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A 3-year-old Thoroughbred was presented for evaluation of hematuria post exercise. On physical examination, an enlarged kidney was identified, as well as serum biochemical abnormalities such as an elevated creatine kinase (CK) and hypoalbuminemia. The kidney was removed laparoscopically and a nephroblastoma was identified.
Ablation d’un néphroblastome par laparoscopie assistée manuellement chez un cheval. Un Thoroughbred âgé de 3 ans est présenté pour évaluation de l’hématurie après l’effort. À l’examen physique, un rein enflé est identifié ainsi que des anomalies biochimiques sériques comme une créatine kinase (CK) élevée et l’hypoalbuminémie. Le rein a été enlevé par laparoscopie et une néphroblastomie a été identifiée.
(Traduit par Isabelle Vallières)
A 3-year-old 500-kg (1100-lb) intact male Thoroughbred was evaluated at the Hagyard Equine Medical Institute because of a recent history of hematuria following exercise. The horse had been treated with nonsteroidal anti-inflammatory agents and antimicrobials. On initial evaluation, the horse was bright, alert, and responsive. Its body condition score was 4/9 (moderately thin). Physical examination and a complete blood (cell) count (CBC) revealed no significant abnormalities. Results of serum biochemical analyses included mildly high creatine kinase activity (855 U/L; reference range: 0 to 350 U/L) and hypoalbuminemia (23 g/L; reference range: 30 to 41 g/L).
Ultrasonographic examination of the right kidney revealed a mass of heterogeneous echogenicity ~10 cm in diameter and involving the cranial pole of the kidney. The mass extended from the cortex into the renal pelvis. Based on the sonogram, differential diagnoses included neoplasia or abscess, although the ultrasonographic appearance and the normal CBC and fibrinogen values were more indicative of a neoplastic lesion. With the history of recent hematuria and the identification of a mass involving the right kidney, surgical removal of the right kidney was recommended.
The horse was fasted for 12 h prior to presentation to the surgical hospital to reduce the volume of ingesta within the digestive tract. The horse’s physical examination was again within normal limits. The horse was sedated with detomidine hydrochloride [0.01 to 0.02 mg/kg, intravenously (IV)] and one 5-mg dose of butorphanol (0.05 to 0.1 mg/kg IV), and restrained within standing stocks with the head cross tied. Additional detomidine was given as needed to maintain sedation. The horse also received 500 mg of flunixin meglumine IV. The right paralumbar fossa was clipped and aseptically prepared with an iodine scrub. Before draping, a 15- to 20-cm vertical line located in the middle of the right paralumbar fossa was infiltrated subcutaneously (SC) and intramuscularly (IM) with 50 mL of 2% mepivacaine. A 10- to 12-cm vertical skin incision was made in the middle of the paralumbar fossa beginning at the level of the dorsal border of the internal abdominal oblique muscle. The subcutaneous tissue and external abdominal oblique muscle were sharply incised, and a modified grid technique was used to expose the peritoneum. The peritoneum was then bluntly penetrated digitally just caudal to the caudal pole of the kidney. With digital manipulation, the opening in the peritoneum was enlarged to allow entry of a hand into the abdomen. With a hand in the abdomen to guard against trauma to adjacent viscera, a 10-mm blunt trocar-cannula unit was inserted through the flank musculature just ventral to the most dorsal margin of the skin incision. Once the trocar-cannula unit entered the abdomen, the trocar was removed. A 320-mm, 0° laparoscope was inserted through the cannula. A laparoscopic injection needle was then inserted through the flank incision, and, with digital manipulation, the tip of the needle was guided in a cranial direction and then dorsal to the duodenum. The tip of the needle was inserted through the peritoneum surrounding the caudoventral aspect of the right kidney. The retroperitoneal space between the right kidney and peritoneum was infiltrated with 20 mL of 2% mepivacaine. Prior to removing the needle from the peritoneum, a small laceration was created in the peritoneum using the tip of the needle. The laparoscopic injection needle was removed, and digital massage of the peritoneum surrounding the right kidney facilitated thorough diffusion of the local anesthetic throughout the retroperitoneal space. The peritoneal laceration was bluntly enlarged digitally, and the right kidney was dissected free from the surrounding retroperitoneal fat to expose the ureter, renal vein and artery. The enlargement of the cranial pole of the kidney was palpable and this region of the kidney dissected easily from the retroperitoneal fat.
To facilitate placement of ligatures around the right ureter and renal artery and renal vein, a sterilized metal ring was attached to size 3, polyglactin 910. The ring was created prior to the surgery by cutting the finger ring from one arm of a mosquito forceps. The cut end of the ring was smoothed and then sterilized for use during this surgery. The 3 polyglactin 910 was attached to the ring by tying a square knot before bringing the ring and suture into the abdomen.
The ureter was double ligated and then transected using laparoscopic scissors. Transecting the ureter allowed easy identification of both the renal artery and vein. Both structures were triple ligated and then transected using laparoscopic scissors. Any remaining soft tissue attached to the kidney was bluntly dissected and the kidney was pulled from the retroperitoneal space into the abdominal cavity. The kidney was manually placed in a sterile plastic bag within the abdomen, to facilitate its removal. The bag with kidney was then removed from the abdomen by pulling the opening of the bag through the abdominal incision. The kidney was removed from the abdominal cavity without complications. The flank incision was lavaged using 1 L of sterile saline. The internal abdominal oblique muscle was closed using 0 Monocryl in a simple continuous pattern. The external sheath of the external abdominal oblique muscle was closed with 2 polydioxone (PDS) in a simple continuous pattern. The skin was closed with 0 Monocryl using a continuous interlocking suture pattern.
The external gross appearance of the kidney revealed marked enlargement of the cranial pole (Figure 1). The renal capsule appeared normal. On cut section, the cranial pole of the kidney contained a well circumscribed white to yellow mass that extended into the renal pelvis (Figure 2). The mass did not appear to erode through the renal pelvis. Histopathology of the mass revealed the mass was a nephroblastoma.
Post-operatively, the horse was treated with antimicrobials including procaine penicillin [22 000 U/kg body weight (BW), IV, q6h] and gentamicin (6.6 mg/kg, IV, q24h). The horse also received flunixin meglumine (1.1 mg/kg BW, IV, q12h). The horse was discharged 48 h after surgery with instructions to continue on antibiotic and anti-inflammatory therapy for another 5 d. The horse’s body condition improved markedly following surgery and the horse was returned to race training 90 d after surgery. Eighteen months after the surgery, the horse was in race training and has raced successfully multiple times at more competitive levels than achieved prior to surgery.
Neoplasias of the equine kidney are not commonly observed and there are few reports of successful surgical removal. In humans, nephroblastomas (embryonal nephroma or Wilms’ tumor) arise from vestigial embryonic tissue and are the most common form of kidney cancer to affect children. In domestic animals, nephroblastomas develop when primitive embryonal renal tissue, metanephric blastema, multiplies out of control, and eventually forms a firm smooth round grayish or tan mass. This type of tumor can contain epithelial, stromal, and blastemal elements (4,5). As they grow larger, these tumors change the normal shape and appearance of the kidney. They can also destroy areas of normal kidney tissue, and cause bleeding into the urine. This was one of the primary clinical signs noted in this horse. Few other signs of renal impairment are observed as the uninvolved kidney undergoes hypertrophy. Rarely is bilateral involvement reported. In some cases, the tumor eventually grows so large that it becomes noticeable as a firm, smooth lump in a patient’s side or abdomen. Without proper treatment, Wilms’ tumor has the potential to spread outside the kidney, most commonly to the lungs and the liver. This is common in children and dogs, but rare in swine. Too few cases have been reported in cats and horses (5). In children, Wilm’s tumors typically have a good prognosis following early surgical removal and subsequent medical management.
Surgical removal of an equine kidney is not a commonly performed procedure. The procedure has previously been described while the horse is anesthetized and using either a rib resection technique or intercostal technique. Unilateral right nephrectomy is performed through a right 16th or 17th rib resection. The intercostal approach to the right kidney was between the 16th and 15th intercostal space (1). For the left kidney, unilateral nephrectomy is performed using either a 17th or 18th rib resection, or a dorsal flank approach (1). Complications with these approaches included poor exposure, post-operative hemorrhage, increased morbidity, and the risks of general anesthesia. One serious complication of the rib resection and intercostal approaches is the potential for intraoperative pneumothorax while under general anesthesia.
Recently, both traditional laparoscopic surgery and hand-assisted laparoscopic surgery (HALS) techniques have been described (2). The hand-assisted laparoscopic nephrectomy technique was previously described for the left kidney, and both kidneys (3,6). This report details a single case of a tumor involving removal of the right kidney. The technique was similar to that described for the left kidney except for the use of a metal ring to facilitate passage of the suture ligatures. This greatly facilitated accurate and efficient placement of the ligatures. Placement of the transected right kidney into a sterile plastic bag also facilitated removal and helped prevent potential abdominal and incisional metastasis.
In conclusion, this report describes a unique case of a renal neoplasia in a horse that was successfully treated with surgery using a standing hand-assisted laparoscopic nephrectomy technique. Surgical removal of the right kidney was performed easily and efficiently with the horse standing using HALS. CVJ
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