I've read up and I think not very often but at least twice a year as gpigs are quite clean animals - unless they're very dirty or your vet recommends it / very ill- try to refrain from pampering them too often. I know it's hard not to
Guinea pigs should not really be bathed except if they have mites or are particularly dirty. The occasional bum bath is fine. Bathing generally stresses them out. I very rarely bath my 5. Betsy gets a bum bath from time to time as she has long hair and gets a bit matted and dirty around her rear end.
I give my long haired piggies a bum bath if needed as they can sometimes get a bit messy if they sit in their pee. I use a burts bees baby shampoo and make sure it is thoroughly washed off. If they don’t need much cleaning then I just use water.
My short haired piggy has never had a bath as she’s clean and I see no reason in stressing her out. I’d read that it can cause skin problems if they’re bathed too often?
My two long haired boys have been bathed twice, and my short haired fellas, just the once. I've had them over a year, but I only bathed them because they were getting a bit smelly. Piggies wash themselves, so they only need a bath if there is a reason for it.
I've bathed mine 4 times in 3 and a half years and 2 of those times were down to mites, he does get regular bum bath's after grease gland cleaning etc. But unless they're getting particularly dirty or having trouble cleaning themselves then it doesn't need doing often.
We bathed new piggy Jezebel because she is long haired and very fluffy and she was soaked with crusty wee and smelled bad, and her chubby sister who also smells of wee might get bathed next week too. I've never bathed my younger slimmer piggies as they keep themselves very clean.
Think the general rule is, bath them if they are stinky and/or wet and crusty or if they have parasites or a skin condition where the vet advises a medicated bath- otherwise dont bother
I gave my long haired Finn a bath just the other day after reading a thread from this forum that if he is dirty, give him a bath.
He did fine but I won't bathe him often as I don't want to stress him out.