Female dogs and cats can also get a really nasty gross infection called a pyometra that causes the uterus to fill up with pus. The uterus is the place in the animals body where the puppies or kittens stay until they are born.

This is a picture of a uterus that was taken out of a female dog that had a pyometra. You can see how big it is. That's because it's filled with pus!! You can even see the pus leaking out of it on one side.

Male dogs and cats can also get cancer anywhere in their reproductive system. For example, testicular cancer, a type of cancer that is impossible if they are neutered.

Neutering or spaying your dog or cat will make it impossible for them to get certain kinds of cancers. It will also really decrease the chances of them getting other kinds of cancers as well. This will allow him/her to live a long healthy life with you.