Canine Diseases

Cataracts

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Cataracts are opacities in the lens of the eye. Many people mistakenly think the cloudiness is on the surface (thought to be a "film" on the eye), but in fact, the cloudy lens is deep inside your pet's eye. Most cataracts are inherited, and are found in many breeds such as the Cocker Spaniel, Poodle, Husky, Schnauzer, Golden and Labrador Retrievers, and terriers. Other causes of cataracts include: diabetes, trauma, inflammation, and puppy milk replacers. Many cataracts will worsen to the point of blindness but certain types, especially in the Retriever breeds, can remain small for the entire life of the patient.

A common phenomenon occurs in many developing cataracts where the patient can develop an allergic-type reaction to the cataract. This allergic reaction is a LOCAL reaction and can result in many complications such as scar formation, glaucoma and permanent blindness.

Cataracts may be treated either medically or surgically. Tests can be performed to determine if the surgical removal of the cataracts will improve his or her vision. In certain cases, cataract surgery is not recommended or the owner decides not to pursue surgery. In these cases, medical treatment of the cataracts is recommended. Because of the possible complications associated with cataracts, it is important to treat cataracts whether or not surgery is performed. These treatments usually include a topical anti-inflammatory once or twice daily. Sometimes a drop that dilates the pupil and allows more light into the eye is used to help your pet see better around the cataracts.

Cataract Information PDF

Eye Cancers

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The eye can be involved in developing cancerous growths or tumors both benign and malignant. These growths can be limited to the eye or be an early sign of tumors developing elsewhere in the body. If unchecked, the can lead to blindness, glaucoma, or even spread to other parts of the body.

Glaucoma

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Glaucoma is the elevation of pressure inside the eye (intraocular pressure) beyond a specific point at which vision is no longer possible. Glaucoma is a frequent cause of blindness in humans and in our pets. To understand glaucoma, it is necessary to understand how the fluid inside the eye normally flows and maintains normal intraocular pressure. Fluid inside the eye (aqueous humor) is produced behind the colored area of the eye (iris) in a portion of the eye called the ciliary body. This aqueous humor is made by filtering blood. The fluid flows through the dark hole in the eye (pupil). Finally the aqueous humor drains from the eye at the junction of the clear cornea and the colored iris (drainage angle) inside the eye and then the aqueous rejoins the blood. The drainage angle is a sieve-like network. This aqueous humor is made inside the eye and passes from the eye at the same rate. This results in a stable intraocular pressure of 15-20mm of Hg. Glaucoma is the consequence of a blockage of the outflow of aqueous humor and a subsequent build-up of pressure inside the eye. The resulting high pressure compresses the optic nerve and results in loss of vision and pain with enlargement of the eye.

Many of us have friends or relatives who have glaucoma. They simply place drops in their eyes several times a day and have very few problems that result in vision loss. In some people medication will not resolve the glaucoma and surgery is necessary. This is what we face in animals all the time and this is what makes glaucoma very difficult to treat in domestic animals. After the initial diagnosis of glaucoma is made, your pet may need aggressive treatment with medication if there is any hope of saving vision.

Glaucoma PDF

KCS

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Keratoconjunctivitis sicca (KCS) or "dry eye" describes the changes in the eye which result from lack of tear production. The eyes of a patient with KCS sting constantly just as ours do on a very windy day. The stinging we feel is due to the wind drying our eyes quicker than tears can be provided. Therefore, the patient with dry eye is uncomfortable almost all the time. When a patient has "dry eye" where there is a lack of the watery layer of the tears, the oil and mucus layers are increased. This leads to a thick, mucoid, greenish discharge that sticks to the hairs around the eye. Often this is the main reason that a patient is presented to the veterinarian. The discharge will clear up when medication is used but will return when the medication is stopped. When this occurs, the patient is often referred to a veterinary ophthalmologist for further examination and treatment. Without treatment, KCS can lead to blindness. Most patients with dry eye will do well if proper medications are administered on a timely basis. No patient needs to lose eyesight due to the dry eye condition.

KCS PDF

Third Eyelid Prolapse (Cherry Eye)

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Prolapse of the gland of the third eyelid or "cherry eye" is the most common primary disorder of the third eyelid. It is thought to result from weakness in connective tissue attachments, allowing the gland to flip up and protrude above the leading edge of the third eyelid where it becomes enlarged and inflamed from chronic exposure. Prolapse can occur in either one or both eyes and generally occurs before 2 years of age. This process is common in American Cocker Spaniels, Lhasa Apsos, Pekingese, Beagles and English Bulldogs. If uncorrected, chronic inflammation and ocular discharge occur. For several decades, surgery to remove the prolapsed portion of the gland was considered to be the treatment of choice; however, as the importance of the gland in tear production has become apparent, surgical repositioning of the gland has become highly recommended. It should not be assumed that retention of the guarantees that dry eye (KCS) will not develop, especially considering that many of the breeds that commonly develop "cherry eye" are also predisposed to "dry eye" (KCS).

Feline Diseases

Corneal Ulcers/Sequestrum

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Corneal ulceration is present when there is a break in the corneal epithelium that exposes the underlying corneal layers (stroma). Your pet may experience increased tearing, squinting, sensitivity to light, red eye, cloudy cornea and possibly intraocular inflammation (uveitis). The diagnosis is made on the basis of these clinical signs and retention of a topically applied fluorescein dye. The first step in treating all ulcers involves searching for and removing the underlying cause which may be eyelid abnormalities, foreign bodies, repeated trauma, dry eye or FHV-1 infection. Infected or progressive ulcers should undergo bacterial and fungal cultures as well as cytologic examination to help guide specific therapy.

Corneal sequestration is a common disorder in the cat, particularly in the Persian and Himalayan breeds. Sequestra may occur after chronic corneal ulceration or chronic irritation. This condition is characterized by a brown to black discoloration varying in size from 1-2 mm to occupying more than half of the cornea. The sequestra can be surgically removed and depending upon its depth within the cornea, a graft may be indicated.

Feline Uveitis

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Uveitis (inflammation within the eye) is one of the most frequent and significant ophthalmic disorders in cats. Both the direct and secondary effects may be destructive to the eye and maintenance of vision. Cats with serious, and often fatal, systemic diseases may first be presented to the veterinarian for ocular signs of uveitis. Possible clinical signs include decreased vision, squinting, redness, elevated third eyelid, cloudy cornea, iris color change and small pupil. Long term sequela include cataract development, lens dislocation and secondary glaucoma.

Potential causes of Feline Uveitis:

Trauma-blunt or penetrating wound
Infectious-feline leukemia virus, feline infectious peritonitis, feline immunodefieciency virus, fungal diseases, yeast and protozoal diseases
Neoplastic (cancer)
Lens induced-cataract or lens dislocation

Because the list of potential underlying causes is so diverse, additional diagnostic testing including a complete history, vaccination status, complete blood count, serum biochemical profile, urinalysis and specific testing for the infectious diseases is performed.

Herpetic Keratitis

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Feline herpesvirus-1 (FHV-1) is a major cause of conjunctivitis and corneal ulceration in both kittens and adult cats. Infection with FHV-1 is common, and the virus is widespread among cat populations. Primary (or first exposure) to FHV-1 can result in fever, sneezing, coughing, upper respiratory conditions, nasal discharge and conjunctivitis. The virus is spread from cat to cat either by direct contact or by aerosolization of the virus. Vaccination against FHV-1 provides temporary immunity. Once cats become infected, they become carriers. The virus becomes latent (inactive) within nerves that supply the eye. Stressful events such as illness, surgery, environmental changes, pregnancy and lactation, vaccination and administration of steroid medications may occur before an outbreak; however, in other cats, no apparent stressor can be identified as a trigger. Establishing an accurate diagnosis has been problematic; therefore, diagnosis may be based on clinical signs and response to treatment.

Treatment should include topical antiviral medications. Trifluridine is available as a commercial ophthalmic preparation; however, other agents such as idoxuridine and vidarabine can be compounded into ophthalmic preparations. These medications require administration 4-8 times daily as they do not kill the virus. Cidofovir has been recently studied and it has been shown to be highly effective at reducing FHV-1 replication. This medication requires less frequent administration allowing for twice daily therapy. Systemic antiviral medications include Lysine and topical antibiotic if ulcerated.

Neoplasia

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Both primary and secondary neoplasms occur in the cat. Early diagnosis is vital, because primary malignant tumors are locally invasive and have a high rate of metastasis (speading to other parts of the body).

Equine

ERU (Equine Recurrent Uveitis)

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ERU is synonymous with "moon blindness". This equine recurrent uveitis can affect any age, type or sex of horse (however Appaloosa horses are predisposed) and is a potential cause of blindness in affected animals. Both eyes can be affected although not necessarily at the same time.

Fungal Keratitis

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Fungi are normal inhabitants of the equine eye, but they can become problematic following a corneal injury. Exposure to hay, grasses, shavings, straw and dust in the environment may influence exposure to fungi and horses may be more susceptible because of the large prominent equine eye. Fungal ulcerations in horses is a serious, sight threatening disease. Diagnosis is made on the basis of visualizing the fungal hyphae during cytologic examination, culture of the organism or histoapthology. Treatment is directed against the fungi as well as against the corneal and intraocular inflammatory responses that occur following fungal replication and death. Combined medical and surgical therapy is generally indicated.

Squamous Cell Carcinoma

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Squamous cell carcinoma is the most common tumor of the eye and surrounding tissues in horses. The cause may be related to ultraviolet (UV) exposure, lack of pigment on the eyelids or tissues surrounding the eye and can increased susceptibility to cancer development. The occurrence rate increases with age. Many areas including the eyelids, third eyelid, conjunctiva and limbus (area where the white sclera meets the clear cornea) are commonly affected. Definitive diagnosis is made based on obtaining a small piece of affected tissue and submitting the tissue for histopathologic examination. Treatment depends on tumor location, tumor size, extent of invasion, vision status, the horse’s purpose and available equipment. If left untreated, it can spread to local tissues, the brain, regional lymph nodes, salivary gland and the lungs. Surgery alone does not provide a cure. Additional therapy (radiation therapy, cryotherapy, hyperthermia or chemotherapy) is also required.