Should I be worried if my pet's eye has redness?
Redness of the eye can have many causes, and is not always a cause for alarm especially if the redness is transient. For example transient redness can simply be
caused by anxiety or excitement.
That being said redness or conjunctivitis can indicate something more serious such as glaucoma or uveitis {inflammation of the inside of the eye). Therefore any persistent redness (conjunctival hyperemia) should be investigated by a veterinarian. Because treatments and reasons for redness can vary, it is important to have a systematic approach to the eye.
Often conjunctival hyperemia will also include swelling of the conjuctival tissue and drainage from the eye. These patients need a complete opthalmic exam to identify the problem. This exam should include testing for "dry eye", staining of the corneal surface to look for ulceration, and tonometry to check the eye pressure for glaucoma.
By completing these tests the presence of concurrent corneal or intraoccular disease can be determined. Because the eye is delicate delaying treatment for these conditions could lead to permanent eye damage or blindness.
Further the eye can be effected by systemic diseases as well, and therefore a thorough physical exam should be completed on the patient. This exam may include blood work and testing for infectious diseases that might influence the eye.
If the patient has simple conjunctivitis, then the next step is to determine the cause. In dogs the condition is rarely caused by a bacterial infection; rather allergies and
environmental irritation are the more common etiologies.
In addition to allergies, there can be foreign particles that get trapped in the eye that need to be removed or flushed out of the eye. And rarely there can be growths associated with the conjuntiva or the third eyelid which should be sampled and biopsied.
Some patients will form small bubbles on the back side of the third eyelid called follicular conjunctivitis. This is usually from particle irritation and occurs in younger dogs. In these cases rinsing the eyes can be helpful as well as topical medication over the course of several weeks.
Some chronic conjunctivitis cases can be driven by allergies and may require long term eye meds. In these cases the use of cyclosporin is likely safer long term than drops
containing steroids. Interestingly these patients may only have involvement in one eye. If these patients have systemic allergies where the eyes are involved, often the treatment for the systemic allergies will keep the eyes under control at the same time.
In conclusion persistent red eyes should be evaluated by a veterinarian within 24-48 hours. There are many possible causes for eye redness, and thorough evaluation is always warranted to determine the correct diagnosis and treatment.