Narrow tear ducts are uncommon in cats, but in the short-nosed breeds the problem is seen more often and can lead to them becoming completely clogged with dirt. There are several causes of clogged tear ducts and the treatment varies by cause.
The tear duct acts as the eye’s drainage system and removes the flow via an opening in the lower and an opening in the upper eyelid. Both openings are in the inner corner of the eye. The flow is then passed on via the tear duct down into a mouth in the nose.
Cats can be born with tear ducts that are not normally developed, either because there is no proper passage for the flow from the eyes, the entrance port from the eye to the tear duct is underdeveloped or because the design of the eyelids causes the tear duct to squeeze. In addition, an eye infection can cause a blockage in the tear duct (dacryocystitis).
Infection with the herpes virus sometimes causes scarring that closes the tear duct. Cat fights can also damage the tear duct.
Blunt-nosed (brachycephala) breeds such as Persians and exotics are most often affected due to the anatomy of the head, nose, jaw and nose.
The symptoms of narrow or blocked tear ducts are increased flow from the edge of the eye, usually from the inner corner of the eye. Typically, reddish-brown discolorations and moist fur are seen under the eye, closest to the bridge of the nose. Often the cat is not affected, but irritation, itching, bad smell and infection can occur in the area, which requires action.
One should be aware that, increased flow from the eyes is not necessarily due to the tear duct but can also be caused by a heavy production of tear fluid, the tear duct then becomes overfilled. This can occur, for example, in connection with irritation of the cornea and then requires immediate treatment. Therefore, the cause of the flow should always be investigated.
Using a slit lamp, the veterinarian assesses whether the cat has normal anatomy and physiology and around and in the eye. It is also examined whether the eye has a normal production of tear fluid. In addition, the vet often stains the cat’s eye (Jones Test) with a dye called fluorescein. This makes it possible to assess the flow of the tear duct as the colored liquid passes through the nostril. At the same time, any damage to the cornea of the eye can be detected. In brachycephalic cats, the dye is sometimes seen to pass through the pharynx instead. In some cases, the veterinarian takes a sample to check if the cat has the herpes virus. Read more about herpes virus in cats here.
In the event of reduced or no flow through the tear duct, the cause is always treated first and foremost. It may be necessary to stun the cat and try to flush through the tear duct. Then you can also judge
if the blockage is permanent due to a congenital defect or scar tissue after injury. If there is a passage, try to clean up as much as possible. In case of infection, it is possible to treat with cortisone and antibiotics locally in the canal, as well as eye drops for several weeks. Sometimes this procedure must be repeated. In some anatomical defects, surgery may be considered.
The prognosis depends on the cause of the problem, but in general the problem may be recurrent.