Repeated sickness in dogs is common but can signal anything from mild stomach upset to serious disease, so it always deserves careful attention and, often, a vet visit.

Likely reasons your dog keeps being sick

When people ask “why does my dog keep being sick,” they usually mean repeated vomiting, diarrhoea, or general tummy upset. The most frequent causes include:

  • Diet problems :
    • Eating something they shouldn’t (bin‑raiding, leftovers, grass, bones, toys).
    • Sudden food changes, eating too much or too fast, very fatty/salty food, or long gaps between meals.
  • Food allergies or sensitivities :
    • Certain ingredients (like specific proteins, grains, or additives) can trigger chronic vomiting, diarrhoea, or itchy skin.
  • Infections and parasites :
    • Bacterial or viral “tummy bugs,” worms, or protozoa can cause repeated sickness episodes, sometimes with diarrhoea, blood, or fever.
  • Foreign objects :
    • Toys, socks, sticks, bones, or other items stuck in the stomach or intestines can cause repeated vomiting and are an emergency.
  • Toxins and medications :
    • Chocolate, grapes/raisins, certain plants, human meds, and some dog medications can all lead to vomiting.
  • Organ disease or chronic illness :
    • Liver, kidney, or pancreatic problems, hormonal disease, and some cancers can show up as ongoing or frequent vomiting.
  • Stress and motion sickness :
    • Travelling, big changes at home, or anxiety can upset the stomach, especially in already sensitive dogs.

A pattern many vets see is a dog who is fine most of the time but vomits a few times a week: that can be dietary sensitivity, mild inflammatory gut disease, or simply eating too fast, but it still warrants a proper work‑up instead of guessing.

When it’s an emergency

Contact a vet or emergency clinic immediately if your dog:

  • Vomits repeatedly in a short time (multiple times in a day) or can’t keep water down.
  • Has vomit with blood, black “coffee‑grounds,” or dark/tarry stools.
  • Shows a swollen, painful belly, restlessness, or trying to vomit but nothing comes up (possible bloat, which is life‑threatening).
  • Is very lethargic, weak, trembling, has a fever, pale gums, or collapses.
  • Is a puppy, very small, elderly, or has other known health issues (they dehydrate fast).

Even if your dog “seems okay” between episodes, chronic or recurring sickness is not normal and should be checked by a vet with history, physical exam, and often stool tests, bloodwork, imaging, or a diet trial.

What you can do at home (short‑term)

These are general tips, not a substitute for veterinary care:

  • Stop all treats and table scraps. Feed only a simple, vet‑approved diet (often bland like boiled chicken and rice, or a prescription GI food) if your vet has said it’s safe.
  • Offer small, frequent meals. This helps dogs who vomit on an empty stomach or bolt their food.
  • Ensure access to fresh water. Encourage frequent small drinks; avoid letting a nauseous dog gulp huge volumes at once.
  • Prevent scavenging. Secure the trash, keep them away from leftovers, bones, and known toxic foods or plants.
  • Track a diary. Note what they eat, when they’re sick, stool consistency, and any changes (new home, stress, walks in different areas); this can be crucial for your vet.

If you’ve already seen a vet and feel “stuck,” it’s reasonable to ask specifically about stool tests, blood tests, imaging, or an elimination diet to rule out allergies or chronic gut disease, as forum vets often suggest in similar “my dog keeps getting sick” threads.

A quick example story

Imagine a 3‑year‑old small dog adopted into a new home who seems happy but gets bouts of diarrhoea and vomiting every few weeks. Owners on forums often wonder if it’s “just a sensitive stomach,” stress from a new environment, or something in the local parks or grass, while vets in those discussions repeatedly recommend ruling out parasites, checking diet carefully, and doing basic tests before assuming it’s nothing serious.

Your own dog’s pattern, age, and exact symptoms will change what’s most likely, so the safest path is to use this as a guide for urgency and good questions to ask your vet, rather than a final diagnosis.

Information gathered from public forums or data available on the internet and portrayed here.