The domestic dog (Canis familiaris) segregates more naturally-occurring diseases and phenotypic variation than any other species and has become established as an unparalled model with which to study the genetics of inherited traits. We used a genome-wide association study (GWAS) and targeted resequencing of DNA from just five dogs to simultaneously map and identify mutations for two distinct inherited disorders that both affect a single breed, the Cavalier King Charles Spaniel. We investigated episodic falling (EF), a paroxysmal exertion-induced dyskinesia, alongside the phenotypically distinct condition congenital keratoconjunctivitis sicca and ichthyosiform dermatosis (CKCSID), commonly known as dry eye curly coat syndrome. EF is characterised by episodes of exercise-induced muscular hypertonicity and abnormal posturing, usually occurring after exercise or periods of excitement. CKCSID is a congenital disorder that manifests as a rough coat present at birth, with keratoconjunctivitis sicca apparent on eyelid opening at 10–14 days, followed by hyperkeratinisation of footpads and distortion of nails that develops over the next few months. We undertook a GWAS with 31 EF cases, 23 CKCSID cases, and a common set of 38 controls and identified statistically associated signals for EF and CKCSID on chromosome 7 (P_raw 1.9×10⁻¹⁴; P_genome = 1.0×10⁻⁵) and chromosome 13 (P_raw 1.2×10⁻¹⁷; P_genome = 1.0×10⁻⁵), respectively. We resequenced both the EF and CKCSID disease-associated regions in just five dogs and identified a 15,724 bp deletion spanning three exons of BCAN associated with EF and a single base-pair exonic deletion in FAM83H associated with CKCSID. Neither BCAN or FAM83H have been associated with equivalent disease phenotypes in any other species, thus demonstrating the ability to use the domestic dog to study the genetic basis of more than one disease simultaneously in a single breed and to identify multiple novel candidate genes in parallel.

Overview Feline ulcerative keratitis is a common presenting complaint and is frequently a sequela of feline herpesvirus 1 (FHV-1) infection; so much so, in fact, that it is fair to assume an FHV-1 aetiology until proven otherwise. Other potential causes of ulceration are trauma or underlying eyelid abnormalities (entropion, ectropion, agenesis, dermoids, neoplasia), lash abnormalities (ectopic cilia, trichiasis), tear film abnormalities or neurological deficiencies (trigeminal nerve paralysis, facial nerve paralysis). Clinical challenges The management of corneal ulceration in cats is frequently challenging, and treatment needs to be tailored carefully to the individual cat, its temperament, and the disease process present. Evidence base The scientific literature on feline ulcerative keratitis is extensive, particularly that related to FHV-1 infection. The aim of this article is to review the aetiology and diagnosis of corneal ulceration in cats with particular reference to the evidence base available. Patient group All age groups and breeds can suffer with ulcerative keratitis. Breed predispositions are present for some forms of corneal ulceration, and these are discussed.

Although ultrasound and MRI are the imaging modalities of choice for the investigation of ocular diseases, the eyes are included in routine CT examinations of the head and should be examined as part of the complete evaluation. This report describes the dimensions, volumes and densities of the normal canine globe in CT. Forty‐four eyes were studied. The mean axial length of the globe was 2.09 cm and its mean volume was 4.65 cm ³ . The mean anteroposterior distance of the anterior chamber was 0.4 cm and of the vitreous chamber was 0.96 cm. There was a statistically significant difference between the mean aqueous humour density, 14.76 Hounsfield units (HU), and the mean vitreous humour density, 11.20 HU (P=0.0009). Statistically significant differences were also seen in both humours in precontrast and postcontrast studies. The mean anteroposterior dimension of the lens was 0.74 cm; its mean equatorial distance was 1.15 cm. The mean volume was 0.43 cm ³ and its mean density was 131.9 HU. There was contrast enhancement of the ciliary body, iris and retina/sclera/choroid complex. This study provides reference values to help in the interpretation of ocular structures on CT scans of the head, where incidental findings can change the medical management of specific cases.