Assessing Rectal Gases in Dogs

It has long been known that a little hydrogen sulfide (HS) contributes a lot to the distinctive odor of intestinal gas. Researchers at the Waltham Centre for Pet Nutrition in Leicestershire, U.K., report a series of experiments that confirms this wisdom and validates a treatment approach for reducing the malodorous fumes from one's canine.1 The successful recipe combines activated charcoal, which sequesters HS in its nooks and crannies; zinc acetate, which binds the gas; and an extract of the yu

Apr 30, 2001
Ricki Lewis
It has long been known that a little hydrogen sulfide (HS) contributes a lot to the distinctive odor of intestinal gas. Researchers at the Waltham Centre for Pet Nutrition in Leicestershire, U.K., report a series of experiments that confirms this wisdom and validates a treatment approach for reducing the malodorous fumes from one's canine.1 The successful recipe combines activated charcoal, which sequesters HS in its nooks and crannies; zinc acetate, which binds the gas; and an extract of the yucca plant, which already enjoys a reputation for quenching the odor of pig and poultry feces.

The participants in the double-blinded, crossover study were one golden retriever, five Labradors, and two English mastiffs. In some trials, each received a treat that included the three ingredients, as well as a placebo treat in others. In the in vitro investigation component, the researchers collected dog feces within 15 minutes of defecation, weighed it, and added the material to phosphate buffer. The resulting slurry was added to bottles with deformable and removable tops, and an agent was added to kill bacteria that would otherwise feast on the pungent contents. The researchers measured the pressure of the emitted gas and converted this into volume. A colorimetric assay determined the concentration of HS in parts-per-million (ppm).

But the dogs weren't finished after pooping. For five hours, for five consecutive days, each animal wore a jacket that held a perforated tube over the anus. The jacket also held a pump containing a sensor that measured the concentration of HS every 20 seconds. From this get-up, data on the number of episodes, their frequency, and the concentration of HS went to a computer for analysis. An episode was defined as a concentration of HS exceeding 1 ppm, which is the lower level at which a person detects an emission. To assess frequency, the researchers calculated the mean interval free time (MIFT), with frequency defined as any "flatulence-free interval" exceeding 20 seconds. They also calculated the "human perception of malodor" on a scale of 1 to 5 as "no odor (1), slightly noticeable odor (2), mildly unpleasant odor (3), bad odor (4), and unbearable odor (5)."

Results were encouraging for those with gassy pets. The in vitro studies revealed that eating the loaded treats had no effect on the total volume of gas produced, but it significantly lowered the HS content. The in vivo experiments also indicated an improvement in the percentages of episodes rated as four (bad) or five (unbearable) as being significantly decreased, and percentage of episodes rated as two (slightly noticeable) was significantly increased when dogs were fed treats containing the three agents." The researchers call for further investigation of this olfactory-offending problem. Perhaps the tests can be extended to breeds such as the Boston bull terrier or the pug dog, which are notorious for their unpleasant gaseous emissions. Or cats.

1. C. J. Giffard et al., "Administration of charcoal, Yucca schidigera, and zinc acetate to reduce malodorous flatulence in dogs." The Journal of the American Veterinary Medical Association, 218:6:892-896, March 15, 2001.