Vet at FirstVet answers:
It can be very difficult to see the difference between an uncomplicated, superficial, irritation in the mucous membranes of the eyes (conjunctivitis) and a deep inflammation of the eye (such as glaucoma, uveitis and corneal ulcers). It is therefore advised to always consult a veterinarian if your dog seems to have a sore eye. Before the appointment make sure to keep the affected eye clean by cleansing it with saline (available at the pharmacy) and preventing your dog from getting to it by using a buster collar. You can also apply tear replacement drops if you have any at home.
If your dog shows any of the following signs you should seek veterinary care immediately:
-Your dog is squinting or cannot keep its eye completely open.
-The area around the eye is painful.
-The cornea (clear part of the eye) is cloudy and you can not see the dog’s normal eye colour.
-The pupils are different in size.
-Your dog has suddenly gone blind.