ABSTRACT OF THE WEEK

Veterinary ophthalmology
Volume 25 | Issue 5 (September 2022)

Prevalence and characteristics of ocular diseases in Sphynx cats: A retrospective assessment (2012-2021) and comparison with non-Sphynx cats.

Vet Ophthalmol. September 2022;25(5):367-375.

Havi Sarfaty¹, Raaya Ezra-Elia², Lionel Sebbag³

¹ EYECARE Clinic, Yahud-Monoson, Israel.; ² EYECARE Clinic, Yahud-Monoson, Israel.; ³ Koret School of Veterinary Medicine, The Hebrew University of Jerusalem, Rehovot, Israel.

Abstract

PURPOSE:To describe the prevalence of ocular diseases in Sphynx cats, and compare disease characteristics with other feline breeds.

METHODS:Medical records of Sphynx cats presented to an ophthalmology referral center between 1/2012 and 4/2021 were examined. Cats of other breeds examined during the same period served as controls.

RESULTS:One hundred ten Sphynx cats were examined during the study period, diagnosed with corneal sequestrum (n = 42 cats), lower eyelid entropion (n = 25), presumed herpetic keratoconjunctivitis (n = 19), conjunctivitis (n = 7), corneal ulcers (n = 6), nasolacrimal duct atresia/obstruction (n = 6), corneal dystrophy (n = 3), eosinophilic keratitis (n = 2), uveitis (n = 2), non-ulcerative keratitis (n = 1), and cataract (n = 1). Corneal sequestrum was significantly more common in Sphynx versus non-Sphynx cats (odds ratio = 8.0, 95% CI = 5.3-12.2, p < .001), and age of diagnosis was significantly younger in Sphynx cats (2.0 ± 1.5 years vs. 5.9 ± 4.0 years, p < .001). Corneal sequestrum recurrence was noted in 19.4% Sphynx eyes and 6.4% non-Sphynx eyes undergoing surgery (p = .015). Lower eyelid entropion-most often bilateral (80%)-was significantly more common in Sphynx versus non-Sphynx cats (odds ratio = 4.1, 95% CI = 2.3-7.1, p < .001), and age of diagnosis was significantly younger in Sphynx cats (0.9 ± 1.4 years vs. 3.5 ± 3.3 years, p < .005).

CONCLUSIONS:Corneal sequestrum and entropion were overrepresented and diagnosed at an earlier age in Sphynx cats when compared with the general feline population. Given the high prevalence, early age of onset, and relatively high recurrence of corneal sequestrum in Sphynx cats, further studies are warranted to better understand etiopathogenesis and preferred therapies.

Companion Notes

Retrospective report comparing the prevalence and characteristics of ocular diseases in 110 Sphynx cats to non-Sphynx cats

Introduction

- Sphynx cat, originally called Canadian hairless

- breed lacks of body hair (alopecia)

- autosomal recessive phenotype linked to a mutation in the Keratin 71 gene

- there are few reports in the scientific literature on systemic disorders in the breed

(presumably inherited)

- muscular dystrophy

- mitral valve dysplasia

- hypertrophic cardiomyopathy

- frequent skin colonization with Malassezia spp

Study design

- study population:

- Sphynx cats presenting to an ophthalmology referral center

(there’s a relatively large caseload of Sphynx cats in authors' practice)

- 110 Sphynx cats included in study

- all cats underwent a complete ophthalmic examination

- cats of other breeds seen during the study period acted as controls

- procedure: records between 01/12 and 04/21 retrospectively reviewed

- 3282 cats examined in practice including 132 Sphynx cats (4%)

- diagnosis of entropion

- exclusion criteria:

- underlying etiology included the following:

- spastic

- secondary to age-related orbital fat loss/enophthalmos

- medial lower eyelid entropion in brachycephalic cats

Results

- history and signalment

- sex:M, 68 cats (42 intact; 26 neutered)

- age at presentation: 1.6 ± 1.8 years with a range of 0.2-12 years

- Sphynx cats were diagnosed with the following:

(106 of the 110 were diagnosed with a single ocular pathology)

- corneal sequestrum, 42 cats

- significantly more common in Sphynx than non-Sphynx cats

- odds ratio: 8.0; 95% CI: 5.3-12.2; p < .001

- age of diagnosis significantly younger in Sphynx cats

- age of diagnosis in Sphynx cats: 2.0 ± 1.5 years

- age of diagnosis in non-Sphynx cats: 5.9 ± 4.0 years

- unilateral in 27 (64%) and bilateral in 15 (36%)

- 7 were bilateral at 1^st examination

- 8 developed sequestrum in contralateral eye following diagnosis in 1^st eye

- 19.8 ± 21.9 months (1-58 months) following diagnosis in 1^st eye

- FHV-1 involvement suspected in 15 of the 42 cats (36%)

- 70% of corneal sequestra were in the axial cornea, 1-6 mm in size

- dark-brown to dark-black in color

- 32 eyes (56%) were managed surgically and 20 eyes were managed medically

- overall followup time for cats with sequestrum: 745 ± 661 days

- of medically managed sequestra

(eyes selected for medical therapy were non-painful and non-inflamed)

- 12 of 20 (60%) sloughed off spontaneously within 53.9 ± 46 days

(with resolution of clinical signs)

- 10 of 12 (83%) were located axially

- 10 of 12 had concurrent corneal vascularization of various extent

- recurrence in cats undergoing surgery

- noted in 19.4% Sphynx eyes and 6.4% non-Sphynx eyes (p = .015)

- diagnosed within 170 ± 297 days

- recurrence with conjunctival flap, 7% (1 of 15)

- recurrence with collagen xenograft, 33% (2 of 6)

- recurrence with corneoconjunctival transposition: 40% (2 of 5)

- lower eyelid entropion, 25 cats

(authors believe entropion may have been missed given lack of haired skin)

- bilateral in 80% of cases

- significantly more common in Sphynx than non-Sphynx cats

- odds ratio: 4.1; 95% CI: 2.3-7.1; p < .001

- age of diagnosis significantly younger in Sphynx cats

- age of diagnosis in Sphynx cats: 0.9 ± 1.4 years

- age of diagnosis in non-Sphynx cats: 3.5 ± 3.3 years

- overall followup time was 1047 ± 648 days

- recurrence of entropion diagnosed in 21% of Sphynx eyes

- within 519 ± 602 days

- presumed herpetic keratoconjunctivitis, 19 cats

- bilateral, 79%

- diagnosis based on clinical signs

- epiphora

- conjunctival hyperemia ± chemosis

- superficial corneal ulcers/abrasions

- all clinical signs resolved rapidly following antiviral treatment

- famciclovir, 64.5 ± 18 mg/kg PO bid

- topical 0.5% cidofovir, 1 drop bid

- oxytetracycline-responsive conjunctivitis, 7 cats

- oxytetracycline 0.5% ointment, affected eye(s), tid for 3-4 weeks

- continued sid if clinical signs recurred when therapy was discontinued

- corneal ulcers, 6

- nasolacrimal duct atresia/obstruction, 6

- corneal dystrophy, 3

- eosinophilic keratitis, 2

- uveitis, 2

- non-ulcerative keratitis, 1

- cataract, 1

“Corneal sequestrum was the most common ocular disease and presented specific features such as early onset, rapid darkening, deep stromal involvement, and relatively high recurrence following surgery.”

Keywords

Herpesvirus; cat; cornea; entropion; sequestrum; sphynx;

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