• Cause: Stargardt disease is a genetic retinal degenerative disease affecting the Labrador Retriever. It is caused by an ABCA4 loss-of-function mutation, which results in accumulation of lipofuscin deposits in the retinal pigment epithelium (RPE). It causes progressive vision impairment dogs. The mutation is a single nucleotide insertion (c.4176insC), that leads to a premature stop codon in exon 28.
• Signs: progressive retinal atrophy-like clinical signs with mydriasis and reduction in vision in dim lighting initially.
• Diagnosis: based on genetic testing and clinical signs of retinal degeneration in the Labrador Retriever.
• Treatment: none available although gene therapy is being developed for humans.
• Prognosis: slowly progressive vision loss over years.

Presenting signs

• Labrador Retriever with slowly progressive vision loss. Initially poor vision is in dim lighting conditions but gradually over time, vision in bright light is also reduced.
• Mydriasis.
• Reduced pupillary light reflexes.
• Tapetal hyporeflectivity and hyperreflectivity.

Acute presentation

• This is not an acute condition but may be acutely noticed.

Geographic incidence

• First reported cases from Sweden. Worldwide.

Age predisposition

• There are low case numbers. The condition is thought to begin in middle age but may not be noticed until more advanced disease is present in the older dog (10 years). The signs and symptoms worsen over time.

Gender predisposition

• None reported.

Breed/Species predisposition

• Labrador Retriever Retriever: Labrador is the only canine breed that has been reported to be segregate the ABCA4 c.4176insC mutation ed to date.

Public health considerations

• None.

Cost considerations

• No treatment is possible.

Special risks

• The ABCA4 c.4176insC mutation is recessive, so breeding two heterozygotes/carriers could produce homozygous/clinically affected dogs. Breeding a carrier to a clear dog will result in approximately 50% of the litter being carriers and 50% being clear. Carriers and clear dogs will not be clinically affected themselves but carriers will pass the mutation to approximately half of their offspring.