The dos and don'ts of treating ocular disease in cats (Proceedings)

Topics

     • Eyelid Agenesis, Apocrine Gland Hidrocystoma, Feline Herpes Virus, Corneal Sequestrum. Eosinophilic Keratitis, Acute Bullous Keratopathy, Diffuse Iris Melanoma, Persistent Pupillary Membranes, Cataracts/Lens Luxation, Hypertensive Retinopathy

Eyelid agenesis

     • The congenital absence of a portion of an eyelid

     • Associated with excessive evaporation and inadequate dispersion of tear film, trichiasis, secondary keratoconjunctivitis, pain, corneal Ulceration

     • Treatment: Variety of blepharoplastic procedures, choice depends on size and position of defect, cryotherapy for trichiasis

Apocrine gland hidrocystomas

     • Common in Persians/himalayan

     • Apocrine sweat gland tumors in the glands of moll. Single or multiple, dark color, benign, resemble human apocrine hidrocystomas

     • Unknown cause: Two theories: Lesion is a proliferative adenomatous tumor, lesion is a retention cyst

     • Treatment of Hidrocystomas: "Observation without treatment" aka benign neglect, drainage and surgical excision (generally recur 6-12 months ), debridement and topical 20% trichloroacetic acid (no recurrence at 12 months)

Feline herpes virus: it's herpes until proven otherwise

     • Alphaherpesvirus. High seroprevalence (90%), Transmission: Direct contact, Aerosolization

     • Infects epithelial cells lining the respiratory tract, conjunctiva and corneal epithelium. Replicating virus results in cytolysis, inflammatory mediated cell damage

     • Occurs 4-6 days post-exposure

     • Establishes latency in trigeminal ganglia (80% of cases)

     • 45% spontaneously reactivate

     • Primary Infection: Maternal antibody wanes at 8-12 weeks, generally self-limiting (10-20d)

     • **Conjunctivitis, Hyperemia, Blepharospasm, Chemosis, Ocular discharge- serous to purulent, Ulceration,

     • Fibrinous/cellular exudate

Feline herpesvirus-1: sequellae

     • Dendritic Corneal ulceration, Ophthalmia neonatorum, Symblepharon, usually occur during severe primary infection, stromal keratitis, eosinophilic keratitis, anterior uveitis, corneal sequestra, KCS, NLD stricture

Feline herpesvirus-1: diagnosis

     • PCR: Not clinically useful because of high prevalence in feline population

     • Virus Isolation in cell culture: Insensitive for chronic infections

     • Fluorescent Antibody (lacks sensitivity)

     • Cytology: Primary infection - Intranuclear inclusion bodies may be seen

     • Antibody detection (serology) : Not useful in vaccinated cats

     • Cause, coinciding, coincidence

Feline herpesvirus-1: treatment

     • Control 2° bacterial infections: Tetracycline to treat Chlamydia and Mycoplasma

     • Antiviral therapies. Topical (Idoxuridine, Cidofovir, Trifluridine). Systemic (Famciclovir, L-Lysine 500mg BID, Interferon). Decrease stress

Chlamydophila felis

     • Transmission: Airborne, direct, fomite

     • Incubation = 3-5 days

     • Shed ~60 days

     • Clinical signs: Young cat (under 1 yr), Unilateral progresses to bilateral in 7 days, CHEMOSIS, hyperemia, serous discharge, blepharospasm. Generally resolve by ~110 days post-infection

     • Diagnosis: Cytology (Intracytoplasmic reticulate bodies (days 3-14)). PCR, Serology (>32), ELISA, IFA (conj scraping), Cell culture.

     • Prevention: Vaccination- MLV and killed

     • Treatment: Tetracyclines (Doxycycline, Clavamox). Topical terramycin or erythromycin

Mycoplasma spp (m. Felis, m. Gatae)

     • Questionable clinical significance. Isolated from clinically normal cats (>80%). Variable conjunctivitis in experimentally infected kittens. Unable to produce clinical disease in experimentally infected adult cats

     • Diagnosis: Culture, Cytology (Epithelial cytoplasmic basophilic inclusions), PCR (M. felis) - High sensitivity/specificity

Corneal sequestrum: corneal necrosis

     • Unique to cats. Persian, Burmese, Himalayan at high risk

     • Cause: Chronic irritation/ulceration, most commonly feline herpes virus and in brachycephalic breeds

     • Signs: black plaque, blepharospasm, epiphora, vascularization, Ulceration

     • Do not debride, Do not perform a keratotomy

     • Treament: Medical Management (Warn the owner there is always a risk of eye perforation with medical management). Topical Anti-viral, Topical Antibiotic, Thick lubrication artificial tear (Genteal gel, I-drop Vet, Tears Renewed).

     • Surgical Therapy (best): Superficial Keratectomy

Eosinophilic keratitis: think "white plaques"

     • Proliferative, white to pink, edematous, irregular, vascularized ingrowth. Originates at the nasal or temporal limbus, adjacent conjunctiva is involved

     • Diagnosis : Cytology: Eosinophils and neutrophils predominant, Mast cells occasionally present

     • Treatment: Topical corticosteroids, Topical cyclosporine/tacrolimus

Mycobacterial keratitis

     • Aerobic, non motile, acid fast bacteria

     • Diagnosis: cytology

     • Chronic in nature requiring long term therapy

     • Fluoroquinolones treatment of choice - moxifloxacin

     • Lamellar or penetrating keratoplasty may be required

Acute bullous keratopathy

     • Formation of vesicles in the epithelium and stroma of an edematous cornea:

     • Diagnosis: Clinical exam findings

     • Treatment: *Hyperosmotic sodium chloride ointment (5%), *Topical antibiotics if ulcerated, *Third eyelid flap, Complete 360 degree conjunctival graft, Thermokeratoplasty

Diffuse iris melanoma

     • Usually slowly progressive (months to years)

     • Arise from pigmented anterior iris surface

     • Secondary effects: Glaucoma, may affect pupil shape and mobility, uveitis

     • Metastasis: 1 report of 63% metastasis rate, Liver, Spleen, & Kidneys > Lung, drainage angle & scleral venous plexus involvement increase risk of metastasis. 1 to several years after enucleation. Many cats, even with metastasis, live many years with few ill effects

     • Treatments: Early — Laser cytophotocoagulation/ablation, Enucleation/Evisceration, Adjunctive therapies: Xenogenic DNA Melanoma Vaccine ????

     • When to consider enuclation: Noticeable thickening of iris stroma with dyscoria or pupil mobility, involvement of ciliary body, extension into sclera, secondary glaucoma, intractable uveitis

Persistent pupillary membranes: embryonic remnants fetal blood vessels

     • Location: Iris to Iris, Iris to cornea (Cornea opacities), Iris to lens (Cataracts)

     • Difference from synechia because arise from iris collarette not pupillary margin

Cataracts/lens luxation

     • It happens in cats

     • Primary and inherited cataracts are rare and usually congenital

     • Secondary: Traumatic, *Anterior uveitis, Glaucoma, Lens luxation (secondary to chronic uveitis and glaucoma)

     • Treatment: Cats do very well with phacoemulsification surgery. Lensectomy for lens luxation (less glaucoma seen compared to canines)

Hypertensive retinopathy

     • Acutely blind cat (happens in dogs too!)

     • Can see the retina billowing towards you without a lens

     • Work up: Blood pressure, Chemistry panel and CBC

     • Treatment: Anti-hypertensive oral medications, Pred Acetate topically TID