FELINE CORNEAL SEQUESTRUM
Corneal sequestrum is a corneal pathology that affects mainly the feline species, although reports in dogs and cats have also been described in the literature.
The ocular signs are a change in corneal colouration that varies from a clear ambar to a dark brown even black colour. Depth varies, it can affect superficial layers of the cornea but it can also be deep, being perforating in some cases.
Etiopathogenesis of corneal sequestrum
Regarding etiopathogenesis, there are important predisposing factors such as chronic corneal ulcers, lagophthalmos and entropion amongst some. The role of Feline Herpesvirus-1 (FHV-1) is not completely understood However, FHV-1 can cause chronic corneal ulceration which could lead as a consequence to a sequestrum formation. We are aware there is also a breed predisposition. Persian, Siamese, Burmese and Himalayan are reported breeds to be affected by sequestrum formation. A more unknown but probably related cause could be a tear film dysfunction. Affected animals usually have brown tears. It is common to remove stained contact lenses when they are used after surgery or just to protect the cornea in superficial sequestrums.
The clinical signs are typical. The main differential diagnosis is a foreign body however the breed and, very likely chronicity, will direct us to the diagnosis of a corneal sequestrum. It tends to affect one eye however some cats may present with a bilateral sequestrum formation. The pigmented area tends to be surrounded by an area of non-adherent epithelium and the degree of associated vascularisation can vary, being mild or severe in some cases. The ocular discomfort of the cat also varies, with animals showing from mild to severe blepharospasm.
Treatment of corneal sequestrum
PDA L-R treatment could be advocated in very superficial sequestrums however surgery is almost always indicated. Superficial keratectomy is the technique used and it can be combined with other surgical techniques such as amniotic membrane , BIosis and A-Cell grafts when the keratectomy is deep. Performing a corneoconjunctival transposition is a very commonly used surgical technique that provides good tectonic and cosmetic results. Recurrence can occur and owners have to be warned of this possibility.
From Panacea-Vet we recommend the chronic use of artificial tears in the form of hyaluronic acid in brachiocephalic breeds. Not only will they help protect corneal exposure, but they will allow owners to identify any corneal changes early.
- Chow, D. W., & Westermeyer, H. D. (2016). Retrospective evaluation of corneal reconstruction using AC ell Vet™ alone in dogs and cats: 82 cases. Veterinary ophthalmology, 19(5), 357-366.
- Balland, O., Poinsard, A. S., Famose, F., Goulle, F., Isard, P. F., Mathieson, I., & Dulaurent, T. (2016). Use of a porcine urinary bladder acellular matrix for corneal reconstruction in dogs and cats. Veterinary ophthalmology, 19(6), 454-463
- Graham, K. L., White, J. D., & Billson, F. M. (2017). Feline corneal sequestra: outcome of corneoconjunctival transposition in 97 cats (109 eyes). Journal of feline medicine and surgery, 19(6), 710-716.
- Glaze MB, Maggs DJ, Plummer CE. Feline Ophthalmology. In: Veterinary Ophthalmology, 6th edn. (ed. Gelatt KN) Wiley Blackwell , 2021; 1724-1728