Characterizing an ideal experimental canine model for penile sentinel lymph node identification

Objective: Develop and evaluate a canine experimental model of penile sentinel lymph node (SLN) detection using a combination of patent blue dye (PB) and technetium99m phytate (99mTc). Methods: The experiment sampled healthy adult male mongrel dogs (N=19; 10-20 kg). After approval by the local ethics committee, we injected99mTc in the glans penis along the midline raphe. After 10 min, PB was injected in the same region. Ten minutes later, we identified hot spots within the inguinals and iliac artery areausing a gamma probe. We dissected identified sites to quantify the radiation at the SLN in vivo and ex vivo and accounted for the stained and unstained nodes. We analyzed the results for statistical significance and determined the level of agreement between the two methods. Results: SLNs were detected in 94.76% of the cases using PB and 99mTc. There was no difference (p>0.05) between the SLNs-count on the left and the right side. However, PB and 99mTc correlated well on the right side (kappa index: 0.642) and perfectly on the left side (kappa index: 1), indicating a high level of consistency. Conclusion: The experimental canine model of penile SLN, in our study, was shown to be feasible.