Electroretinographic measures and their correlation with retinal vascular calibers in bitches with pyometra-induced systemic inflammatory response syndrome.

Pyometra is characterized by a uterine inflammatory process that leads to systemic inflammatory response syndrome (SIRS). Bitches with pyometra-induced SIRS (P-SIRS) develop marked retinal microvascular alterations that may affect ERG findings. Therefore, this study aimed to assess potential changes in implicit times, wave amplitudes in pyometra-induced SIRS. Furthermore, we evaluated possible correlations between retinal vascular calibers and ERG parameters in the same patients. A prospective observational study was conducted on 14 bitches diagnosed with P-SIRS and 10 clinically healthy bitches (CG). In the P-SIRS group, the caliber of the retinal arterioles was significantly smaller (p = 0.0004), whereas venules were significantly larger (p = 0.008). The amplitude of the a-wave in the mixed rod-cone response was significantly smaller in the P-SIRS group compared to the CG (p = 0.03). The a-wave implicit times in the mixed rod-cone response were negatively correlated with both retinal arteriolar (p = 0.01) and venular (p = 0.03) calibers (Table 5; Fig. 3). Positive correlations were also observed between arteriolar (p = 0.04) and venular (p = 0.01) calibers and photoreceptor negative response (PhNR). This study demonstrated that retinal arteriolar constriction and venular dilation in pyometra-induced SIRS reduces the a-wave amplitude in the mixed rod-cone response. The observed correlations between retinal vascular calibers and the implicit times of the a- and b-waves, as well as between PhNR and vessel calibers, suggest that SIRS-induced changes in retinal vasculature can alter retinal blood flow, which is reflected in ERG parameters.