Finally, it is important to recognize that different commercial products contain different sources of protein hydrolysate
— and it has been shown that, while not all animals known to be allergic to a protein will react to the hydrolyzed version
of that protein, at least 20 percent will — thus illustrating the limitations of using these diets as the definitive means
of ruling out an adverse reaction to food.
Nevertheless, because novel protein diets have been proven effective in dogs with IBD, and because hydrolyzed diets have the
advantage of not sensitizing the dog to a new protein during the initial treatment phase, they are a very reasonable choice
for a dog with IBD.
Many dogs with severe intestinal disease, and especially IBD, have cobalamin deficiency — which can be associated with persistent
diarrhea and lack of response to therapy. Cobalamin deficiency is corrected by replacement with injectable cyanocobalamin
at a dose of 25 mcg/kg once weekly for four to six weeks and then once monthly thereafter, as needed to maintain normal serum
levels. In dogs with true IBD that require life-long therapy to control their signs, it is possible they will require life-long
cyanocobalamin injections as well. It may take as long as three to four weeks, once starting appropriate therapy, to see any
response, so it is important to be patient and not expect an immediate response.
Protein-losing enteropathies (PLE)
Protein-losing enteropathies (PLE) comprise a complex group of gastrointestinal (GI) diseases, causing severe loss of proteins
(especially albumin and similar-sized proteins) from the GI tract. PLE's common clinical signs include anorexia, weight loss
and small-bowel diarrhea. PLE can be a primary disease entity, such as the disorders that occur in Yorkshire Terriers, Basenjis,
Lundehunds and Soft-Coated Wheaten Terriers, but is most often secondary to a wide variety of diseases and disorders of the
small bowel (e.g., lymphangiectasia, infiltrative diseases of the bowel and IBD). One of the most challenging aspects of PLE
therapy is selection of an appropriate diet.
The initial treatment for dogs diagnosed with severe PLE may require aggressive intravenous therapy for correction of the
hypoalbuminemia, electrolytes and mineral abnormalities. Plasma or hetastarch (or other colloid) therapy (10-20 ml/kg) often
is administered to provide both plasma proteins and coagulation factors in dogs that are severely edematous or who are hypercoagulable
(e.g., have significant risk of developing pulmonary/venous thromboembolism) from low antithrombin levels.
Alternatively, total parenteral nutrition (TPN) may be initiated to provide a source of protein and energy, as well as to
improve oncotic pressure. Nutritional support in the form of elemental diets may be required in dogs with severe PLE no matter
what the cause, because the gut may not be able to appropriately digest or absorb the nutrients in polymeric (intact) diets.
There are a variety of human enteral nutrition supplements that can be used, but a low-fat, lactose-free diet is preferred
(e.g., Vivonex TEN). Most other human elementals are not low-fat, and therefore not good choices for PLE dogs. Vivonex alone
should only be used as a short-term diet because it is too low in protein to support the nitrogen and amino-acid requirements
of dogs (and especially cats).
For long-term nutritional support using elemental diets, amino-acid supplements and vitamins should be added to provide a
more balanced diet or they must be used in combination with another diet. In these dogs, a combination of the elemental diet
with a hydrolyzed diet or a homemade, ultra low-fat, highly digestible diet may be effective. The hydrolyzed diets often are
reasonable choices because they are low-fat and highly digestible, but not all animals do well on them. Homemade diets frequently
are chosen for severe PLE dogs because they can solve several important therapeutic goals:
1) The protein source can be novel and highly digestible (e.g., turkey, venison, egg).
2) The amount of fat can be easily controlled (no-fat to ultra low-fat) — which is extremely important for PLE management.
3) They are usually highly palatable.
Dogs with less severe hypoalbuminemia (e.g., serum albumin greater than 1.5 and less than 2.0 g/dl) often can be started on
a commercial diet designed for GI disease. The key to dietary management of PLE is finding a diet that is low in fat, highly
digestible and well tolerated (e.g., does not cause diarrhea), but allows the gut to absorb proteins presented.