Page 571 - Small Animal Clinical Nutrition 5th Edition

592 Small Animal Clinical Nutrition

through a variety of direct and indirect mechanisms (Table 30-
Table 30-2. Effects of surgery that may have nutritional 3). These problems should be anticipated and feeding tubes
VetBooks.ir implications for cancer patients. Possible nutritional placed before therapy because early feeding lessens the adverse
Cancer
Surgical
sites procedures problems effects of therapy. Chemotherapeutic agents affect normal and
Head, neck, Mandibulectomy Difficulty prehending, malignant cells but have the greatest effect on rapidly prolifer-
tongue Maxillectomy chewing and ating cells such as epithelial cells of the GI tract. The degree to
Glossectomy swallowing food which GI function is affected depends on the chemotherapeu-
Esophagus Esophagectomy, with Dysphagia
or without reconstruction Regurgitation tic agent, drug dosage, duration of treatment, rate of metabo-
Stomach Gastrectomy, partial or Altered gastric lism and the individual animal’s susceptibility.
complete emptying Small bowel villous damage is a major side effect of some
Diarrhea
Small Resection Malabsorption chemotherapeutic agents and may be greatly intensified when
intestine Diarrhea radiation therapy is given concurrently. The rapid renewal rate
Intestinal obstruction of the alimentary tract epithelium usually means that clinical
Large Colectomy, partial or Fluid and
intestine complete electrolyte problems from drug-induced mucositis are short-lived.
imbalances Nausea and vomiting commonly accompany the administra-
Pancreas, Pancreatectomy Diabetes mellitus tion of many anticancer drugs. Alterations in smell and taste are
liver Cholecystectomy Maldigestion
Cholecystoduodenostomy reported to occur in people and may occur in animals. Side
effects experienced during chemotherapy make it difficult for
some patients to consume adequate amounts of food.
Corticosteroids such as prednisone are used in chemothera-
Table 30-3. Effects of chemotherapy that may have nutritional peutic protocols for some cancers, most notably lymphoma.
implications for cancer patients.
High doses or prolonged therapy with corticosteroids causes
Alterations in smell or taste profound polydipsia and polyuria and increased loss of water-
Constipation soluble vitamins.
Decreased appetite
Diarrhea It is important to consider the effects of nutritional manipu-
Food aversions lation and supplemental therapies on the pharmacokinetics and
Nausea pharmacodynamics of standard cytotoxic chemotherapy.
Stomatitis, glossitis, pharyngitis
Vomiting Clients often regard supplements as harmless and may not
report their use to the treating clinician in both human and vet-
erinary medicine.However,growing evidence suggests that cer-
tain supplements may have toxicity of their own,and may inter-
undergoing mandibulectomy for oral neoplasia, nearly half had act with other drugs, including chemotherapeutic agents. Her-
an enteral feeding tube placed at the time of surgery, and tubes bal supplements may affect metabolizing enzymes, interfering
were used for a median of 74 days postoperatively. Tube place- with pharmacokinetics of some drugs. Antioxidants may
ment was deemed an appropriate aspect of management for squelch free radicals responsible for the anticancer effect.
oral neoplasia as 72% of the cats experienced dysphagia postop- Because omega-3 (n-3) fatty acids have been associated with
eratively, and 12% never regained the ability to eat. Ad- improved survival and decreased side effects in dogs with lym-
ditionally, 83% of owners were satisfied with the outcome of phoma,and have many possible anticancer properties,the effect
treatment (Northrup et al, 2006). of these fatty acids on the handling of doxorubicin was recent-
The nutritional sequelae of gastric and intestinal resection are ly examined. Dogs with lymphoma were enrolled prospectively
directly related to the site and extent of resection and to the and randomized to receive a food either high or low in omega-
individual functions of the various segments.The ability of var- 3 fatty acids. There was no significant difference between food
ious segments of the small intestine to increase absorptive capa- groups in this study (Selting et al, 2006).
bilities over a period of several months prevents major clinical Fatty acids, vitamins and herbal remedies are readily available
problems after small bowel resection unless the resection is over the counter and it is important to understand the possible
massive. With massive resection, malabsorption (short bowel effects of these and other supplements, such as singular amino
syndrome) becomes the primary nutritional problem (Chapter acids, antioxidants and flavonoids on cancer therapy.
59). In people, colon surgery is usually well tolerated.The large
water and electrolyte losses in the early postoperative period Radiation
decrease rapidly after surgery. Feeding frequency and nutrient Veterinary patients receiving radiation therapy may have com-
composition of the diet should be closely managed to optimize plications that affect food intake. The complications of radia-
nutritional support for patients with surgical treatment of GI tion vary according to the region of the body radiated, dose,
cancers. fractionation and associated antitumor therapy such as surgery
or chemotherapy. Complications may develop acutely during
Chemotherapy radiation or become chronic and progress even after radiation
Chemotherapeutic agents may contribute to malnutrition therapy has been completed (Table 30-4).