If you notice your cat pawing or rubbing at its eye a lot, and there is discharge coming from it, it's important to take them to your veterinarian. They may have a corneal sequestrum, which is a dark brown to black spot on the cornea. The most common cause of a corneal sequestrum in cats is the feline herpes virus, but it can also be caused by other injuries to the eye. There are medical and surgical treatment options available, so with the proper treatment, your cat can make a full recovery!
What is a corneal sequestrum in cats?
A corneal sequestrum is a dark brown to black spot on the cornea, typically in the center of the cornea and typically affecting only one eye. This happens when blood and tissue from an injury become stuck to the cornea.
What causes a corneal sequestrum in cats?
There are many factors that contribute to the formation of a corneal sequestrum, but they are not well understood. Corneal sequestra most often occur after a prior corneal ulcer or a chronic, nonhealing ulcer. A corneal sequestrum in cats is often associated with feline herpesvirus (FHV-1) infection.
Cats that are treated with topical corticosteroids are at risk of developing corneal ulcers and sequestra from activation of latent feline herpesvirus. Up to 50% of cats that appear clinically normal have feline herpesvirus present in their corneas.
Other ocular diseases may also make cats more likely to develop a corneal sequestrum. These include mild trauma, entropion/trichiasis, and keratoconjunctivitis sicca (dry eye). Any cat, regardless of age, sex, or breed, can be affected by the disease, although brachycephalic breeds (Persians, Himalayans, etc.) may be more likely to be affected.
What are the clinical signs of a corneal sequestrum in cats?
Clinical signs that may be associated with a corneal sequestrum in cats include:
- Tearing
- Discharge (that is either reddish or dark)
- Squinting
- Pawing or rubbing at the eye
How is a corneal sequestrum in cats diagnosed?
A corneal sequestrum in cats can be diagnosed on clinical examination by your veterinarian with the presence of a dark, almost black plaque in the corneal stroma.
What are the treatment options for a corneal sequestrum in cats?
The goal of treatment is to remove the corneal sequestrum while preserving corneal function and preventing recurrence. There are both medical and surgical options available.
Medical therapy for a corneal sequestrum in cats typically includes a combination of topical antibiotics and antivirals, as well as oral pain medication. Ocular lubricants may also be used to help keep the cornea moist and prevent further irritation. Medical therapy is typically used in a non-emergent, non-painful eye.
Surgical therapy is an effective treatment for ocular pain, and for eyes that are actively ulcerating and/or inflamed. Keratectomy is considered the gold-standard surgical treatment. This involves the removal of the corneal sequestrum and surrounding necrotic tissue, followed by the use of a topical antibiotic in the eye. Lesions that are very superficial can occasionally be manually debrided with topical anesthesia and without anesthesia.
If your cat is experiencing corneal pain, your veterinarian may recommend an Elizabethan collar (E-collar) to prevent them from further injuring themselves or developing a secondary infection. It's important to keep in mind that the pain associated with ocular surgery and the application of topical medications (particularly some antiviral agents) is often worse immediately after treatment before it gradually improves. If an underlying feline herpesvirus infection is present, antiviral drugs will be utilized to address this as well.
The use of atropine can be beneficial in relieving pain. Topical atropine is a medication that dilates the pupil and helps relieve pain. It can be applied every 12-24 hours to achieve the desired effect in most situations and then tapered once the pupil remains dilated. However, prolonged use of atropine can decrease tear production.
What is the prognosis for a corneal sequestrum in cats?
The prognosis for corneal sequestra in cats is generally good with early diagnosis and treatment. However, corneal ulceration and perforation can occur if the sequestrum is left untreated. Recurrence rates after surgery vary and can be as high as 25%.
A corneal sequestrum is a dark brown to black spot that forms in the middle of the cornea. This happens when the cornea gets injured and the blood and tissue from the cornea become stuck to the middle of the cornea in a black or brown spot. The most common cause of a corneal sequestrum in cats is the feline herpes virus, which can be activated by any injury to the eye. Other ocular diseases may also make cats more likely to develop a corneal sequestrum. These include mild trauma, entropion/trichiasis, and keratoconjunctivitis sicca (dry eye). Any cat, regardless of age, sex, or breed, can be affected by this disease. Treatment options include medical and surgical treatment. With proper treatment, the prognosis is good for cats with a corneal sequestrum. If you have any questions, please contact your veterinarian.