Dietary Intervention

 5. Dietary Intervention

Coax Feeding

When a cat exhibits a decreased appetite it is natural to try to tempt it to eat by offering a variety of palatable foods. Very often the caregiver will further attempt to coax the patient to eat by putting the food close to the cat’s face or actually placing food in its mouth. Sometimes these techniques can be successful and lead to adequate food intake by the patient. However, such efforts are labor intensive and time consuming. A feeding plan with specific caloric goals should be formulated in advance so the caregiver can assess the adequacy of the patient’s food intake. Furthermore, it is very important to recognize that cats sometimes associate nausea, general indisposition, or pain with the act of eating or even the sight or scent of food. This is called learned food aversion and can further complicate achieving adequate food intake in a patient.

Dietary Aversion

If a food is associated with distress, an unpleasant experience (hospitalization) or digestive problem (poisoning), the food is likely to be avoided in the future. This phenomenon is known as aversion. Aversion is a form of negative conditioning used by animals to avoid foods that are unsuitable for them.
In cats, aversion sets in very quickly. A single meal associated with unpleasantness leads to a refusal to eat. Such aversion can persist for at least 40 days (Bradshaw et al., 1996).The smell alone of a food associated with digestive disorders is enough to elicit aversion. Cats even go so far as to show aversion for their usual food if it is served in the presence of an air current bearing the odor of a food to which they have developed an aversion.

Therefore, whenever attempting to coax feed a cat, one must remain alert to the signs of food aversion (Table 4) and recognize that there will be circumstances when it will be necessary to resort to assisted feeding for a time because of the risk of causing or exacerbating this condition. Table 5 lists some general guidelines on how to approach these patients. However, every patient will be different and it is necessary to observe each individual’s behavior in order to decide how best to proceed.

Assisted Feeding

Much of the information gleaned in your nutritional assessment will aid in making the choice of the best route for assisted feeding access. Other information to evaluate in the decision making process should include:
- Assessment of gastrointestinal tract function
- Assessment of other organ systems that may have an impact on the patient's ability to tolerate specific nutrients
- Assessment of the patient's ability to tolerate a feeding tube and tube placement
- Assessment of the patient's risk for pulmonary aspiration.

If parenteral nutrition is contemplated, it is also necessary to include assessment of the ability to obtain vascular access and the patient’s fluid tolerance.

There are some additional considerations to take into account when assessing cancer patients for assisted feeding. Certain chemotherapeutic agents can impair wound healing with the consequence of a greater risk of septic complications with tubes that are placed into the peritoneal cavity (e.g., gastrostomy and enterostomy tubes). This risk can be magnified if the patient is receiving immunosuppressive drugs. Radiation therapy can have similar consequences if the tube placement is within the field of treatment. The esophagostomy tube has many of the advantages of a gastrostomy tube but carries a lower risk of serious septic complications (Figure 5). These tubes are simple and inexpensive to place and usually well-tolerated by feline patients.

Figure 5. Assisted feeding by esophagostomy tube. Esophagostomy tubes are relatively non-invasive and simple to place and provide well-tolerated access for assisted feeding in feline patients.

One final consideration is the fact that assisted feeding is a form of life-support. Used properly it could have the benefit of both prolonging life and ensuring a better quality of life for the patient. However, there may be circumstances, in terminal patients, where humane euthanasia is in the better interest of the patient then prolonging life. It is often more difficult for involved pet owners to terminate life supporting therapies than to initiate them and therefore the decision to use assisted feeding in a patient should bear in mind these ethical issues.

Figure 6 is a decision tree that illustrates how these various factors should be taken into account to choose the safest and most effective route of assisted feeding. Assisted feeding in feline patients is covered in more detail in Chapter 13.

Figure 6. Decision tree to determine the route of assisted feeding.

Diet Selection

In general, diet selection is based on which of patient’s problems can and should be addressed with nutrition and the nutritional requirements of the patient. While there have been many investigations of ways in which diet and specific nutrients may be used to slow or antagonize tumor growth, modulate immune function, or counteract the cancer cachexia syndrome, most of this research has been done in rodent models or human patients. There have been preliminary clinical investigations involving canine cancer patients, but none to date that have involved cats. A canned low carbohydrate diet that was fortified with fish oil and arginine was found to increase survival time and disease free interval in dogs with stage III lymphoma (Ogilvie et al., 2000). With the exception of the additional fish oil, many conventional canned cat foods have a similar formulation to the diet that was used in this investigation.

The major consideration for diet selection for cats with cancer should be acceptance by the patient. The diet should meet feline nutritional requirements and if it does not, it should be supplemented to address any deficiencies. Ideally, the diet should be of high caloric density, as this will aid in ensuring sufficient energy intake by the patient, especially in cases when appetite is decreased. In addition, if the patient has clinical signs or disease secondary to or in addition to cancer that would benefit from dietary management, efforts should be made to select and feed a diet formulated to address those conditions.

Lastly, in patients with alimentary neoplasia, in particular lymphoma, nutrient malabsorption can occur. While this can lead to generalized protein-calorie malnutrition, it can also lead to specific micronutrient deficiencies. One nutrient deficiency which has been reported in cats with gastrointestinal disease, including lymphoma, is cobalamin deficiency (Simpson et al., 2001). Cats with inflammatory bowel disease complicated by cobalamin deficiency have shown improved weight gain and response to therapy with parenteral supplementation of this vitamin (cobalamin, 250 ìg SC once weekly, for 4 weeks) (Ruaux et al., 2005). It is our clinical impression that cats with alimentary lymphoma also can benefit from parenteral cobalamin supplementation.