DS research

Dental disease is recorded as being the second most common clinical problem encountered in the donkey, after disorders of the feet. It has the potential to cause significant pain, which may go unrecognised in these stoic animals. Prophylactic dentistry is essential.

Note that this chapter uses the TRIADAN nomenclature and refers to a complete dental formula of 44 teeth (11 teeth in each one of the 4 quadrants): 3 incisors, 1 canine, 4 premolars (including wolf tooth) and 3 molars. The cheek teeth (CT) refer to 3 premolars and 3 molars (TRIADAN nomenclature 06 to 11).

The definition used for a 'geriatric' donkey is one that is over 20 years old. Many donkeys living as companions, rather than feral or working individuals, will live far beyond this age and have a long, fulfilling life. They deserve special care.

This most stoic of species represents a challenge for the clinician even though many problems faced by the geriatric donkey are similar to those seen in horses and ponies. The mixture of lifestyle, lack of monetary value and stoicism, often compounded by the lack of vigilant management experienced by many donkeys, frequently result in the occurrence of significant unrecognised disease. The geriatric donkey tends to 'suffer in silence'. Poor body condition may be veiled beneath the thick coat and common pathologies such as foot, dental, respiratory and liver disease and insulin dysregulation often go unnoticed or undiagnosed in the non-athletic individual.

An important consideration when deciding on treatment or control will be the quality of life of the donkey, both at the time of presentation and going forward. Unrecognised disease, or even controlled recognised conditions, may lead to pain and distress. Unremitting pain, anxiety or chronic discomfort will inevitably impair the donkey's quality of life. Euthanasia should be seen as a positive tool in the veterinarian's 'welfare kit' and may be the best outcome for a geriatric donkey in chronic discomfort or one that an owner is no longer able to keep.

This chapter concentrates on conditions commonly seen as a result of longevity and lifestyle. Other conditions which cannot be ruled out of the differential diagnosis can be found in other chapters.

Most conditions of the gastrointestinal system present as in horses and ponies.

The prevalence of colic varies according to the donkey population and can be a cause of significant mortality.

There is a high risk of hyperlipaemia and gastric ulceration secondary to periods of inappetence or starvation.

By recognising the importance of subtle behavioural clues and a thorough diagnostic evaluation, donkeys with colic may be treated effectively. Treatment of secondary hyperlipaemia and gastric ulceration will ensure that the donkey has an improved chance of making a full recovery. Key preventative health measures will reduce the incidence of colic.

Surgical treatment of colic is not covered in this chapter, because the approach is the same as for the horse and pony.

In their natural habitat donkeys browse on sparse, fibrous vegetation, wandering over long distances in a semi-desert environment, and survive for perhaps 10 - 15 years. In developed countries, with their characteristically damp temperate climates, most donkeys are kept as pets, enjoying a surfeit of good grazing and taking little exercise. They may well live beyond 30 years of age. Consequently, it is almost inevitable that food problems will develop in this environment.

Good hoof care is essential if these problems are to be minimised. This necessitates attention to each of the following:

• Daily hoof care and regular, route in farriery
• Good pasture and stable management
• Correct feeding
• General health care.

Neglect of any of these is a risk factor for the development of foot problems.

Unless otherwise stated, this chapter focuses on the donkey kept in the UK and similar environments.

For the purpose of this article the 'geriatric' donkey will be taken as one that has reached the age of 20 years. Many donkeys in the UK live far beyond this somewhat arbitrary age designated for vereran status.

Whereas veterinary clinicians working with developing countries rarely see a donkey over the age of 12 years, in the UK it is quite normal to be presented with a donkey well over 30 years of age. Whilst some exceptional animals manage to live happy and comfortable lives well into their forties, it is useful to remember that the average age of death of donkeys at The Donkey Sanctuary in Sidmouth, Devon, is still 27 years of age (Svendsen, 1997).

This chapter will try to help guide the clinician to recognise and treat the most common problems encountered when dealing with elderly donkeys. Many such conditions are simply those of old age and are similar in many ways to those encountered in any other ageing population of animals.

Neonate survival is described as a major problem among working donkeys globally.

Risk factors for the survival of the neonatal donkey foal are similar to those for horses and ponies but consideration of the donkey specific differences could improve the survival rate and future health of the donkey.

The lack of preventative care for many female donkeys during pregnancy is an important factor. Programmes for vaccination and parasite control are essential during the pregnancy and an appropriate diet for the pregnant animal is necessary.

Many people wrongly assume that the donkey’s normal behaviours are less expressive than those seen in horses and ponies and do not appreciate that a healthy donkey should not appear dull. The donkey will still suffer from pain but the survival strategy of this prey species is to mask the obvious signs of pain. Subtle changes in a donkey’s behaviour may indicate severe pain and serious disease. Dull companion or pet donkeys are most likely to be suffering from impaction colic, pain and/or hyperlipaemia. Dull or apathetic working donkeys may be suffering from multiple problems, including exhaustion.

Therefore, any donkey exhibiting subtle changes in normal behaviour and appetite, or with a dull demeanour, should be examined thoroughly and urgently to detect the underlying cause(s).

This chapter offers an overview of the types of surgery commonly performed at The Donkey Sanctuary. A standard equine surgical text should be consulted for a more detailed explanation of the surgical techniques discussed. References to surgeries specific to the donkey are included at the end of the chapter.

A review of the last 160 surgeries performed under general anaesthetic at The Donkey Sanctuary shows that the majority are routine castrations and the removal of dermal masses. In addition, operations on the hoof and distal phalanx are relatively common due to keratomas and/or septic pedal bone. In young donkeys we also see a number of tenotomy operations necessitated by flexural deformities of the distal inter-phalangeal joint. Less common are dental surgeries requiring the removal of cheek teeth, the removal of chondroids from the guttural pouch, exploratory laparotomy, enucleation of the eye and wound management. Exploration of the frontal and/or maxillary sinus is frequently required under local anaesthetic and sedation.

Different populations of donkeys have different surgical problems. For example, in Donkey Sanctuary projects overseas, which concern a younger population of working, breeding animals, there is a higher incidence of work-related wounds and dystocias.

The age range of donkeys presented for surgery can be a challenge. Many donkeys are presented for castration in their 20s, and geriatirc donkeys often require surgical procedures. As in the horse, donkeys with increasing age show different problems. At The Donkey Sanctuary we have seen no instances of squamous cell carcinoma of the external genitalia, nor melanomas in grey animals. Pedunculated lipoma causing colic is rare, despite the tendency of the donkey to be obese.

For centuries the donkey has been regarded as a robust and willing servant of man, and most veterinarians accept that, as a species, it suffers rather fewer skin diseases than most other domestic animals. However this may be more in the perception than the actuality because the donkey tends to show few signs of cutaneous discomfort. The concept of a skin diseas being a significant factor in the overall health of the animal is not widely appreciated; it is largely viewed as trivial and incidental.

Many of the skin diseases of the donkey (and the horse for that matter) have not been well characterised and so they are often given the names of the 'similar' disorders in humans and other animals. This is probably unjustified and may even be grossly misleading when treatments are sought. Extrapolation from other species only works if the conditions have identical pathophysiology and if the various species have identical treatment requirements and tolerances. In the case of the donkey, little is known and much is assumed. Some of the skin disorders that afflict donkeys in troical climates are very serious both to the donkey itself and to its owners. Zoonotic implications should be considered where fungal skin infections in particular, such as Trichophyton and Microsporum spp. (the causes of dermatophytosis/ringworm) and others such as Cryptococcus spp. and Histoplasma spp. organisms are endemic.

Donkeys differ from horses and ponies, with differences in anatomy, physiology and temperament that are important to be aware of when planning sedation, anaesthesia and analgesia. Protocols for donkeys may be based upon those used in horses and ponies, but careful attention must be paid to the different pharmacological and handling requirements as well as the variations necessary for certain procedures. It is also important to note the difficulties in judging the weight of a donkey.

The doses for drugs may be different to those used in horses and ponies because of an altered drug metabolism. Such differences are thought to be a result of the donkey being a desert adapted animal, with differing body fluid compartment distribution and faster oxidative metabolism of many drugs compared to horses and ponies.