Dogs process some human foods very differently from people. For a Shih Tzu, small body size means a given piece of food represents more exposure per unit of body weight than it would for a large dog, but size alone cannot tell you whether an ingestion is safe.

The product, ingredients, concentration, amount, timing, health history, and individual sensitivity all matter. Do not use online dose calculations to decide whether to wait.

If your Shih Tzu ate a potentially toxic food: remove access, keep the package, and call a veterinarian, emergency clinic, or animal poison-control service. Report what was eaten, approximately how much, when, the dog’s current weight, and any symptoms. Do not induce vomiting or give a home remedy unless a veterinary professional gives specific instructions.

1. Xylitol (birch sugar or wood sugar)

Xylitol is a sweetener used in some sugar-free gum, mints, candy, baked goods, toothpaste, mouthwash, cough products, supplements, and nut butters. Product formulas change, so read the current ingredient list rather than relying on the brand name.

The U.S. Food and Drug Administration’s xylitol guidance explains that xylitol can cause a rapid insulin release in dogs, leading to dangerously low blood sugar; some exposures can also affect the liver.

Possible signs include:

  • vomiting;
  • decreased activity or weakness;
  • staggering or poor coordination;
  • collapse; and
  • seizures.

Do not wait for signs. If a product contains xylitol—or the ingredients are unavailable—call a veterinary professional or poison-control service immediately. Do not give sugar, food, or another substance unless directed for the individual case.

2. Grapes, raisins, sultanas, and Zante currants

These Vitis fruits can cause acute kidney injury in dogs. The Cornell grape and raisin toxicity guide states that tartaric-acid concentration and individual sensitivity vary, so the exact toxic amount is not known.

That uncertainty is why “only one” is not a reliable reason to monitor at home. Contact a veterinarian or pet poison-control service after any known ingestion.

Possible signs may include vomiting, diarrhea, reduced appetite, lethargy, abdominal discomfort, changes in thirst or urination, weakness, tremors, or inability to urinate. A dog may appear normal early, so symptom absence does not establish safety.

3. Chocolate, cocoa, coffee, and caffeine

Chocolate and caffeine-containing products contain methylxanthines. Concentration differs widely: cocoa powder and baking chocolate contain much more than many milk-chocolate products, while coffee beans, grounds, energy products, and some supplements create different exposures.

The Merck Veterinary Manual overview of chocolate toxicosis notes that effects can involve the digestive, cardiovascular, and nervous systems and that individual susceptibility varies.

Possible signs include:

  • vomiting or diarrhea;
  • restlessness, agitation, or panting;
  • increased thirst or urination;
  • a rapid or abnormal heart rhythm;
  • tremors; and
  • seizures.

Keep the wrapper and report the exact product, cacao percentage if shown, amount missing, and time. Do not calculate a home “safe dose”; veterinary and poison-control professionals use case-specific product data and the dog’s condition.

Allium plants can irritate the gastrointestinal tract and damage red blood cells in dogs. Risk can come from raw, cooked, dried, powdered, or concentrated ingredients, so sauces, seasoning mixes, baby foods, soups, and prepared dishes may matter even when pieces of onion are not visible.

Possible signs include vomiting, reduced appetite, weakness, pale gums, rapid breathing, elevated heart rate, or dark urine. Some effects may not be obvious immediately.

The ASPCA list of people foods to avoid notes that dogs are at risk depending on the amount ingested. A veterinarian or poison-control professional should assess the actual recipe, amount, timing, and dog rather than an owner converting an online percentage into a home threshold.

5. Macadamia nuts

Macadamia nuts can cause illness in dogs. They may appear alone, in cookies, chocolate, trail mix, nut butter, or baked goods, creating more than one potential hazard in the same product.

Possible signs include weakness, poor coordination, vomiting, tremors, reduced activity, or increased body temperature. Chocolate or xylitol in the same food changes the case, so provide the full ingredient list.

Contact a veterinarian or pet poison-control service after suspected ingestion. Do not assume another type of nut has the same risk profile, and do not offer nuts as a way to test tolerance.

What information to collect

Without delaying the call, gather:

  • the product name and current ingredient list;
  • a photo of the wrapper or recipe;
  • the amount originally present and amount remaining;
  • the earliest and latest possible ingestion time;
  • the dog’s current weight, age, conditions, and medications;
  • any vomiting or chewed packaging; and
  • current behavior and symptoms.

Do not risk a bite by taking an item from a dog who is guarding it. Use distance and contact a professional for safety guidance.

Why symptoms are not a screening test

Different toxins act on different body systems and timelines. A dog can look normal before measurable injury develops. Conversely, vomiting after eating an unknown item does not identify the toxin.

Seek emergency care for collapse, seizures, marked weakness, breathing difficulty, blue or gray gums, severe tremors, unresponsiveness, or inability to stand. Follow the triage advice you receive even if symptoms improve on the way.

Prevention without guesswork

  • Store food and food-containing products behind a closed, secure barrier.
  • Check ingredient lists on sugar-free products, toothpaste, supplements, and nut butter.
  • Keep handbags, backpacks, parcels, bins, and compost inaccessible.
  • Ask visitors and children not to feed the dog without permission.
  • Save veterinary and local animal poison-control contact options before an emergency.
  • Treat missing wrappers and chewed packages as part of the exposure report.

Human foods that are not toxic can still cause choking, obstruction, pancreatitis, or gastrointestinal upset. “Not on this list” does not mean appropriate for a particular dog.

Key takeaway

Xylitol, grapes and raisins, chocolate and caffeine, Allium foods, and macadamia nuts all warrant professional guidance after suspected ingestion. The safest response is to identify the product, preserve the label, and call promptly—not to wait for symptoms or calculate a dose at home.

Also review 10 household hazards for Shih Tzus and the broader Shih Tzu health and safety guide.

Sources and further reading

This article provides general education and cannot assess an exposure. Contact a veterinary professional or animal poison-control service for case-specific advice.