Dog Diarrhea: Metronidazole vs. Natural Options

A potent antibiotic known as metronidazole is one of the most common prescriptions for dogs with diarrhea in the veterinary world. This prescription would appear to be an excellent option for veterinarians, dog lovers, and their dogs because it reaches hard to treat infections. And, it is effective against Giardia. What wasn’t known until recently was it destroys our dog’s gut health. 

What’s Giardia?

Before we dive into the effects of metronidazole, it’s first important to understand what Giardia is. Giardiasis involves a parasitic infection by a protozoan known as Giardia intestinalis

Since this is a microscopic parasite infection, diagnostic tests must be run in order to provide a valid diagnosis. Regardless of life stage, Giardia can’t be seen without a microscope. 


Giardia is generally caused by consuming infectious cysts (also microscopic). Dogs contract the parasite by eating feces, eating grass containing the parasite, or drinking water containing the parasite. Or, it could be transferred by your dog simply stepping in a small amount of feces and licking her paws clean.

Unfortunately, many pet parents don’t want the tests run, or don’t have the funds to run the testing, and Giardia is often treated regardless if the dog has the symptoms. 

It’s important to note, even with the symptoms, it doesn’t necessarily mean your dog has Giardia. There could be some type of gut dysbiosis (gut isn’t balanced). 


Some dogs are asymptomatic and may not show any symptoms at all when the parasite is contracted. Others will show bouts of excessive diarrhea and/or vomiting. If left untreated, this could lead to severe dehydration and other areas of the body becoming vulnerable (lowered immune system). 


As mentioned above, Giardia is most commonly treated with metronidazole. We’ll dive a bit deeper into the prescription momentarily.

Metronidazole: The Most Commonly Prescribed Drug for Diarrhea

Metronidazole, although it’s been shown to have a few positive effects, has been found to result in long-term damage to the dog’s gut health. Special bacteria in the dog’s gut, known as fusobacteria, are completely destroyed. And, the effects of the prescription continue long after the medication is stopped. 

According to a study published by the Veterinary Journal of Internal Medicine, “Microbiome composition was significantly altered, with decreased richness, and decreased abundance of Fusobacteria that did not fully recover after 4 weeks.” Four weeks following the termination of Metronidazole, the production of bile acids were still significantly slow, as were vitamin levels, nucleobases, and antioxidants. 


Once a veterinarian realized the metronidazole only temporarily helped the dog, but resulted in a worsened imbalance of the gut biome, probiotics would be given. There’s just one problem. The metronidazole destroyed more than just one strain of bacteria in the gut. The dog’s gut needs more.

Fecal Transplant

A fecal transplant would be the next option to mitigate the effects of metronidazole. According to Dr. Gary Richter, “the concept of fecal transplantation is simple, albeit gross. By transplanting feces from a healthy patient, we seed the sick patient’s GI tract with more beneficial flora and help resolve underlying inflammation and the symptoms of IBD. Even within the human medical field, fecal transplantation is gaining ground as a treatment for patients with long-term bacterial imbalances.”

A fecal transplant is more promising than the implementation of probiotics, but it still takes a significant amount of time to balance out and begin regulating the gut properly. 

Animal Biome

Due to the level of disgust associated with fecal transplants, Animal Biome has developed another option for pet parents to consider. Animal Biome has a complete process they go through to determine what your dog’s gut looks like so it can be treated properly. 

First, they send you an at-home gut health test kit. You collect a small stool sample and return the test kit to Animal Biome using a prepaid mailing container. Two to three weeks later, you will receive a report indicating what your dog’s (or cat’s) gut health looks like along with a personalized diet, supplements if necessary, and recommended changes in lifestyle. 

Another Option: Diagel

If your veterinarian has recommended metronidazole, you should be sure to ask as many questions as possible. Is the metronidazole an absolute necessity, or can you look into something else?

Diagel offers a completely natural alternative to metronidazole. There is no antibiotic present and it focuses on improving the gut health rather than suppressing it. 

Diagel is particularly helpful in dogs with diet changes, changes in water, environmental factors, and/or stress. Firm stools generally appear in as little as 24 hours. Ingredients include:

  • Orange fiber
  • Carvacrol
  • Psyllium seed husks
  • Eugenol
  • Cinnameldehyde
  • Chamazulene
  • Carb bean shell
  • Thymol
  • Cranberry powder
  • Sesquiterpenoid

About Angela Ardolino

Angela Ardolino Author PhotoAngela Ardolino is a holistic pet expert who has been caring for animals for over 20 years. Angela owns and operates Fire Flake Farm, her animal rescue farm, as well as two locations of a natural pet salon and shop, Beautify the Beast. She’s also the founder of CBD Dog Health, which offers high quality, all-natural cannabis health and wellness products. As well as the founder of MycoDog, a sustainable mushroom tincture line designed for dogs.

To see Angela on her rescue farm today, surrounded by animals, is to truly see her in her element. Looking at this furry, joyful family you would never suspect that Angela and her pets were once full of aches, pains and anxiety. Angela is the mother to Odie (15-year-old mini-schnauzer), Nina (10-year-old Doberman), Jolene (9-year-old mutt), Maza (9-year-old mutt), Rhemi (10-year-old poodle), multiple ducks, roosters, chickens and geese, plus pigs Ellie and Penelope, Brenda the one-legged pigeon, and the many dogs that she fosters from time-to-time at Fire Flake Farm.