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My neutered dog has a growing red spot on his penis. What is it?

Updated on September 23rd, 2025

Pet's info: Dog | Mixed Breed | Male | neutered | 12 lbs

Around my dogs penis is huge redish purple spot and it’s getting bigger. We don’t know if it’s from him being too sexual active with the three females dogs that are in heat right now or maybe it’s a huge rash? Maybe a infection since he is neutered ?

1 Answer

Most Helpful Answer

Answered By Andrea M. Brodie, DVM

Veterinarian

Published on March 10th, 2018

Unfortunately it is hard to tell when we cannot see exactly where on the penis this purple spot is. If it is a round swollen area, then that would be the bulbus which swells during copulation and locks the penis in the vagina of the female. If people separate the two dogs rather than wait until they part themselves, this bulbus can get injured and the female can also get injured. It is not a good idea to let this male mate with the three females in heat as he will introduce bacteria into their vagina and possibly uterus and so could cause a uterine infection (pyometra). If you could take some good photos of your dog's penis, we could better assess the situation and give you a more specific answer.

1Pet Parents found this answer helpful

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