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

Abstract

Case summaryA 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 informationThe 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.

The use of tear ferning test in cats for evaluation of ocular surface

“…The STT strip is made of soft, absorbent and malleable paper, thereby minimizing reflex tearing or damage to the cornea and adjacent structures during tear collection. In contrast, tear collection with capillary microtube can lead to eye damage caused by voluntary and involuntary movements of cats, as they were not sedated in this study [5,22,23]. This is especially important if more than one test is performed during the same examination, as the manipulation of cats' eyes can lead to exfoliation of conjunctival cells and/or release of TF components that are not normally expressed.…”

“…The TF is responsible for lubrication, nutrition and protection against microbial and toxic agents [2]. Disruption of TF dynamics can lead to dry eye or the ocular surface can become more susceptible to the onset of diseases [3][4][5].…”

An eye on the dog as the scientist's best friend for translational research in ophthalmology: Focus on the ocular surface

“…Schirmer tear strips are routinely used to measure tear volume for clinical assessment of dry eye disease in humans and veterinary species. 160,219,[252][253][254][255][256] The strips are made of Whatman no. 41 cellulose filter paper and possess specific characteristics to promote tolerance (5-mm width × 35-mm length, 0.22-mm thick, 20-25 µm porosity, foldable extremity for ease of insertion).…”

Impact of acute conjunctivitis on ocular surface homeostasis in dogs

“…3,7,8 Conjunctivitis is a common ocular surface disease and is known to lower tear film stability in many species, including humans, 9 dogs 10,11 and cats. 12,13 Primarily, the loss of tear film homeostasis results from altered mucin secretion onto the ocular surface by the conjunctival goblet cells. 14 However, the relationship between conjunctivitis and the tear film is more complex and also involves neurosensory stimulation from ocular irritation, 15,16 changes in tear volume, and variations in tear clearance.…”