A dog’s eyes can alert an owner to a possible illness. A yellowish discharge from an eye may mean a serious eye disease that requires treatment by a veterinarian.
Yellow, green or reddish eye discharge may indicate a variety of illnesses in a dog. As a general rule, the more discharge the eye produces, the more serious the condition, according to VetInfo.com.
A yellowish discharge usually indicates the presence of white blood cells in the form of pus. Pus frequently accompanies a bacterial or fungal infection.
Conjunctivitis, a common infection of the eyeball and eyelid tissues, can cause a dog’s eye to produce a yellowish discharge, according to PetPeoplesPlace.com.
Infections in or around the eye socket, including the sinus cavities and the back teeth, can manifest themselves as a discharge from the eye.
A veterinarian can perform a series of tests to determine the problem causing the eye discharge and prescribe medication, according to PetPlace.com. Owners should never use over-the-counter eyedrops meant for humans.