Yes, they can get them from playing in your backyard. They can drop off other animals or birds that may use your backyard as a passageway. I agree with your vet that prevention is better than a cure. I don't like not treating Batty, but his skin needs to be sorted first IYKWIM. Once his skin is sorted then I'll look into tick prevention. He loves his checks though, I give him a bit of a puppy massage and he's usually dead to the world, upside down when I'm finished
The cat is treated with frontline although I don't actually think it does much.
Batty gets checked twice a day every day because I'm not treating him if that makes sense?
The lady with the pug may not be experienced or just may not like her dog playing rough. She may be overly paranoid too. Who knows lol?
It's hard for new owners when they see their 'babies' playing rough and growling and biting and carrying on. A lot of people don't realise that that is how puppies learn what's right and what's wrong. I hope the chi is ok and comes out of it's shell soon though. I have my suspicions about what may be happening, but I'll keep quiet about it for now I think.