ISSN 2398-2969      

Retina: dysplasia

icanis

Introduction

  • Abnormal development and growth of the retina resulting in retinal folds, rosettes and sometimes retinal detachment Retina: detachment.
  • Cause: inherited in many dogs, acquired forms develop from insults experienced in utero or soon after birth.
  • Signs: no clinical signs with mild forms; blindness Blindness with severe forms; one form is accompanied by skeletal chondrodysplasia.
  • Diagnosis: signs, ophthalmoscopic examination.

Pathogenesis

Pathophysiology

Multifocal retinal dysplasia

  • Separation of the neural retina from the underlying retinal pigment epithelium (RPE), probably via dysplastic development. 
  • Retina is thrown up in folds.
  • Folds may number a few to many.
  • Primarily located in the dorsal tapetal retina, adjacent to the dorsal artery and vein.

Geographic retinal dysplasia

  • Involve larger areas of the retina and are more rounded or patchy in shape. Duplication of retinal layers may occur, with formation of retinal rosettes.
  • In working strains of the English springer spaniel the lesions are difficult to differentiate from post-inflammatory lesions.
  • Cataract formation and intra-ocular hemorrhage may also be seen.

Total retinal detachment

  • The retina is so dysplastic that is does not remain attached to the retinal pigmented epithelium.
  • The neural retina is often seen lying within the vitreous humor.
  • Hyaloid remnants may be a feature of this condition thus resulting in the subsequent formation of cataracts Cataract.
  • Some dogs (eg Labrador retriever, German shepherd dog, Samoyed) also have skeletal chondrodysplasia Carpus: osteochondrodysplasia and are achondrodysplastic dwarfs.

Acquired dysplasia

Inheritance patterns

  • Inheritance patterns are variable.
  • Many forms of multifocal dysplasia are suspected to be autosomal recessive traits.
  • Skeletal and ocular abnormalities are believed to be carried by one gene, with recessive effects on the skeleton and incompletely dominant effects on the eye.
  • Genetic mutations responsible for oculoskeletal dysplasia in the Labrador Retriever (drd1) and the Samoyed (drd2) have been identified, and genetic tests are available through Optigen (www.optigen.com/opt9_rdosd.html).
  • In the Labrador Retriever and the Samoyed, the study concluded that heterozygotes may exhibit a milder ocular phenotype that ranges from vitreal strands and/or localized retinal dysplasia characterized by focal or multifocal folds, to large plaques of dysplastic retinal tissue. Heterozygotes may not have any skeletal abnormalities.

Diagnosis

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Treatment

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Outcomes

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Further Reading

Publications

Refereed papers

  • Recent references from VetMed Resource and PubMed.
  • Goldstein O, Guyon R, Kukekova A et al (2010) COL9A2 and COL9A3 mutations in canine autosomal recessive oculoskeletal dysplasia. Mammalian Genome 21 (7-8), 398-408 PubMed.
  • Long S E, Crisp S M (1999)Inheritance of multifocal retinal dysplasia in the golden retriever in the UK. Vet Rec 145,702-704.
  • Holle D M, Stankovics M E, Sarna C R et al(1999)The geographic form of retinal dysplasia in dogs is not always a congenital abnormality. Vet Comp Ophthalmol 2, 61-66.
  • Carrig C B, Sponenberg U P, Schmidt G M et al(1988) Inheritance of associated ocular and skeletal dysplasia in Labrador retrievers. J Am Vet Med Assoc 193, 1269, 1998.
  • Myers V N, Jesyk G D, Aguirre G et al(1983) Short-limbed dwarfism and ocular defects in the Samoyed dog. J Am Vet Med Assoc 183,975.
  • Carrig C D, MacMillan A, Brundage S et al(1977) Retinal dysplasia associated with skeletal abnormalities in Labrador retrievers. J Am Vet Med Assoc 170,49.

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