Eating something they should not is the most common reason for vomiting in both dogs and cats. Some cases of acute diarrhea begin the same way, with table scraps, trash, or other unexpected items. Their digestive tract may react quickly, and some mild cases improve with supportive care. An empty stomach overnight, motion sickness, pancreatitis, kidney or liver disease, a swallowed object, and medication reactions can all produce the same picture. In cats, an occasional hairball is normal, but a cat vomiting every week is not.

When your dog’s diarrhea arrives alongside vomiting, more of the gastrointestinal tract is involved than a single upset would suggest. Acute diarrhea paired with repeated vomiting also drains more fluid at once, so dehydration builds faster. That combination can disturb the balance of beneficial bacteria in the gut. One episode of vomiting followed by loose stool in a pet who is otherwise bright is a different situation than one who cannot keep water down. Cats reach that point sooner because they carry less reserve and stop eating earlier.

Location tells us as much as cause. When the small intestine is involved, we tend to see large volumes of watery stool, weight loss, and vomiting alongside it. When the large intestine is involved, we see frequent small amounts of soft stools, straining, and mucus, usually with less vomiting. Vomiting shows up more often when the small intestine is affected, while urgency and straining point toward the large intestine. Cats can make this harder to catch, since they withdraw and eat slightly less rather than showing obvious signs, and the first clear signal often appears in the litter box. Watch your dog’s bowel movements or your cat’s litter box habits. Regular cat wellness exams catch a lot of this earlier.

Roundworms, hookworms, whipworms, and giardia can contribute to digestive issues in both species. Symptoms may include soft stool, mucus, or changes in bowel movements, and diagnostic testing helps identify whether parasites may be involved. Year-round prevention helps reduce the risk of future infections. Certain bacteria, including Escherichia coli, Salmonella, and Clostridium, may also contribute to gastrointestinal irritation. A viral infection is a more serious concern, and parvovirus in unvaccinated puppies or panleukopenia in unvaccinated kittens requires prompt veterinary attention. A food allergy can also show up in both dogs and cats. 

Chronic diarrhea usually points somewhere deeper. Inflammatory bowel disease inflames the lining of the intestine, and weight loss, poor coat quality, and intermittent vomiting often accompany it. Older cats bring a separate list, since conditions affecting the thyroid, kidneys, pancreas, or intestinal tract can all produce loose stool or repeated vomiting. String and ribbon deserve their own warning, since a linear foreign body can damage a cat’s intestine within days.

Acute hemorrhagic diarrhea syndrome causes sudden bloody diarrhea and rapid fluid loss, and fluid can shift quickly enough to push a dog toward hypovolemic shock within hours. Bloody diarrhea deserves prompt veterinary attention, especially when paired with vomiting, weakness, dehydration, or other concerning symptoms. In cats, going more than a day or two without eating risks liver condition, which makes appetite loss more time-sensitive in a cat than in a dog. Our Myrtle Beach team can evaluate your pet and help determine the appropriate next step.