The conjunctiva of your dog's eye is the membrane that covers the inner surface of his eyelids. In a healthy dog, the conjunctiva should be about the same color as his gums. Where a bright red conjunctiva is a sign of inflammation, purplish or brownish coloration combined with swelling usually indicates bruising. Seek veterinary attention immediately if your dog's conjunctiva appear bruised. Your vet will evaluate your dog to determine whether it is caused by injury or underlying disease.
Bruising From Injury
Your veterinarian will be able to determine if the discoloration and swelling on your dog's conjunctiva is due to injury. Rough play with another dog is often the cause, as well as misjudging a turn when running figure eights in the backyard and running into something. Your vet will examine your dog's eyes for scratches on the eyeball itself as well as the lid and surrounding skin. He may prescribe drops or salves to promote healing of minor injuries.
The Big C
A group of cancers known as myeloproliferative disorders cause purplish bruises on the eyelids, but bruising is not usually limited to the eyes. The condition is often accompanied by lack of appetite, excessive thirst and lethargy. Vomiting and diarrhea and even seizures may be present. Your vet will check your dog for bruising in other parts of his body and conduct tests to determine whether myeloproliferative disease is present. This bone marrow disorder is a form of leukemia and may require chemotherapy, blood transfusions or drug therapy. If your dog has this, you can hope to have him around about a year, which is the average survival rate.
A Dreaded Disease
While typhus traditionally is associated with overcrowded kennels or poor hygiene, your dog can pick up the typhus bacteria on a hike or city park through fleas or ticks. The conjunctiva of the eye turns a muddy brown and your dog may have unusually foul breath odor and all-over shaking. Your dog may sit listlessly and stare into space. Immediate veterinary care is imperative as many dogs die within the first 24 hours. With treatment, only about 50 percent of dogs with typhus survive.
Sjögren-like syndrome can cause swollen, inflamed conjunctiva that may appear bruised due to a lack of adequate tear production. The condition is usually accompanied by ulcers in the mouth and inflamed gums. The chronic condition is an autoimmune disease that hits adult dogs, though the underlying cause is not known. Your vet will do a blood count, urinalysis and biochemical profile to determine if your dog has Sjögren-like syndrome. Treatment includes replacement tears, anti-inflammatory drugs, antibiotics and immunosuppressive treatment.