Why?

Soy sauce contains approximately 900–1000mg of sodium per tablespoon — roughly 40% of the maximum daily sodium recommendation for a 30-lb dog in a single tablespoon. This extremely concentrated salt load causes rapid hypernatremia: the sodium level in the blood rises faster than the body can compensate.

High blood sodium pulls water out of brain cells, causing them to shrink. The resulting neurological effects — disorientation, tremors, seizures — can progress to cerebral hemorrhage. A 10-lb dog that laps up a small puddle of spilled soy sauce or gets into a dish at a sushi restaurant can receive a dangerous sodium dose within minutes.

The high sodium content also stresses the kidneys, which must work to excrete the excess. Dogs with any pre-existing kidney condition are at higher risk.

How much is dangerous?

A tablespoon or two of soy sauce can cause sodium poisoning in a dog under 10 lbs. The sodium concentration (5,700mg/100g) is far above safe levels.

What are the symptoms?

ONSET:Symptoms within 30–120 minutes of significant ingestion.
  • extreme thirst
  • vomiting
  • diarrhea
  • lethargy
  • tremors
  • seizures
  • coma

What should I do?

Emergency vet care. IV fluid replacement must be done carefully — too-rapid correction causes cerebral edema. Do not force-feed water.

Frequently asked questions

My dog licked soy sauce off the floor — is that dangerous?

A very small lick (a few drops) from a spill is unlikely to cause toxicity in a large dog. More than a tablespoon, or any amount in a small dog, warrants a vet call.

Is low-sodium soy sauce safe?

Low-sodium soy sauce still contains very high sodium relative to dog safe levels. It is not safe for dogs.