Hi, We can always change the product to next size without any problem.

All Revolution/Stronghold products are formulated differently according to weight and each weight class formula has the same mg/weight ratio. So the larger the dog, the more Selamectin is in the dosage however the mg/weight ratio remains the same.

Revolution flea control will maintain its efficacy after periods of wetting. The manufacturer states that dogs and cats who bathe (including shampooing), swim and who are wetted by rainfall will still be protected by Revolution so long as such wetting does not occur within 2 hours of the Revolution being applied

Hi, The official information states that It is for dogs/puppies over 6 weeks of age and cats/kittens over 8 weeks of age. Safe to use in pregnant and nursing dogs. Still it would be good idea if you get some advice from your vet.

Good question! You need either Pfizer's Stronghold/Revolution Pink formula for puppies and kittens under 5 lbs. You can click on either of the links below to go to the products you seek: http://goo.gl/6aD10d http://goo.gl/Pp2nOa Thanks for the inquiry!