Is it possible for a dog to be allergic to another dogs coat?
I take my german shepherd every once in a while to play with an american bulldog. The american bulldog’s owner told me that her dog stayed itching himself all night long after it played with my dog. My dog is free from fleas & ticks. The other dog is also free from fleas & ticks. Someone mentioned dogs can be allergic to other dogs coats. Is this possible?

Hmmm. A German Shepherd has a double coat. I would seem possible that allergens or pollen could adhere to the undercoat or to the outer coat. So, I guess my answer would be that the other dog could be allergic to something that is on the shepherd’s coat, but not to the coat itself.
It the shepherd goes for walks in any wooded area or rolls in the grass etc, then pollen could easily be found on the coat.
My son’ s dog is allergic to spruce pollen and he lives in Alaska. There are spruce trees all over the place up there.
Pollen or allergens could cause a skin reaction or a nasal/cough type reaction depending on whether it was breathed in or rubbed onto the skin.