Let’s look at why your dog might have an upset stomach.
It ate rotting or contaminated food
(or something else it shouldn’t have)
In healthy dogs, this is the most likely culprit. Some dogs like to get into the trash or compost to find a snack. Your dog might have ingested something rotting, moldy or fetid and is paying the price. If you know your dog likes to forage for food, you may need to find ways of limiting its access to waste areas like compost piles.
Dogs also sometimes eat poop and dirt, which can cause an upset belly, especially if there were toxins or parasites in the waste.
If you take your dog hiking off leash, it may have eaten something like a mushroom, another animal’s feces, sticks, mud, or other plant life . It can be hard to keep track of what your dog has access to out in the wilderness, but if your dog is routinely coming home from hiking and getting sick, you may want to consider keeping it on a leash and see if you can monitor what it’s snacking on.
It may have been exposed to a bacteria or virus
This can happen anywhere — the world is full of bacteria and viruses and your dog spends a lot of time nosing around. If you live near a body of water that is also used by the local wildlife, your dog can pick up bacteria from swimming. Some possible bacterias your dog can pick up in water are: cyanobacteria, cryptosporidiosis, giardiasis, and pythiosis.
Your dog doesn’t even need to go in the lake: if it’s roughhousing with or licking another dog that had been in the water, yours might be able to pick up bacteria.
Many bacterias and viruses include upset digestive systems (vomiting, diarrhea) as symptoms.
Your dog may have picked up doggie illness
According to the American Veterinary Medical Association (AVMA), dogs can get canine influenza, which is a newer illness spread through respiratory secretions and contaminated surfaces, bowls, collars and leashes. Symptoms are similar to that of kennel cough: cough, fever, and snotty nose.
To avoid other serious and contagious illnesses like canine distemper (symptoms include runny eyes, vomiting, fever, coughing, diarrhea and more) and canine parvovirus, keep your dog’s vaccinations up to date. Parvo and distemper are considered core vaccines and most dogs are given vaccinations as puppies. These vaccinations need to be periodically updated.
If your dog is a rescue and you don’t know it’s history, your vet may be able to do a blood test to see if the vaccines are still in its system.
Dogs can also get fungal infections that lead to vomiting and digestive issues.
“In general, the fungus infects the body through the respiratory tract and causes fever, coughing, lethargy and flu-like or pneumonia-like signs,” according to the AVMA. “If eaten, digestive problems (e.g. pain, diarrhea) can occur.”
The AVMA breaks down what fungal organisms are more prevalent across the United States: “Histoplasmosis is more common in the Eastern and Central U.S.; blastomycosis is more common in the Southeast, Southcentral and Midwest regions; cryptococcosis is more common in the Pacific Northwest region; and coccidioidomycosis is more common in the Southwest U.S.”
Leptospirosis is caused by the Leptospira bacteria, which is found in contaminated water, food or soil. This also can cause vomiting, fever, abdominal pain and kidney or liver fever, but a vaccine is available.
There are other illnesses that cause vomiting and digestive issues. Talk with your vet if your dog’s upset digestive system doesn’t appear to be caused by food in order to treat any underlying conditions.
Sometimes, new medications can also cause your dog’s tummy to get upset. If you’ve recently added a medication, your dog could be reacting to it.
Your dog has food allergies
Food allergies make up about 10 percent of dog allergy cases. Dogs can also experience food intolerance, which isn’t quite the same thing but can have similar signs.
“Many owners assume that a dog with a chronically upset stomach has food allergies, but many dogs who have chronic upset tummies may have a food intolerance; if there is no hypersensitive immune response, it’s not an allergy,” according to Whole Dog Journal.
Pets aren’t born with food allergies. Allergies can develop over time and repetition. Your dog may happily eat lamb for years and then get symptoms. Genetics can also play a role; some breeds may be more prone to allergies.
Gastrointestinal problems (chronic flatulence and diarrhea) can be a sign of a food allergy or sensitivity. The most common dog food allergens are beef, dairy, wheat, egg, chicken, lamb, soy, pork, rabbit and fish, according to Fetch by WebMD. Preservatives and dyes in dog food can also cause sensitivities.
To determine if your dog has a food allergy or sensitivity, you can try an elimination diet. This involves limiting your dog to one protein (preferably one it hasn’t eaten before) and one carbohydrate for weeks to see if this results in an improvement.
If your dog’s symptoms improve, you can start adding new proteins and carbs one at a time. If your dog’s symptoms get worse, you’ll need to restart the elimination diet with a new protein/carb combo. Keep treats to a minimum.
You may need to do an elimination diet for eight to 12 weeks, depending on how your dog does.
Food allergies, like serious medical conditions, come with more than one symptom. An upset stomach won’t be the only thing your dog is experiencing.