By: Dr. Juli, DVM @itsDrJuli
Your dog explores the world through their nose, paws, and mouth. However, the curious nature of your four-legged companion can also get them into trouble. For some pups, a sip of water from the local river, a bite of scraps out of the garbage can, or finishing their human's leftover dinner may be their favorite snacks. Ingestion of foods other than pet-safe snacks or their daily diet is one of the most common culprits for doggy diarrhea. Diarrhea or other gastrointestinal (GI) problems are the most common reasons pet owners seek veterinary care for their pups.
Fortunately, there are numerous tools and medications to ease your dog's symptoms, including antibiotics like metronidazole. Veterinarians commonly prescribe this medication, but as pet owners, it is imperative to be informed of the use and potential side effects so you can adequately monitor your dog's treatment.
What is Metronidazole?
Metronidazole is an antibacterial, antiprotozoal medication known by the brand name Flagyl, Protistat, Metrogel, or Metizol. It is a prescription drug designed for humans that has not been FDA-approved for animals. However, it is frequently and legally used off-label by veterinarians to treat diarrhea or other GI inflammatory problems in pets.
Metronidazole targets the DNA in anaerobic bacterial pathogens that do not require oxygen to thrive. Metronidazole is also effective against protozoal infections like giardia. Additionally, this medication can penetrate the blood-brain barrier, making it effective against some central nervous system infections.
Common Uses for Metronidazole in Dogs
Metronidazole is prescribed for various ailments due to its unique action mechanisms, including anti-inflammatory medication for large intestine problems like colitis or irritable bowel disease. However, how metronidazole works to decrease GI inflammation is not fully understood.
Common uses of metronidazole include treatments for:
- Protozoal infections, like giardia
- Dental or oral infections
- Diarrhea-causing bacterial infections, like E. coli or Clostridium spp.
- Soft tissue infections, or abscesses
- Meningitis
- Inflammatory bowel disease (IBD)
Metronidazole Usage and Proper Dosage for Dogs
Because its antibacterial properties are limited to anaerobic bacteria, veterinarians frequently prescribe metronidazole with other antibiotics to address multiple bacteria types. A veterinary examination and testing, including a fecal test, complete blood count, and blood chemistry, will help determine the underlying cause for your dog's diarrhea and if they are a candidate for metronidazole.
Metronidazole may be given as an injection, topical ointment, oral capsule, oral tablet, or oral liquid suspension. Oral formulations are generally prescribed twice daily and should be provided with food. Metronidazole is known for its bitter taste, so never crush the tablets or open the capsules before giving them to your dog. The proper dose of metronidazole, frequency, and duration of a prescription depends on your dog's breed, diagnosis, and body weight.
Underlying health conditions, like liver disease or kidney disease, will also affect the medication's safety. Provide your DVM with your dog's complete medical history, including current medications or supplements, to ensure they are not contraindicated.
Medications which may be dangerous to give with metronidazole include:
- Some chemotherapy drugs
- Anti Seizure medications (i.e., phenobarbital, phenytoin)
- Cyclosporin (i.e., Atopica)
- Cimetidine
- Warfarin
Common Side Effects of Metronidazole
When properly dosed, metronidazole is generally a safe medication for most dogs. However, it's critical to strictly follow your veterinarian's dosing instructions and monitor your pup closely for any adverse effects or reactions. In rare cases, allergic reactions, including hives, breathing difficulties, and increased heart rate, may occur. Additionally, metronidazole should be used cautiously in puppies, pregnant or nursing dogs, dogs with underlying health issues, dogs with low white blood cell levels, or seizures.
Although rare, other potential side effects of metronidazole may include:
- Nausea or vomiting
- Drooling
- Diarrhea
- Gagging/regurgitation
- Fatigue
- Loss of appetite
- Fever
- Discolored urine
- Yellowing of the skin, eyes, and gums
- Inflamed skin or blood vessels
Incorrect dosing or long-term metronidazole may result in more severe effects, including tremors, seizures, muscle stiffness or spasms, dilated pupils, eye twitching, or weakness.
If your dog exhibits unusual behavior or side effects while taking metronidazole, immediately stop the medication and call your veterinarian. Additionally, if you accidentally miss a dose, never double up on the medication, and give the next dose at the prescribed time.
How to Support Your Dog's Digestive Health
Dogs and their owners are happiest when they are healthy and disease-free. However, even dogs of the most diligent pet parents can experience occasional GI upset. Diarrhea can occur for various reasons, including stress (i.e., stress colitis), infections, illness, or medication side effects. Ensuring your dog has optimal digestive health will help decrease the chances of more severe GI problems.
Ways to support your dog's digestive health include:
- Bringing your dog for yearly or more frequent veterinary examinations
- Regularly giving veterinary-prescribed anti-parasite medication
- Feeding an AAFCO-approved complete and balanced diet
- Promoting overall gut health with a probiotic
- Providing healthy, dog-safe snacks, like pupsicles made with dog-safe bone broth
- Avoid feeding your dog table scraps or any rich, fatty foods
- Preventing your pup from drinking from any rivers, lakes, or standing water (a common place where protozoan parasites live)
Diarrhea happens, and fortunately, there are a variety of veterinary-prescribed treatments to nip the problem in your dog's butt. However, never give your dog any medication like metronidazole unless your family veterinarian prescribes it.
For more information and tips on your dog's health, check out the Native Pet blog.
