Anthony P. Carr, Dr. med. vet., DACVIM
A recent survey defines and demystifies the clinical signs of this disease in cats.
Chronic weight loss and diarrhea can be frustrating conditions to resolve in cats. There are many differential diagnoses to consider, but new research suggests that one we should more closely examine is exocrine pancreatic insufficiency (EPI).
The diagnosis of EPI has become more common since the assay for feline trypsin-like immunoreactivity (fTLI) became available. The test is considered diagnostic for EPI if a concentration of < 8 µg/L is found. Previously, making the diagnosis was more complicated and based on clinical signs and several fecal digestion assays.
Researchers have published little information on EPI in cats—some individual case reports and three case series that reviewed 41 cases.1-3 The case series showed that weight loss was the most common clinical sign of EPI in cats. Diarrhea was common but not present in all cats and often not like the typical feces noted in dogs (voluminous and malodorous with signs of steatorrhea). Polyphagia was uncommon. Patients ranged in age from 3 months to 16 years, with most being middle-aged.
Although the cases in the series are interesting, they provide information on a small number of patients. Consider that in 2010, veterinarians submitted 775 samples to the Gastrointestinal Laboratory at Texas A&M University with fTLI concentrations consistent with a diagnosis of feline EPI.4
At the 2011 ACVIM Forum in New Orleans, researchers from the GI Laboratory and Department of Clinical Sciences at Texas A&M presented an abstract outlining the results of a new EPI survey.5 The team searched its database over a 15-month period for cats with a TLI concentration below 8 µg/L. Questionnaires were sent to the veterinarians who submitted the samples, and 150 surveys were returned.
Many breeds were affected by EPI, although the study could not definitively show that there is no clear breed predilection. The affected cats' mean age was 8.1 years ± 4; 41 percent were females and 59 percent were males. Body condition was poor with a median of 3/9. Of the cats with EPI that had their cobalamin concentrations measured, 77 percent were deficient, and many had undetectable concentrations. In affected cats in which the folate concentration was tested, 47 percent showed an increase.
The most common clinical sign in this study was weight loss, which was seen in 91 percent of the cats. The amount of weight loss varied widely from 40 g (1.4 oz) to 6.82 kg (15 lb) with a median of 1.4 kg (3 lb). Loose stools were seen in only 62 percent of affected cats. Other clinical signs included poor haircoat (50 percent), anorexia (45 percent), increased appetite (42 percent), depression (40 percent), watery diarrhea (28 percent) and vomiting (19 percent). Concurrent diseases were also commonly reported (58 percent). The most common ones were inflammatory bowel disease (IBD, 21 percent), diabetes (14 percent), pancreatitis (11 percent) and hepatic lipidosis (6 percent).
Of the cats affected with EPI, 68 percent were treated with pancreatic enzyme supplementation. Doctors saw a good response in 66 percent of treated cats, a partial response in 24 percent and a poor response in 10 percent.
As the largest EPI study to date, this survey offers valuable clinical information. There are always potential methodological issues with survey studies, which may introduce bias depending on the response rate. However, the response rate in this case doesn't seem to detract from the data's clinical relevance.
What we have learned is that EPI in cats is not as rare as we once thought it was. The clinical presentation deviates significantly from the typical presentation in a dog. Weight loss is common in both dogs and cats and can be quite pronounced. However, in cats diarrhea is not a consistent finding. The diarrhea also appears to be much less severe when present and often doesn't have the characteristics we expect to see, such as large-volume, highly fluid and greasy stools. Polyphagia does occur in some cats, but almost half the cats were reported to have a decreased appetite.
A variety of concurrent diseases were found, most of which are not surprising. In most cases, the etiology of EPI in cats likely relates to chronic pancreatitis and easily explains the 11 percent of cats that were thought to have pancreatitis in this study.1-4 In dogs it usually is related to pancreatic acinar atrophy, which may also be the cause of EPI in very young cats.4 With chronic pancreatitis you can also see the development of endocrine pancreatic insufficiency, such as diabetes. Hepatic lipidosis has also been linked with pancreatitis. IBD was reported in 21 percent of the cats with EPI, which may well have to do with what is termed triad disease or triaditis. In cats it has been shown that there is a statistical association between IBD, pancreatitis and cholangiohepatitis.
Treatment for EPI with pancreatic enzyme supplementation was successful in a large percentage of the cases. The cats with EPI also had other issues that might have impacted management. Most of the cats had low cobalamin concentrations. It has been previously shown that in cats with hypocobalaminemia, supplementation of parenteral cobalamin is often needed to resolve GI signs (250 µg subcutaneously weekly for six weeks, then once monthly with periodic checks of serum concentration).
In addition, the presence of EPI may be associated with small intestinal dysbiosis (formerly termed small intestinal bacterial overgrowth). The low cobalamin and high folate concentrations would certainly point toward this diagnosis. If pancreatic enzyme supplementation and cobalamin injection do not resolve signs, consideration should be given to antibiotic therapy. Dietary therapy is also important to consider, although there are no studies that suggest which diets should be used.
This study does suggest that we should test fTLI concentration in cats with unexplained weight loss or chronic diarrhea, even if the animals are very young. The presence of hypocobalaminemia should also increase the suspicion that EPI is present. EPI should also be considered in those cats with diabetes that appear to have good glycemic control but consistent weight loss or diarrhea.
In a cat with unexplained weight loss in which blood work, the thyroxine concentration, thoracic radiographs and abdominal ultrasound do not establish a diagnosis, I would often perform endoscopy to determine if occult neoplasia or some form of IBD were present. Based on this study, I will certainly measure fTLI, cobalamin and folate concentrations before pursuing more expensive and invasive diagnostic procedures.
Anthony Carr, Dr. med. vet., DACVIM, is a professor of small animal clinical sciences at the Western College of Veterinary Medicine in Saskatoon, Saskatchewan.
1. Steiner JM, Williams DA. Serum feline trypsin-like immunoreactivity in cats with exocrine pancreatic insufficiency. J Vet Intern Med 2000;14:627-629.
2. Kook PH, Zerbe P, Reusch CE. Exokrine Pankreasinsuffizienz bei der Katze [Exocrine pancreatic insufficiency in the cat]. Schweiz Arch Tierheilkd 2011;153:19-25.
3. Thompson KA, Parnell NK, Hohenhaus AE, et al. Feline exocrine pancreatic insufficiency: 16 cases (1992-2007). J Feline Med Surg 2009;11:935-940.
4. Steiner JM. Exocrine pancreatic insufficiency in the cat. Top Companion Anim Med 2012;27:113-116.
5. Xenoulis PG, Wooff P, Zoran DL, et al. Feline exocrine pancreatic insufficiency: 150 cases. J Vet Intern Med 2012;26:765.