Collie eye anomaly11/30/2022 ![]() ![]() It is therefore advised that puppies of affected breeds are screened at 6-7 weeks of age.Melanin pigmentation of the RPE or postnatal tapetal development may mask small areas of choroidal hypoplasia in approximately 30% of affected puppies by 16 weeks of age ('go normal' phenomenon).Faulty obliteration of optic vesicle and abnormal differentiation of retinal pigment epithelium leading to abnormal development of choroidal and scleral tissues.The mutation responsible for choroidal hypoplasia is inherited as an autosomal recessive trait and a DNA test is available Inherited diseases: genetic tests. The genetic basis of coloboma has not been identified.Dogs with colobomata are at risk of retinal detachment and intraocular hemorrhage which tend to occur in the first few years of life. Prognosis: if choroidal hypoplasia alone is present then the prognosis is good and signs are rarely progressive.Diagnosis is challenging in dogs with subalbinotic fundi and the choroidal abnormalities can be masked by postnatal tapetal development and pigmentation in some individuals. A 'pale patch' is present temporal to the optic nerve head where abnormal choroidal vessels are seen against a white scleral background. Diagnosis: the key feature of choroidal hypoplasia is diagnosed on ophthalmoscopy.Signs: on a spectrum from no perceivable visual deficits to complete blindness dependent on severity of lesions.The characteristic feature is choroidal hypoplasia which may be accompanied by other abnormalities including optic nerve or peripapillary colobomata, retinal detachment and intra-ocular hemorrhage. Cause: hereditary and congenital disorder in the Collie breeds, in particular the Shetland Sheepdog and Rough and Smooth Collie. ![]()
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