Inherited retinal dysplasia and persistent hyperplastic primary vitreous in Miniature Schnauzer dogs

Abstract

The objectives of this study were to define the clinical syndrome of retinal dysplasia and persistent primary vitreous in Miniature Schnauzer dogs and determine the etiology. We examined 106 Miniature Schnauzers using a biomicroscope and indirect ophthalmoscope. The anterior and posterior segments of affected dogs were photographed. Four enucleated eyes were examined using routine light microscopy and scanning electron microscopy. A pedigree was constructed and related dogs were test-bred to define the mode of inheritance of this syndrome. Congenital retinal dysplasia was confirmed in 24 of 106 related Miniature Schnauzer dogs. Physical and postmortem examinations revealed that congenital abnormalities were limited to the eyes. Biomicroscopic, indirect ophthalmoscopic, and neuro-ophthalmic examinations confirmed that some of these dogs were blind secondary to bilateral retinal dysplasia and detachment (nonattachment) (n = 13), and the remainder had generalized retinal dysplasia (n = 11). Fifteen of these dogs were also diagnosed with unilateral (n = 9) or bilateral (n = 6) persistent hyperplastic primary vitreous. Nutritional, infectious, or toxic etiologies were not evident on physical, postmortem, light microscopic, or transmitting and scanning electron microscopic examination of four affected Miniature Schnauzers. We examined the pedigree and determined that an autosomal recessive mode of inheritance was most likely. Three test-bred litters including those from affected parents, carrier and affected parents, and carrier parents confirmed this mode of inheritance. This study confirms that retinal dysplasia and persistent hyperplastic primary vitreous is a congenital abnormality that is inherited as an autosomal recessive condition in Miniature Schnauzers.

Unilateral persistent hyperplastic tunica vasculosa lentis/persistent hyperplastic primary vitreous (PHTVL/PHPV) in a German shepherd dog

“…Fluorescein dye staining was negative Behind and attached to the lens, a triangularshaped echogenicity could be seen (white arrows) which continued as a tubular hyperechoic strand to the optic disk that could be seen as a hypoechoic region (black arrows) feature. Persistent hyaloid arteries are not accompanied by proliferative primary vitreous or posterior lens capsule plaque and cataracts, and PHPV may or may not be accompanied by patent hyaloid arteries (Grahn et al 2004).…”

Electroretinographic examination for evaluation of retinal activity in dogs with retinal dysplasia

“…It is thought that the condition is inherited as an autosomal recessive trait (MacMillan and Lipton 1978). Until now, this has been confirmed in, for instance, Miniature Schnauzers, where rd is accompanied by PHPV (Persistent Hyperplastic Primary Vitreous) (Grahn et al 2004). In Labrador Retrievers and Samoyeds, it has been established that OSD (oculoskeletal dysplasia) is inherited as an autosomal dominant condition with incomplete penetrance (Nelson and MacMillan 1983;Carrig et al 1988).…”

“…In a study by O'Toole et al (1983), dysplastic lesions in English Springer Spaniels were detected in an ophthalmoscopic examination straight after birth, whereas Holle et al (1999) found that in the case of geographic retinal dysplasia, the lesions were rarely noticeable earlier than week 10 of life, which may be associated with tapetal development which can last for up to the first 6 months of life (Cook 2013). It has been noted that single or multiple retinal folds may become less visible with age (Grahn et al 2004) or may disappear completely, after which the fundus returns to normal (ACVO Genetics Committee 2014). This is most probably associated with a redevelopment of the retina (O'Toole et al 1983;Cispin et al 1999;Holle et al 1999;Grahn et al 2004).…”

“…It has been noted that single or multiple retinal folds may become less visible with age (Grahn et al 2004) or may disappear completely, after which the fundus returns to normal (ACVO Genetics Committee 2014). This is most probably associated with a redevelopment of the retina (O'Toole et al 1983;Cispin et al 1999;Holle et al 1999;Grahn et al 2004). Furthermore, because an ophthalmoscopic examination is subjective in nature, it gives rise to differences in how the fundus is evaluated.…”

“…The third type is characterised by a separation of the neurosensory retina from the RPE ( Figure 5). This form is diagnosed directly after birth (Grahn et al 2004) or during retinal maturation, i.e. approximately in Week 6 of life (Aguirre et al 1972;Martin 2010).…”