November 16, 2023

Stomach Problems in Dogs: Common Causes and Potential Remedies

Medically reviewed by Bradley J. Waffa, MSPH, DVM and Ruby Fishbein, RVT

If you’ve noticed your dog seems to have an upset stomach, read on! We’re here to examine a few common reasons for gastrointestinal (GI) upset and share some simple tips to help your dog feel better. Whether Fluffy began a new diet, got into that super-securely-closed trash can, or simply caught a “stomach bug,” a pet with an upset stomach is never fun. For you or for them!


Common Cause #1: New Diets

If your pet’s stomach is feeling a bit off after introducing a new diet, don’t worry – you’re not alone! Sometimes pets need extra time to adjust to changes in their food. For those with pets whose stomachs are extra picky, a simple trick before you dive into a new diet is to take it slow, transitioning onto the new diet over several days.

Start by mixing 25% of the new food with 75% of the old food for the first few days, then transition to a 50:50 mix a few days later. Then after a few days on 50/50, wean to 25% of the old diet with 75% of the new diet. Finally, after several more days, you can begin giving the new diet exclusively. The transition should occur slowly over 1-2 weeks, depending on how sensitive your dog’s stomach is. If your dog is having persistent GI issues despite the gradual change, it may be time to consult with a veterinarian.

Truss Tip: If you need to change your pet’s diet, do so gradually over several weeks, mixing the new food with the old.

Common Cause #2: Inappropriate Snacks

Another common cause of stomach upset is from a pet (or their owner) making questionable food choices. When dogs have a knack for a snack, you never know what they might swallow – from socks to squeakers to bacon or raisins. Some items should be discouraged and some should be off-limits altogether.

High-fat treats, bacon, lunch meats, and even rawhide can cause acute GI upset in sensitive dogs; remember that just because an item is marketed for dogs doesn’t mean that it will necessarily agree with them. (For these pets consider beginning a bland diet as described below).

Many human food items are toxic to dogs—foods like onions/garlic, chocolate, grapes/raisins, and Macadamia nuts, among others. You should always consult a reliable veterinary resource before offering a human food item as a snack, and if in doubt about an ingredient’s safety, just don’t feed the treat! Sure, that puppy dog stare might make you feel awful, but it’s better than making your pet feel awful. A helpful resource is the ASPCA.

If your little Guy Fieri overindulged and sampled something from the “not supposed to eat” list anyway, give your vet a call immediately or call ASPCA poison control at 888-426-4435. Quick action is key – your vet might be able to work some magic to dodge a potential tummy upset or, worse, foreign body surgery. In some cases, simple at-home care and monitoring may be an option for treating your pet. But without consulting a veterinarian there is always a risk it could become a more serious situation, so never hesitate to make the call.

Truss Tip: Ensure your dog’s environment is free from potential hazards and monitor their diet closely.

Common Cause #3: Intestinal Parasites

Worms and single-celled protozoan parasites can wreak havoc on a dog’s digestive system. Common culprits include giardia, roundworms, and hookworms, especially in puppies or dogs who have not been getting consistent flea/tick and heartworm prevention (many of these products protect against GI parasites too!).

Pets can’t always tell us when something’s wrong, but their behavior might be a clue. Keep an eye out for symptoms like changes in appetite, weight loss, diarrhea, or visible worms in their stool. If something seems off, it’s time to visit your veterinarian. If parasites do sneak in, veterinary treatments are highly effective. A veterinarian can guide you on the best approach based on the specific parasite.

Truss Tip: Regular veterinary check-ups and preventive medications can help protect your dog from infections and parasites.

Other Potential Issues

There are hundreds of different causes of GI signs (e.g. vomiting, diarrhea, decreased appetite, etc.) in dogs, some of which can be life-threatening. Dogs can bloat, they can have bowel obstructions, they could be poisoned, among many other things, and the early symptoms of these can all look the same! Further, sometimes relatively benign causes of diarrhea can still become life-threatening if they lead to dehydration. The advice shared here is not intended to replace an evaluation with a veterinarian, but rather to illustrate and troubleshoot some common causes of GI signs that may be readily apparent to pet owners.

If you notice persistent or severe digestive issues, consult with a veterinarian for professional guidance.


At Truss Vet, we regularly treat dogs with stomach issues. We’re open 10am to 10pm (closed Saturday) and offer same-day and walk-in care. Come and see us!