Trust not a horse's heel, nor a dog's tooth.

Understand the thought

Meaning in plain English

The saying warns against trusting a horse’s heel or a dog’s tooth. It singles out parts of familiar animals associated in the image with possible harm.

What the words are saying

The two body parts make caution concrete, but the text gives no situation, technique or assessment of an animal. As an explicit analogy, familiarity should not make a person overlook a known source of risk. The phrase does not establish that every horse or dog is dangerous, nor does it provide handling instructions. Its useful contrast is between confidence and attention.

Everyday example

A group checks a familiar arrangement’s actual limitations instead of assuming long use means nothing can go wrong.

When to use it

Use it as a stated analogy about familiarity and caution.

Agent-assisted editorial interpretation. This explains the words; it does not by itself verify their author or earliest origin.