Cucumber — Food safety facts
Safe to share · Dogs · full breakdown on the linked food page
Safe and hydrating. Low in calories. Peel or slice for very small pets.
Dogs and cats carry the same rating (Safe to share), so the notes below hold for either pet.
Cucumber is not toxic to dogs. The real limit is calories, fat and salt, so treat it as a small extra alongside the normal ration rather than a meal in itself.
There is no poisoning risk here, and the usual problem is simply eating too much at once: a heavy fat or salt load can bring on loose stools or a single vomit. Offer water, keep an eye on the pet for 24 hours, and do not induce vomiting.
The full verdict, portion guidance and serving notes are collected on the Cucumber food facts page.