Retinopathy of Unknown Etiology in Greyhounds

In the Literature

Price PSA, Hunt H, Cox NR, Mitchell NL, Irving AC. Retinopathy in greyhound dogs: prevalence, fundoscopic, and histopathological findings. Vet Ophthalmol. 2023. doi:10.1111/vop.13153

The Research …

Fundic lesions have been described in a small set of greyhounds in Australia and the United States,^1,2 and similar lesions have been identified in working dogs in New Zealand, with one report associating lesions with ocular larval migrans.^3,4 Retinopathies of unknown etiology have also been described in other breeds,^5,6 with a report in border collies suggesting X-linked inheritance.⁷

In this study, the prevalence of retinopathy (ie, abnormal changes to the retina) in greyhounds (n = 200) in the Manawatu/Whanganui region of New Zealand was examined. All dogs underwent fundoscopy and fundic photography, and retinal histopathology was performed on the eyes of 7 greyhounds with previously diagnosed ophthalmoscopic retinopathy.

Fifty greyhounds were diagnosed with retinopathy of unknown cause. Males were more likely than females to be affected bilaterally and have more severe lesions. Lesions ranged from mild chorioretinal scars that did not affect vision to severe retinal atrophy and blindness and included well-circumscribed, focal, multifocal, or geographic areas of tapetal hyperreflectivity with variable pigmented foci. Dogs with retinopathy were more likely to have abnormal pupillary light reflexes, and one dog with severe retinopathy had a negative menace response. Retinopathy was not associated with racing status, stakes, or number of racing starts. Multifocal retinal detachment was identified in 5 of the 7 dogs in which histopathology was performed.

… The Takeaways

Key pearls to put into practice:

• Dogs with retinopathy may be behaviorally visual with a normal menace response. Retinopathy is thus best diagnosed via dilated fundic examination and indirect fundoscopy.

• Prevalence of retinopathy was high in this study but historically has been low in greyhounds (1%-7% in the United States) and other sighthounds (eg, <1% in whippets in the United States).^2,8

• Retinopathy has many potential causes (eg, infectious, inflammatory, toxic, inherited). Inherited retinopathies are of particular concern for future breed health; dogs with these conditions should not be bred.

• Although retinopathy may not be treatable, it may be preventable if an underlying cause is identified and addressed.

• If a dog with retinopathy does not have a breed predisposition for inherited retinopathy and/or is clinically ill, a diagnostic investigation to rule out systemic causes of retinopathy (eg, hypertension, neoplasia, diffuse unilateral subacute neuroretinitis from larval migrans) and referral to an ophthalmologist are recommended.

• The American College of Veterinary Ophthalmologists Blue Book provides information on breed-specific diseases and disease prevalence.⁸