The effect of surgery on lymphoscintigraphy drainage patterns from the canine brachium in a simulated tumor model

Objective To determine the effect of surgery on lymphoscintigraphy drainage patterns from the canine brachium. Study design Experimental study. Animals Eight healthy research beagles. Methods A predefined area of skin measuring 2 × 1.5 cm in dimension was designated on either the right or left brachium. Preoperative lymphoscintigraphy was performed with technetium sulfur colloid injected into the subcutaneous tissues around the predefined anatomic location in a four‐quadrant technique. Dogs underwent surgery for excision of the predefined area of skin, subcutis, and fascia of the lateral head of the triceps muscle with 1‐cm margins. Eighteen days after surgery, lymphoscintigraphy was again performed with technetium sulfur colloid injected into the subcutaneous tissues around the surgical scar in a four‐quadrant technique. Results Sentinel lymph nodes were identified in eight of eight dogs preoperatively and in eight of eight dogs postoperatively. Agreement between the results of the preoperative and postoperative lymphoscintigraphy studies was identified as complete in four of eight dogs and partial in four of eight dogs. Sentinel lymph node identification occurred immediately in three of eight dogs preoperatively and in eight of eight dogs postoperatively. Conclusion Sentinel lymph node identification occurred faster postoperatively. Agreement or partial agreement between the results of the preoperative and postoperative lymphoscintigraphy studies was observed in eight of eight dogs. Clinical significance Surgery appears to have an effect on lymphoscintigraphy drainage patterns. Additional studies are required to compare preoperative and postoperative sentinel lymph node mapping patterns in tumor‐bearing dogs. However, this study provides preliminary information regarding the effect of surgery on sentinel lymph node identification.