Ah you made it sound like his symptoms were similar to distemper so I asked.There's no actual reason to think he has distemper, so my vet didn't do a blood test to rule it out, no.
Once he's out of the apt and away from the cat, his nose is dry and he's a normal healthy puppy. The only symptoms he gets inside are slightly itchy eyes, clear watery nasal discharge, and sneezing if the cat's right in his face.
because he is allergic to a pet you have.... If you have a cat you really need to consider a regular allergy medication for him since he can have a reaction at any time.... Its really not fair to just wait for him to have a flare up and then give him benadryl....He's not on meds for allergies, other than benadryl. Why on earth would he be?
The dog will have reactions even in the slightest form if cat hair is on the floor/furniture/bed/etc so regular allergy medication IMO is just humane at this point