Also prescribed for summer itching - up to 2 tablets (4mg each) twice a day for a 25 kilo dog (so 3 for a 38 kilo). You can get Asda own brand cheaper than the vet.
sorry but i still think its worth talking to the vet first so that you are sure about what is wrong and that piriton will help. After the initial consultation, our vet sells piriton at supermarket prices.