Comparison of Dietary Interventions
Cats fed both Diets A and B had a numerical reduction in the mean weekly number of vomiting episodes, with little to no change in weekly diarrhea episodes, over the 4-week period (Table 2). There were no differences between diet groups in the mean weekly number of vomiting or diarrhea episodes (p > 0.05). Significant differences were seen in vomiting episodes over time within cats fed Diet A between week 0 and weeks 2–4. These had fold changes in the number of vomiting occurrences of 3.24, 3.74, and 2.72 (indicating reduction of 69.1, 73.3, and 63.2%), respectively, with p values of 0.008, 0.003, and 0.029, respectively (Table 3). Changes in vomiting episodes within cats fed Diet B did not reach significance over the 4-week study period (p > 0.05) (Table 3). There were no statistical differences in the change of diarrhea episodes over the 4-week study (p > 0.05).
Table 2  Estimated means and 95% confidence intervals (CIs) for weekly vomiting and diarrhea episodes in 28 cats with chronic gastroenteropathy.
Table 3  Estimated fold changes, 95% confidence intervals (CIs), and p values for significance of change in vomiting over the 4-week study period in 28 cats with chronic gastroenteropathy.  Significant p-values are listed in bold text.  The vomiting probability also numerically declined in both groups of cats over the 4-week study. At weeks 0–4, cats fed Diet A had a probability of vomiting of 0.98 [95% confidence interval (CI) 0.42–1.00], 0.80 (95% CI 0.19–0.99), 0.3 (95% CI 0.03–0.87), 0.20 (95% CI 0.01–0.82), 0.20 (95% CI 0.01–0.82), respectively. At weeks 0, 1, 2, 3, and 4 cats fed Diet B had a probability of vomiting of 0.96 (95% CI 0.45–1.00), 0.86 (95% CI 0.27–0.99), 0.92 (95% CI 0.35–1.0), 0.78 (95% CI 0.20–0.98), and 0.57 (0.10–0.94), respectively. Statistical differences were seen between time points within cats fed Diet A between week 0 and weeks 2–4, with odds ratios of 0.008, 0.005, and 0.005 respectively (p values of 0.038, 0.023, and 0.023) (Table 4). The change in probability of vomiting within cats fed Diet B did not reach significance over the 4-week study period (p > 0.05) (Table 4).
Table 4  Estimated fold changes, 95% confidence intervals (CIs), and p values for significance of all contrasts for vomiting probability.  Significant p-values are listed in bold text.  Fecal Consistency Scale scores were available for only 4 (31%) cats fed Diet A and 10 (67%) cats fed Diet B. The model of FCS against day and diet over the 4 weeks showed no significant differences between the diets in the change in fecal score (p > 0.05). There was no correlation between the frequency of vomiting or diarrhea over the 4-week period and the presence of fecal enteropathogens detected via PCR or antibody testing (p > 0.05). Similarly, neither Spec fPL results nor age of the cat correlated with the frequency of vomiting over the 4-week period (p > 0.05).