Page 327 - Withrow and MacEwen's Small Animal Clinical Oncology, 6th Edition

CHAPTER 16 Supportive Care for the Cancer Patient 305

they often are problematic to manage at home and are limited Parenteral Support
to the use of liquid enteral products because of the small tube If enteral support is not an option, then parenteral nutrition (PN)
diameter. The two most widely accepted means of implementing
VetBooks.ir long-term enteral support involve placement of an esophagostomy support should be considered. Parenteral support can be either
partial (PPN) or total (TPN). PPN has also been termed periph-
tube or a gastrostomy tube. The esophagostomy tube typically is
placed under light anesthesia (techniques for placement have been eral PN because it is typically delivered through peripheral veins.
described elsewhere). 308 Once secured the tube site typically is Prospective clinical studies examining outcomes after parenteral
wrapped, and the insertion site should be examined every 24 to support have not been performed in veterinary medicine, and
48 hours for signs of cellulitis and discharge. These tubes typically only a handful of retrospective investigations characterize com-
are recommended for intermediate- to long-term feeding (2 weeks plication rates. 312–317 In veterinary patients, particularly cats, the
to 3 months). metabolic complication most often encountered is hyperglycemia.
Gastrostomy tube placement should be considered when sup- Mechanical complications also are prevalent, such as feeding line
plemental feeding is required for longer than 6 to 8 weeks. 308,309 problems and inadvertent removal. A common misconception is
Advantages include direct gastric delivery of nutrients, and the that sepsis is a common complication, when in fact it is quite
fact that emesis does not cause tube eversion. Anesthesia is rare. 312–317 Parenteral support should be considered only when
required for placement, which can be performed via surgical or enteral support is not an option because of medical complications;
percutaneous endoscopic approaches. The endoscopic approaches enteral support is considered superior because it prevents transmi-
are generally safe and effective but are associated with a higher gration of bacteria to the portal blood and improves the patient’s
risk of complications. 309 The author (JJW) prefers surgical place- immunologic status. 318
ment in large breed dogs because they may be predisposed to Parenteral support is not well studied in veterinary medicine
separation of the stomach from the body wall after endoscopic and the relative use and utility of the three main substrates (glu-
placement, increasing the risk of cellulitis, and/or peritonitis. cose, amino acid, and lipid) differ, depending on the source of
Peritonitis is the most serious complication after tube placement, information. 319–321 Some advocate using glucose and lipid to
because the peritoneum is disturbed with this approach, which meet the energy requirements and then add in amino acids to
also leads to a permanent stoma from the stomach to the out- the formulation based on the protein needs per kilogram of body
side of the body. 308,309 After successful placement the gastros- weight. Others advocate adding just above the minimal protein
tomy tube can be used within 24 hours; it should not be removed requirement as amino acids making up part of the RER. The
before 2 weeks to allow adhesion and fibrosis of the gastric wall protein requirements for ill cats and dogs currently is unknown,
to develop. Once a stoma has formed, the original surgically and we can only assume that the requirement is similar to that of
placed tube may be replaced with a low-profile or “button” feed- healthy normal animals. Extrapolation from human data suggests
ing device. Owners should be aware that these low-profile devices that protein turnover may be higher during catabolic illness, and
need replacing every 6 to 8 months and require mild sedation for we often add slightly more protein than required. An elegantly
replacement. 310 designed study found that approximately 2.3 grams of protein per
Esophagostomy and gastrostomy tubes allow for a diverse kilogram of body weight is sufficient for an IV amino acid solu-
number of products to be used for feeding, beyond the liquid vet- tion in dogs. 322 This suggests that adding 2.5 to 3 g/kg of amino
erinary diets. Many over-the-counter and veterinary therapeutic acid solution for a dog appears sufficient, and 4 g/kg often is used
diets can be blended for feeding; however, when some products as a starting point for cats. Amino acids come in several different
are blended with water, they result in less than 1 kcal per milliliter. formulations and strengths (e.g., 5.5%, 8.5%, and 10%). Addi-
Table 16.9 list some diets that provide higher caloric density and tionally, amino acid solutions come with and without electrolytes.
can be passed through a 7 French or greater diameter catheter. Amino acids with electrolytes typically provide basal sodium, chlo-
These products tend to be higher in protein and fat and can be fed ride, magnesium, phosphorus, and potassium when used at 1.5 to
at reduced volumes and rates when nausea or food volume is an 2.5 g/kg body weight of protein; however, these are used less often
issue. In addition, a typical dog or cat receiving a slurry of food in cats and dogs, particularly in cats whose protein requirement
at 1 kcal/mL is meeting its fluid requirements. 311 Similarly, dogs may be higher. When amino acids are used with electrolytes, the
and cats that are not actively consuming water at home should be electrolytes provided should be considered before additional elec-
provided 1 kcal/mL. trolytes are supplemented in fluids. Fig. 16.3 describes a typical

TABLE 16.9 Selected High Protein/Calorie Products for Tube Feeding of Cancer Patients and the Amount of Water
Needed to Make a 1 Kcal/mL Mixture to Meet Daily Fluid Requirements
Product Calories (kcal/mL) Protein (g/100 kcal) Fat (g/100kcal) Water needed for 1 kcal/mL
Royal Canin Recovery RS 1.1 9.9 6.4 18
(5.8 oz)
Hill’s a/d (5.5 oz) 1.2 9.2 6.3 30
Purina CN (5.5 oz ) 1.4 8.0 7.5 53
Carnivore Care (2 oz.; 2.6 9.0 6.2 220
56 gr.) a
a For dry powder products, 50 cc of water and thorough mixing are required for preparation before the product is administered.