RUNNY EYES (EPIPHORA ) OR TEAR STAINING IN DOGS
Epiphora is a condition that causes an abnormal overflow of tears. Causes of epiphora due to the shape of the eyes is seen in many breeds. The overproduction of tears can be congenital due to distichiasis – turning in of the eyelashes, or entropion – the turning in of the eyelid. Young shelties, shih tzus, Lhasa apsos, cocker spaniels, pekingese, bulldogs, dachshunds, and miniature poodles are most commonly affected with distichia. Entropion is most commonly seen in some Chinese shar peis, pugs, mastiffs, poodles, Labrador retrievers and chow chows. The upper or lower lid may be affected. This condition may occur secondary to eye irritation.
Tear stains in dogs are a common problem, visible as reddish-brown marks around the dog’s eyes, most easily seen on dogs with white or light-coloured hair. They are usually the result of the dog producing too many tears or having an inability for the tears to drain away as normal. Watery ocular (eye) discharge is a common concern of pet owners. Excessive tears drain down the pet’s face and, in time, the chronic exposure to moisture produces skin irritation, infection, and odor. The fur becomes stained reddish brown due to tear pigments called porphyrins, an especially non-cosmetically appealing problem in white-furred pets. The medical term for this condition is epiphora and it is one of the most difficult conditions to resolve in all of veterinary ophthalmology.
What are tear stains in dogs?
Some dogs produce too much of a pigment-containing molecule that can be found in dog tears and cause the staining. When the dog’s body breaks down red blood cells, a naturally occurring molecule remains as a waste product. These molecules, known as porphyrins, contain iron, which is responsible for the red colouration, which gets darker when exposed to sunlight. Porphyrins are usually excreted via the digestive system but in dogs, they are also removed from the body in urine, saliva and tears. Darker coated dogs can also suffer from tear stains, but the marks are harder to see on the dark hair. It is a good idea to check your dog’s eyes regularly for any problems.
There are two causes of epiphora (excess tearing) in pets: irritation to the eye and abnormal tear drainage.
Irritation to the Eye
One of the eye’s natural responses to irritation is to produce more tears. This helps flush away any irritants that might have contaminated the eye surface. If excessive tearing is accompanied by squinting or pawing of the eye, or if the excessive tearing should occur suddenly, this should be taken as an obvious sign of eye pain and veterinary attention should be sought at once. Any accompanying loss of vision is also an emergency.
It is the more chronic cases that are harder to manage. Eyes can certainly become chronically irritated from viral conjunctivitis (probably the most common reason for excessive tearing in cats), from glaucoma (painful increase in eye pressure in the eye), from reaction to certain eye medications, or more commonly from eyelash or eyelid abnormalities.
Some breeds of dogs naturally have hair in their eyes and this does not cause irritation in most cases, but in some cases it can. Hairs can grow from the face at an angle so that they rub against the eye. Eyelashes can also grow at abnormal angles and rub on the eye. Eyelashes can even grow on the inner surface of the eyelids or corner of the eye and cause irritation. Often magnifying instruments are needed to discover these tiny hairs and delicate surgical procedures are needed to address them. Complicating the situation, however, is the fact that breeds that tend to have eyelid and eyelash problems also tend to be the same as those with faulty tear drainage anatomy (see below), which makes it hard to determine which of many possible causes is to blame.
Allergy, irritating dust or smog in the air, trauma, or infection can lead to excessive tears from conjunctivitis. These problems, indicated below, are treated medically.
- Corneal ulcer
- Feline upper respiratory infection
- Airborne allergy
- Brachycephalic breeds
Normal Tear Drainage
Once we are certain that there is no painful condition, we consider that the eye’s drainage ducts may not be normal. The normal eye is most efficient at draining tears. Looking at the inner corner of the eyelids (the side nearest the nose) one can see the pink, moist caruncle and on the eyelid margins upper and lower openings called nasolacrimal punctae. These are essentially drainage holes for tears. The punctae are the openings to small passages called canaliculi, which in turn open into the lacrimal sac. The lacrimal sac drains into the nasolacrimal duct, which drains tears into the nasal passages and throat. (This is why we get runny noses and sniffles when we cry, and why we can taste our tears when we cry.)There are many problems that can occur along this drainage route. One common problem, especially in poodles, bichon frises, and brachycephalic breeds, is simply that the eye socket is shallow. This means that tears overflow from the corner of the eye because the eyelid space there is not deep enough to contain them. These tears never make it to the punctae and instead spill down the sides of the nose. This condition cannot be repaired; it is simply the conformation of the dog’s face.
Alternatively, the eyelids may be turned inward (a condition called entropion) blocking the puncta and preventing drainage. Another problem may be long hair acting as a wick drawing tears from the eye to the skin, especially in breeds where hairs grow on the caruncle. This hair may be kept trimmed; though, if the hair is part of the nasal skin fold of a brachycephalic breed, surgery may be needed to remove or alter the skin fold.
Old infections or injuries may cause enough scarring to close the punctae, canaliculi, or nasolacrimal ducts. Sometimes a vigorous flushing of saline through the ducts, performed under general anesthesia, can re-open them. Sometimes the puncta are congenitally closed (common in poodles and cocker spaniels) and can be surgically re-opened.
It is fairly easy to determine if there is a problem with drainage in a non-invasive way that is sometimes called the Jones test. A stain for eyes called fluorescein is dropped onto the eye and if the tear drainage system is intact the dye should be evident at the nostrils after a couple of minutes.Surgery to reopen drainage is a procedure that not all veterinarians are comfortable performing. Discuss with your veterinarian whether referral to a specialist would be best for you and your pet. In this case, special equipment is needed.
Causes of Tearing in Dogs
Epiphora can be caused by numerous conditions. Some common causes of tear flow obstruction include:
- Congenital deformity resulting in failure of one or more of the drainage holes to be open (imperforate puncta). This condition is most common in the American cocker spaniel.
- Inefficient drainage of tears from partial closure of the drainage openings, increased kinking of the drainage duct in the nose, or wicking of tears onto hairs that sit in the crease where the eyelids meet. This combination of problems is common in certain breeds of dogs, such as the Maltese terrier, Bichon frise, miniature poodle, Pomeranian, American Eskimo and Shih tzu.
- Abnormally small tear duct openings
- Inflammation within or near the tear duct system
- Tear duct scarring after severe conjunctivitis
- A foreign body lodged within the tear duct . This is most common in outdoor, hunting-type dogs
Epiphora can also result when tear production increases due to irritation of the eye or stimulation of the tear glands. Common causes of epiphora in this group include:
- Hair rubbing on the eye from deformities of the eyelids, eyelashes growing in an abnormal location (distichiasis), or hair growing in a direction that bring it close to the eye (trichiasis)
- Inflammation of the eyelids themselves (blepharitis)
- Conjunctivitis
- Keratitis, or inflammation of the cornea
- Corneal ulcerations, abrasions, scratches, wounds
- Foreign body on the surface of the eye or exposure to irritants, such as smoke, chemicals, and soaps
- Glaucoma
- Anterior uveitis, or inflammation of the iris and ciliary body
- Irritation or stimulation of tear glands from topical eye medications
- Irritation from suture material around the eye from a recent surgery
- Infection or irritation around or under the eye or within the eye socket (orbit)
- Tearing with eating, which is a rare form of stimulation of the tear glands
Some of the above disorders cause both obstruction of tear flow and excessive tearing.
CAUSES OF TEAR STAINING
A common misconception about tear staining (Figure 1) is that it is due to excessive tear production. Most dogs with tear staining have normal tear production and do not have an underlying ocular problem. However, many dogs have a normal variation in their eyelid conformation that causes tears to drain onto their face rather than draining down the nasolacrimal puncta and into the nasolacrimal system.
There are three common variations in eyelid conformation that cause tearing onto the face rather than down the nasolacrimal system. They include:
- Tight medial canthal ligament:The medial canthal (palpebral) ligament is tighter in some dogs which causes the medial portion of the eyelids to slightly roll inward. This creates a partial, functionally obstructed nasolacrimal puncta which then causes tears to spill over onto the face.
- Haired lacrimal caruncle (Figure 2):The lacrimal caruncle is a triangular prominence in the medial canthus which normally has fine hair and a few sebaceous glands. Some dogs have longer hairs which then wicks tears onto the face bypassing the nasolacrimal puncta.
- Medial canthal troughing (Figure 2):Medial canthal troughing occurs when the skin at the medial canthus forms with a widened trough-like triangular area which funnels tears onto the face, again avoiding the nasolacrimal puncta.
TREATMENT OF TEAR STAINING IN DOGS
Some treatment options for dealing with tear staining in dogs include:
- Step one in treating tear staining is keeping the hair around the eyes and nose as short as possible.
- The next step is to keep the face clean and dry. A warm washcloth and baby shampoo are safe to use to clean around the eyes. There are many types of eyelid and eyelash cleaning pads that can also be used to clean the face and around the eyes. Contact lens solution can be used to clean around the eyes—not in the eyes! The boric acid in the contact lens solution oxidizes the iron in the porphyrins and may lighten the staining. After washing the face, always dry the area with a clean towel to prevent ulcerative dermatitis secondary to wet skin.
- Tylosin-containing products claim to treat or prevent tear staining. Tylosin’s effect is unpredictable and often has intermittent efficacy. Because tylosin is an antibiotic, there is controversy using it for cosmesis due to possible drug resistance. There is also controversy regarding tylosin’s addition to over the counter medications that do not always list it as an ingredient or identify how much tylosin is in the product.
- Many probiotic supplements claim to decrease tear staining as well.
Compiled & Shared by- Team, LITD (Livestock Institute of Training & Development)
Image-Courtesy-Google
Reference-On Request.
