Dry Eye in Dogs (Sicca Syndrome)

Dry eye syndrome in dogs is a form of inflammation of the eye or inflammation of the cornea (a transparent structure of the eye that allows vision) and surrounding tissue. It is a condition that is referred to as KCS (keratoconjunctivitis sicca). This syndrome is also known just as “sicca”. The main consequence of dry eyes is a reduction of tear film production. The sicca syndrome is curable. The chances to prevent the onset of this disease are good if prevention measures are properly implemented. If your dogs’ race is known to be prone to dry eye and you want to prevent it, you can skip to the “Dry Eye in Dogs Prevention” section. But if your dog has already signs of dry eye, please read this article very carefully and don’t worry, at the end of the article you will know what you should do to help your dog.

Causes of Dry Eye in Dogs

Tears are created in the glands of the eye. There are two lacrimal glands and the gland of the third eyelid. Tears moisturize the eye and flush out harmful agents that act irritatingly or infectiously from a concave part of the eye called the conjunctival sac. Also, tears use proteins that have antibacterial action to protect the eye.¹Hunter T., Ward E. Keratoconjunctivitis Sicca (KCS) or Dry Eye in Dogs. VCA Hospitals. Retrieved 25 July 2020. Any lack of tears makes the conjunctiva damaged and dry, and it becomes an ideal medium for the development of bacterial, viral, and fungal infections.

Causes of dry eye in dogs can be hereditary, but usually, they are caused by infections of the lacrimal duct or eye by bacteria, viruses, or fungi. Some of the causes of keratoconjunctivitis in dogs can be deficiencies of certain components of tears, and it also can happen that the dog was born with an eye defect, which leads to reduced tear production.

Various types of trauma to the lacrimal gland or duct can also lead to a blockage of the lacrimal duct. A common cause of KCS is an autoimmune reaction of the lacrimal gland, and racial predisposition, which occurs most commonly in Pugs and Yorkshire Terriers.

Other types of dry eye disease in dogs are associated with nervous symptoms, hormonal disorders in the form of decreased thyroid function, and systemic diseases.²Hunter T., Ward E. Keratoconjunctivitis Sicca (KCS) or Dry Eye in Dogs. VCA Hospitals. Retrieved 25 July 2020. General anesthesia and chronic flow of conjunctivitis can also lead to the emergence of dry eye.

Symptoms of Dry Eye in Dogs

Most common symptoms that occur in dry dog eyes are the following:

• Sore, red, itchy and irritated eyes
• Excessive blinking and clicking
• Eyelid twitching
• Discharge of yellow mucus, pus, or liquid leaking from the eye
• Discomfort
• Hypersensitivity to light
• Impaired vision
• Keeping the eyes closed
• Protrusion of the third eyelid (“cherry eye”)
• Rubbing of the eyes
• Whining

If a chronic form of the disease develops, then the following symptoms occur:

• Swollen, inflamed eyelids
• Thick, yellow discharge
• Recurrent eye injuries
• Ulcers
• Dark pigment and prominent blood vessels on the surface of the eyes
• Reduced or loss of vision that results from scars on the cornea
• Dull eyes and dull appearance

If not treated on time, dogs can develop corneal scars that lead to its coloration to a brown color called corneal hyperpigmentation. Simultaneously, small blood vessels appear through the cornea (an effect called neovascularization), which can make it unpleasant to look into your dog’s eyes. In severe cases of neglect and untimely treatment, vision loss can occur.

Types of Dry Eye in Dogs

Dry keratoconjunctivitis in dogs is divided into types that are actually named after the cause of the KCS: immune-mediated KCS, bacterial, viral, and fungal KCS, KCS caused by systemic diseases, and KCS caused by drugs.

Immune-Mediated KCS

The autoimmune type of dry eye disease in dogs is an inherited disease. What happens is that the body’s immune system reduces tear production by attacking its own cells that produce part of the tear film. Those cells are cells of lacrimal glands (tear-producing glands).

In dogs, immunogenic keratoconjunctivitis is also called Uberreiter’s keratitis. Keratitis literally means inflammation of the cornea. Keratosis is a light to dark brown coloration of the cornea that results from the aforementioned inflammatory condition. This is caused by the accumulation of squamous cells (thin, flat cells that make up the composition of the epidermis).

Uberreiter’s keratoconjunctivitis or syndrome is a chronic disease of unclear etiology. It is assumed that the cause is the influence of solar radiation. This type of conjunctivitis is progressive but can be kept under control. The dog rarely goes blind, and the changes that take place in the eye are milder in older dogs, while they are more severe in younger ones. It is treated with local and subconjunctival corticosteroids.

Bacterial, Viral and Fungal KCS

Bacterial causes of conjunctivitis are staphylococci, pneumococci and streptococci. Staphylococcus aureus is a gram-positive bacterium that is found in dogs under normal conditions on the surface of the skin. Staphylococci usually cause local infections on the skin and can spread through the blood or lymph throughout the body. Staphylococci are known to cause infections of the mucous membranes, including the mucous membranes of the conjunctiva.

Minor traumas and injuries on the surface of the mucous membrane or skin are an ideal medium for the entry of pathogens or bacteria into the body. A factor that contributes to this is certainly the weakened immune system, which leads to the reduced ability of the organism to defend itself naturally against pathogens.

The virus that most often causes KCS is canine distemper virus. It leads to a systemic response of the organism; thus, this KCS also belongs to keratoconjunctivitis caused by systemic diseases.

Fungal diseases of the ear are the cause of otitis media, and they are most often associated with the comparative or consequent development of keratoconjunctivitis caused by fungi in dogs.

KCS Caused by Systemic Diseases

KCS can occur as a result of some changes in the work of glands in the body and thus the secretion of hormones. Decreased thyroid function (hypothyroidism) leads to reduced secretion of its hormones, and improper functioning of the pancreas leads to an increase in blood sugar levels which can lead to diabetes. Diabetes causes dehydration and dry eyes.

A disease called Cushing’s disease is caused by a malfunctioning pituitary gland (the main gland in the body which regulates the work of all other glands) that secretes too many hormones into the blood. This way, the pituitary gland disrupts the normal function of all other glands, including the lacrimal glands. This reduces tear production and leads to a dry eye condition.

Nervous system diseases and chronic middle ear infections are also systemic diseases that lead to keratoconjunctivitis. One such nervous disease occurs when the facial nerve, which innervates the tear glands to produce tears, is damaged, where they stop producing tears and dry out the eye.

Certain congenital diseases (diseases that are noticeable after the birth of a dog) can lead to the development of KCS, and these are reduced lacrimal glands or their complete absence. Also, prolapse and removal of the gland of the third eyelid, or a disease known as “cherry eye,” can cause keratoconjunctivitis.

KCS Caused by Drugs

Keratoconjunctivitis can be caused by the use of certain drugs. These include sulfonamides, topical anesthetics, and aspirin. It is known that generalized anesthesia can also lead to dry eye in dogs. During operations that require generalized anesthesia, carnivores (meat-eating animals; the term predominantly refers to dogs and cats when talking about pets) tend to dry out the surface of the eye, so it is necessary to occasionally instill eye drops if the operation is long-term. If this is not done over time, dry eye can develop in dogs. Therapeutic radiation has a very similar effect, especially if it is long-lasting and if it is applied close to the eye.³Dry Eye (Keratoconjunctivitis sicca. The American College of Veterinary Ophthalmologists. Retrieved 21 July 2020.

Dog Breeds That Are More Likely to Develop Dry Eye

About 5% of all dogs in the world have the possibility of getting some kind of dry eye during their lifetime. Middle-age to older dogs are most commonly affected by KCS. Brachycephalic dogs or those with a shortened hard palate are more predisposed to the formation of “dry eye”. Most of the changes that occur on the nose are also manifested on the eyes, and especially in dogs in which these passages are shortened and these cavities are in close contact. Therefore, the order was determined starting from breeds of dogs with shorter to longer hard palates: 

• English Bulldog
• English Springer Spaniel
• American Cocker Spaniel
• Cavalier King Charles Spaniel
• Boston Terrier
• West Highland White Terrier
• Yorkshire Terrier
• Shih Tzu
• Pekingese
• Doberman Pinscher
• German Shepherd
• Samoyed
• Bloodhound
• Pug
• Chihuahua
• Lhasa Apso
• Miniature Schnauzer

Although these breeds are more at risk of developing dry eye syndrome than others, it can also occur in other breeds, but they do not have a genetic predisposition, so they are less susceptible to the development of this disease.

Diagnosis of Dry Eye in Dogs

The diagnosis is made based on anamnesis, clinical signs, and visual inspection of the eye. An additional diagnostic method can be the measurement of eye pressure, which is very important to check for the presence of glaucoma. This is important because glaucoma gives very similar symptoms to keratoconjunctivitis. If the intraocular pressure is increased, further methods are performed to differentially diagnose whether it is glaucoma or KCS.

The severity of the condition can be determined using the Schirmer Tear Test (STT). The test is performed in such a way that a piece of special paper touches the lower lid on the outer corner of the eye. The paper is left to absorb eye moisture for 60 seconds. In fact, what the test assesses is the quantitative ability of the eye to moisten, and it is read by examining the length of the moistened paper.

If the length is less than 10 mm, the dog is diagnosed with keratoconjunctivitis, and if the length is less than 5 mm, the condition is considered severe. A dog or its tear glands are considered healthy if the length of the moistened paper is greater than 15 mm.⁴Dry Eye in Dogs. Wagwalking. Retrieved 21 July 2020.

As a consequence of various traumas, but also in the chronic course of KCS, ulcers can appear on the surface of the cornea. A fluorescein eye test in dogs is used to detect and confirm keratoconjunctivitis quickly. The cornea is stained with a fluorescent dye and then observed in the dark under UV light to spot areas of the eye that fluoresce, and these are actually abrasive or ulcerative areas.

In cases where we know that it is an immune-mediated keratoconjunctivitis, the choice of tissue that the organism will attack is completely random. In cases where there is eye trauma, the vet performs a visual examination to discover whether the dog was injured during the game or the attack. In cases like this, it can happen that the trauma heals on its own, but the swelling caused as part of the inflammatory response of the organism should be resolved by appropriate measures. When infection with various agents is suspected, a mucosal swab is sent to the laboratory for processing.

Conjunctivitis is a local disease, but it can occur as one of the symptoms of a general infection, so it’s necessary to perform a systemic examination of the dog.

Dry Eyes in Dogs Treatment

There are many ways and methods to treat keratoconjunctivitis in dogs, but the most common is drug treatment. Of the drugs, antibiotic drops and topical corticosteroids in the form of steroid eye drops are most commonly used, but they have a number of side effects. Cyclosporines are the best choice in the treatment of keratoconjunctivitis in dogs in whom the disease has taken hold and in whom alternative therapies have not helped.

Among others, the drug Optimmune has shown great success in treating dry eye in dogs. Artificial tears can also be used in dry eye therapy, and they give good relief, but the only problem is that they need to be used about 4-6 times a day.

In immune-mediated forms of KCS, immunosuppressants are prescribed to the dog. However, they must not be used during the period when the infection is active. The healing rate of dogs in the case of a combination of these two types of drugs is 80%.

In fungal-induced keratoconjunctivitis, antifungals are used in therapy. Acupuncture also can be used as one of the methods of treatment because it can help to decrease the irritation of the eye and to reduce inflammation and pain.

Keratoconjunctivitis can also be treated surgically, to transpose the parotid canal so the eye gets constantly hydrated. By irritating the eye, the cornea becomes dark, which reduces the dog’s field of vision. This crescent-shaped, dark part of the cornea can be removed by surgical method. This changes the refraction of the cornea. The wound is then sutured and allowed to heal. The method is called superficial keratectomy. However, this method is used in rare cases.

Another surgical procedure, which is also rarely performed, is repositioning of the salivary duct so that it secretes saliva on the eyes. This treatment is used only if no other has succeeded, because there is a complication of excessive secretion of saliva on the eye during chewing food.

Dry Eye in Dogs Natural Remedies

The most wishful solution to this disease is to cure it by alternative methods at home, but this doesn’t always work so in the end we still have to ask for veterinary help. Don’t rely fully on alternative methods if the symptoms get worse.

One of the best natural remedies is fish oil, which is also sold in the form of capsules.

Capsules are used once a day, one capsule covering all daily needs for vitamins D3 and A. Vitamin D3 is good for preserving bones and teeth, and vitamin A preserves vision and supports the normal functioning of the heart and brain. Fish oil is rich in essential oils and in omega-3 and omega-6 fatty acids. Retinal circulation contributes to eye diseases, and the use of vitamin D prevents their onset. Also, the use of omega fatty acids in the diet can reduce the risk of DNA damage, preventing the development of hereditary diseases.

Dry Eye in Dogs Medication

The most commonly used drugs in dogs in the treatment of keratoconjunctivitis are Optimmune (Atopica) and Tacrolimus. Optimmune is one of the cyclosporines that are very effective in the treatment of ophthalmic diseases. Cyclosporine is produced in the form of eye drops and ointments. Cyclosporine eye ointment does not produce systemic and toxic reactions when used in dogs, because a very small part of the drug is reabsorbed into the body through systemic circulation. It’s effective in about 80% of cases of dogs with KCS. It is often recommended as a treatment choice for KCS because it has a lower rate of systemic side effects compared to corticosteroids used topically on the eye.

However, care should be taken when using this medicine in dogs weighing less than 2 kg and under 6 months of age, and in female dogs in pregnancy and lactating because the safety of cyclosporine has not been studied in these animals. In cases of keratoconjunctivitis caused by bacterial agents, local antibiotics and anti-inflammatory drugs are used, while in the treatment of neurogenic KCS, Pilocarpine (Isopto-Carpine®) has been used successfully.

Tacrolimus is a relatively new drug used to treat dry eye in dogs and cats. It is very similar to Optimmune, because both of these medicines are used to stimulate tear production. Tacrolimus is produced in the form of ointment or liquid preparation, and it is recommended to use it twice a day. Tacrolimus is more commonly used in chronic cases of dry eye because it has shown greater efficacy than cyclosporine in this case.

Optimmune Eye Ointment for Dogs

Optimmune (cyclosporine) is used in dogs for the treatment of keratoconjunctivitis and chronic superficial keratitis. Cyclosporine belongs to a group of medicines that have an immunosuppressive effect. Optimmune leads to increased tear production and reduces local inflammation of the eyes, cornea, and lacrimal glands. It should be applied to the affected dog about two to three times a day, depending on the severity of the case.

The recommended duration of treatment is 3-8 weeks. Treatment should not be discontinued; if it is, the clinical signs will return quickly. In very rare cases, the recommended treatment is for life due to the severity of the case. Then, cyclosporine is used 1-2 times a day.

Because Optimmune has a suppressive effect on the immune system, its prolonged use can result in various bacterial or fungal infections.

In case of viral or fungal eye infection, it is contraindicated to use the preparation. Therefore, it is necessary to bring the dog for regular check-ups. Also, Optimmune should not be used if there are ulcers (deep wounds) present on the cornea of ​​the eye.

Dry Eye in Dog Supplements

Dietary supplements can prevent a large number of eye diseases in dogs. The most commonly used in the diet of dogs preventively, or even after the onset of KCS, are vitamins A, C, D and E. A complex of vitamin B that raises immunity is also very important, but its intake must be controlled as it can lead to excessive weight gain. Beta-carotene and zinc are best used with those vitamins in diet for better sight. Liver oil, which is rich in omega-3 fatty acids, can also be used in a supplementary diet because it improves eye’s oil film.

It is also important to mention the Eyebright plant, known as Euphrasia rostkoviana.⁵Stoss M., Michels C., Peter E., Beutke R., Gorter R.W. The Journal of Alternative and Complementary Medicine. Dec 2000.499-508.http://doi.org/10.1089/acm.2000.6.499 This plant is used for rinsing the eyes, in treatment for conjunctivitis and in dog nutrition by mixing it with food.

Eyebright is an herb that has been used by Europeans for centuries to deal with irritation and redness of the eyes. It has been shown to be an excellent source of the tannins that have anti-inflammatory effects, and flavonoids luteolin and quercetin, which inhibit or prevent the work of immune system cells called mast cells. Otherwise, these cells release histamine, which is responsible for the symptoms of allergic conditions.

Euphrasia can be found in stores that specialize in herbal products in the form of compressed and found sprays, and the dried plant can also be easily prepared in the form of these products and in the form of tea. Two to 3 grams of dried parts of the plant are used to prepare tea. When using a dried plant for the preparation of nasal spray, it should not be grown with harmful pesticides. You can also buy the final product online.

In any case, the recommended daily dose of any of these preparations is 1-5 times a day, at best three times a day. Eyebright plants can be used preventively, in addition to therapy after dry keratitis.

Research on the benefits of this plant in the treatment of eye diseases has been done on humans. In combination with chamomile, eyebright protects the cornea from harmful effects of the sun’s rays and inflammation. In combination with rose, produced in the form of fat in a tube, this plant eliminates the symptoms of allergies, swelling, redness and mucoid liquid from the eye.

Also, beef liver, either raw or cooked, can be used in dog food; it is rich in vitamins A and B6, which are great in preserving eyesight. Supplements containing calcium and minerals can also be used.

Diet for Helping Dry Eye in Dogs

For a diet that will have a very favorable effect on the condition of your dog’s eyes, various herbal preparations can be introduced, as well as the meat of certain animals. Animal products that are rich in vitamins vital for improving eyesight include beef liver, beef heart, eggs (not more than one a day), sardines, salmon and tuna.

As for fruits and vegetables, pears, carrots, kale, parsley, spinach, and peas may be used (not in large quantities because they swell, like most legumes). Dried fruits, such as prunes, apricots, and peaches, and 2 teaspoons of almonds daily can be given to your pet, but not in large quantities, because dried fruits contain a lot of sugar. It is necessary to add to this diet preparations that contain calcium and minerals.

Dry Eye in Dogs Prevention

Selective breeding can reduce the occurrence of keratoconjunctivitis. However, this is not a sufficient guarantee that it will not happen because the cause is not only a racial genetic predisposition but also various traumas, inadequate diet, weakened immunity, external influences (mechanical and the influence of the sun’s rays).

Adequate prevention can be carried out by bringing dogs to check-ups regularly, to maintain ear and eye hygiene. A diet rich in nutrients and omega fatty acids boosts immunity and preserves vision so it is very significant. By keeping the dog’s immunity at a high level, we enable his body to fight various types of systemic diseases that can occur.

By introducing supplements into the pet’s daily diet, we enable him to fulfill all the needs of his body for vitamins, minerals and amino acids on a daily basis, which are vital in the body’s defense against inflammation.

Conclusion

There is a large number of over-the-counter medications nowadays that are available to successfully prevent the onset of KCS disease. These medications should ensure the maintenance of hygiene and moisture in the eyes of dogs. However, dogs diagnosed with KCS must be monitored for life and have adequate medical care. It is very important that the dry eye is diagnosed as soon as possible so a timely response can be made.

If your dog has a shortened hard palate, is middle-aged or older, or belongs to the group of dogs that are more likely to develop the dry keratoconjunctivitis listed in “Dog Breeds That Are More Likely to Develop Dry Eye“, you should know that supplement therapy is the best treatment choice to begin with. A wide range of commercial vitamins that can be bought without a prescription, liver oil, as well as meat and vegetables that are rich in vitamins and minerals that affect the improvement of the dog’s vision should definitely be included in the dog’s daily diet. Supplementary diet, in addition to having many benefits in the prevention of keratoconjunctivitis, has a positive effect on the immune system itself, strengthening the dog’s organism and preparing it to be as resistant as possible in case of any disease.

For chronic cases, there is a very small degree of healing, i.e., the therapy must be carried out for life. The scar tissue that is created completely disappears, and until then, the lost vision cannot be restored, which means that the processes that take place during this disease are irreversible (normal state and functions cannot be restored). Scars resulting from ulcers on the surface of the eye can result in blindness if left untreated.

The disease cannot even be completely eradicated by selection in mating dogs, because it does not occur only as a consequence of a hereditary factor. The best way of treating is prevention using supplements and an adequate diet.

Frequently asked questions (FAQs) about dry eye in dogs