One commonly known remedy for chigger bites is to apply nail polish to reduce itchiness. This does not kill the chigger or treat the bite in any way. It simply seals the area off from the air, which keeps the sore from itching so badly. If you want to apply something to relieve itching, it's much better to use a salve or cream that contains antihistamines (Caladryl or hydrocortisone salves are the most common). Like nail polish, these treatments will seal the bite from the surrounding air, but they will also help to prevent infection. If the welts continue to irritate your dog for more than a couple of weeks, they might be infected and you should take him to see the vet.
