I have an unusual question here.

My Mum has 2 Border Terriers, Charlie (my dogs brother) who will be 3 in August. Charlie had his balls removed, one was undescended and found to be on his kidney. He had this done over a year ago, so he is now a neutered dog.

She then bought Millie (BT) who has just had her 2nd season. Today Charlie was mating with Millie????? and from what my Mum has told me, thy actually tied. Can anyone explain this?

I take it they did remove both and not just the one which was retained in the abdomen?

Its quite normal for him to still want to mate, they only removed his balls,
thats all, the instint is still there, over time he may quiten down and it will happen less and less, but some dont, my 13 year old was done when he was about 3, he still trys it from time to time, he also still marks, neutering dosent realy stop it, the only time it does is if there done before there sexualy mature.

A visual "mating" by castrates is possible, the tie most often does not last very long.
There is no reason for concern - that is if the vet did his job. I had a dog who also had one testicle in the hide somewhere. I had a surgery made to remove this one. Funny enough it was still there when he died 10 years later, caused by a cancer that was most likely caused by that testicle. So sometimes you better keep an eye on those vets.

Notice that a female dog that thinks she has been mated may develop soe false pregnancy, which in some cases may ignite an uteritis.

After I posted this, I went online and searched "neutered dogs mating" and it bought up a whole lot of incidences. Wow, although I have never ever bred a litter, I have owned both dogs and bitches for about 20 years and as they say, you learn something new every day.

Thank you all for your replies!

Hopefully its only the thought that counts