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What Antibiotics Do to Your Dog’s Gut Microbiome & The Environment

Updated: Feb 23, 2022

Antibiotics are often prescribed after surgeries to prevent infection during recovery. While prophylactic use of antibiotics can help to prevent infections, it can also have severe and adverse effects on your dog’s gut microbiome and gut health. In a recent study by the Western University of Health Sciences, researchers found that dogs (n=6) treated with post-surgery antibiotics had very different gut microbiomes compared to dogs (n=6) that were not administered post-surgery antibiotics, though the effects of these microbiome differences are still being understood.

A MiDOG collaboration with Western University unveils the impact of prophylactic antibiotics on canine fecal microbiome in orthopedic emergency cases.

What is the microbiome?

All animals have microorganisms that live in and on them. Most of these microbes are commensal (live peacefully) or are beneficial to the host. Collectively, the microbes that live in your dog’s GI tract are called the “gut microbiome” and these microbes work in concert to keep your best friend happy and healthy.

When the gut microbiome is thrown out of balance your dog could experience disorders like inflammatory bowel disease and diarrhea. The gut microbiome also impacts other areas of your dog’s well-being. For example, in both humans and animals, the gut microbiome has been shown to play important roles in developing allergies, arthritis, and diabetes.

The Importance of the Gut Microbiome & Health

The Microbiome & Digestion

A large proportion of the gut microbiome resides in the large intestine and the microbes living there are responsible for breaking down many of the nutrients that were not absorbed earlier in the digestive tract. For example, dogs and humans typically cannot digest fiber on their own, but the microorganisms living in the gut live symbiotically with the host and turn these fibers into starches for the microbes and host to absorb. Without these microbes, the energy from cellulose fibers would be lost as waste.

The Microbiome & the Immune System

The immune system is a complex network of cells and organs that fight infection and disease. When pups are born their immune systems are not fully developed and need to be “trained” to detect which microbes are friends and which are foe. Part of the training occurs as the pups drink their mothers’ breastmilk, which contains part of the mother’s microbiome. In this way, the mother’s microbiome is transferred to the pup and jumpstarts the pup’s own gut microbiome. Over time the pup’s immune system co-develops with these healthy gut microbes and begins to recognize foreign microbes as potential pathogens.

The Microbiome & Antibiotics

Liberal use of broad-spectrum antibiotics, such as those prescribed prophylactically after surgery, can cause several issues that can be harmful to your pet. These antibiotics can kill both the ‘bad bacteria’ that could make your dog sick and also the ‘good bacteria’ that help to keep your dog healthy. Researchers from Western University found that dogs on the cefazolin antibiotic have a higher incidence of Streptococcus equinus (a bacterial pathogen) in their gut microbiome after 36 hours compared to dogs that were not given cefazolin. It’s thought that this bacterial pathogen was able to colonize the antibiotic administered dogs because their commensal flora had been depleted by the antibiotic treatment.

Antibiotic Stewardship

Broad-spectrum antibiotics can impact not only your dog’s microbiome health but also the surrounding environment. Several studies have shown that unused (or unmetabolized) antibiotics are disposed in the trash or excreted as waste. Many of these unused antibiotics end up leeching into surrounding waterways and the environment. All these wasted antibiotics have resulted in a drastic rise in multi-drug resistant bacteria in our food, environment, and hospitals.

Read the abstract here.

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