Clinical and magnetic resonance imaging features of idiopathic oculomotor neuropathy in 14 dogs: Canine Idiopathic Oculomotor Neuropathy

Ophthalmoplegia/ophthalmoparesis (internal, external, or both) has been reported in dogs secondary to neoplasia affecting the oculomotor nerve and is usually given a poor prognosis. The purpose of this retrospective study was to describe the clinical findings, magnetic resonance imaging (MRI) findings, management, outcome, and follow-up in a group of canine cases with idiopathic oculomotor neuropathy. Inclusion criteria included cases with ophthalmoplegia/ophthalmoparesis (internal, external or both) as sole neuroophthalmologic signs, complete ophthalmic and neurologic examination, head MRI, and a minimum follow-up period of 1 year. Dogs with progressive neurological signs not related to oculomotor neuropathy were excluded. Fourteen cases met the inclusion criteria. All cases were unilaterally affected. Magnetic resonance imaging showed equivocal enlargement of the oculomotor nerve in three cases, mild enlargement in five, and marked enlargement in six. Contrast enhancement was present in 12 cases, being marked in six. When present, the contrast enhancement was focal in eight cases and diffuse in four. The median follow-up time was 25 months. External ophthalmoparesis improved in seven cases, five cases under no treatment and two under systemic corticosteroid therapy. The clinical signs in the other seven cases remained unchanged. Idiopathic oculomotor neuropathy should be included as a differential diagnosis in dogs presenting with unilateral ophthalmoplegia/ophthalmoparesis (internal, external, or both) with the absence of other neurologic and ophthalmic signs, and with the MRI findings restricted to the oculomotor nerve. Idiopathic oculomotor neuropathy has a good prognosis as the clinical signs do not deteriorate and they can improve without treatment

Clinical, histopathological and genetic characterisation of oculoskeletal dysplasia in the Northern Inuit dog

Seven Northern Inuit Dogs (NID) were diagnosed by pedigree analysis with an autosomal recessive inherited oculoskeletal dysplasia (OSD). Short-limbed dwarfism, angular limb deformities and a variable combination of macroglobus, cataracts, lens coloboma, microphakia and vitreopathy were present in all seven dogs, while retinal detachment was diagnosed in five dogs. Autosomal recessive OSD caused by COL9A3 and COL9A2 mutations have previously been identified in the Labrador Retriever (dwarfism with retinal dysplasia 1-drd1) and Samoyed dog (dwarfism with retinal dysplasia 2-drd2) respectively; both of those mutations were excluded in all affected NID. Nine candidate genes were screened in whole genome sequence data; only one variant was identified that was homozygous in two affected NID but absent in controls. This variant was a nonsense single nucleotide polymorphism in COL9A3 predicted to result in a premature termination codon and a truncated protein product. This variant was genotyped in a total of 1,232 dogs. All seven affected NID were homozygous for the variant allele (T/T), while 31/116 OSD-unaffected NID were heterozygous for the variant (C/T) and 85/116 were homozygous for the wildtype allele (C/C); indicating a significant association with OSD (p = 1.41x10-11). A subset of 56 NID unrelated at the parent level were analysed to determine an allele frequency of 0.08, estimating carrier and affected rates to be 15% and 0.6% respectively in NID. All 1,109 non-NID were C/C, suggesting the variant is rare or absent in other breeds. Expression of retinal mRNA was similar between an OSD-affected NID and OSD-unaffected non-NID. In conclusion, a nonsense variant in COL9A3 is strongly associated with OSD in NID, and appears to be widespread in this breed

Corneal ulcerative disease in dogs under primary veterinary care in England: epidemiology and clinical management

Abstract Background Corneal ulcerative disease (CUD) has the potential to adversely affect animal welfare by interfering with vision and causing pain. The study aimed to investigate for the first time the prevalence, breed-based risk factors and clinical management of CUD in the general population of dogs under primary veterinary care in England. Results Of 104,233 dogs attending 110 clinics participating within the VetCompass Programme from January 1st to December 31st 2013, there were 834 confirmed CUD cases (prevalence: 0.80%, 95% confidence interval (CI) 0.75–0.86). Breeds with the highest prevalence included Pug (5.42% of the breed affected), Boxer (4.98%), Shih Tzu (3.45%), Cavalier King Charles Spaniel (2.49%) and Bulldog (2.41%). Purebred dogs had 2.23 times the odds (95% CI 1.84–2.87, P < 0.001) of CUD compared with crossbreds. Brachycephalic types had 11.18 (95% CI 8.72–14.32, P < 0.001) and spaniel types had 3.13 (95% CI 2.38–4.12, P < 0.001) times the odds for CUD compared with crossbreds. Pain was recorded in 385 (46.2%) cases and analgesia was used in 455 (54.6%) of dogs. Overall, 62 (7.4%) cases were referred for advanced management and CUD contributed to the euthanasia decision for 10 dogs. Conclusions Breeds such as the Pug and Boxer, and conformational types such as brachycephalic and spaniels, demonstrated predisposition to CUD in the general canine population. These results suggest that breeding focus on periocular conformation in predisposed breeds should be considered in order to reduce corneal disease