Nutritional treatment in critical care patients is an important factor of the complete treatment plan. Assessment of nutritional status and careful consideration of the disease course will help the selection of the most appropriate feeding method. Enteral nutrition is better than parenteral nutrition when the gastrointestinal tract is functional. Common routes of enteral feeding include nasoesophageal, esophagostomy, gastrostomy, and jejunostomy feeding tubes. Parenteral nutrition is indicated for patients who cannot tolerate enteral feedings, or are high-risk anesthetic candidates for feeding tube placement.

An anorexic, 4-kg, pancreatitis patient is admitted for assisted nutrition support by feeding tube. This cat’s resting energy requirement is: RER=30×4+70=190 calories per day. Using a standard illness factor of 1.2, this cat requires 228 calories per day. The maximum meal size is 45 ml/kg (stomach capacity of the cat). The cat is fed one-third of the RER (76 calories) on day 1, two-thirds of the RER (152 calories) on day 2, and all of the RER after day 3. The risk of refeeding syndrome supports the practice of slow initiation of full nutritional support, monitoring of electrolytes and glucose, phosphorus, anemia and addition of vitamins (especially thiamine) in the nutritional formula.

Appetite-stimulating medications will need to be considered in each case to ensure rational use of these agents. Appetite-stimulation drug should never replace monitoring and ensuring adequate caloric intake, and may not be appropriate in some cases, such as critically ill or severely malnourished patients. Enteral feeding is a more appropriate choice to ensure adequate nutrition in these patients. If caloric intake remains insufficient after 2–3 days of using an appetite stimulant (or maximum 3–5 days since cessation of food intake), further measures (including enteral feeding) must be considered.

Appetite stimulants used in cats:

1.  Cyproheptadine

2.  Diazepam

3.  Megestrol acetate

4.  Mirtazapine

5.  Nandrolone

6.  Oxazepam

7.  Prednisolone

Antiemetics and prokinetics: Vomiting in cats is a complex coordinated reflex, resulting in expulsion of gastric contents, coordinated by neurons distributed in the brainstem. Antiemetics are used to control or prevent vomiting through specific receptor interactions mediated either centrally or peripherally, making some more effective in cats than others.

1.  Mirtazepam

2.  Metoclopramide

3.  Dolasetron and ondansetron

4.  Maropitant

5.  Phenothiazines

6.  Cisapride

Tempting cats to eat: Where possible and appropriate, persuading a cat to eat is preferred over other feeding methods. Warming the food to just below body temperature may help encourage intake. If this is not successful, colder foods may be tried, as cats show variation in their preferences. Some cats will eat while being offered food by hand. Placing a small amount of wet food gently in the cat’s mouth or on the paws may initiate feeding. A variety of foods may be offered, and some cats only eat at night when the wards are quiet.

Conclusion

This presentation will address enteral nutrition for critical care patients, along with clinical case examples focusing on pancreatitis and hypertrophic cardiomyopathy due to hyperthyroidism.

References

1.  Chan DL. The inappetent hospitalized cat: clinical approach to maximising nutritional support. J Feline Med Surg. 2009;11:925–933.

2.  Michel KE. Management of anorexia in the cat. J Feline Med Surg. 2001;3:3–8.

3.  Sparkes AH. Assessing and tempting the finicky cat. In: Proceedings of the Western Veterinary Conference. Las Vegas, NV, USA; 2005.