The presence of only one testicle in the scrotum is called cryptorchidism or testicular ectopia. Normally, a dog's testicles descend into the scrotum at two months of age, but in some cases, testicular descent can be a little slower.
Both of these statements are false. The dog does not necessarily have to become pregnant before being spayed.
The vaccination schedule for dogs and cats depends on their lifestyle, the contacts they have, and therefore the risks they are exposed to.