[anonymously]

I have owned dogs for decades too, neutered and intact. In my experience an intact male dog exposed to a female dog in heat will become frustrated and very uncomfortable. Sometimes aggressive.

The dog I mentioned above was 4 years old and neutered shortly after the event. The vet wondered if the kennel had used the dog for breeding (without my consent) to cause such a reaction.
The dog was a Yorkie and positive for cryptorchidism.