Reduction in grass eating behaviours in the domestic dog, Canis familiaris, in response to a mild gastrointestinal disturbance

Grass eating behaviour in the domestic dog may be related to gastrointestinal distress. To explore this theory, the current study observed grass eating behaviours in dogs fed a standard diet with and without supplementation of a fructo-oligosaccharide (FOS). The FOS diet temporarily induced loose, watery stools to simulate a mild gastrointestinal disturbance. During both FOS Diet and Standard Diet periods, dogs were presented with couch (Cynodon dactylon) and kikuyu (Pennisetum clandestinum) grasses, and the time spent eating grass and the number of grass eating and vomiting events was recorded. Our study found that dogs spent significantly more time eating grass when fed the standard diet and producing normal stools than when they were fed the FOS diet and producing loose stools, suggesting that dogs do not use grass to self-medicate a diarrhoeal gastrointestinal disturbance. However, this does not preclude that other forms of gastrointestinal disturbance may be self-medicated by grass eating behaviours. Importantly, dogs did not use grass as an emetic, as there were only two vomiting events and 374 grass eating events observed. Alternatively, the reduction in grass eating may be attributable to a feeling of satiety caused by the fermentation of FOS. For further clarity, future research should examine the effect of other gastrointestinal disturbances, such as constipation (hard, dry stools) or nausea, on grass eating behaviour in the domestic dog.