Snake size according to fang width?

Asked September 16, 2020, 8:26 AM EDT

My lab mix dog has just survived a snake bite to his ear thanks to emergency vet care. I was walking him on my farm in Bertie County in eastern North Carolina. I never saw the snake but I witnessed my dog getting bit. I never heard a rattle of a rattle snake, which I know are numerous in Bertie. The vet treated him with anti-venom assuming it was a rattle snake. The fang marks were around 2.5 inches apart. Can you estimate the size of the snake based on the fang mark width? I am also learning that rattle snakes do not always rattle before striking. Is this true?

Bertie County North Carolina

3 Responses

Thank you for your question. There have been several studies to attempt to correlate the distance between fangs and body length of venomous snakes. According to one study, Interfang Distances of Rattlesnakes: Sexual, Interspecific, and Body Size-related Variation, and Implications for Snakebite Research and Management, published in the journal Wilderness and Environmental Medicine, the authors developed a formula for estimating the length of the snake based on distance between fang marks.

Based on the formula developed in the study above, the snake that bit your dog would be approximately 65 inches long. The timber rattlesnake has a maximum length of approximately 78 inches and the cottonmouth's maximum length is approximately 72 inches.

Here's a link to the study:

As to your question about rattlesnakes not rattling, it is true that rattlesnake do not necessarily rattle. They normally do, because this is a way to warn potential threats to stay away. However, if an animal or person suddenly comes upon a rattlesnake, and it perceives an immediate threat, it may bite without sounding its rattle.

I hope this information helps, and thank you for contacting Ask an Expert.


Thank you very much. I appreciate your quick reply. Although it doesn't make me feel any better knowing it was a whopper of a snake that bit my dog, at least now I know the approximate size.
Penny Adams

You're welcome! Contact us any time.