Yep. Go for a female and while many people often suggest puppies in these situations, I'm going to buck the trend and suggest an older puppy rather than a 10-12 week old tiny baby. The reason for this is simple. Puppies squeak and whine. Rat terriers often have crazy prey-drives. That added on top of a grumpy dog and a puppy's fragility would make me not want to go there.Picture an older, neutered male rat terrier, always grumpy toward new dogs.
His housemate, a female JRT, was just put to sleep recently. The rat terrier is very clearly depressed. The family is looking for another dog.
Question: should they be looking for, specifically, a FEMALE companion for him? I.E., is there a greater chance of trouble between him and another male (who would also be neutered)?
BTW, the family was considering adding another dog before the JRT passed. This isn't any sort of impulse purchase.