Canis ISSN: 2398-2942

Retina: sudden acquired retinal degeneration syndrome

Synonym(s): SARDS

Contributor(s): David L Williams, David Gould

Introduction

  • Signs: sudden onset blindness or rapidly progressive blindness over a period of days, often accompanied by Cushingoid signs (polydipsia, polyuria, weight gain over preceding months).
  • Diagnosis: history, clinical signs, ophthalmoscopy, hematology, biochemistry, adrenal axis testing, sex hormone testing, electroretinography (ERG).
  • Treatment: no treatment possible.
  • Prognosis: visual prognosis is poor, with permanent loss of sight. Systemic signs (PU/PD) may spontaneously reduce over a period of months in some cases.

Pathogenesis

Etiology

  • Etiology is not known. A significant number of cases (40-60%) show Cushingoid systemic signs but the etiopathogenic link with Cushing's is unclear; only 12-17% of cases can be confirmed with Cushing's Hyperadrenocorticism based on adrenal axis testing. However, 85% have elevated sex hormones.

Predisposing factors

General
  • Overweight, middle-aged, female, small breed dogs.
  • Association with Cushing's syndrome is some cases.

Specific

  • None known.

Pathophysiology

  • Sudden loss of photoreceptor function - both rods and cones equally affected.
  • Cause is unknown but presumed to be a toxic 'knockout' of rod and cone photoreceptors.
  • Retinal toxicity due to aberrant endogenous corticosteroid production has been proposed as a potential mechanism. Corticosteroids have been shown to be retinotoxic in some species, and the link with Cushingoid signs may point to a similar mechanism in dogs.
  • In humans, a similar condition of sudden onset blindness may be associated with cancer-associated retinopathy. However, there is no evidence of this in dogs.

Timecourse

  • Acute onset.

Epidemiology

  • Unknown.

Diagnosis

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Treatment

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Outcomes

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Carter R T, Oliver J W, Stepien R L, Bentley E (2009) Elevations in sex hormones in dogs with sudden acquired retinal degeneration syndrome (SARDS). JAAHA 45 (5), 207-214 PubMed.
  • Montgomery K W, van der Woerdt A, Cottrill N B (2008) Acute blindness in dogs: Sudden acquired retinal degeneration syndrome versus neurological disease (140 cases, 2000-2006). Vet Ophthalmol 11 (5), 314-320 PubMed.
  • van der Woerdt, Nasisse & Davidson (1991) Sudden acquired retinal degeneration in the dog. Prog Vet Comp Ophthal 1, 11-18.

Other sources of information

  • Cullen C L, Webb A A (2007)Ocular Manifestations of Systemic Disease.In:Gelatt's Veterinary Ophthamology. 4th edn. Gelatt K N (ed). Blackwell Publishing, Iowa, US. pp 1470-1537.


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