DS research

The pathophysiological process is triggered in response to a negative energy balance resulting in mobilisation of fats from adipose tissue. Although this is a normal response to a fasting state, in hyperlipaemia the rate of lipolysis exceeds the rate of uptake of triglycerides into peripheral tissue for use as an energy substrate. The accumulation of plasma triglycerides results in fatty infiltration of organs such as the liver, pancreas and kidneys, which can in turn, lead to multiple organ failure.

Hyperlipaemia is a life-threatening disease to which donkeys are particularly prone, both as a primary or secondary condition. The matabolic pathways are complex, involving many factors. Basically, hyperlipaemia occurs when animals mobilise triglyceride from body fat reserves in response to a negative energy balance achieving plasma levels over 5 mmol per litre. The end result is multi-organ failure as lipid is deposited in the liver and kidneys. The initial clinical signs are easy to miss, especially in donkeys and, if early treatment is not initiated, the disease will progress rapidly to terminal stages.

This chaper briefly discusses a range of infections not usually found in the UK and, hence, referred to as exotic. The geographic distribution of these infections may be limited for two main reasons. Firstly, transmission of infection may depend on specific arthropod vectors that occur only outside the UK. Secondly, concerted disease control efforts may have led to eradication of disease in the UK. However, resurgence of such diseases in the UK might be expected more frequently as a result of increased movement of people and animals, expansion of the European Union, where disease security is dependent on its weakest point, and the consequences of global warming.

Specific scientific information is lacking for many infections that affect donkeys. Therefore, relevant information on diseases as they manifest in the horse has occasionally been included in this chapter. Diseases are discussed in outline only, with an emphasis on the factors relevant to donkeys. This chapter should, therefore, be read in conjunction with standard texts describing the diseases and their diagnosis and treatment in more detail.

Although the donkey shares a common ancestor with the horse (the Hyracotherium or the Dawn Horse), the evolution of these two species diverged approximately four million years ago. They then adapted to different environments and disease challenges, which may explain the different epidemiology observed with some infections.

Donkeys are stoic animals. They frequently hide pain and display subtle clinical signs. This must be taken into account when assessing quality of life, an important consideration when deciding on treatment or control of a condition. Unrecognised disease or even 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 considered where the quality of life of a donkey is compromised.

A thorough post-mortem examination is a valuable tool to identify the cause of death, both because clinical signs are often subtle and because there is a need to share information and evidence regarding the health and welfare of donkeys.

Dental disease is the main oral disorder of equines in the United Kingdom and is of major importance in general equine veterinary practice. Up to 10% of general equine veterinary practice time involves dental-related work. Dental disorders are much more common in older equids (and indeed generally in all species). The donkeys at The Donkey Sanctuary in Devon have an average life expectancy of 27 years - over double that recorded in many developing countries - and it is not surpirsing that periodontal disease was noted to be 'almost inevitably present' by one author when examining the aged donkeys.

Donkeys may develop dental disorders that could go unnoticed by owners. This may partly be due to the fact that owners do not feel their donkey requires regular dental examinations if they are 'not putting a bit in its mouth', and partly because some owners are not aware that donkeys frequently develop sharp enamel overgrowths or malocclusions simply from the dietary alteration of their domesticated environment. A study of 233 horses found 24% to have dental disorders present that had nto been detected by their owners, highlighting how difficult it is to detect dental disease in equids.

This chapter provides a brief overview of ophthalmology. For more detailed ophthalmology notes, refer to The Colour Atlas and Text of Equine ophthalmology (Barnett et al, 1995).

As there is very little difference in ocular anatomy and disease between the horse and the donkey, the veterinary surgeon can follow the same approach to the examination of the horse's eye when dealing with the donkey. The examination must be thorough and methodical, with an emphasis on recording the history to decide a treatment regime and monitor response. However, more research needs to be done to understand the propensity for chronic ocular surface disease.

A particular feature of ophthalmic disease in equids is the serious consequence of inadequate initial treatment due, in part, to the character of their inflammatory response. Most of the differences between donkey and the horse are in their nature. Donkeys are more stoical, so may not present olular disease in its early stages because of their muted pain response. First examination may reveal a more severe or chronic problem. Sedation is less frequently needed because the reserved nature of the donkey aids examination and treatment. However their strong palpebral muscles make blocking the frontal nerve an essential part of examining a painful eye. Donkeys are generally very tolerant of nasolacrimal and subpalpebral lavage devices if these are required for treatment delivery.

Differences in occurrence of eye problems in the donkey may exist when compared to the horse. The more dynamic use of the horse makes it more prone to traumatic injuries to the eye. The donkey may be more prone to organic foreign bodies lodging in the eye, due to its habit of feeding with head buried into hay or straw, and in winter by its tendency to develop a think coat and hairy face. These differences may also present a seasonal variation in occurrence.

It has long been recognised that community-based animal health workers (CAHWs), who are veterinary paraprofessionals working within livestock-owning communities, have a role in the delivery of animal health services, especially in developing countries. More recently the World Organisation for Animal Health, the Organisation International des Epizooties (OIE), has recognised the significance of this cadre of paraprofessionals.

By being a part of the community for which they help to provide veterinary services, CAHWs can extend the outreach and efficiency of their national State Veterinary Service, for example, by providing reports of disease outbreaks from remote areas which would not otherwise be regularly generated. At the same time, CAHWs can provide a basic clinical service to livestock owners in places that are poorly served by veterinarians, public or private.

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‐quality 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.

Although closely related, there are important differences in physiology and behaviour between the donkey and the horse that influence the presenting signs of certain conditions which affect both, especially abdominal pain or 'colic'. This chapter will discuss the possible causes, the approach to the diagnosis and the treatment of the common causes of colic in the donkey in the UK. Most consideration will be given to the treatment of the common gastrointestinal conditions causing colic. Surgical techniques are not described and standard equine surgical textbooks should be referred to if surgery is intended. Indications for exploratory laparotomy are described in Chapter 16.