A practical approach to caring for patients with appetite reduction

Anorexia is defined as a lack of appetite for food (Michel, 2001; Delaney, 2006) with the deleterious effects well documented (Kyriazakis, 2010). Thus the importance of addressing the underlying cause and ensuring sufficient food consumption cannot be overemphasized. Implementation of such nutritional support is one aspect of patient care in which veterinary nurses (VNs) play an integral role (Chan, 2006). Since anorexia is a common clinical problem associated with many systemic diseases (Quimby et al, 2010), one of the challenges frequently encountered by VNs in small animal practice involves encouraging patients to eat. This paper will discuss the nurse's role in caring for animals with a lack of, or reduction in, appetite while also considering the harmful effects of inadequate nutrition and methods used to stimulate appetite.

Anorexia or hyporexia?

Appetite can be adversely affected when circumstances interfere with the initiation of food intake (for example in the case of facial trauma or dental disease), or act to promote negative stimuli during a meal so that the food intake is terminated (Saker and Remillard, 2010). One of the initial signs that owners will recognize as an indicator that their animal is unwell is a reduction or loss of appetite. At this stage, it is essential for veterinary nurses to differentiate between the terms anorexia, a lack of appetite, and hyporexia, a reduction in appetite (Delaney, 2006). Consideration should also be given to the factors adversely affecting appetite (Table 1).

Anorexia is one of the more common systemic effects associated with conditions such as uraemia, neoplasia, diabetic ketoacidosis and disorders resulting in inflammation and fever (Remillard et al, 2001). During anorexia, the animal initially exhausts glucose and then stored glycogen. After 36 hours of fasting, gluconeogenesis takes place and amino acids are mobilized for glucose synthesis. Fat is metabolized from adipose tissue to supply energy needs, thus dogs and cats that are totally or partially starved utilize fat and protein as energy sources. After the first 4 days of food deprivation, muscle protein is catabolized. If the animal has malignant disease or burns, further protein losses occur (Chan, 2009). A history of anorexia for longer than 3 days predisposes an animal to become malnourished (Table 2), warranting rapid nutritional intervention (Chan and Freeman, 2006). Feline hepatic lipidosis is a potentially life-threatening condition and an example of the need for adequate energy intake, an objective best achieved via placement of a feeding tube (Lumbis and Chan, 2008; Hand et al, 2010).

Formulation of a feeding plan

Within small animal practice, the nursing team is often responsible for providing nutritional support and plays a fundamental role in nutritional intervention (Chan, 2006). It is important to consider that the provision of supportive care that addresses problems involving hydration and electrolyte status, pain, body temperature, vitamin B deficiencies and nausea can result in appetite being re-established in many patients (Michel, 2001).

In addition to ascertaining the underlying reasons for an alteration in food intake, it is essential to establish the patient's nutrient needs and feeding goals in light of its physiologic or disease condition. When formulating a feeding plan, it is important to communicate with the owners and consider some of the patient's normal dietary habits at home, for example:

• The exact brand and variety of food usually fed (e.g. adult maturity, sensitive stomach)
• Texture preference (e.g. moist/semi-moist/dry)
• Preference of food consistency (e.g. faked/sliced/ chunks) and kibble shape
• Flavour preference (e.g. chicken rather than fish)
• The design of the food bowl (e.g. shallow/deep, ceramic/plastic/stainless steel)
• The timing of meals — dogs often have specific meal times whereas cats more commonly ‘graze’ throughout the day
• The location of the food bowl (e.g. in the utility room rather than the kitchen) and in cases of cats, the height (e.g. floor or worktop) (Michel, 2001; Delaney, 2006; Hand et al, 2010).

To ascertain whether a sufficient amount of food is being consumed, it is necessary to calculate the patient's resting energy requirement (RER). This is the amount of energy (measured in kilocalories) required for maintaining homeostasis while a patient rests quietly in a stress-free, non-fasted, thermo-neutral environment (Hand et al, 2010) and can be calculated using the following formula:

RER = 70 x (bodyweight in kg)^0.75

An easier way to calculate this is provided in the following example:

For a patient weighing 35 kg:

(Gajanayake et al, 2011).

For animals weighing between 2 and 30 kg, the following linear formula gives a good approximation of energy needs:

RER = (30 x bodyweight in kg) + 70

Traditionally, there was a practice involving multiplying the RER by an illness factor of between 1.0 and 2.0 to account for increases in metabolism associated with different conditions and injuries. The subjective nature of such factors, combined with their potential for overfeeding, has led to the discontinuation of this practice. Current recommendations involve use of the RER as a baseline, modifying food intake according to changes in bodyweight and body condition score (Chan, 2009).

Following the formulation of a feeding plan, it is essential to ensure that the prescribed nutrition is actually delivered. A study by Remillard et al (2001) to estimate the number of canine patients receiving their daily RER revealed poor feeding practice with delivery of over 95% of RER achieved for only 27% of the 821 day study period. Reasons attributed to this disparity included poorly written feeding instructions (22%), orders to have food withheld (34%) and patient refusal to eat (44%). A later study investigating the percentage of prescribed enteral nutrition delivered to hospitalized small animal patients, found that the amount of food delivered over 24 hours constituted a median percentage of 90% of the patient's daily kilocalorie requirement (Michel and Higgins, 2006). In contrast, nausea or vomiting and conflict with other treatments were the most common recorded reasons for incomplete feeds. Such results highlight the importance of patient planning, interprofessional collaboration between personnel and provision of explicit instruction.

A feeding method that utilizes as much of the functioning gastrointestinal tract as possible should be adopted while also ensuring that it is suitable for the patient's condition and initial hospitalization period. In certain situations, this may involve altering the way that food is presented and fed. For example, when feeding a patient with oesophageal disorders, a common recommendation is to offer a moist diet rolled into palm-sized balls (Figure 1) and fed with the animal raised in an upright position (Davenport et al, 2010).

Practical considerations when feeding patients

As Agar (2001) indicates, unless food is being actively consumed by the patient, its formulation and suitability is insignificant. Encouraging animals to consume their daily energy requirement while in a diseased, and/or stressed, state can be particularly challenging. While there are a number of feeding strategies, the choice over which one to use should be based on its ability to meet the feeding goals of the patient in light of its condition and nutritional status.

Variety

When feeding anorexic patients, a common approach involves offering a variety of different diets (Figure 2). As recognized by Hill (2009), dogs and cats are willing to consume a consistent diet for prolonged periods. It could therefore be argued that the concept of variety is an anthropomorphic influ-ence, resulting from owners’ recognition of their own feeding habits. While variety is associated with increasing food intake in healthy animals, this approach is not recommended for sick animals (Delaney, 2006), particularly those that are at high risk of developing food aversion.

Preventing food aversion

Food aversion can occur when an animal consumes a previously favoured diet, yet links this to unpleasant sensations (Michel, 2001) leading to a refusal to eat. In contrast, it can also be the outcome of feeding a previously unfed diet such as veterinary therapeutic diets when introduced in a stressful environment, e.g. when hospitalized or feeling unwell (Forrester et al, 2010). As reported by Hill (2009), diets are more readily accepted by dogs and cats when they are introduced slowly over a couple of weeks and in the absence of nausea. It is important to minimize the likelihood of such an occurrence, especially in the presence of disease for which there are limited commercial therapeutic dietary options (Delaney, 2006). In these instances, it may be necessary to avoid exposure to foods that need to be fed long term until any nausea has subsided.

Eliminating barriers

Another important consideration is to eliminate barriers to eating. These include physical barriers such as a buster collar as well as less obvious impediments such as dental or oral pain (Delaney, 2006). To improve access to food, the food can be raised up to the patient's height (Figure 3). Alternatively, providing the patient is being supervised, buster collars can be removed to enable the patient to eat unaided. Limitations in patient movement or a reduction in visibility can also account for a reduction in food intake therefore food bowls should be placed within reach of patients. For example, large dogs that have recently undergone surgery to amputate a limb may experience difficulties in reaching the ground and may benefit from the use of a bowl stand.

Environment

The environment in which patients are fed can have a significant impact on food consumption (Michel, 2001). A common recommendation is to feed animals in a quiet and peaceful setting. While this could prove hard to achieve in a busy practice, Delaney (2006) advises the use of a novel setting such as an office, laundry room or courtyard; a concept which could be achieved for non-infectious patients. If patients are to remain in their kennel when being offered food, Michel (2001) recommends avoiding scheduling feeds at the same time as treatments or other potentially fearful events. Delaney (2006) also advocates the provision of a hiding area for cats, which could encourage food consumption in shy eaters, as well as ensuring that food bowls are situated away from the litter tray (Figure 4).

Increasing palatability of food

Encouraging voluntary food intake in patients typically involves increasing palatability, a method achieved via many strategies. Delaney (2006) reports the positive effects associated with the warming of food, attributing this to the associated increase in aroma. In contrast, Michel (2001) highlights the counterproductive effects that this practice has had on human patients and suggests the provision of chilled food taken from a fridge. Texture is another significant factor affecting the palatability of food, particularly in cats, therefore the owner should be consulted regarding any learned texture preference by their pet (Delaney, 2006). Altering the nutrient composition of a diet, particularly by increasing the fat content, has also proved beneficial in certain situations. Yet, as Michel (2001) highlights, any changes must be considered in relation to the patient's condition and tolerance of these nutrients as well as their energy requirements.

Assisted feeding techniques

Once a decision has been made to instigate assisted feeding, the most appropriate method and route of delivery must be established. Enteral feeding involves the delivery of food via the gastrointestinal tract (Saker and Remillard, 2010) and in the absence of contraindications including persistent vomiting, severe malabsorption and an inability to guard the airway, is considered preferable to parenteral nutrition (Campbell et al, 2010).

Coax feeding

Providing a patient is not displaying overt signs of nausea and discomfort, coax feeding is a non-invasive and relatively stress-free form of oral feeding (Michel, 2001). This method involves encouraging an animal to eat, usually by offering small quantities of food, either by hand or by placing it in the mouth or on the paws, while talking to and stroking the patient (Figure 5). Early satiety is commonly associated with anorexia (Saker and Remillard, 2010) therefore offering smaller quantities of food may also prove less overwhelming and lead to a reduction in food wastage. Furthermore, Delaney (2006) emphasizes the significant impact that the choice of food server has on the success rate of this method, advocating the use of staff members who have had limited prior encounter with the patient, for example, veterinary care assistants. Yet, as Michel (2001) identifies, the time investment and intensity of labour associated with this method of feeding often precludes its use over prolonged periods.

Force feeding

Force feeding is a method often reserved for hypo-rexic animals that fail to consume sufficient food voluntarily and typically involves the delivery of food via a syringe or spoon. While the use of this method is still reported (Brunetto et al, 2010), its poor efficacy, risk of food aversion and other serious complications such as aspiration pneumonia are well documented (Michel, 2001; Hand et al, 2010; Gajanayake et al, 2011).

As Michel (2001) reports, a small amount of food placed in the mouth or paw of a hyporexic animal may stimulate interest in eating. However, forcing food on an apathetic patient is futile and should be rejected in favour of alternative, less stressful and more tolerable methods (Saker and Remillard, 2010).

Appetite stimulants

The use of pharmacological intervention for the successful stimulation of appetite has been well documented (Long and Greco, 2000; Delaney, 2006; Quimby et al, 2010). Agents used for this purpose include cyproheptadine, benzodiazepines, glucocorti-coids, anabolic steroids, mirtazapine and B vitamins. In an unpublished study by Casamian-Sorrosal and Warman (2010), the use of mirtazepine was evaluated in a small animal clinical setting. In the first 24 hours post administration, mirtazepine was successful in stimulating appetite in 86% of dogs (n = 43) and 83% of cats (n = 26). The mean percentage of RER consumed during this period was 67% in dogs (range 10–160%) and 60% in cats (range 10–130%). Out of those patients who ate within the first 24 hours, appetite was maintained by 95% of dogs and 100% of cats for a further 48 hours, however this was not quantified.

Despite these findings, as Chan (2009) and Michel (2001) highlight, reliance on pharmacological agents to treat anorexia without addressing the underlying cause should be avoided. In addition, reported adverse effects must be respected and the use of appetite stimulants for the long-term resumption of adequate voluntary food intake remains unfounded (Michel, 2001; Delaney, 2006).

Tube feeding

In veterinary practice, the provision of enteral nutrition can be met via use of feeding tubes (Gajanayake et al, 2011). The timing at which tube feeding should be instigated is subject to debate. General consensus indicates that patients should go no longer than 3–5 days without sufficient calorie intake, however the presence of underlying disease and clinical signs may warrant earlier intervention (Chan, 2009). Complications associated with enteral tube feeding are categorized by Holahan et al (2010) as mechanical, technical or gastrointestinal. Studies to compare the use of intermittent and continuous delivery of enteral tube feeds revealed an increased likelihood of technical complications with the latter method (Campbell et al, 2010; Holahan et al, 2010). Yet the percentage of feeds delivered remained similar, with both methods facilitating adequate nutrient intake with minimal gastrointestinal complications. The types of feeding tube commonly available in small animal practice include naso-oesophageal, oesophagostomy and gas-trostomy tubes. Selection is based on patient, technical and owner factors (Table 3) and should be suitable to meet the patient's needs.

Monitoring

Daily monitoring is essential to determine the progression of a patient's health and nutritional status and to examine whether goals and expected outcomes are being met. The frequency of monitoring needs to be identified based on each individual patient, its conditions and the procedures being performed. Monitoring enables rapid identification of any complications and deterioration in condition. In addition to daily measurement of bodyweight, the body condition score should also be recorded, thus identifying any alteration in fluid shifts (Lumbis and Chan, 2008). Regardless of the method of feeding, it is essential for veterinary nurses to accurately quantify and record an animal's food intake (Figure 6). If more than one type of diet is being offered, a careful measure of the amount of each must be made in terms of weight/volume (i.e. grams or mls).

When monitoring and evaluating nutritional interventions, it is important for veterinary nurses to adopt a uniform and cyclical approach by use of a nursing process (Figure 7). Such a procedure enables continued assessment and evaluation of the patient's nutritional needs and identifies objectives and a nutritional plan based on meeting their dietary requirements. This should be completed as part of a more thorough nursing care plan (Table 4). Poor communication and record keeping by veterinary personnel is a significant contributory factor behind animals failing to receive their full daily calorific requirements (Michel and Higgins, 2006). Therefore, in order to be effective, the prescribed care plan and feeding schedule must be clearly communicated to all those involved in the care and treatment of the patient.

Conclusion

Nutrition is a critical component of caring for and treating small animals and one in which nursing staff play a crucial role. It is vital that veterinary nurses utilize their knowledge and skills to assist in the identifi-cation of patients at risk of malnutrition, formulation of feeding plans and provision of necessary nutritional support. Anorexia should not be considered a normal consequence of illness, therefore it is essential to identify the reasons for a reduction in appetite and address the primary underlying disease.

Key Points

• Nutritional support and assessment is an integral part of optimal patient care and one in which veterinary nurses play a fundamental role.
• Anorexia should not be considered a normal consequence of illness, therefore it is essential to identify the reasons for a reduction in appetite and address the primary underlying disease.
• A history of anorexia for longer than 3 days predisposes an animal to become malnourished, warranting rapid nutritional intervention.
• When formulating a feeding plan, consider the patient's personal preferences and normal dietary habits.
• A feeding method that utilizes as much of the functioning gastrointestinal tract as possible is most desirable.
• Calculate the energy requirement for each patient and ensure that food intake is accurately quantified and recorded.
• Adopt a uniform and cyclical approach to the frequent monitoring and evaluation of nutritional intervention.