What Type of Probiotics are Healthy for Dogs
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Dog Probiotic Side Effects, Risks, and Considerations

Katelyn Son


Medically reviewed by

Ivana Crnec, DVM

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Probiotics can help with many issues like allergies, diarrhea, or the digestive tract and are essential for healthy gut bacteria in dogs. They are particularly important for dogs exposed to toxins, bacteria, and allergens.
However, it’s only natural to want to know the benefits, risks, and side effects before you offer probiotics to your dog’s health regimen. 
In this article we talk about how probiotics for dogs work and support gut health, what they can help with, and the potential side effects.

Do Probiotics Cause Side Effects in Dogs?

Do Probiotics Cause Side Effects in Dogs
Probiotics can cause minor side effects in dogs like flatulence, diarrhea, or nausea. However probiotics are generally well-tolerated in dogs. Any side effects your dog is experiencing typically aren’t life threatening and can often  be rectified with a dose modification.
Probiotics are healthy bacteria strains found in your dog’s body, mainly in the GI tract, mouth, respiratory organs, nasal cavity, dermis, and genitals. 
Sometimes the body will not receive enough probiotics from the dog food alone, leading to a weakened immune system and health problems.
Probiotics are undoubtedly helpful in such situations, but your dog can also take them daily for the following health benefits: 
  • Allergy Relief. Allergies are related to a weakened immune system. Whether your dog struggles with seasonal or food allergies, a common side effect is an itchy skin. The American Journal of Veterinary Research found that, when administered to puppies, probiotics reduced atopic dermatitis’s immune reactions with lasting results.
  • GI Tract Health. Probiotics are essential for gut health and the correct absorption of nutrients. Dogs struggling with gastrointestinal disease or sensitivity need probiotic supplements to ease symptoms like skin reactions and loose stool. Probiotics are also an important part of the treatment of inflammatory bowel disease
  • Obesity Management. According to the Journal of Animal Physiology and Animal Nutrition, an altered gut microbiome is observed in obese pets. When gut health is supported, digestion is improved, and obesity risk is lowered. 
  • Anxiety Reduction. Probiotics can ease the effects of stress and anxiety on the gut. Drugs that are usually administered for stress and anxiety in dogs can have severe complications and adverse reactions. However, probiotics ease the symptoms of stress naturally and healthily. 
  • Boosted Immune System. Probiotics support the optimal immune response through a process called immunomodulation. A robust and healthy immune system is critical for preventing issues like yeast infections, colitis, pancreatitis, and GI inflammation. The use of probiotics for dogs can also prevent smelly breath.
As aptly stated by a joint study on the Microbiota and Probiotics in Canine and Feline Welfare, “The health and well-being of companion animals, just as their owners, depends on the gut microbes.”
However, like any other supplement, dog probiotics can cause side effects in sensitive pets. The side effects can occur after a sudden implementation, changes in the probiotic strains, or giving large dosages. 

What are the Negative Side Effects of Taking Probiotics?

The side effects of probiotics in dogs are usually related to the digestive system and include reactions like diarrhea, constipation, fluctuance, appetite change, or nausea. 
Luckily, most side effects are benign, transient and can be managed through dosage modifications. If they persist and you are worried, talk to your trusted veterinarian
Last but not least, it should be noted that after implementing probiotics, the dog’s symptoms may worsen before they improve. 
This is not a real side effect, but an expected turn of events as the gastrointestinal tract needs time to adjust to the influx of new live bacteria. 

Risks and Considerations for Dog Probiotics

Risks and Considerations for Dog Probiotics
A probiotic dose of 1 to 4 billion CFU daily is adequate for maintaining your dog’s health. For hefty dogs, you can aim a little higher and give your pet up to 5 billion CFU daily. (Our Honest Paws Probiotics contains 5 billion CFU per stick).
While an underproduction of probiotics can impact the canine body negatively, it’s natural to assume that too much of a good thing may not be a good thing. Probiotics are safe for your dog, but too much may increase the frequency and longevity of unwanted side effects. 

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Honest Paws Pre+ Probiotics
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  • Specially formulated with both dog probiotics and prebiotics.
  • Avoid diarrhea, loss of appetite, constipation, and many other problems.
  • Helps promote the production of natural antibodies, fight free radicals, and support a healthy immune system in your dog.

Low-Quality Probiotics May Cause Side Effects in Dogs

Low-quality probiotics are more likely to trigger side effects in dogs. This is because such products are often made using ingredients with questionable qualities and contain low levels of live bacteria. 
Even if you purchased a high-quality probiotic, always check the expiration date on the product and, based on the manufacturer’s recommendations, keep it in the refrigerator or dark place. 

Side Effects due to Weakened Immune Systems in Dogs

If your dog has a weak immune system, you need to be careful in giving them the right probiotic source. This is because dogs with compromised immune systems due to disease, malnutrition, or simply old age are more likely to trigger side effects. 
For example, if the Lactobacilli overgrow on rare occasions, they can enter your dog’s bloodstream and produce inflammation. 

Allergic Reactions to Probiotics for Dogs

If you’re giving your dog probiotics to treat a food allergy, the last thing you want is a supplement that contains irritating ingredients like gluten, soy, proteins, eggs, flavorings, or other mix-ins. 
Make sure you check the ingredient label, especially if you’re buying your dog some probiotic treats or kibble.

Potential Drug Interactions with Dog Probiotics

Antibiotics and antifungals can decrease the efficiency of certain strains of probiotics. The same concept applies to other frequently used over-the-counter and prescription medications. 
To avoid such issues, you must talk to your trust vet. It is even possible for probiotics to interact with other supplements, including vitamins and herbal therapies. 

What Type of Probiotics are Healthy for Dogs?

What Type of Probiotics are Healthy for Dogs
There are many different types of probiotics, some are specific to humans, others specific to dogs, and some overlap. 
Experts develop probiotic strains of canine origin specifically for use in canine nutrition. They do this by isolating lactic acid bacteria from canine feces and then separating them. 
According to the 2017 study, most microorganisms resistant to stomach acid and digestive bile are isolated for probiotic use.
Here is a short overview of some canine-specific beneficial bacteria: 
  • Bifidobacterium animalis supports healthy digestion, improves stool quality, and helps dogs recovering from illness and prolonged medication use. 
  • Bifidobacterium longum is a potent bacterium with several powers. It manages stress and reduces anxiety. This probiotic strain is also excellent in preventing loose stools and managing the symptoms of food allergies. 
  • Bacillus coagulans is a good gut bacteria that produce lactic acid and overwhelms terrible bacteria. It also acts as an anti-inflammatory.
  • Bacillus subtilis has a strong effect on the dog’s immune system, and before the development of antibiotics, it was used to treat urinary tract infections. 
  • Bacillus indicus supports the production of vitamin K2, B complex vitamins, and quinols. It also enhances the synthesis of digestive enzymes in dogs with exocrine pancreatic insufficiency.
  • Lactobacillus acidophilus assists intestinal health and immune function. It enhances the absorption of nutrients and is potent in fighting off harmful bacteria and infections. 
  • Lactobacillus rhamnosus promote a healthy and robust colon wall. They are useful in the treatment of diarrhea in animals. Studies have also shown its effectiveness in treating atopic dermatitis. 
  • Lactobacillus fermentum has a high survival rate against acid and bile. It has been shown to reduce GI tract disorders and boost the immune system.  
  • Lactobacillus sakei has been used in canine studies to treat atopic dermatitis, skin allergies, and other and skin disorders. 
  • Lactobacillus casei lives in the mucosal membranes. It is an important part of the gut-brain axis, meaning it can affect your dog’s mood and emotions. 
  • Enterococcus faecium is not suitable for humans but is excellent for canines. It aids digestion, balances the bacteria population, and is helpful during diet changes or alongside antibiotics treatment.
  • Saccharomyces boulardii is a healthy yeast helpful for managing diarrhea and inflammation-triggered GI issues (for example, inflammatory bowel disease). This yeast can also protect the gut microbiome during antibiotic treatments.
A probiotic that combines 3-4 of these strains will have the best results in your pet. Lactobacillus acidophilus and Bifidobacterium are the most common strains of bacteria and will enhance nutrient absorption, alleviate stomach upset and boost the immune system. 
To ensure maximum efficacy, make sure you combine the probiotics with prebiotics. Prebiotics are non-digestible starches or fiber that feed the probiotics, thus encouraging the growth of good gut microorganisms.  
Prebiotics can be found in mushrooms, chicory root, dandelion greens, bananas, apples, flaxseeds, leafy greens, and other water-soluble fibrous foods. They usually contain essential vitamins and fatty acids that further support the immune system and boost your dog’s health.  

Our Final Thoughts on Dog Probiotic Side Effects

Dog Probiotic Side Effects
Probiotic supplements for dogs are great to promote gut health. They are not a quick fix, as it can take time for the good bacteria in the gut to heal and find equilibrium. However, when used correctly and in the right dose, the live cultures from probiotics are essential for gut health and overall wellness. 
However, as your dog’s gut bacteria reach a healthy and happy balance, you may identify some side effects of dog probiotics. Every dog will react differently, and it’s a good idea to contact your vet if the side effects persist or are troubling.