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Use caution

DogSafe severity score
3/10

Plain cooked tuna is not toxic, but tuna salad brings mayonnaise fat, high sodium, and, in most recipes, diced onion, celery salt, or relish.

Part of our guide to Picnic and Potluck Foods: What's Safe for Dogs.

Check Tuna Salad for your dog

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Why Tuna Salad needs caution

Plain cooked tuna is not toxic, but tuna salad brings mayonnaise fat, high sodium, and, in most recipes, diced onion, celery salt, or relish. Onion is the meaningful one: it causes oxidative damage to red blood cells. Tuna is also relatively high in mercury, so it is not a food to give regularly.

Part of the Chicken Salad guide

For related dog-safety questions and product-by-product answers, see the complete chicken salad guide.

Signs to watch for

Vomiting, diarrhea, excessive thirst, lethargy, pale gums, dark urine

Related items

Check the exact item or ingredient before assuming two similar exposures carry the same risk.

What to do next

Check for onion and relish in the recipe, note the portion size, and call your vet if allium was involved or your dog is small.

🚨Step-by-step: what to do in the first 10 minutes →
Animal poison control

A closer look at tuna salad

Plain cooked tuna is not toxic, but tuna salad brings mayonnaise fat, high sodium, and, in most recipes, diced onion, celery salt, or relish. Onion is the meaningful one: it causes oxidative damage to red blood cells. Tuna is also relatively high in mercury, so it is not a food to give regularly. The details below use the specific facts for this exposure, rather than treating it like every other food question.

1. Start with the exact exposure

For a closely related comparison, read Canned Tuna. Onion exposure is dose-by-weight and delayed, so a few days of watching is warranted. Mercury is not a one-meal concern; it matters if tuna becomes a habit.

2. Use the facts to decide whether to monitor or call

Another helpful reference is Egg Salad. A small amount of onion-free tuna salad in a healthy medium or large dog is usually just monitored. If onion or relish was in it, if a small dog ate a real portion, or if you see pale gums, dark urine, or lasting weakness.

3. If the details are uncertain

Follow the first 10 minutes guide. Check for onion and relish in the recipe, note the portion size, and call your vet if allium was involved or your dog is small.

FAQ

How much Tuna Salad is dangerous?

Onion exposure is dose-by-weight and delayed, so a few days of watching is warranted. Mercury is not a one-meal concern; it matters if tuna becomes a habit.

Can I treat this at home?

A small amount of onion-free tuna salad in a healthy medium or large dog is usually just monitored.

When should I call the vet?

If onion or relish was in it, if a small dog ate a real portion, or if you see pale gums, dark urine, or lasting weakness.

SourcesUpdated August 11, 2026
  • ASPCA APCC, people foods to avoid feeding your pets (onions, garlic and chives; fatty foods; salt)
  • Pet Poison Helpline, onion and garlic toxicity
  • Merck Veterinary Manual, Allium species toxicosis
Read DogSafe's sources and review policy →
Compiled from veterinary poison-control and medical reference sources, including the ASPCA Animal Poison Control Center, the Pet Poison Helpline, and the Merck Veterinary Manual. This is general educational information, not a diagnosis or a substitute for examination by your veterinarian. DogSafe's severity ratings are our own assessment, calculated from published guidance and your dog's weight. In an emergency, call ASPCA Animal Poison Control at 888-426-4435 or the Pet Poison Helpline at 855-764-7661.