic disease. 2 / 19

3 Respiratory disease. As a non-athletic animal, many cases of respiratory disease go unnoticed until they are highly advanced. Undetected, reversible small airway disease has often progressed to irreversible fibrotic changes in the lung (Figure 10), and are resistant to therapy. Increases in intrapleural pressures and weakening cartilage rings also leads to an increased incidence of tracheal collapse (Figure 11). Donkeys may present with severe dypnoea and in cases of tracheal collapse, a peculiar, characteristic honking cough occurs. In cases of severe lung disease, cor pulmonale has been seen due to the increased strain on the heart. Cushing s disease. This is seen in the donkey, as it is in older horses, with similar presenting signs. These include hirsutism, immunosuppression, recurrent laminitis, polydipsia and polyuria. Diagnostic and treatment protocols mirror those for the horse. In many cases symptomatic management is all that is required. Senility. Some geriatric donkeys appear to become increasingly senile, showing signs of aimless wandering, circling and appetite loss, in the face of normal blood parameters and unremarkable physical exam. I assume these cases show some similarities to the condition in geriatric dogs, and such cases are managed conservatively until euthanasia is necessary. Many donkeys suffer from failing eyesight and cataracts in later life. However, these animals can have a good quality of life if the deterioration in sight is gradual and their environment is kept stable. Limb and joint deterioration. Many donkeys suffer from osteoarthritis of single or multiple joints, as well as chronic hoof disease. NSAIDs and nutritional joint supplements should be used as necessary. Hyperlipaemia It is well known that donkeys are peculiarly prone to this life-threatening condition and that overweight individuals are especially so. Other risk factors include being female, particularly if pregnant or lactating, any concurrent illness and stress. Donkeys often have a quieter lifestyle than horses and ponies, and may react more adversely to what are considered routine lifestyle changes, such as travelling, mixing and environmental changes. They are also noticeably more stoical than the horse in their behaviour and subtle signs of illness may go unnoticed. Any dull donkey should be attended to promptly and examined thoroughly for signs of hyperlipaemia. Clinical signs include anorexia, sham eating and drinking, reduced gut sounds, dry mucus-covered faeces, halitosis, tachycardia, tachypnoea, pyrexia, ventral oedema and, terminally, ataxia and collapse. Blood samples should be taken in all suspect cases and examined visually and for full haematology and biochemistry profiles (Figures 12 and 13). Complicating hepatic and renal disease may alter the prognosis, even if triglycerides are normalised by treatment. In many cases, the sanctuary has found that pancreatitis and gastric ulceration complicate the condition and require additional therapy. The management of this condition requires reversal of the negative energy balance via oral or parenteral routes3. We find that a mixture of approximately 250g of Ready Brek two to three times daily, warm water and electrolytes fits easily through a pony-sized stomach tube 3 / 19

4 and can be used as a readily available, cheap energy source for anorexic donkeys without ileus. Hyperlipaemia often complicates any disease process in the donkey and it is sensible to blood sample all donkeys with concurrent illnesses, such as colic, choke and dental disease. Due to the vagueness of the clinical signs, a full examination should be performed including rectal examination. Many practitioners are wary of performing a rectal exam. However, in the experience of practitioners at the sanctuary, the procedure has not resulted in rectal damage. Clearly, animals should be well restrained, and sedated if necessary, and it may not be possible to examine the abdomen as fully as in a horse. However, the information gained - even from a limited examination (including faecal consistency, mucous membrane quality, and possible impactive colic) - is often invaluable in decision making. In miniature or fractious individuals, abdominal ultrasound may be preferred if facilities permit. Ideally, vets should educate their clients about potential risk factors for the development of hyperlipaemia and be prompt with instituting therapy. References 1. Bell N J and Thomas R S (2001). Use of sterile maggots to treat panniculitis in an aged donkey, Vet Record 149(25): Thiemann A K (2003). Treatment of deep injection abscess sterile maggots in a donkey, World Wide Wounds ( 3. Hammond A (2004). Management of equine hyperlipaemia, In Practice 26(10): / 19

5 Figure 1. A severely obese donkey. 5 / 19

6 Figure 10. A lung with end-stage fibrosis. 6 / 19

7 Figure 11. Longitudinal sections of collapsed trachea. 7 / 19

8 Figure 12. A swollen liver typical of terminal hyperlipaemia. 8 / 19

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10 Figure 13. A severely hyperlipaemia serum sample. As donkeys are subtle in exhibiting signs of hyperlipaemia, swift action when encountering a dull donkey is needed. 10 / 19

11 Figure 2. Large fat deposits in the linea alba. Figure 3. Maggots being used to debride a wound. 11 / 19

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14 Figure 4. The typical incisor profile of an aged donkey. 14 / 19

15 Figure 5. Mandible of an elderly donkey with multiple problems. Figure 6. Kidney stones, which in this case caused renal failure. 15 / 19

16 Figure 7. End-stage liver fibrosis. Weight loss and general dullness are indicators of organ failure. 16 / 19

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18 Figure 8. A liver with multiple tumours. 18 / 19

19 Figure 9. A lung with multiple tumours. // 19 / 19 Powered by TCPDF (