Exocrine pancreatic insufficiency (EPI) is a digestive condition in which there is inadequate production of pancreatic enzymes from pancreatic acinar cells. The condition is well known and documented in dogs; affected canines almost always experience weight loss in the face of a good appetite, have a thin body condition, and have diarrhea unresponsive to first-line treatments. EPI has historically been considered rare in the cat, and very few studies have been published regarding this condition in felines. The clinical presentation and response to treatment of cats with EPI is different from that in dogs.
In this retrospective case series, the largest study to date published regarding cats with EPI, 1,095 feline patients with a feline trypsin-like immunoreactivity (fTLI) level consistent with EPI (< 8 µg/L; reference range, 12-82 µg/L) were identified in the database of the Gastrointestinal Laboratory of Texas A&M University's College of Veterinary Medicine and Biomedical Sciences. The investigators contacted a random sample of veterinarians who submitted their patients' blood for this test, and received 150 completed questionnaires from these practitioners. Responding veterinarians were asked to use the patient's medical record information to complete the questionnaire, and not just respond from memory.
Of the 150 cats included in the study, 94 were domestic shorthairs, 26 were domestic longhairs or mediumhairs, and the rest represented a variety of breeds—Maine Coon, British Shorthair, Siamese, Ragdoll, Abyssinian, Balinese, Himalayan, and Savannah. The median age of the cats was 7.7 years (range, 3 months to 18.8 years); 61 cats (41%) were spayed females, while 89 (59%) were male, 86 of whom were neutered. Previously the clinical impression was that cats with EPI were middle-aged or elderly; in this study, a number of young cats were represented.
The most common clinical sign of EPI in the study population was weight loss, noted in 137 (91%) of the patients; 8 of these animals had weight loss as the only clinical sign. Median weight loss was 1.41 kg and median body condition score was 3/9. Unformed feces was noted in 93/149 patients; about 2/3 of these animals had occasional watery diarrhea, which is a common clinical sign of EPI in dogs. In one study of EPI in dogs, 95% of patients had diarrhea. Other salient clinical signs seen in many of the patients included poor hair coat (50%), increased appetite (42%), anorexia (42%), uncommon in dogs; lethargy (40%), and vomiting (19%). Only 32% of the cats (48/149) had the triad of classic clinical signs seen in canines with EPI: weight loss, unformed feces, and increased appetite.
In 119/150 patients serum cobalamin and folate were also measured. Of this subgroup, 92 (77%) had hypocobalaminemia (median, 149 ng/L; range 149-1001 ng/L), and 83 (70%) had serum cobalamin levels below the detection limit of the test (< 150 ng/L). In cats with hypocobalaminemia, serum fTLI concentrations were lower than in normocobalaminemic cats. Low serum cobalamin and high serum folate concentrations were found in 45/119 (38%) of the cats in whom serum cobalamin and folate were measured. Concurrent medical problems, including gastrointestinal disease (30/150; 20%), endocrine disorders (21/150; 14%) including diabetes mellitus (13/150; 9%), pancreatitis (11%), and hepatic lipidosis (6%), were present in 87 (58%) of the patients.
The cats diagnosed with EPI received a variety of treatments. Cats receiving pancreatic enzyme replacement therapy (ERT), either powder or tablet, included 121/150 patients; these animals had lower body condition scores, more weight loss of longer duration, and lower fTLI and cobalamin levels. In 45% of the cats (65/146), antibiotics were employed, often metronidazole; glucocorticoids were used in 34/146 (23%). The use of antibiotics was not found to affect outcome in this study, so antibiotics are of unknown benefit in feline EPI, although they may be needed to treat other concurrent diseases. Cobalamin treatment was administered to 72/147 cats; none of the cats had received cobalamin prior to the diagnosis of EPI. Other treatments offered included probiotics, H2-receptor antagonists, parasiticides, and medications required to treat concurrent diseases. In 64/124 of the cats, dietary therapy was attempted, including hypoallergenic diets, gastrointestinal diets, elimination diets, high fiber diets, and homemade diets, and in some of these cases, a switch was made to a regular commercial diet.
Over half of the cats (78/137; 57%) no longer had clinical signs of EPI at the time of questionnaire completion by their veterinarians. For the 121 cats in which outcome information was available, response to treatment was reported as good in 60% (70/121), similar to dogs; partial in 27% (33/121), and poor in 13% (13/121). The only two factors that were predictive of good clinical outcome were the serum fTLI and cobalamin concentrations, and multivariable statistical analysis demonstrated that the effects of these variables were independent of each other. This finding suggests that the best patient outcomes are likely obtained by offering both ERT and cobalamin supplementation. Those animals with serum fTLI < 4 µg/L were 3.2 times more likely to have a good response to ERT; those receiving cobalamin therapy were 3.0 times more likely to have a positive clinical response, whether or not they were hypocobalaminemic prior to treatment.
Further work needs to be done to investigate the possible etiologies of EPI in cats. Hitherto, chronic pancreatitis has been considered to be a major predisposing etiology for feline EPI. The fact that this study identified a significant number of young cats with EPI suggests that there may be other underlying causes such as pancreatic acinar atrophy, as in dogs, as well as pancreatic hypoplasia or aplasia, and Eurytrema procyonis infection.
Like many other serious health conditions in cats, feline EPI may be accompanied by a few vague and nonspecific clinical signs. EPI should be suspected, and fTLI should be evaluated, in any cat with unexplained weight loss or anorexia, even if the patient does not have abnormal stools. Cobalamin should be supplemented in all feline EPI patients, even those whose test results demonstrate normocobalaminemia, because tissue cobalamin is depleted before hypocobalaminemia develops. The authors speculate that those cats with partial or poor response to ERT may have not been concurrently supplemented with cobalamin.