Enhanced electroretinogram in cats induced by exposure to mercury acetate

The present study was undertaken in order to verify whether, and how, retinal functions are affected by subacute poisoning with organic mercury. Mercury acetate in various concentrations (0.025-0.25 mg/kg per day) was injected subcutaneously every second day to adult cats (N = 20) throughout a 2.5-4.0-week period. The electroretinogram (ERG) was recorded and the Hg2+ concentrations in the blood were determined. In nearly 90% of the intoxicated cats an enhanced electroretinogram (scotopic b-wave amplitude) was found as compared to its level in the normal control cats (N = 10). The latency of the ERG was found to be appropriately shorter, up to a maximal difference of nearly 20% in comparison to the controls. Hg2+ was present in the blood of the exposed cats during a 2.5-month period following the exposure. It is concluded that exposure to mercury acetate induces a permanent increase in the excitability level of the cat's retina.