Pupillary Membrane Persistence in a Feline

Background:Pupillary membrane persistence (PMP) is a congenital abnormality, which is not usually reported in felines. It is characterized by remnants of the fetal membrane that persist as filamentous tissue across the pupil. In general, this change does not cause any clinical symptoms. However, the filaments may either attach to the cornea and cause small opacities in it or attach to the lens and cause cataracts. In most cases, there is no visual impairment, so treatment is not prescribed. This report aims to describe a case of PMP in a domestic cat diagnosed at the Veterinary Hospital of the State University of Santa Cruz (HV-UESC). Case: A two-and-a-half-year-old mixed-breed castrated male cat was brought to the HV-UESC with dermatological complaints. Upon physical examination, the animal was alert with a body temperature, heart, and respiratory rate within the normal parameters for the feline species. The lymph nodes were non-reactive, and the coloration of the oral mucosa was normal. There was no ophthalmic complaint from the owner, nor any loss of visual acuity. In addition, the animal had moderate pruritus, redness, and alopecia in the region of the ears, head, neck, chest, and back. Bristle samples were collected for an optical microscope analysis and an infestation with lice (Felicola subrostratus) was confirmed. An endectocide containing selamectin (15 mg; single application every 30 days) was prescribed. During physical examination, filamentous tissue crossing from iris to iris through pupil was observed in both eyes. The eyelid, corneal, and pupillary reflexes were within normal ranges. An ophthalmic evaluation did not identify conjunctival hyperemia or episcleral vessel congestion, and the eyelid, corneal, and pupillary reflexes were determined to be within the normal range. A slit-lamp biomicroscopy did not detect any anterior chamber alteration besides the filamentous tissue previously mentioned. An examination of the fundus of the eye by direct ophthalmoscopy revealed that the crystalline lens, retina, optic nerve, and retinal vessels all looked normal with no other ophthalmic alteration. Thus, the diagnosis was PMP, and because of the absence of visual impairment or any other ophthalmic abnormality, no treatment was initiated. Discussion: Feline PMP is a rare condition. Since the present case, a few studies about this alterations in cats were found in the literature about. As in cats, this ophthalmopathy is uncommon in horses and cattle. The present report describes a case of PMP, a poorly described alteration in veterinary medicine, which was diagnosed by ophthalmic examination and slit-lamp biomicroscopy. As reported previously, PMP was an incidental finding during physical examination, since most animals with this alteration present little impairment of visual acuity. However, in some cases, membranous filaments may attach to the cornea and/or lens causing opacities and/or cataracts that may result in vision defects. This did not occur in the present case. In previous studies too, other ophthalmic alterations beyond PMP were not observed, thus corroborating the findings of our case. In the present case, as there were no other ophthalmic changes, it was not necessary to initiate any type of treatment. In conclusion, the lack of information regarding the epidemiology of PMP in cats warrants further studies of this alteration. Although infrequent in cats, this condition can easily be diagnosed in the routine examinations of this species.