Page 463 - Small Animal Internal Medicine, 6th Edition

CHAPTER 28 General Therapeutic Principles 435

When elimination diets are effective, improvement is maintenance needs of mature dogs and cats that are not
typically evident within 3 weeks, although rare patients lactating or losing a significant amount of energy or protein.
VetBooks.ir require 6+ weeks. It is critical that no other foods or treats the food, or feeding the animal a more palatable diet (e.g.,
In some cases, simply sending the animal home, warming
(e.g., flavored pills, toys, medications) be given to the animal
during this time. If signs resolve during this time, the diet
intake. Force-feeding by manually placing food in the ani-
should be continued for at least 4 to 6 more weeks to ensure chicken baby food for dogs) will result in adequate caloric
cause and effect as opposed to a spontaneous, fortuitous mal’s mouth seldom works in hyporexic animals. Mirtazap-
fluctuation of the disease. ine is usually an effective appetite stimulant for dogs and
Partially hydrolyzed diets (Purina HA, Nestle Purina; cats. It is administered once daily in dogs and once every
Hill’s z/d, Hill’s Pet Products; Hypoallergenic Hydrolyzed three days in cats. Maropitant (an antiemetic) is often helpful
Protein HP diets and Ultamino Royal Canin) have been for- if nausea is the cause of hyporexia. Cyproheptadine stimu-
mulated in an attempt to eliminate proteins large enough lates some cats to eat, but seldom induces a severely anorectic
to cause immunologic reactions. Although these diets are cat to ingest adequate calories. Diazepam rarely causes acute
not uniformly effective, many dogs and cats with dietary feline hepatic failure and is not recommended. Megestrol
allergy or intolerance will experience clinical improvement acetate is an excellent appetite stimulant but occasionally
when eating these diets exclusively. The partially hydro- causes diabetes mellitus, reproductive problems, or tumors.
lyzed proteins may also make such diets easier to digest Cobalamin injections have been noted to increase appetite
and absorb. in some patients. Appetite stimulants are usually less effec-
Ultra–low-fat diets are indicated in dogs with PLE due to tive in dogs than in cats.
intestinal lymphangiectasia. Because long-chain fatty acids Feeding tubes are a reliable way to ensure adequate caloric
enter and accumulate in lacteals, removing them from the intake. Intermittent orogastric tube feeding is useful for
diet helps prevent dilation and rupture of lacteals and sub- animals that need nutritional support for a relatively short
sequent intestinal lymphatic loss. Medium-chain triglycer- time, although it may be used for longer periods in orphaned
ides (MCTs) were once recommended as supplements to low puppies and kittens. It is typically done two or three times
fat, reducing diets; however, MCT oil has an unpleasant taste daily, using manual restraint and a mouth gag. A tube is
and is not as effective as was once thought, so it is no longer measured and marked to correspond to the length from the
recommended. tip of the nose to the midthoracic region. The tube is then
Fiber-enriched diets may ameliorate diarrhea in many carefully inserted through a mouth gag to the premarked
patients with large bowel disease (especially those with point. If the animal coughs or is dyspneic, the tube may have
minimal inflammation). Although once considered impor- entered the trachea and should be repositioned. To ensure
tant, distinguishing soluble from insoluble fiber is no longer safety, the tube should be flushed with water before warmed
thought critical because many fibers have characteristics of gruel is administered. Gruel should be given over several
both. A commercial high-fiber diet may be used, or fiber may seconds to 1 minute. Because relatively large-diameter tubes
be added to the current diet. Psyllium hydrocolloid (e.g., can be used, homemade gruels may be administered. The
Metamucil) or coarse, unprocessed wheat bran may be added major disadvantage is the need to physically restrain the
to the pet’s diet (i.e., 1-2 teaspoons or 1-4 tablespoons per animal. Indwelling tubes circumvent this problem.
can of food, respectively). Supplementing too much soluble Nasoesophageal tubes are useful in animals with a func-
fiber can produce diarrheic stools. If the patient is fiber- tional esophagus, stomach, and intestines. They are easy to
responsive, clinical improvement is generally seen within 4 place but difficult to maintain in vomiting animals. The clini-
to 5 days of beginning the diet. cian first anesthetizes the nose by instilling a few drops of
Fiber-supplemented diets might also lessen constipa- lidocaine solution in one nostril. Then a sterile polyvinyl
tion not due to obstruction, rectal pain, or megacolon due chloride, polyurethane, or silicone tube (diameter depends
to colonic inertia. Such a diet should be fed for at least 2 on the animal’s size, but 5F-12F is typical) lubricated with
weeks before assessing efficacy, although most animals that sterile water-soluble jelly is inserted into the ventromedial
respond do so within the first week. Some cats will not eat nostril. The animal’s head is restrained in its normal position,
these diets or fiber supplements. Canned pumpkin pie filling and the tube is inserted until the tip is just beyond the tho-
is effective as a fiber and usually palatable; 1 to 3 tablespoons racic inlet. If the clinician encounters difficulty in passing the
may be given daily. It is important that the animal main- tube, the tip should be withdrawn, redirected, and advanced
tain adequate water intake, lest the increased dietary fiber again. If the clinician is unsure whether the tube is in the
produce obstipation. esophagus, thoracic radiographs should be obtained.
Tape is applied to the tube, and then the tape is glued or
SPECIAL NUTRITIONAL sutured to the skin along the dorsal aspect of the nose. If the
SUPPLEMENTATION tube touches sensory vibrissae, the animal will not tolerate
If the animal refuses to ingest adequate calories, special it. It may be necessary to place an Elizabethan collar on
nutritional supplementation is necessary. Daily nutritional some animals to prevent them from pulling out the tube.
requirements should be calculated to avoid underfeed- Only small-diameter tubes (e.g., 5F) can be used in small
ing. Approximately 60 kcal/kg/day is reasonable for the dogs and cats, which limits the rate of administration and