Page 465 - Small Animal Internal Medicine, 6th Edition

CHAPTER 28 General Therapeutic Principles 437

Enterostomy tubes are indicated in animals with func- Nasoesophageal, esophagostomy, and gastrostomy tubes
tional intestines when the stomach must be bypassed (e.g., are typically used for bolus feeding. Animals that have been
VetBooks.ir recent gastric surgery). Laparotomy or endoscopy is typically hyporexic for days to weeks should usually start by receiving
small amounts (e.g., 3-5 mL/kg) every 2 to 4 hours. The
used to place these tubes. When placing it surgically or lapa-
roscopically, a 12-gauge needle punctures the antimesenteric
until the animal is receiving its caloric needs in three or four
border of the intestine, and a sterile 5F plastic catheter is amount is gradually increased and the frequency decreased
advanced aborally through the needle until approximately daily feedings. The clinician should expect to ultimately
15 cm extends into the intestinal lumen. The 12-gauge needle administer 22 to 30 mL/kg at each feeding to most dogs and
is removed, and a purse-string suture is placed to prevent the cats. Larger volumes may be given if they do not cause vom-
catheter from moving freely. The needle is then used in the iting or distress.
same manner to make a pathway for the catheter to exit Jejunostomy tubes are designed for constant-rate feeding
through the abdominal wall. The antimesenteric border of using an enteral feeding pump. The clinician should begin
the intestine is sutured to the abdominal wall so that the sites by feeding the animal a half-strength diet at one half the rate
where the tube enters the intestine and exits the abdomen that will ultimately be necessary to meet the animal’s caloric
are opposed. Traction sutures are used to secure the needs. If diarrhea does not result after 24 to 36 hours, the
catheter. clinician increases the flow rate to what will ultimately be
Another technique is to first place a percutaneous gas- needed. If diarrhea still does not occur, the diet may then be
trostomy tube and then insert the jejunostomy tube changed from half strength to full strength. Constant infu-
through the gastrostomy tube (i.e., a Peg-J tube). The jeju- sion of these same diets may be done through gastrostomy
nostomy tube is then directed into the duodenum either by and esophagostomy tubes in animals that readily vomit
dragging it with a flexible endoscope, or by directing a when fed in boluses (e.g., some cats with severe hepatic lipi-
guide wire into the duodenum and running the tube over dosis). Animals that are critically ill and vomit readily might
the guidewire through the gastrostomy tube and into the benefit from “microalimentation,” in which very small
duodenum. Alternatively, one may use a flexible endoscope amounts of liquid diet (e.g., 1-2 mL/h in 30-40 kg dogs) are
to grasp a guide wire entering the esophagus from the nose infused via nasoesophageal tubes in an effort to provide
into the jejunum, drag that wire into the jejunum, and some nutrition to the intestinal mucosa and prevent bacterial
then pass a tube over the guide wire (i.e., a nasojejunos- translocation and sepsis.
tomy tube).
The small diameter of enterostomy tubes often necessi- PARENTERAL NUTRITION
tates administration of commercial liquid diets (see Table Parenteral nutrition is indicated if the animal’s intestines
28.2), which are best infused at a constant rate. The rate cannot reliably absorb nutrients. It is the most certain
necessary to administer daily caloric needs is calculated. method of supplying nutrition to such animals but is
Half-strength feeding solution is administered at one half the expensive and can be associated with severe metabolic and
calculated rate on day 1. The next day the rate of administra- infectious complications. If parenteral nutrition will be
tion is increased to the calculated rate, but half-strength used, one should consult with a nutritionist. If parenteral
solution is still used. On the third day a full-strength solution nutrition is administered, the animal should also receive
is administered at the calculated rate. If diarrhea occurs, the some oral feeding, if possible, to help prevent intestinal
rate of administration can be decreased or fiber (e.g., psyl- villous atrophy.
lium) can be added to the liquid diet. If placed surgically or
laparoscopically, the tube should be left in place for 10 to 12
days to allow adhesions to develop around the area and ANTIEMETICS
prevent leakage. When enteral feeding is no longer neces-
sary, the clinician simply removes the sutures and pulls out Antiemetics are indicated for symptomatic therapy in many
the catheter. animals with acute vomiting, those that are severely nause-
ated, and those in which vomiting is contributing to morbid-
DIETS FOR SPECIAL ENTERAL SUPPORT ity (e.g., discomfort or excessive fluid and electrolyte losses).
If the feeding tube diameter is sufficiently large, a gruel made Peripherally acting drugs (Table 28.3) are less effective than
by blending one can of dog or cat food (e.g., feline p/d [Hill’s centrally acting ones but may suffice in animals with minimal
Pet Products]) plus 0.35 L of water provides approximately disease. Oral administration is unreliable in nauseated
0.9 kcal/mL and is useful for dogs and cats. Elemental diets animals. Parasympatholytics (e.g., atropine, aminopentam-
are rarely needed in animals with severe intestinal disease. ide) have some central activity, but are generally no longer
Some elemental diets (e.g., Vivonex, Nestle Nutrition) do not recommended. Centrally acting antiemetics are more effec-
have as much protein as desired for dogs and cats (see Table tive. Parenteral administration is often preferred to ensure
28.2); therefore some of the water used in mixing the ele- blood levels in vomiting patients. Suppositories are conve-
mental diet is replaced with 8.5% amino acids for injection nient, but their absorption is erratic.
(e.g., 350 mL water + 250 mL 8.5% amino acids). When Maropitant (Cerenia) is a neurokinin-1 (NK-1) receptor
feeding cats, the clinician must be sure that sufficient taurine antagonist that is effective in preventing vomiting in a wide
is present in the diet. range of conditions. Approved for use in dogs and cats, it has