He is probably having skin reactions to mosquito bites - feed him garlic powder in his daily food to help him ward off fleas, ticks and mosquitos. Canned or cooked pumpkin is not anti-parasitic, but it is still good for him. He might benefit from some dog vitamin tablets too - gives him all the vitamins and minerals he needs.
If he is going to continue on his raw meat diet - then he needs to be dewormed every 90 days - thoroughly cooked meat has less of a chance to infect him with parasites - but if he should pick up an infection then the 3 times per year schedule should keep him healthy.