Laurie Anne Walden, DVM Photo by Alexandre Debiève on Unsplash Most dogs and cats cope very well with vision loss. They rely more on the sense of smell than on the sense of sight. Blind animals can have happy, comfortable lives with some help from their owners.
Pets with gradual vision loss often adapt so well that their owners don’t realize their pets are having trouble seeing until they’re completely blind and bumping into things. Animals with sudden blindness can take longer to adjust. Safety and Navigation Use gates and other barriers to block a blind animal’s access to stairs, swimming pools, fireplaces, and other dangers. Use foam cushioning (child safety equipment) to pad furniture corners. Keep the floor clear of trip hazards like toys and laundry. Keep blind animals in a crate or other secure space whenever they’re unsupervised, at least while they’re adjusting to their loss of vision. This space can also become a safe, familiar retreat. Blind animals can have a hard time navigating stairs, especially descending. Be patient and use a harness and treats to show blind dogs how to manage stairs. Consider covering short runs of steps with a ramp. Nonslip strips applied to stair treads might make a blind pet feel more secure. Dogs and cats that sleep on furniture might need a ramp or steps so they don’t have to jump up and down. To help blind pets learn their way around the house, don’t pick them up and carry them; let them walk on their own. Different floor surfaces (mats or rugs) can help them identify specific areas like doorways and the location of food and water bowls. A radio left on at all times in one room and scents applied to furniture at the pet’s head height can also help orient them inside the house. Face whiskers help animals feel obstacles, so don’t have their whiskers trimmed at grooming appointments. Vests with circular extensions around the head or chest (halo vests) are available for blind dogs who keep bumping into things. Exercise and Mental Health Blind animals need exercise just like every other animal, but they shouldn’t go outdoors unsupervised. Even a small fenced yard can have holes and fallen branches that would pose a risk to a blind pet. If you don’t have a fenced yard that’s safe and familiar to your dog, keep your dog on a leash. When walking your blind dog, attach the leash to a harness instead of a collar in case you need to pull your dog away from a hazard. Teach your dog verbal cues like “left,” “right,” and “stop.” An unexpected touch can frighten a blind dog, so warn people who approach that your dog is blind. Consider using a dog vest with the words “Blind dog” or “Do not pet.” Be very careful if another dog approaches while you’re walking your dog. A blind dog can’t read other dogs’ body language. If you let your dog interact with another dog, be sure that the other dog is friendly and that your dog is comfortable with the interaction. Provide toys that stimulate senses other than sight. Use toys with bells (with supervision—bells can be a choking hazard), catnip toys for cats, and tracking games for dogs who enjoy following scents. For some animals, playing contact games like tug of war might be easier than chasing toys by sound or scent. Some animals experience anxiety while they’re adjusting to vision loss. Keep your pet’s routine consistent, stay positive around your pet, and provide a safe retreat like a crate. Behavior changes like hiding, reluctance to walk or play, growling, barking, and snapping can all be signs of anxiety. Contact your veterinarian if your pet has any of these changes or seems to be having trouble adapting. Some pets benefit from short-term or long-term prescription anxiety medications. For more ideas, see the ACVO Vision for Animals Foundation website: https://www.visionforanimals.org/coping-with-a-blind-dog/ Image source: https://unsplash.com/photos/SEX4KAz9ExQ Laurie Anne Walden, DVM Photo by kowal854 on flickr The retina is a structure made of layers of photoreceptor cells and nerve cells at the back of the eye. The retina converts light into electrical signals that are sent to the brain to be interpreted as visual images.
Disorders of the retina cause vision loss. Whether the animal becomes completely and permanently blind depends on the cause. Inherited disorders, infection, inflammation, eye trauma, eye cancer, and metabolic diseases that affect the whole body can all cause retinal disorders. Progressive Retinal Atrophy Progressive retinal atrophy is the name for a group of inherited disorders that cause gradual blindness as the retina degenerates. Progressive retinal atrophy is most common in purebred dogs but also happens in cats and mixed-breed dogs. Some of the dog breeds at more risk than others are poodles, cocker spaniels, Labrador retrievers, golden retrievers, miniature schnauzers, dachshunds, Siberian huskies, mastiffs, and pugs. Depending on the genetic variation, progressive retinal atrophy can cause vision loss starting very young (in puppies) or later in life. Vision gradually deteriorates over time. Affected animals eventually become blind. Night blindness—loss of vision in low light—is the first sign in many animals. Because dogs and cats usually adapt well to vision loss, owners might not realize their pet’s vision has been affected unless they move the furniture or take their pet to an unfamiliar place. The condition isn’t painful and doesn’t affect the rest of the body, so animals with progressive retinal atrophy don’t feel unwell. Progressive retinal atrophy is diagnosed with an eye examination, usually by a veterinary ophthalmologist. Electroretinography, which measures electrical activity in the retina, is also sometimes used. DNA tests can identify genetic variations that put a dog at risk. No treatment for progressive retinal atrophy is available. However, because affected animals feel fine, they can continue to live normal lives with environmental management (to prevent falls from heights, for example). Some animals with progressive retinal atrophy also develop cataracts, but they aren’t good candidates for cataract surgery because they would still be blind after the surgery. Animals carrying genetic variations linked to progressive retinal atrophy shouldn’t be used for breeding. Retinal Detachment Retinal detachment is separation of layers of the retina from their normal position. The many possible causes include high blood pressure, eye trauma, infection, inflammation inside the eye, immune system problems, eye cancer, and inherited conditions of the retina. Depending on the cause, retinal detachment can affect one or both eyes and can cause gradual vision loss or sudden total blindness. If the cause is something that affects the whole body, the animal might have other signs of illness. Retinal detachment is diagnosed with an eye examination and sometimes ultrasonography of the eye. Other tests are needed to find the cause. Treatment for retinal detachment depends on the cause and whether the retina is only detached or is also torn. Medical treatment is aimed at whatever caused the retinal detachment. In some cases, the retina can be repaired surgically. The best chance for saving vision is by diagnosing and treating the detachment very soon after it occurs. Sudden Acquired Retinal Degeneration Syndrome Sudden acquired retinal degeneration syndrome (SARDS) causes sudden total blindness in dogs because of loss of function of the photoreceptor cells of the retina. The cause is not known. Dogs of any breed, including mixed-breed dogs, can be affected. Miniature schnauzers, dachshunds, pugs, and other small dogs seem to have SARDS more often than others, according to the American College of Veterinary Ophthalmologists. The average age of onset is 7 to 10 years. Along with vision loss, many patients with SARDS have decreased energy and increased appetite, thirst, and urine volume during the first few months. These signs are similar to those of hyperadrenocorticism (Cushing disease). However, no definite link to endocrine disorders like Cushing disease has been found. Ongoing research has suggested that SARDS might be caused by a neuroendocrine or autoimmune disorder, but these possibilities also haven’t been proven. SARDS is diagnosed by electroretinography showing no electrical activity in the retina. An eye examination won’t show any abnormalities at first. After some time has passed, a veterinary ophthalmologist might find retinal degeneration on examination. Because we don’t know how or why SARDS develops, it’s not possible to predict which dogs are at risk. There is also no treatment. Dogs with SARDS become fully blind but still have a good quality of life with some help from their owners to keep them safe. More Information To read more about eye disorders in animals, see the American College of Veterinary Ophthalmologists website: https://www.acvo.org/common-conditions1. Image source: https://www.flickr.com/photos/kowal854/49042126841/ Laurie Anne Walden, DVM Photo by M Burke on Unsplash The 3 main allergy categories in dogs and cats are allergies to environmental substances, fleas, and food. Food allergies are the least common, diagnosed in about 15% to 20% of dogs and cats with itchy skin and less than 1% of dogs and cats with any disease.[1] Many animals with allergies are allergic to multiple substances in different categories.
Causes An allergy develops after the immune system has become sensitized to the trigger substance. This means that food allergies take time to develop. Any food ingredient that a dog or cat has been eating for a while could potentially cause a food allergy. A new food that an animal just started eating wouldn’t cause allergy symptoms. The most commonly reported food allergy triggers are ingredients that are most common in dog and cat diets; examples are beef, chicken, dairy products, wheat, and fish. But anything an animal has eaten could theoretically be responsible, and studies have reported individual dogs and cats becoming allergic to foods as diverse as kidney bean, barley, and tomato.[2] Signs Itching is the most common sign of any type of allergy in dogs and cats. Itching caused by a food allergy is typically nonseasonal, but because animals with a food allergy can also be allergic to environmental substances, their itching might be worse at certain times of the year. Food allergies cause the same skin problems as other allergies. Repeated skin and ear infections are common. Food allergies can also cause digestive tract symptoms. These are some of the signs:
Diagnosis The only way to diagnose food allergy in dogs and cats is with an elimination diet trial. An elimination diet is formulated to eliminate all possible allergy triggers from the animal’s food. Food allergy is diagnosed if the allergy signs improve during the diet trial. Single-ingredient challenge trials are then used to pinpoint the trigger ingredients. An elimination diet trial usually lasts at least 8 weeks. During the trial, the animal can eat nothing except the elimination diet and approved treats: no flavored medications, table food, chew toys made from animal products, and so forth. Two types of prescription diets are used as elimination diets. Limited-ingredient diets have unusual protein and carbohydrate sources the pet is unlikely to have eaten before. Hydrolyzed protein diets have proteins broken down into molecular units too small to trigger an allergic response. Home-cooked elimination diets are appropriate for some pets and are best planned with the input of a veterinary dermatologist or nutritionist. Just changing the brand or flavor of dog or cat food doesn’t work to diagnose a food allergy. Commercial grain-free, raw, and boutique diets also don’t work as elimination diets. Nonprescription dog and cat diets usually contain some of the same ingredients (possible allergy triggers), might contain protein or carbohydrate sources not listed on the label, and can be cross-contaminated with other foods during manufacture. Veterinary dermatologists use skin tests to identify environmental substances that cause an allergic response, but skin tests can’t effectively identify food ingredients that trigger allergies. None of the blood and saliva tests that claim to diagnose food allergy have been found to be reliable. Treatment Animals with allergies are often allergic to multiple substances, so the more allergy triggers you can eliminate, the more comfortable they’ll be. For pets with food allergies, avoiding trigger ingredients reduces the allergic response. Elimination diets that are nutritionally complete can be fed long term as therapeutic diets. Some pet owners prefer to find a less expensive nonprescription diet that lacks their pet’s trigger ingredients. Effective flea prevention is especially important for animals with allergies to eliminate the possibility that a flea allergy is contributing to the itch. References 1. Olivry T, Mueller RS. Critically appraised topic on adverse food reactions of companion animals (3): prevalence of cutaneous adverse food reactions in dogs and cats. BMC Vet Res. 2016;13(1):51. doi:10.1186/s12917-017-0973-z 2. Mueller RS, Olivry T, Prélaud P. Critically appraised topic on adverse food reactions of companion animals (2): common food allergen sources in dogs and cats. BMC Vet Res. 2016;12:9. doi:10.1186/s12917-016-0633-8 Image source: https://unsplash.com/photos/l1UsjV2WrNM Laurie Anne Walden, DVM Photo by freddy dendoktoor on publicdomainpictures.net Glaucoma is caused by increased pressure inside the eye. It can be painful and often causes blindness even with treatment. Acute glaucoma is an emergency, so dogs and cats with any signs of eye discomfort or vision loss need to be examined by a veterinarian right away.
Causes Pressure inside the eye, or intraocular pressure, is controlled by a balance of fluid production and fluid drainage. In dogs and cats, glaucoma results from decreased fluid drainage. Fluid drains out of the eye mostly at the angle where the clear cornea and the colored iris meet inside the eye. This area, called the iridocorneal angle, contains a sieve-like network of tiny ligaments and tissues that regulate fluid flow. Anything that interferes with the iridocorneal angle can cause glaucoma. Primary vs secondary glaucoma Primary glaucoma is caused by an inherited problem with the structure or function of the iridocorneal angle. Some of the dog breeds at increased risk are cocker spaniels, beagles, basset hounds, Siberian huskies, and Samoyeds. Primary glaucoma is a progressive disease. Affected dogs need lifelong treatment, and the chance they will eventually become blind is high. Primary glaucoma is very rare in cats. Secondary glaucoma is caused by another eye disease (like uveitis, lens luxation, cataract, or cancer of the eye) that results in physical blockage of the iridocorneal angle. Acute vs chronic glaucoma Acute glaucoma is an increase in intraocular pressure for less than a day. Chronic glaucoma is an increase in intraocular pressure for longer than a day. The best chance for saving vision is to start treatment during the acute stage. However, the early signs of glaucoma can be subtle or mistaken for another eye problem, so glaucoma often isn’t diagnosed until it’s chronic. Signs Glaucoma causes the same signs of eye discomfort as other eye disorders. Animals with glaucoma can also have subtle behavior changes caused by eye pain. The signs usually start in only 1 eye but might not be noticed until chronic glaucoma has affected both eyes. These are some of the signs of glaucoma:
Diagnosis A high intraocular pressure measurement confirms the diagnosis of glaucoma. Devices used to measure intraocular pressure in animals are similar to those used in humans. Animals with glaucoma benefit from referral to a veterinary ophthalmologist to evaluate the iridocorneal angle and assess the risk of glaucoma in the other eye. Animals with secondary glaucoma usually need additional tests. Treatment Glaucoma is managed, not cured. The goals of treatment are to prevent pain, preserve vision as long as possible, and delay glaucoma onset in the other eye. Animals with acute glaucoma need emergency treatment to quickly reduce intraocular pressure, and they are typically hospitalized for intraocular pressure monitoring and pain management. Some patients need surgical treatment. Dogs with primary glaucoma need ongoing treatment with eye drops, oral medication, or both. Once an eye with glaucoma is irreversibly blind and painful, the kindest option is surgery to remove the eye. Animals tend to do well with this surgery and feel much better after the eye is removed. Prognosis For dogs with primary glaucoma, the long-term prognosis for vision is typically poor. However, early diagnosis and treatment can help these dogs stay comfortable and able to see for some time. Blind animals can have a very good quality of life with care and environmental management. If secondary glaucoma is identified and treated quickly and the cause can be eliminated, the prognosis for retaining vision is better than with primary glaucoma. Image source: https://www.publicdomainpictures.net/en/view-image.php?image=460143 Laurie Anne Walden, DVM Photo by Elisa Kennemer on Unsplash Warm weather brings some extra risks for pets. Some animals need protection from sunlight, and all animals need protection from hot temperatures.
Sun-Related Skin Conditions Ultraviolet (UV) radiation in sunlight causes skin damage in animals just like it does in humans. Fur and melanin (dark pigment) protect the skin from UV rays, so animals with short white hair or no hair are at higher risk than those with thick dark fur. Most animals with sun-related skin disease spend a lot of time outdoors, but even indoor cats can develop skin disease caused by UV rays coming through windows. Sun-related skin damage typically affects areas of the body that don’t have thick fur and are exposed to the sun. Any part of the body with thin or light-colored hair can be involved, but these are the most common areas:
Solar dermatitis, also called actinic dermatitis, is skin disease caused by exposure to UV radiation. It can be mistaken for allergic skin disease because the lesions are similar and it is often seasonal. Affected skin is red, painful to the touch, and scaly or flaky. Bumps and oozy lesions might develop. Over time, the skin becomes thickened and scarred. Because solar dermatitis usually causes a secondary skin infection, the lesions might improve with antibiotics, at least at first. UV radiation causes mutations within skin cells, so solar dermatitis can transform into skin cancer (squamous cell carcinoma or hemangiosarcoma, for example). These cancers are malignant: they can spread throughout the body. Solar dermatitis and skin cancer are diagnosed with skin biopsy. Heat Stroke Heat stroke is a life-threatening risk to animals during warm weather. Unlike solar dermatitis and skin cancer, it doesn’t require direct exposure to UV rays. The outdoor temperature doesn’t even have to be very hot for an animal to develop heat stroke. The temperature inside a parked car quickly rises higher than the outside temperature, so animals inside parked cars are at risk even in moderately warm weather. Brachycephalic (short-nosed) animals like pugs and bulldogs are at especially high risk. Signs of heat stroke include panting, dark red or purple gums, vomiting, collapse, and seizures. Heat stroke requires immediate first aid (cooling with water, not ice) and emergency veterinary care. For more information, see the blog post on heat stroke. How to Protect Your Pet The best way to protect animals is to minimize their exposure to UV rays and heat:
Sources
Image source: Elisa Kennemer on Unsplash Laurie Anne Walden, DVM Photo by Wall Boat on Flickr Uveitis is inflammation inside the eye. Some of the many conditions that cause uveitis affect the whole body, so a diagnosis of uveitis often triggers a series of tests to find the cause.
The uvea is a pigmented layer within the eye. The iris, which gives the eye its color, is the part of the uvea that you can see when you look at your pet’s eyes. The other structures of the uvea (ciliary body and choroid) are behind the iris, sandwiched between other layers of the eye. The uvea has a blood supply to deliver nutrients to the eye, so anything that can travel through blood vessels—like infectious organisms and cancer cells—can reach the uvea and cause uveitis. The uvea also produces and drains fluid within the eye. Inflammation of the uvea interferes with fluid balance inside the eye, so untreated uveitis can lead to glaucoma (increased eye pressure) and blindness. Causes Some of the things that cause uveitis are problems with the eye itself:
Problems outside the eye can also cause uveitis:
Signs Uveitis causes the same nonspecific signs of eye trouble (like redness) as nearly every other eye disorder. It can also cause changes that are more specific to inflammation inside the eye, like a change in iris color. Animals with uveitis sometimes have no obvious signs at all. These are some of the signs of uveitis:
Diagnosis Uveitis is diagnosed by examining the eye with an ophthalmoscope to look for signs of inflammatory debris inside the eye. The eye exam might be the only diagnostic test needed if it reveals an eye problem that’s causing the uveitis. If the animal doesn’t have an obvious eye abnormality causing the inflammation, the next step is to conduct diagnostic tests to find the cause. The animal will most likely have baseline blood tests, tests for various infectious organisms (especially viruses and the many organisms carried by fleas and ticks), and possibly x-ray imaging or ultrasound. The patient might need to be referred to a veterinary ophthalmologist. Treatment Uveitis is treated with medication to reduce inflammation. This medication is usually in the form of eye drops or eye ointment. Some animals need oral medication in addition to eye medication. The purpose of this anti-inflammatory medication is to relieve pain and reduce the risk of glaucoma. Whatever caused the uveitis also needs to be treated. The prognosis for uveitis depends on the cause. If uveitis is diagnosed quickly and the underlying cause is treatable, the prognosis is generally good. Some conditions that cause uveitis have a more guarded prognosis. Image source: Wall Boat on Flickr Laurie Anne Walden, DVM This French bulldog has narrowed nostrils and prominent facial skin folds. Photo by Dan Blackburn on Unsplash. The French bulldog is now the most popular dog in the United States, according to the American Kennel Club (which defines popularity by the number of purebred dog registrations). This result is no surprise; Frenchies have been rising in the popularity ranks for several years. But these little dogs have a host of potential health problems, just like other animals bred to have flat faces and short noses.
Brachycephalic Head Shape Short-headed (brachycephalic) animals like English bulldogs, French bulldogs, pugs, and Persian cats have a shortened upper jaw and nose. The lower jaw is typically not shortened, so when they close their mouths, their lower incisor teeth might stick out in front of the upper incisors. Brachycephaly affects only the bones, not the soft tissues (skin, tongue, soft palate, and so forth), so brachycephalic animals have too much soft tissue for their face size. This is why brachycephalic animals have skin folds between their nose and eyes. They have the skin to cover a nose that just isn’t there. Respiratory Problems In a brachycephalic animal, the soft tissues inside the mouth and throat are crammed into an upper jaw that’s too short to hold them. All of this excess tissue blocks the airway, causing a cascade of problems related to the increased effort of breathing. The term brachycephalic airway syndrome describes problems caused by anatomic abnormalities that are common in brachycephalic animals. These abnormalities include narrowed nostrils, an elongated soft palate, and everted laryngeal saccules (tissue near the vocal cords that is pulled into the airway because of labored breathing over time). Brachycephalic animals might also have an enlarged tongue. Some have an abnormally narrow trachea, which increases the work of breathing and the risk of problems during anesthesia. Other Problems Brachycephalic animals are more likely than others to have heat stress. Their relatively shallow eye sockets and large eyelid openings increase their chance of developing corneal ulcers, dry eye, and other eye problems. Infections can develop between skin folds. Some brachycephalic animals have digestive tract problems like chronic vomiting, possibly related to gastric reflux caused by chronic labored breathing. They usually have crowded or malpositioned teeth. Natural birth is not possible for some brachycephalic dogs because the mom’s pelvis is too narrow for the puppies’ heads. Some breeds—including French bulldogs—usually require cesarean (surgical) delivery. Signs If you have a brachycephalic pet, watch for these signs of trouble:
Treatment Anatomic problems like narrowed nostrils, elongated soft palate, and everted laryngeal saccules can be corrected with surgery. You can see photos of these problems and more information about surgery on the American College of Veterinary Surgeons website: https://www.acvs.org/small-animal/brachycephalic-syndrome. One “treatment” for brachycephalic airway syndrome is to stop breeding dogs for extreme face shape. If you’re thinking of getting a French bulldog or another brachycephalic pet, reward breeders who breed for good health: choose a dog with round (not slit-like) nostrils, minimal or no skin folds near the eyes, and the ability to run, play, and sleep while breathing freely without snorting or gagging. Image source: Dan Blackburn on Unsplash Laurie Anne Walden, DVM Photo by Hermes Rivera on Unsplash Eyelid problems are common in dogs and cats. Some eyelid disorders cause damage to the eyeball itself and can affect vision. A pet with eye redness, eye drainage, eyelid swelling, an eyelid lump that is new or changing, or signs of eye discomfort (squinting, pawing at the eyes, rubbing the face) should see a veterinarian.
Benign Masses In dogs, most eyelid masses are benign tear gland tumors called meibomian gland adenomas. These masses are located along the lid margin and typically look like raised, bumpy, pink or dark brown lumps. Other types of benign tumors also occur in dogs and cats. A chalazion is a firm lump caused by a blocked tear gland. This type of lump is near the lid margin under the skin, not right on the lid margin like a meibomian gland adenoma. Benign eyelid masses can irritate the cornea (the clear structure at the front of the eye) and can enlarge over time. These masses are usually removed surgically. Removing an eyelid mass means removing part of the eyelid, so it’s best to do the procedure while the mass is still small. Cancerous Masses Most eyelid masses in cats, and some in dogs, are malignant cancers. Many types of cancer affect the eyelids, just like the rest of the skin; some examples are squamous cell carcinoma, melanoma, and mast cell tumor. The only way to know for sure if an eyelid lump is benign or malignant is to send it to a laboratory for analysis. If an eyelid mass is large or located near the inner corner of the eye, referral to a veterinary ophthalmologist is often the best option in case the patient needs reconstructive eyelid surgery. Cherry Eye The term cherry eye is an informal name for prolapse of the gland of the third eyelid. The third eyelid (nictitating membrane) is a pink structure at the inner corner of dogs’ and cats’ eyes. In animals with cherry eye, a tear gland protrudes out of its normal location behind the third eyelid; it looks like a smooth pink or red lump. Cherry eye is treated by surgically replacing the gland in its normal position. The prolapsed gland shouldn’t be removed entirely because it produces tears. Removal of the gland would put the animal at risk of dry eye (keratoconjunctivitis sicca). Swollen Eyelids Eyelid swelling could be caused by an allergic reaction, a benign or cancerous mass, inflammation, or infection. Eyelid swelling due to an allergic reaction is sudden and often affects both eyes. Because eyelid swelling is sometimes the first sign of a more serious reaction called anaphylaxis, it always warrants a call or visit to a veterinary clinic. An animal that has swollen eyelids along with other concerning symptoms like vomiting or wheezing should be taken immediately to an emergency clinic. Entropion (Rolled-in Eyelids) In animals with entropion, one or more eyelids are rolled inward so eyelashes and hair rub on the cornea. Entropion can be genetic or breed associated, especially in animals with loose facial skin and animals that are brachycephalic (short faced). The condition can also be caused by scarring, other eyelid disorders, or excessive squinting from eye discomfort. The damage to the cornea is uncomfortable at best and can eventually impair vision. Entropion is corrected with surgery. Young animals with entropion can sometimes be treated with a simple tacking procedure to help the eyelids roll back out to the normal position as they grow. Abnormal Hairs Occasionally hairs similar to eyelashes grow in the wrong location, either along the eyelid margin (distichia) or inside the eyelid (ectopic cilia). These hairs can cause significant pain and corneal ulcers. They’re hard to see and are typically found only with magnification during an ophthalmic examination to find out why an animal has a corneal ulcer. If they’re causing discomfort, the hairs and their follicles need to be removed. Eyelid Inflammation Inflamed eyelids are red and swollen, sometimes with oozy discharge and visible sores along the margins. The hair on the eyelid might be thin or missing. Eyelid inflammation has many possible causes, including immune-mediated disease, parasites (like mange mites), bacterial or fungal infections, and irritants. Diagnosis might require skin scrapings, cultures, and biopsy. Treatment depends on the underlying cause. More Information You can see photos of some of these conditions on the American College of Veterinary Ophthalmologists website: https://www.acvo.org/common-conditions1 Image source: Hermes Rivera on Unsplash Laurie Anne Walden, DVM Photo by Jennifer Shishmanian on Unsplash Keratoconjunctivitis sicca (KCS), or dry eye, is common in dogs and can also affect cats. KCS is caused by a problem with the quantity or quality of the tear film. The condition is uncomfortable and can cause blindness. For most patients, KCS is managed with lifelong eye medication.
Causes Tears are produced by glands in the eyelids and third eyelid. The tear film contains water, mucus, and oil. Deficiencies in any of the components of the tear film compromise its functions: lubricating the cornea (the clear structure at the front of the eye), removing debris, and providing nutrition to the cornea. Anything that affects the tear-producing glands can cause KCS. Brachycephalic (flat-faced) animals with protruding eyes that aren’t completely covered by the eyelids also develop KCS symptoms because of excessive water evaporation from the surface of the cornea. These are some of the causes of KCS:
Signs Animals with KCS typically have thick, sticky eye discharge. The discharge is thick because the watery part of the tear film is decreased or absent, so the tear film that remains is made mostly of mucus and oil. Either 1 or both eyes are affected, depending on the cause of the KCS. Tear film deficiencies increase the risk for corneal ulcers, long-term damage to the cornea, and impaired healing of the cornea. These are signs of KCS and the resulting corneal damage:
Diagnosis The tear film quantity is measured with the Schirmer tear test, in which a sterile paper strip with measurement markings is placed inside the lower eyelid for 1 minute. The distance that the tear film is absorbed along the strip shows whether the animal has low tear production. Veterinary ophthalmologists use other tests to find out whether a patient has a problem with tear film quality. Treatment Animals with KCS are treated with a combination of eye medications, most of which need to be applied 2 or 3 times a day. Medications include tear stimulants that reduce immune-mediated inflammation, tear replacements to lubricate the eye, and other medications to treat corneal damage. KCS can be managed but not cured, so medical treatment needs to continue for the rest of the animal’s life. For animals whose KCS doesn’t respond to eye medication, a few surgical options are available. The most common of these is parotid duct transposition, which involves rerouting a salivary duct from the mouth to the inside of the lower eyelid so the animal basically drools onto the eye. This procedure is performed by a veterinary ophthalmologist. Image source: Jennifer Shishmanian on Unsplash Laurie Anne Walden, DVM Photo by Antonio Lapa on Unsplash The conjunctiva is a thin membrane that covers the insides of the eyelids and the white part of the eye. Inflammation of the conjunctiva, or conjunctivitis, makes the eye look red. Conjunctivitis is sometimes called pinkeye. This name is a bit misleading, though, because lots of other eye disorders—some very serious—also cause redness of the eye.
The conjunctiva is a mucous membrane, like the membranes lining the nose and mouth. It protects the eye, helps lubricate the surface of the eye with tears, aids in eye movement, and is part of the system that heals damage to the cornea. Causes Conjunctivitis has many possible causes in dogs and cats:
Signs Signs include eye redness, squinting, blinking more than usual, and eye discharge. The discharge can be watery and clear or it can be cloudy, yellow, or greenish. The tissues around the white of the eye and the insides of the lids might look puffy. The animal might rub or paw at the eye because of itching or discomfort. Diagnosis Conjunctivitis can’t be diagnosed just by the appearance of the eye. Redness and discharge are part of the eye’s response to any abnormality, so other problems need to be ruled out before conjunctivitis can be diagnosed. Diagnosis includes a general physical examination, an eye examination with an ophthalmoscope, and a corneal stain to identify ulcers or other damage to the cornea. Other tests include measuring tear production, measuring eye pressure (to rule out glaucoma), and sometimes swabbing or scraping the conjunctiva to obtain samples for laboratory analysis. Treatment Conjunctivitis is treated with topical medication (eye drops or eye ointment); oral medication is sometimes also used. The type of medication depends on the cause of the conjunctivitis. Antibiotics are usually part of the treatment, either to eliminate a primary bacterial infection or to prevent a secondary bacterial infection. Cats with known or suspected herpesvirus conjunctivitis sometimes need antiviral medication. Eye medications used to treat conjunctivitis often contain a steroid (such as dexamethasone or hydrocortisone) to reduce inflammation. However, steroids interfere with corneal healing, so before a steroid-containing medication is used, the cornea must be stained and examined with an ophthalmoscope to be sure there is no corneal ulcer or scratch. If your pet has eye medication from an earlier episode of conjunctivitis, don’t use it to treat a new episode of eye redness unless your veterinarian has instructed you to. And never use any over-the-counter (nonprescription) eye product in an animal without first consulting your veterinarian. Photo by Antonio Lapa on Unsplash |
AuthorLaurie Anne Walden, DVM Categories
All
Archives
August 2023
The contents of this blog are for information only and should not substitute for advice from a veterinarian who has examined the animal. All blog content is copyrighted by Mallard Creek Animal Hospital and may not be copied, reproduced, transmitted, or distributed without permission.
|
RSS Feed
|
Office Hours
Monday through Friday 7:30 am to 6:00 pm
|
|
Site powered by Weebly. Managed by IDEXX Laboratories