The effect of photodynamic therapy on cisterna chyli patency in rats.

OBJECTIVE: To radiographically and histologically evaluate the effects of photodynamic therapy on the cisterna chyli in rats. STUDY DESIGN: Experimental study. ANIMALS: Adult male Sprague-Dawley rats (n = 60). METHODS: Cecal lymph nodes were injected with the photodynamic compound verteporfin. A 690 nm, 500 mW diode laser was then directed at the area of the cisterna chyli for either 0, 1.5, or 3 minutes. Cisterna chyli patency was evaluated using lymphography, and histologic changes were evaluated on postoperative Days 1, 3, 5, 7, and 14. RESULTS: Histologically, minimal to marked injury to the cisternal and/or pericisternal tissues was present in all treated rats at all time periods. Radiographically, 8/20 cisternae were occluded in the 1.5-minute treatment group (including 1/4 on Day 1, 2/4 on Day 3, 3/4 on Day 5, 0/4 on Day 7, and 2/4 on Day 14), and 9/20 cisternae were occluded in the 3-minute treatment group (including 0/4 on Day 1, 1/4 on Day 3, 3/4 on Day 5, 3/4 on Day 7, and 2/4 on Day 14). There was minimal to no histologic evidence of tissue injury in control rats. All control cisternae were radiographically open. CONCLUSIONS: Further investigations into the timing of laser application and light dose, or alternative photodynamic agents are required to limit injury to adjacent tissues and to improve the effectiveness of cisternal photoablation.

Laparoscopic-assisted colpotomy for ovariectomy in the mare.

OBJECTIVE: To describe a technique for ovariectomy through a colpotomy using a chain écraseur with laparoscopic guidance and report outcome in 4 mares. STUDY DESIGN: Case series. METHOD: After insertion of a laparoscope into the abdomen through the left flank, colpotomy was performed to allow introduction of an écraseur into the caudal aspect of the abdomen. Grasping and removal of the ovary and evaluation of the pedicle was observed via the laparoscope. The laparoscope was then inserted in the right flank for right ovariectomy. The colpotomy was closed in a continuous suture pattern using laparoscopic or long needle holders. RESULTS: Insertion of a laparoscope allowed ready identification of the ovaries and capture within an écraseur, including assurance that no other tissues were contained within écraseur chain. The mesovarial pedicles were easily be examined for hemorrhage. Surgical time for ovariectomy was 10-15 minutes with no postsurgical complications. Closure of the colpotomy healed without complications. CONCLUSION: Laparoscopic-assisted écraseur ovariectomy is inexpensive, rapid, and a safe alternative to other methods of open and laparoscopic ovariectomy.

Performance of the 808-nm diode laser on equine upper airway tissue is enhanced by intravenous administration of indocyanine green.

OBJECTIVE: The objective was to develop a protocol whereby 808-nm diode laser irradiation combined with intravenous (IV) indocyanine green (ICG) could be used in non-contact mode with equal surgical efficacy to the Nd:YAG on equine tissues. BACKGROUND DATA: The 808-nm diode laser, delivering 20-40 W of power, has been produced for veterinary medical applications. This laser's power output is less than that of most neodymium:yttrium-aluminum-garnet (Nd:YAG) lasers. ICG is absorbed at a wavelength of 810 nm, which when concentrated in tissue should be an excellent absorber for the energy produced by the 808-nm diode laser. METHODS: This study compares the depths and widths of thermal penetration achieved with the 808-nm diode laser in equine respiratory tissue after intravenous injection of ICG. ICG was administered at two doses: 1.5 mg/kg and 3 mg/kg. The 808-nm diode laser and Nd:YAG laser were set to deliver 200 J of energy. The depths and widths of thermal penetration obtained were compared. RESULTS: Lesion depth and width tended to be greater in the ICG + 3 mg/kg group than in the ICG + 1.5 mg/kg group. Even so, the 1.5-mg/kg dose substantially increased the efficacy of the diode laser. Plasma ICG concentrations peaked at 5 min post-administration and then dropped markedly; lesion depth decreased after peaking at 7 min post-administration. CONCLUSION: This study demonstrated that the 808-nm diode laser, when augmented with intravenous ICG, will be as effective a surgical tool as the Nd:YAG laser on equine upper airway tissues when applied using a non-contact fiber.

Anatomic reference for computed tomography of the head of the foal.

The purpose of this study was to produce an anatomic reference for computed tomography (CT) of the head of the foal for use by radiologists, clinicians, and veterinary students. The head from each of 2 foals, euthanized for reasons unrelated to head pathology, was removed and prepared for CT scanning. Using a third-generation CT scanner, 5-mm contiguous transverse images were acquired. The heads were then frozen and sectioned using a band saw, with the cuts matched as closely as possible to the CT slices. The anatomic sections were photographed and radiographed. The radiographs and anatomic photographs were digitized and matched with the corresponding CT image. Each CT image was compared with its corresponding radiographic and anatomic section to assist in the accurate identification of specific structures. Clinically relevant structures were identified and labeled in corresponding images (CT, anatomic slice, and radiograph of slice). Only structures identified in the CT image were labeled in 1 of the other 2 images. Sagittal (reference) images of the horse's head were reconstructed from the transverse CT scans, and were used to indicate the level from which each of the transverse images was obtained. Corresponding labeled images were then formatted together with a legend for identification of specific anatomic structures.