Canis ISSN: 2398-2942

Curly coat dry eye syndrome

Synonym(s): Congenital keratoconjunctivitis sicca and ichthyosiform dermatosis syndrome CKCSID

Contributor(s): Claudia Hartley, David Gould

Introduction

  • Cause: congenital keratoconjunctivitis sicca and ichthyosiform dermatosis syndrome is an inherited (autosome recessive) condition in Cavalier King Charles spaniel dogs. The causative genetic mutation is FAM83H on the canine chromosome 13.
  • Signs: breeders report affected dogs were born with a 'rough' or curly coat, which initially grows poorly and later develops scaling of the coat and thickened footpads. In adulthood, the coat has a frizzy crimped appearance that is sparse with areas of scurfiness particularly of the dorsum. Breeders and owners also reported mild intermittent pruritus in most cases. Hyperkeratinization of the footpads, and areas of the glabrous skin are common. Fissures/cracks may appear in hyperkeratinized foot pads causing lameness. Poor nail growth with 'fret' lines are also present, with frequent nail sloughing and attendant lameness. Breeders also report recurrent bouts of conjunctivitis and/ or corneal ulceration following eyelid opening. Corneal fibrosis, vascularization, and pigmentation are common chronic ocular signs seen in adult cases. Some cases have been noted to have poor dental health with gingivitis, caries, and halitosis (some cases reported to have subjectively reduced saliva production).
  • Diagnosis: tentative diagnosis is based on clinical appearance and history. Schirmer tear test readings are subnormal. Definitive diagnosis can be confirmed by genetic testing (Animal Health Trust, Newmarket).
  • Treatment: the congenital KCS is treated with immunomodulatory drugs (topical ciclosporin or topical tacrolimus) and lacrimomimetics / tear replacements. Response to KCS treatment can be variable. Owners report that regular nail clipping can help reduce the frequency of nail sloughs (and pain). Many owners have reported improvement with essential fatty acid supplementation, but the coat changes are generally life-long.
  • Prognosis: skin and nail issues can be managed but require prolonged treatment/management and dedicated owners. Treatment responsive cases generally have less severe keratitis, but rarely achieve total corneal clarity. Keratitis may progress with fibrosis and pigmentation and attendant visual deficits, in some cases resulting in no menace response (blindness). Most blind cases are those that fail to respond to lacrimostimulant/ immunomodulatory treatment. The coat and nail disease require ongoing management life-long to reduce incidences of lameness (due to nail sloughs) and degree of scurfiness, but are not curable. Many cases are euthanased.

Pathogenesis

Etiology

  • Autosomal recessive inheritance.
  • Causative mutation FAM38H on canine chromosome 13.

Predisposing factors

General

  • Inherited.

Pathophysiology

  • Pathophysiology of KCS Eye: keratoconjunctivitis sicca component not fully understood (histopathology of lacrimal glands in euthanased affected cases were unremarkable).
  • Dermatosis - ichthyosiform with failure of keratinization - resulting in hyperkeratinization and scurf.
  • Pathophysiology of dental issues unknown (salivary glands normal on histopathology from affected cases).

Timecourse

  • Life-long.

Epidemiology

  • Inherited, cases originally described could be traced back to a common ancestor.
  • DNA test now available to allow screening of breeding dogs.

Diagnosis

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Treatment

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Prevention

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Outcomes

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Further Reading

Publications

Refereed Papers

  • Recent references from PubMed and VetMedResource.
  • Forman O P, Penderis J, Hartley C, Hayward L J, Ricketts S L, Mellersh C S (2012) Parallel mapping and simultaneous sequencing reveals deletions in BCAN and FAM83H associated with discrete inherited disorders in a domestic dog breed. PLoS Genetics 8 (1), 1-9 PubMed.
  • Hartley C, Donaldson D, Smith K C, Henley W, Lewis T W, Blott S, Mellersh C, Barnett K C (2012) Congenital keratoconjunctivitis sicca and ichthyosiform dermatosis in 25 Cavalier King Charles spaniel dogs. Part I: clinical signs, histopathology, and inheritance. Vet Ophthalmol 15 (5), 315-326 PubMed.
  • Hartley C, Barnett K C, Pettitt L, Forman O P, Blott S, Mellersh C S (2012) Congenital keratoconjunctivitis sicca and ichthyosiform dermatosis in Cavalier King Charles spaniel dogs. Part II: candidate gene study. Vet Ophthalmol 15 (5), 327-332 PubMed.
  • Barnett K C (2006) Congenital keratoconjunctivitis sicca and ichthyosiform dermatosis in the cavalier King Charles spaniel. JSAP 47 (9), 524-528 PubMed.

Other sources of information


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