1 EDITORIAL

Clinical nutrition TO some the term ‘clinical nutrition’ simply means diseases caused by nutritional deficien- cies, excesses or imbalances. However, the sub- ject extends far beyond these limitations.

Most nutritional requirements that have been determined for the cat and dog relate to the ani- mal with normal physiological control. We must also question what happens if this is compro- mised by a disease process or when major organ systems start to fail; if the gastrointestinal tract becomes non-functional; if sodium is retained by the body, as occurs in heart failure; or if the liver can no longer synthesise proteins in sufficient amounts to meet demand. Almost every clinical case requires nutritional consideration. An orthopaedic case could be exposed to a serious risk factor if, during its convalescence the owner were to feed an all-meat ration with an inverse ca1cium:phosphorus ratio that would not be con- ducive to optimal bone healing. Would failure to discuss diet with the owner be negligence?

The potential for diet to have an impact on health has been known since the first treatises on human and veterinary medicine. Despite this, nutrition has never been the sole domain of the veterinary profession. Farriers, stockmen, dog breeders, pet shop owners, friends, neighbours and food manufacturers have probably had as much influence on establishing attitudes to the feeding of domesticated animals as have veterinary surgeons.

Food is frequently blamed for illness, and sometimes such a relationship is logical, eg, tran- sient gastroenteritis following a novel meal, but on other occasions the link may be more tenuous and proving direct relationships between dietary intake and illness may be difficult. However, an inappropriate diet certainly can be the cause of illness.

Undernutrition will be seen only occasionally by practising veterinary surgeons as a result of accidental starvation, or cruelty. Overnutrition is far more common, and yet it is something of which many pet owners are either unaware, or unconcerned. Veterinary surgeons see many obese cats and dogs, yet few owners present their animal as an obesity ‘problem’. Presumably that is because owners are generally unaware of the dangers of obesity. If that is true, the veterinary profession has an important job to do in client education.

Monitoring bodyweight is a useful parameter and weight loss or gain of more than 10 per cent may be an early signal of dietary inadequacy or excess, or of metabolic change. A change in bodyweight may occur before the recognition of clinical signs in many diseases.

There are many pitfalls in the provision of a complete and balanced ration as complex inter- relationships between nutrients, and cooking or processing can affect bioavailability and utilisa- tion even if nutrients are present in adequate amounts, The basic principles of clinical nutri- tion are to provide sufficient amounts of energy and essential nutrients to meet the animals needs, and to avoid unnecessary amounts of nutrients that might have a role in disease. Energy and specific nutrient requirements may be normal, increased or decreased, and the form and route by which they can be given may vary in the presence of disease.

Modifying nutrient intake can improve clinical signs by reducing the production of undesirable metabolic products, eg, reducing dietary protein can reduce blood urea nitrogen and, or, ammonia levels; reducing fat intake can minimise lipidaemia.

Progression or recurrence of some diseases may be delayed or prevented by removing or minimising dietary risk factors. Concurrent dis- ease, especially in older animals, makes the choice of the most appropriate nutritional ratio- nale quite complex. Nevertheless, this is just as important as the clinical assessment for surgical intervention, or for a therapeutic regimen.

Few authors of scientific papers record data on diet even when nutrition would be expected to be important. Our understanding of the subject would be greatly enhanced if journals insisted on nutritional details as part of the minimum database in papers submitted for publication.

Dietary management is assuming an increas- ingly important role for many clinicians, which coincides with consumer concern about the dan- gers of incorrect diet, and a desire for the health benefits of good nutrition.

Despite the tremendous progress already made, the subject is still in its infancy and many new clinical applications of nutritional principles are being developed. It is timely that clinical nutri- tion should be the theme of several papers in this issue, and that the veterinary profession should no longer consider nutrition to be an ‘alternative’ form of medicine, but an integral part of the man- agement of clinical cases with the scientific importance that it deserves.

MIKE DAVIES

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