Baby gets a rash whenever he goes to grandmas

[Emmw]

I need some help as I'm not sure what to do or what's causing this but every time we go to grandmas my 10 month old gets a rash all over his legs arms and torso, it doesn't happen anywhere else the only thing I can think of is the dog causing it but I'm not sure, has this ever happened to anyone else? Did you find out what was causing it?.

It could very well be the dog. My DN is the same and has been side she was a baby.

It could easily be the dog or perhaps some of the detergents/cleaning products/cosmetics she uses.

It could be the dog.

Alternatively, does she give him anything to eat/drink?
Does he nap in a cot there where she has washed the bedding?
It could be her detergent if she is giving lots of cuddles, or even her perfume/cosmetics.

Forgot to add that it could also be house dust mites, particularly if DS is crawling around and DGM isn't particularly good at hoovering up before you arrive.

Also agree it could be any of the other things suggested by PP, especially food and drink.

Are you with DS the whole time? DGM isn't giving him anything to eat or drink when your back is turned?