ASSESSMENT OF OROCECAL TRANSIT-TIME IN CATS BY THE BREATH HYDROGEN METHOD - THE EFFECTS OF SEDATION AND A COMPARISON OF DEFINITIONS

Oro-caecal transit times (OCTTs) were assessed in 10 healthy adult cat s by the lactulose breath hydrogen method with either no sedation (gro up A), or after the intramuscular administration of three sedative reg imens: a combination of acetylpromazine at 0.1 mg kg(-1) with buprenor phine at 10 mu g kg(-1) (group B). ketamine at 5 mg kg(-1) with midazo lam at 0.1 mg kg(-1) (group C), or medetomidine at 50 mu g kg(-1) (gro up D). For each test, the OCTT was defined by four methods: a visual a ssessment, the first maintained 4 ppm increase in hydrogen production, and the first maintained 0.5 ml hr(-1) increase in hydrogen productio n assessed by two cumulative sum methods. Depending on the definition, the median OCTTs of the cats were between 113 and 131.5 minutes in gr oup A, 86.5 and 97.5 minutes in group B, 218 and 235.5 minutes in grou p C and 86.5 and 97.5 minutes in group D. By two of the definitions, t he median OCTTs in group C were significantly longer than in group A ( P less than or equal to 0.037) and approached significance by the othe r two definitions. The use of sedatives significantly increased the in ter-individual variability of the OCTTs, particularly in groups C and D. There were significant differences between the median OCTTs defined by the four different methods, but all the methods were very highly a nd significantly correlated (r(s) less than or equal to 0.9503, P<0.00 01).