Purina pro plan veterinary diets canine ha hypoallergenic is a complete dry food formulated to help dogs that suffer from food allergies food allergies often cause skin or digestive system irritation you might notice that your dog is itching a lot or has skin redness or infections maybe it has frequent bouts of vomiting or diarrhoea your vet will try to establish whether your dog is suffering from a food allergy this often involves an elimination diet a diet which avoids provoking a resp