causes of crusty nostrils
Sometimes smelling the ground or rolling a ball around with his nose can cause a dog to pick up debris that can adhere to nose and dry-up. Illnesses like distemper, parvovirus, allergies, or an upper respiratory infection can cause a dog's nose to become runny, and the mucous build-up can become dry and crusty. Conditions like lupus and hypothyroidism can cause crusting of the nose as well.