
Hi and welcome :-)
We had a similar problem with my Newfie when she was a pup. Vet also prescribed Cefalaxin which cleared it up for the duration of the tablets but it came back right away as soon as the course ended. Our vet at the time seemed to have no interest in establishing the cause, just treating the symptoms.
I changed her food to elimiate all grains from her diet as some (especially corn/maize) are known to be allergens for some dogs. This helped a bit. I now feed a predominantly raw diet but have learned that rice seems to be ok for her.
We changed to a new vet who immediately looked for ways to bring her skin condition under control without the need for antibiotics continuously. In the beginning she had weekly baths, alternating Malaseb (anti-bacterial) shampoo one week and Epi-soothe the next. He also recommended a therapetic dose of Fish Body Oils (3 x 1000mg daily) plus Vitamin E (1 x 400iu daily). An anti-histamine (chlorphenamine maleate -
not the 'one a day' variety) might help to eliminate itch. I can't recall what dose we gave when she was a pup but another poster posted this recently which might help:
PIRITON DOSAGE FOR DOGS
Tablets are 4mg, dosing is:
Small dogs 2-4mg every 8-12hrs
Large dogs 4-8mg every 8-12hrs
Maximum recommended dose 0.5mg/kg every 12 hours
There are contraindications so if your dog has medical conditions or is on other medications then check with your vet before giving them.
(Taken from BSAVA formulary 5e) Her skin condition is now pretty much under control. She has an occasional serious flare up requiring antibiotics but the rest of time the little patches that crop up can be treated quickly with a little bit of Fuciderm ointment. We don't need to bath her often either but when we do we use Quistel shampoo and conditioner.
HTH