Inappetence and anorexia are common problems in feline patients. Inadequate nutrient intake is, at best, detrimental and interferes with healing. At worst, it is life-threatening. Cats have only a limited ability to conserve body protein; this can result in negative nitrogen balance, protein: calorie malnutrition, and deterioration of protective mechanisms impacting immunity, red cell hemoglobin content, muscle mass as well as the ability to repair tissues. Additionally, cats have limited storage of many other nutrients as well as a restricted ability to down-regulate numerous metabolic processes. Their design is best suited to eating multiple small meals per day, high in protein, and moderate in fat. Inappetence and anorexia should be dealt with promptly and adequately.
Meeting the patient’s nutritional needs is not a substitute for localizing the cause for this inappetence. It is, however, necessary and allows time to identify the cause. Providing nutrients may be the most challenging part of any therapeutic regimen, and recovery or attaining the best possible QOL in cats may depend on our ability to ensure optimal nutrition.
The first question that must be answered is: why has this cat stopped eating? Is it because of a loss in appetite or some other reason? Nausea may be of neurologic origin (e.g., vestibular disease or irritation of the chemoreceptor trigger zone or the vomiting center by inflammation, neoplasia, or chemicals including metabolites or drugs). It may be a result of dehydration or may originate with GI inflammation for any reason (e.g., ileus, colitis, upper intestinal or gastric disease). However, decreased food intake may be due to other factors, such as dysphagia, pain (e.g., oral, dental, GI, multisystemic, etc.), dislike of the diet (e.g., boredom, altered palatability, spoilage), aversion, fear (e.g., environmental changes including those in the social demographics).
Nutritional support should be considered for the severely malnourished cat (20% weight loss, body condition score 1–2/9) or moderately malnourished (a 10% weight loss, BCS 3–4/9) who also have catabolic disease. Some cats will benefit from early intervention even at normal weight and condition if they suffer from advanced renal disease, hepatopathy, protein losing GI or glomerular disease, pancreatitis, or bile duct obstruction.
Inappetent cats, and those not ingesting adequate protein, shift into a catabolic state. They are at risk for hepatic lipidosis, especially if ill and possibly at a greater risk if previously obese. Lipidosis is a disease of dysfunctional lipoprotein metabolism; it is important to calculate the daily caloric and protein requirements as part of the therapeutic plan. (Calories: 50 kcal/kg ideal BW/day; 4.5 g protein/kg ideal BW/day.) The diet needs to be balanced for energy (protein, fat, +/- carbohydrates), vitamins, and minerals. It needs to be palatable taking the following four factors into account: texture, aroma, taste, and consistency. Bowls should be wide and flat to avoid interfering with whiskers. The environment should be non-threatening, so a hospital setting is especially off-putting. Feline facial pheromone may be beneficial to reduce stress.
Rehydration and correction of electrolyte imbalances are important but oft overlooked goals in the correction of inappetence and anorexia. Anti-emetics have a place if the cat is vomiting. In gastric-origin nausea, agents such as H2 antagonists, gastroprotectants, proton pump inhibitors, or prostaglandin E agonists may be beneficial depending on the cause of the gastric upset.
Appetite stimulants including cyproheptadine (1 mg/cat PO BID), mirtazapine (1–2 mg/cat PO q48h) may help jump-start a cat’s appetite, but keep track of total calories consumed. If a cat is eating but not enough, supportive feeding (assisted syringe feeding or tube feeding) must be considered. A cat eating small amounts of baby food will not meet his caloric needs until he eats 2–3 jars/day. Meat baby food is not balanced, but is sufficient for several weeks. There are several diets specifically designed for the assisted feeding of cats (Royal Canin Recovery, Hill’s a/d™, Purina PVD CN™, Eukanuba Maximum Calorie™), liquid balanced enteral diets for cats (Clinicare™, Rebound™) Additionally, we can make a slurry from any canned food; blend with a liquid feline diet rather than water to minimize loss of calories.
There are several options for assisted feeding each with advantages and disadvantages. In general, the author starts with syringe assisted feeding until the cat is stable enough to allow the brief anaesthetic required for the placement of an esophageal tube. With concurrent liver disease, give three doses of vitamin K1 (1.0 mg/kg q12h SC) prior to tube placement, biopsies or any other procedure that might result in bleeding. Placement of esophageal tubes is discussed elsewhere. The instrumentation for this procedure is very basic requiring only the following: 14–16 Fr red rubber feeding tube/urinary catheter, Carmalt or other long curved forceps, a scalpel blade, suture and bandaging materials and a multiple use injection port (prn adaptor).
Calculating how much to feed requires that you know the patient’s current weight as well as their healthy weight and the caloric densities (kcal/ml) of the diet you are intending to use (see Table 1). Use 50 kcal/kg as a rough guide to determine calories needed. Start by feeding 1/3–1/2 of the calories needed for the current, inappetent weight. On day two, feed 2/3–3/4 of this number and on day three, feed the full calories needed for the current weight. For weight gain, gradually increase to the calories needed for the cat’s healthy weight.
Table 1. Caloric Densities of Convalescent Diets, for Calculating Feeding Volumes
Rebound™: 1 kcal/ml
Clinicare™: 1 kcal/ml
Royal Canin/MediCal Recovery™: 1.23 kcal/ml
Hill’s a/d™: 1.3 kcal/ml
Purina PVD CN™: 1.23 kcal/ml
Eukanuba Maximum Calorie™: 2.1 kcal/ml
- 3.4 kg sick cat BCS 3/9, healthy weight 4.0 kg BCS 5/9
- 3.4 kg x 50 kcal/kg/day = 170 kcal by day 3 170 kcal = 81 ml Eukanuba Maximum Calorie
- Or 131 ml of Hill’s a/d or Royal Canin Recovery or PVD CN
- Day 1 feed 30–40 ml of Max Cal or 44–65 ml of the other diets
- Day 2 feed 54–61 ml of Max Cal or 87–98 ml of the other diets
- Day 3 feed 81 ml Max Cal or 131 ml of the other diets
Once stable, gradually increase to meet caloric requirements for 4 kg healthy weight.
- 4 kg x 50 kcal/kg/day = 200 kcal (95 ml Max Cal vs. 154 ml of the other diets)
With surgically placed tubes there is a delay in how quickly one can start to use them; with an esophageal tube only a 2–3-hour delay is required to ensure full recovery from anaesthesia whereas gastrostomy and jejunostomy tubes require a longer wait of 10–12 hours. Cats can eat with any of these tubes in place. It is recommended to avoid offering food for a week to reduce the likelihood of them developing aversion to the food offered. Once a cat is eating well with the tube in place the question becomes when one can remove the tube. Weigh the cat and, as long as he/she is eating well, avoid using the tube (for nutrients) for a week then reweigh the kitty. If the weight is stable (or increased), then it is safe to remove the tube. Because of stoma formation (except nasoesophageal tubes), removal does not require anaesthesia. Remove the suture (purse-string or stay sutures) and pull the tube out. In the case of a gastrostomy tube, its bulb must be straightened out the bulb/balloon by inserting a straight probe through the tube while concurrently pulling the tube out. Suturing is not required for any of the skin openings. Cleanse minimal serous discharge that may occur for 2–3 days.
Feeding frequency: the number of feedings per day, (and hence intervals), is determined based on the volume of food tolerated per feeding. Start with 6 ml and increase by 6 ml increments to about 36–48 for most cats. In the uncommon case of the patient who cannot tolerate even 6 ml boluses despite antiemetic therapy (see pancreatitis notes in these proceedings), trickle feeding may be instituted. Trickle feeding is a technique in which liquefied food is syringed into an empty fluid bag and administered gravitationally or by pump assistance via an intravenous line attached to the large bore feeding tube or by use of a large syringe filled with food and syringe pump. Renew food and delivery tubing and syringe at 12-hour intervals to avoid bacterial contamination. A promotility agent may be warranted as well. A good client reference is the Animal Medical Center of Canberra’s website: www.greencrossvets.com.au.
The success of assisted feeding is measured objectively by weight gain. Subjective measures will include improved coat quality, increased energy, muscle recovery and innumerable other effects that the client will appreciate. An improved quality of life is the goal whether recovery form the underlying problem is possible or not.
Please email me if you would like the video of how to place an e-tube or for the using a feeding tube video.