Felis ISSN 2398-2950

Retina: taurine-deficient retinopathy

Contributor(s): Dennis E Brooks, David Williams

Introduction

  • First reported in 1970.
  • Cause: chronic dietary taurine deficiency.
  • Signs: blindness; bilateral mydriasis and absent pupillary light reflexes.
  • Diagnosis: signs, measurement of [plasma taurine].
  • Treatment: supplementation of diet with taurine.
  • Prognosis: depends on severity of lesions and on concurrent systemic (cardiac) disease.

Pathogenesis

Etiology

  • Diet deficient in the amino acid taurine Taurine.
  • Possibly also defect in taurine absorption in animals on diets with adequate taurine.

Specific

  • Feeding canned food since there is a higher dietary requirement for taurine in canned than dry food.

Pathophysiology

  • Unique to cats and ferrets due to their reduced ability to produce taurine from casein.
  • Occurs in cats fed diets deficient in taurine or its precursors.
  • First recorded in cats fed on dog food.
  • Initial bilateral central retinal degeneration   →   atrophy of affected area   →   involvement of entire retina.
  • Some animals may also develop dilated cardiomyopathy Heart: dilated cardiomyopathy (DCM).
  • Taurine is an amino acid.
  • There are a number of hypotheses as to how deficiency causes disease:
    • It may function as a neurotransmitter in retina.
    • It may stabilize cell membranes via a role in calcium ion transport across cell membranes.
  • As taurine is depleted from tissues during prolonged deficiency   →   progressive retinal degeneration   →   photoreceptor cells die as [retinal taurine] < 50% normal. Cones are affected first, then the rods.
  • Deficiency also increases platelet aggregability   →   predisposes to thromboembolism Thromboembolism: aorta, and reduces absorption of lipids   →   reduced absorption of fat soluble vitamins.
  • Retinal changes are typical in this condition.
  • A focal ovoid hyperreflective lesion develops in the area centralis lateral to the optic disc  Retina: taurine deficient retinopathy 01 - experimental DSH .
  • A second lesion then develops on the medial side of the disc and as the 2 lesions enlarge they fuse Retina: taurine deficient retinopathy 03 - experimental DSH .
  • Ultimately the whole fundus is affected with hyper-reflectivity and blood vessel attenuation Retina: taurine deficient retinopathy 07 - advanced (experimental DSH) .

Timecourse

  • Animals progress to total blindness over 1-2 years if not treated.

Diagnosis

This article is available in full to registered subscribers

Sign up now to purchase a 30 day trial, or Login

Treatment

This article is available in full to registered subscribers

Sign up now to purchase a 30 day trial, or Login

Prevention

This article is available in full to registered subscribers

Sign up now to purchase a 30 day trial, or Login

Outcomes

This article is available in full to registered subscribers

Sign up now to purchase a 30 day trial, or Login

Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Schmidt S Y, Berson E L, Hayes K C et al (1976) Retinal degeneration in the taurine-deficient cat. Trans Am Acad Ophthal Otolaryngol 81 (4 pt 1), OP687-693 PubMed.

Other sources of information

  • Petersen-Jones S & Crispin S (2002) BSAVA Manual of Small Animal Ophthalmology. 2nd edn. British Small Animal Veterinary Association. ISBN 0 905214 54 4


ADDED