Given that asthma attacks can be severe, and occasionally even life-threatening its probably best to avoid your friend s house if possible. If you must go, you should go armed with your asthma reliever puffer (salbutamol, albuterol etc..) - note that all puffers should be should be used through a spacer device or as a turbuhaler. It would also be a good idea to take an anti-histamine tablet. Loratidine usually does the trick and does not cause a lot of drowsiness. If you usually take a preventer puffer (containing steroids) I would double the dose of this for the couple of days before the visit. If despite the above the cats and dogs cause you to feel you really are having an asthma attack you should seek medical advice immediately.