Exclusive feeding of a highly hydrolyzed herring-protein diet is associated with reduced CIBDAI scores and body-weight gain in dogs with severe chronic enteropathy: a prospective open-label pilot study

Background Chronic enteropathy (CE) is common in dogs, and hydrolyzed protein diets are a mainstay of management, particularly in food-responsive enteropathy. Evidence for exclusive feeding of highly hydrolyzed fish-protein diets in client-owned dogs with high clinical activity scores remains limited. This pilot study does not claim that enrolled dogs had failed a previous hydrolyzed-protein trial. Methods Ten client-owned dogs with severe CE (Canine Inflammatory Bowel Disease Activity Index [CIBDAI] ≥ 7) were enrolled in an open-label, uncontrolled, prospective pilot study. All dogs were fed exclusively a commercial diet containing highly hydrolyzed herring protein (manufacturer specification: 70% of peptides <2 kDa; remainder ≤5 kDa) for 8 weeks. CIBDAI, an ordinal composite score, was the principal clinical outcome and was analyzed only with the Wilcoxon signed-rank test and reported as median (IQR). Body weight and a clinicopathological panel were recorded at baseline and day 56. CIBDAI was assigned at both time points by the same attending clinician at the enrolment site. Owners completed a non-validated, exploratory questionnaire on palatability, acceptance and perceived well-being. Results CIBDAI decreased from a median of 9 (IQR 8–11) at day 0 to 0 (IQR 0–1) at day 56 (Hodges–Lehmann median change = −8.5 points, approximate 95% CI −10 to −7.5; Wilcoxon exact p = 0.002). Body weight increased in all 10 dogs, from 7.89 ± 4.04 kg to 9.38 ± 4.55 kg (mean change +1.49 kg, 95% CI 1.04–1.94). Serum total protein and albumin increased within adult reference intervals (mean changes +2.6 g/L and +2.5 g/L). Exploratory increases in ALT, creatinine and fructosamine were also observed; these analytes are not markers of protein status and are not interpreted as beneficial nutritional endpoints. Owners reported perceived clinical improvement within 1–3 days in 6/10 dogs and within 3–6 days in 4/10 dogs. The diet was described as palatable in 9/10 dogs. No dog had a documented unsuccessful prior hydrolyzed-protein trial: 5/10 owners had been offered such a diet and declined it, 4/10 had never been offered one, and 1/10 could not recall. Available detail on prior diets is given in supplementary table. Conclusion In this small, uncontrolled, open-label pilot cohort, exclusive feeding of the test diet was associated with a large reduction in CIBDAI and with weight gain. The design cannot establish the efficacy of herring hydrolysate, the relevance of peptide molecular size or superiority over other hydrolyzed or elimination diets, and it does not support a recommendation to use this formulation before immunosuppressive therapy. Randomized, blinded, comparator-controlled studies with predefined primary endpoints are required.