For veterinary doctors, antibiotics are a crucial tool for treating bacterial infections in pets. However, these antibiotics aren’t picky when deciding which bacteria to eliminate in your pet’s gut microbiome. As the drugs wipe out “bad” bacterial pathogens, your pet’s gut could also lose lots of key “good” bacteria that help the digestive system function properly. Some of those beneficial bacteria absorb crucial nutrients, or aid in fighting inflammation, while others help maintain a strong immune system. Loss of key beneficial bacteria may cause an ongoing bacterial imbalance in your pet’s gut that can contribute to or worsen health conditions like chronic digestive disorders.

A new study published in the Journal of Veterinary Internal Medicine investigated the effects of metronidazole on the microbiome in healthy dogs. The authors found that a 14 day course of treatment with metronidazole given to healthy dogs, resulted in significant changes in microbiome composition, including severely decreased amounts of a key beneficial bacteria, Fusobacteria. After 30 days of post-metronidazole treatment the dog's bacterial community did not recover, the canines were missing key bacteria for healthy gut function.