A psyllium-supplemented gastrointestinal diet is effective for the management of chronic constipation in cats: a 6-month controlled clinical trial

Objectives This study evaluated the efficacy of a psyllium-enriched diet for the management of chronic constipation in cats. Methods A multicentre, controlled, blinded, 6-month trial randomly assigned client-owned cats to a gastrointestinal test diet containing 6% psyllium or similar control diet containing 0.5% psyllium (as-fed values). Inclusion criteria included two or more constipation episodes in the previous 6 months and two or more constipation signs for 14 days or longer. Constipation severity (stool consistency and frequency, and defecation pain/difficulty) was scored on days 7, 30, 60, 90 and 180. Cats could switch diets if constipation signs did not improve or the diet was not tolerated. Diet failure was defined as study withdrawal due to lack of improvement in constipation, new gastrointestinal signs or diet switch. Cats switching diets were considered as new cases in the group into which they moved, and statistical analyses (linear and linear mixed models) included them in both diet groups. Results Of 49 cats enrolled, two were removed for non-compliance, leaving 26 in the test group (18 assigned, eight switched from control) and 30 in the control group (29 assigned, one switched from test). Of the remaining cats, 19/26 and 11/30 completed 6 months of the test and control diets, respectively. The rate of diet failure for gastrointestinal reasons was significantly higher in the control group than in the test group (22/30 [73.3%] vs 7/26 [26.9%]; P = 0.0005). Constipation signs improved significantly from baseline in both groups at each visit after day 7. For stool consistency, improvement was significantly greater in the test group vs control group except at day 30. Conclusions and relevance In cats with chronic constipation, a 6% psyllium-supplemented gastrointestinal diet resulted in sustained improvement of clinical signs, a significantly lower probability of diet failure and greater improvements in stool consistency than a control gastrointestinal diet.