If your dog has developed a big, swollen earflap, it’s most likely to be due to a condition called an aural haematoma. Treatment for a swollen ear will depends on the cause - contact your vet for an appointment.
Phone and video consultations are on the rise, and photos are becoming an important part of having an appointment with your vet. This page explains how to take useful pictures for your vet to look at.
Dogs can have allergic reactions just like people. Common triggers include insect stings, plants and medications (including vaccinations).