The Acute Effects of Isoflurane and Propofol on the Olfactory-Cognitive Ability of Brown Root Rot Disease Fungus Detection Dogs
Scent detection dogs may get injured when performing their tasks and anesthesia is needed for medical attention of these dogs. Currently there is no study evaluating the effect of anesthesia on the olfactory ability of scent detection dogs. This study examined the effects of two commonly used anesthetics, isoflurane (an inhalant agent) and propofol (an injectable agent), on canine olfactory-cognitive circuitry in detecting brown root rot fungus (BRR). The study also evaluated a novel linear route scent detection system utilizing a leash suspended by a guide wire to minimize human hints in dogs. We hypothesized that 1) both anesthetics would reduce the scent detection ability of the dogs; 2) isoflurane would have a greater negative impact on the olfactory acuity of the dogs, and 3) the established linear system would provide a way to evaluate the short term effect of the anesthetic agents on the scent-detection dogs. Eight beagle dogs (age ranges from 1 to 9 years old, median age = 3) trained for BRR detection were used in this double-blinded, randomized, cross-over study. Each dog received two treatments, isoflurane and propofol, in a randomized order with an 11-day washout period between treatments. Immediately prior to the anesthesia, a baseline BRR detection test result was obtained, and the success rate of detecting BRR for each dog was recorded. The dog was then anesthetized with either propofol or isoflurane and a light plane of anesthesia was maintained on each respective anesthetic for 30 minutes. Soon after anesthesia recovery (upon endotracheal extubation), the same scent detection test was conducted again at 0.5, 1, 2, 4, and 24 hours after the dog was extubated. The results showed that neither anesthetic agents had a significant (p = 0.869) impact upon the olfactory-cognitive ability of the dogs at any given testing time interval when compared with the baseline performance. Furthermore, isoflurane did not have a greater impact on the olfactory acuity of dogs compared to propofol (p = 0.669) and no significant difference in the overall effect between the two anesthetics (p = 0.278). We concluded that isoflurane and propofol do not cause negative effect on canine olfaction within 24 hours. There is no difference in effect between these two drugs. And the linear route scent detection system provides a way to evaluate these dogs before and after anesthesia treatments objectively.
Ko, Purdue University.
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