It would have been like when a human gets a vasectomy; though if he never chased the ladies, the parvo might have caused that.

'trouble nuggets' lol

I adopted one male dog as a puppy and had him fixed at about 6 months old. When he was about a year old we rescued another male dog from a high kill shelter. He was about 4 at the time, but had to be fixed before they would release him from the shelter. I few years later we moved and our new landlord had a couple of dogs. He swore they were fixed, but one of his females went into heat. My older dog knew what to do with that since he wasn't fixed early on. He started to go after the female in heat. My younger dog was larger and he caught the scent as well. He mounted the female and she stood for him. Anyway, I've seen this happen with cats too. I don't think there's really a definitive answer to your question. It could really go either way. The bottom line is that a fixed dog can't reproduce and that's what it's really all about.

Our dog never got a chance even to be tempted.

Thanks!

limited to sperm issues, but include low testosterone levels driving mating desire, behavioral causes influencing lack of desire with a given female, physical problems (e.g., pain in copulating from injury or osteoarthritis/hip dysplasia or pain to the penis, urethra, etc.)

Parvovirus has been shown to cause infertility, abortion, and stillbirths in female dogs. Not specifically in male dogs, unlike some infections (e.g., brucellosis) or bacteria causing prostatic infections.

But, "sterility" as it sounds like your veterinarian used the term is nonspecific and it is more likely the dog had low sexual drive from hormone insufficiency--even if he had testicles. Or, perhaps he just did not encounter a female in heat.

Sometimes dogs (and cats) will even molest stuffed toys.