Feline dry eye syndrome of presumed neurogenic origin: a case report

Abstract

Case summary: A 14-year-old female spayed Abyssinian cat, which about 1 year previously underwent thoracic limb amputation, radiotherapy and chemotherapy for an incompletely excised vaccine-related fibrosarcoma, was presented for evaluation of corneal opacity in the left eye (OS). The ocular surface of both eyes (OU) had a lackluster appearance and there was a stromal corneal ulcer OS. Results of corneal aesthesiometry, Schirmer tear test-1 (STT-1) and tear film breakup time revealed corneal hypoesthesia, and quantitative and qualitative tear film deficiency OU. Noxious olfactory stimulation caused increased lacrimation relative to standard STT-1 values suggesting an intact nasolacrimal reflex. Various lacrimostimulants were administered in succession; namely, 1% pilocarpine administered topically (15 days) or orally (19 days), and topically applied 0.03% tacrolimus (47 days). Pilocarpine, especially when given orally, was associated with notable increases in STT-1 values, but corneal ulceration remained/recurred regardless of administration route, and oral pilocarpine resulted in gastrointestinal upset. Tacrolimus was not effective. After 93 days, the cat became weak and lame and a low thyroxine concentration was detected in serum. The cat was euthanized and a necropsy performed. Both lacrimal glands were histologically normal, but chronic neutrophilic keratitis and reduced conjunctival goblet cell density were noted OU.

Relevance and novel information: The final diagnosis was dry eye syndrome (DES) of presumed neurogenic origin, associated with corneal hypoesthesia. This report reinforces the importance of conducting tearfilm testing in cats with ocular surface disease, as clinical signs of DES were different from those described in dogs.

Figure 1

Clinical images of the ocular surface of the (a,d) right and (b,c,e) left eyes of a 14-year-old female spayed Abyssinian cat with neurogenic dry eye syndrome in both eyes on (a,b) days 11, (c) 35 and (d,e) 63 after initial presentation

Figure 2

Time course describing lacrimostimulant and lacrimomimetic therapy, as well as Schirmer tear test-1 (STT-1) values for the right eye (dark gray) and left eye (light gray) of a 14-year-old female spayed Abyssinian cat with neurogenic dry eye syndrome in both eyes. The horizontal dashed line represents the minimum STT-1 value considered normal in cats (9 mm/min). Day number is relative to initial presentation

Figure 3

Confocal photomicrographs of the cornea of a 14-year-old female spayed Abyssinian cat with neurogenic dry eye syndrome in both eyes. Note the (a) thin, disorganized epithelium with few hyper-reflective epithelial cells and leukocytes scattered within superficial to intermediate epithelial layers; (b) diminished to regionally absent sub-basal nerve plexus; (c) normal oval-shaped and elongated nuclei of keratocytes in the mid corneal stroma; and (d) normal corneal endothelial morphology and cell density (2400 cells/mm²; reference value 2520 cells/mm²). Bar = 50 µm

Figure 4

Photomicrographs of the cornea (a) OD and (b) OS of a 14-year-old female spayed Abyssinian cat with neurogenic dry eye syndrome OU. Both corneas had mild neutrophilic inflammation (black arrowhead), neovascularization (white arrow), anterior stromal fibrosis (asterisk), epithelial attenuation with segmental erosion and detachment (black arrow). Bar = 200 µm for gross images and 50 µm for insets

Figure 5

Photomicrographs of the third eyelid OS of a 14-year-old female spayed Abyssinian cat with neurogenic dry eye syndrome OU. Sections were stained using the periodic acid–Schiff technique and goblet cells are stained magenta. Relative to published reference intervals, conjunctival goblet cell density is markedly decreased on the (a, arrow) anterior and (b, arrowhead) posterior surfaces of the third eyelid. Bar = 100 µm

Figure 6

Photomicrographs of the (a) orbital lacrimal gland OD and (b) third eyelid gland OS of a 14-year-old female spayed Abyssinian cat with neurogenic dry eye syndrome OU. Note the (a) small aggregates of lymphocytes (arrow) around lacrimal lobules embedded in adipose tissue OD; and (b) mild-to-moderate numbers of perivascular lymphocytes and plasma cells (arrowhead) in the lamina propria of the third eyelid gland OS. Bar = 100 µm for (a) and 200 µm for (b)