Collie eye anomaly

From Dog
Choroid hypoplasia in a Collie[1]

Collie eye anomaly (CEA; congenital posterior segment anomaly) is an autosomal-recessive genetic ocular disease of dogs characterized by choroidal hypoplasia, retinal detachment, intraocular hemorrhage and coloboma of the retina, uvea, sclera or optic disc[2] and neuroretinal non-attachment.

Other ocular anomalies associated with this condition were distichiasis, persistent pupillary membranes, distinct remnants of the hyaloid artery, corneal dystrophy and unilateral cataracts[3].

CEA is inherited as an autosomal recessive trait that has a penetrance reaching 100 percent, and has been located to canine chromosome 37.

Prior to selective breeding programs to eliminate this disease from collie breeds, incidences of CEA in Collies were as high as 60% of breeding stock[4].

As the name suggests, this disease is frequently observed in the Collie breeds but also occurs in other breeds such as the Hokkaido dog[5], Border Collie, Shetland Sheepdog, Lancashire Heeler[6] and Australian Shepherd[7], where coloboma and microphthalmia also occur[8].

Dogs may show a wide variety of clinical symptoms and severity of lesions, often localized to defects (coloboma) of choroidal development in the temporal quadrant of the ocular fundus[9].

Many dogs exhibit no obvious clinical consequences and retain apparently normal vision throughout life, while severely affected animals develop secondary retinal detachment, intraocular hemorrhage, and blindness[10].

At risk dogs can be tested from 10 weeks of age[11].

A tentative diagnosis can be attained with ophthalmic fundoscopy with characteristic choroidal hypoplasia in the bilateral temporal area adjacent to the optic nerve head, appearing as whitish areas.

Confirmation usually requires PCR and DNA testing of blood samples for the CEA-associated mutation[12].

A definitive diagnosis would include multifocal retinopathy, progressive retinal atrophy and persistent hyperplastic tunica vasculosa lentis in the Doberman[13].

There is no treatment for this condition and dogs blinded by this condition are often euthanized.

References

  1. TSH
  2. Walser-Reinhardt L et al (2009) Collie Eye Anomaly in Switzerland. Schweiz Arch Tierheilkd 151(12):597-603
  3. Stades FC & Barnett KC (1981) Collie eye anomaly in collies in the Netherlands. Vet Q 3(2):66-73
  4. Bedford PG (1982) Collie eye anomaly in the United Kingdom. Vet Rec 111(12):263-270
  5. Mizukami K et al (2012) Collie eye anomaly in Hokkaido dogs: case study. Vet Ophthalmol 15(2):128-132
  6. Bedford PG (1998) Collie eye anomaly in the Lancashire heeler. Vet Rec 143(13):354-356
  7. Munyard KA et al (2007) A retrospective evaluation of congenital ocular defects in Australian Shepherd dogs in Australia. Vet Ophthalmol 10(1):19-22
  8. Lowe JK et al (2003) Linkage mapping of the primary disease locus for collie eye anomaly. Genomics 82(1):86-95
  9. Lowe JK et al Linkage mapping of the primary disease locus for Collie eye anomaly. Genomics 82:86–95
  10. Rampazzo A et al (2005) Collie eye anomaly in a mixed-breed dog. Vet Ophthalmol 8(5):357-360
  11. Wallin-Håkanson B et al (2000) Collie eye anomaly in the rough collie in Sweden: genetic transmission and influence on offspring vitality. J Small Anim Pract 41(6):254-258
  12. Chang HS et al (2010) A novel rapid genotyping technique for Collie eye anomaly: SYBR Green-based real-time polymerase chain reaction method applicable to blood and saliva specimens on Flinders Technology Associates filter paper. J Vet Diagn Invest 22(5):708-715
  13. Leppänen M & Saloniemi H (1998) Screening and controlling canine inherited ocular diseases in Finland: epidemiological, economical and health promotional aspect. Vet Ophthalmol 1(4):203-210