What causes ulcers in a cat's eyes
Sick cat eyes
Herpes keratoconjunctivitis in cats
The feline herpes virus (FHV-1) is considered to be one of the most common causes of inflammation of the conjunctiva and cornea in cats. The main symptoms are conjunctivitis, ulcerative keratitis, runny nose with discharge from the eyes and nose, and follicular laryngitis. Dr. Hannes Meißel reports on keratoconjunctivitis in cats caused by herpes and shows that the clinical picture of the disease can vary greatly, as individual immunity, potentiation by other viruses and bacterial infections influence the severity of the problems.
The virus is transmitted through contact, but mostly through droplet infections after excretion through nasal and eye secretions and saliva. Cats that recover from the disease can be considered virus shedders for a long time. The virus reservoir consists of recovered permanent shedders and animals that are clinically inapparently infected. The problem with the disease is that around 80% of cats suffering from FHV-1 are latent carriers with a 45% chance of reactivating the virus and contributing to the spread of the infection.
After intranasal inoculation, the herpes viruses cause lysis and focal necrosis in the mucosal epithelium of the upper respiratory tract; The conjunctiva and cornea are equally affected. In most cases the infection remains localized here; the lungs are rarely involved. Infections of the genital tract are always observed in generalized infections, since the virus has a high affinity for the pregnant uterus; this leads to abortions and infections of the fetuses in utero. The incubation period is 2 - 5 days; it varies, as does the duration of the disease (usually 2 weeks) depending on the amount of virus inoculated.
In herpes conjunctivitis, serous eye discharge and bilateral conjunctival hyperemia occur after an initial infection; the cytopathic effects vary the clinical symptoms. In many cases, the primary infection does not have to leave any permanent damage to the eye.
A distinction is made between ophthalmia neonatorum under closed eyelids as a mixed infection in addition to FHV-1 with chlamydia and mycoplasma, recognizable as swelling of the eyelids with protruding mucopurulent exudate in the nasal corner of the eye: The rapid opening of the ankyloblepharon by blunt separation of the eyelids and introduction of broad spectrum antibiotics prevents Symblepharon and Pseudopterygium.
Without timely treatment, neonatal herpes conjunctivitis in the 2nd to 4th week of life with delayed opening of the eyelid gap leads to corneal ulcer and consecutive symblepharon and / or pseudopterygium or corneal perforation.
The term symblepharon is understood to mean the adhesion of the eyelid to the eyeball, but especially of the eyelid and eyeball conjunctiva or of the conjunctiva and nictitating skin after ulcerative keratoconjunctivitis. In doing so, a scarring conjunctival duplication always pushes itself into the narrowed and deformed eyelid cleft area like a perforated diaphragm, including the herniated eyelid. A pseudo- or scar pterygium is a conjunctival duplication which, after ulcerative conjunctival and corneal lesions, pushes itself over the corneal defect and its extent is firmly attached to the base.
Stress factors can reactivate the virus in older animals that have already survived an infection: The cats usually develop bilateral conjunctivitis without infection of the upper respiratory tract. Blepharospasm, reduction in tear production and reduction in sensitivity of the cornea occur concomitantly; Since the cats are very sensitive living beings, many, even more harmless, changes come into question as stress factors: A new animal is temporarily or permanently taken into the family, a new partner or guests disturb everyday life, holidays or changes in the apartment irritate the cat, Visits to the vet for vaccination or anesthesia stress the cat, noise from craftsmen in the house or unpleasant smells can be a major problem for the cat.
Eosinophilic conjunctivitis has been associated with FHV-1, although the cause is not fully understood; it is possibly an immune-mediated late form of herpes conjunctivitis. It shows up as a bumpy conjunctival thickening, pseudomembranous coating and a tendency to keratoconjunctivitis sicca. In herpes keratitis, a distinction is made between postnatal and juvenile or adult infections.
Large and deep corneal defects are found in the postnatal manifestation of neonatal and early juvenile mixed infections of the upper respiratory tract as well as the conjunctiva and cornea. These defects are first repaired with a pannus-like granulation tissue, which later changes into vascularized connective tissue (scar pterygium). Depending on the extent of the previous loss of substance, it partially or completely covers the cornea; the eyelid gap is considerably reduced and deformed.
Similar to conjunctivitis, the actual herpes keratitis occurs from the 6th month after the primary infection has already been overcome, usually without respiratory symptoms and occasionally without noticeable reddening of the conjunctiva. The characteristic multiple superficial, punctiform or dendritic corneal defects can often be seen with the naked eye; Staining with fluorescein sodium or bengal pink improves the diagnosis. Simultaneous erosions can easily lead to a corneal ulcer without treatment; Descemetocele with risk of perforation can develop, probably as a result of secondary bacterial infections.
Chronic keratoconjunctivitis can also develop into eosinophilic keratitis with a tendency towards keratoconjunctivitis sicca or into stromal keratitis with diffuse corneal edema, superficial vascularization and a tendency to scarring fibrosis, fatty corneal degeneration and hyperkeratosis of the cornea. Eosinophilic keratitis can result from autoimmune derailment from herpes keratitis. Typical are the white plaques on the cornea and a pannus-like vascularization of the cornea. Eosinophilic granulocytes and mast cells are detected cytologically.
Black corneal necrosis (cornea nigra, corneal sequester) is an expression of chronic irritation of the cornea in which at least some herpes viruses have been detected. This disease, which is particularly common in cats, affects one or more often both eyes, although both eyes are not affected at the same time. Since especially brachycephalic cats - possibly with nasal entropion - get sick, corneal microtraumas are responsible for the development of the darkly pigmented lesion; Disturbances in the local mechanism of corneal metabolism can also be involved. The lesions are mostly in the center of the cornea; Parts of the cornea die off, the necrosis increases in size and turns into a lacquer-like, shiny, dry, black plaque that is demarcated at the edge and sometimes has a tendency to detach itself from the cornea, which very rarely actually occurs. Later superficial vascularization and the formation of a granulating wall at the edge of the sequester occur. Histopathologically, degenerate collagen and fibroblasts with an adjacent zone of lymphocytes, plasma cells, neutrophils, macrophages and giant cells are found in the sequester. The color of the necrosis varies from light brown to black; the pigment does not arise from melanin; but rather through a metabolic disorder of the cornea through polymerisation of the oxidized forms of tyrosine, DOPA, epinephrine and catecholamines.
For the treatment of keratoconjunctivitis in cats caused by herpes, we have different options available, depending on the severity and form of the disease. Since stress is an extremely important trigger in the development of the therapy, care should be taken during therapy not to additionally stress the cat through the effort of the treatment. Cats in particular, with their aversion to almost any kind of medication, pose great problems for the owner. Fortunately, two drugs that are relatively easy to apply and that are used in good time have been able to help cats decisively: ¼ tablet of famciclovir
(e.g. Famvir) for at least 3 weeks and every day for life lysine in the form of a very digestible paste (e.g. Enisyl - F from Vetoquinol). Famiclovir must also be given for life in some cats. Both preparations are very well tolerated, slight central nervous disorders were only observed in very small cats, but these immediately disappeared without consequences after discontinuation of the drug.
In addition, if necessary, antivirals such as Triherpine or Trifluman can also be used locally in drop form; temporary reddening of the conjunctiva or increased blinking are occasionally observed. Antibiotics against secondary pathogens, tear substitutes such as protagent and interferon as feline recombinant
Interferon (Virbagen omega in NaCl 0.9% 1:10 (500.00 U / ml)) can also be used. Dry debridement with a cotton swab after local anesthesia (e.g. Novain drops) and / or touching with 3.5% Solutio Jodi spirituosa can improve the healing process.
In particularly serious cases and in black corneal necrosis, a superficial keratectomy is performed under the surgical microscope. Although it is clear that the virus cannot be cut away, removing the corneal layers succeeds in calming the situation and achieving a stable, pain-free cornea. The surgical procedure for symblepharon and scar pterygium is usually not promising; the results of all efforts are very frustrating and mostly lead to only temporary improvements.
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