State-of-the-Art Lecture: Minimally Invasive Surgery—From Everyday Procedures to the State of the Art
World Small Animal Veterinary Association Congress Proceedings, 2019
P. Mayhew
Department of Surgical and Radiological Sciences, University of California, Davis, CA, USA

Minimally invasive surgery (MIS) in veterinary medicine is experiencing a rapid increase in popularity. These surgical techniques allow veterinary species to enjoy many of the same benefits that humans experience when undergoing less invasive procedures. In this lecture, we will discuss procedures that every general practitioner that performs routine soft tissue surgery can hone his or her skills on as well touch on the state of the art procedures that are being performed at the cutting edge of the field and envisage where MIS will go in the future.

One of the reasons that laparoscopic surgery is very much within the reach of general practitioners in private practice is that many of the routine soft tissue procedures being performed through a celiotomy approach lend themselves very well to a laparoscopic approach. These include elective ovariectomy and ovariohysterectomy, gastropexy, cystotomy, abdominal organ biopsy, and cryptorchidectomy. All that is required to make these procedures a success in every practice is an initial investment in some specialized equipment and enough passion for the topic to go out and seek additional training in the field. Because the fundamental knowledge of anatomy and surgical technique are already in place when you are performing surgery routinely there is no reason to fear making the switch to laparoscopy for some of these procedures. Furthermore, because these are routine surgical procedures, most practices will have the necessary caseload to ensure a business plan can justify the financial outlay required to purchase good quality equipment to initiate an MIS program in most practices.

Laparoscopic procedures can be broadly separated into totally laparoscopic procedures and laparoscopic-assisted procedures. As the name suggests totally laparoscopic procedures involve all necessary manipulations being performed within a closed body cavity. Laparoscopic-assisted procedures involve the telescope and instruments aiding in the process of exteriorization of an organ through a small “assist” incision allowing the surgeon to operate on that organ outside the body cavity.

Laparoscopic-assisted procedures are a good way to start the learning curve for certain procedures that lend themselves well to this approach such as gastrointestinal biopsy, gastropexy and ovariohysterectomy. The assisted approaches are simpler to perform and are a good steppingstone to totally laparoscopic procedures or the more advanced laparoscopic procedures. There are also some procedures where a laparoscopic procedure can be performed in the early stages of the learning curve before moving on to the more technically challenging but perhaps more advantageous to the patient, totally laparoscopic approaches. A good example of one of these procedures might be the totally laparoscopic gastropexy technique. An essential skill that is taught to all prospective human MIS surgeons is intracorporeal suturing. While this has received relatively little attention in the veterinary literature to date it has recently been made simpler by the development of the barbed sutures (e.g., VLOCä, QuilläAND Stratafixä). These sutures avoid the need for laborious intracorporeal knot-tying and have simplified procedures such as totally laparoscopic gastropexy that was first described by the author in 2009.1 Intracorporeally-sutured gastropexy has now been described by several authors2-4 and represents a step forward in the development of a minimally invasive gastropexy. It has been shown that dogs undergoing totally laparoscopic gastropexy return to normal activity more rapidly compared to those undergoing traditional laparoscopic-assisted gastropexy.1

As surgeons gain greater and greater skill in laparoscopy more advanced surgical interventions can be mastered. Small numbers of LS have been described in experimental and clinical canine patients in the literature.5-7 The principal indication for splenectomy in cats and dog is for resection of potentially neoplastic lesions, which in many cases can be very large. If splenic size and/or lesion size is substantial a careful assessment needs to be made as to whether a laparoscopic approach is recommended. One difficulty with this procedure is that physical manipulation of heavy organs can be challenging laparoscopically and care has to be taken not to cause iatrogenic rupture of splenic lesions, which could lead to seeding of neoplastic cells within the abdominal cavity. However, there is a significant subset of dogs and cats that present for splenectomy that have smaller lesions or diffuse splenic disease that may be good candidates for this procedure. Both multiport,5 single port6 and laparoscopic-assisted splenectomy7 have now been described. In this author’s opinion single-port splenectomy is best designed for small dogs and cats and larger dogs with larger masses are most easily treated using the laparoscopic-assisted technique.

Laparoscopic adrenalectomy is another procedure performed regularly in humans for resection of both adrenocortical tumors as well as pheochromocytomas and lends itself very well to veterinary patients.8-12 We have performed this procedure now in >80 dogs and around 10 cats and feel that it can be performed efficiently, safely and with a very low complication and conversion rate. Case selection is absolutely paramount in these cases with careful exclusion of cases that have vascular invasion into the caudal vena cava being critical. For this reason, we always perform a CT angiogram study pre-operatively to rule out vascular invasion. Tumors up to 5 cm can readily be excised with experience although early in the learning curve it is better to select smaller masses that are technically less challenging to resect. We believe that LA is one procedure that lends itself so well to a laparoscopic approach that in the future, adrenal gland tumors might be routinely approached in this fashion, by those with the appropriate equipment and experience.

Thoracoscopic surgery offers an exciting new modality for treatment of a variety of thoracic disease processes. In humans suggested advantages of VATS include a reduced volume of thoracic drainage, less post-operative pain, shorter hospital stay and a more rapid return to normal function. Limited objective comparisons of “open” versus VATS procedures have been reported in the veterinary literature but similar advantages are likely to be present in small animal patients. The most common interventions performed in veterinary thoracoscopy include pericardectomy, lung lobectomy, thoracic duct ligation and cranial mediastinal mass resection amongst others. The level of complexity increases with thoracoscopic interventions and familiarity with open thoracic surgery is obviously an advantage in these cases. While some procedures such as pericardectomy and thoracic duct ligation can be performed just using the pneumothorax that occurs when open chest cannulae are introduced into the chest, lung resection usually requires the use of specialized anesthetic techniques such as one-lung ventilation which increases the complexity of the case and requires careful anesthetic monitoring.

We can only guess where veterinary minimally invasive surgery will go in the future. We have many perceived limitations compared to the human MIS field but innovation and technology often surprise us with their ability to break down theoretical barriers to progress. I envision MIS developing much rapidly in veterinary medicine in the next decade compared to the last as access to high quality equipment and training improves and our clients demand the same procedures for their much loved companion animals as they would want for themselves.


1.  Mayhew PD, Brown DC. Prospective evaluation of two intra-corporeally sutured prophylactic laparoscopic gastropexy techniques compared to laparoscopic-assisted gastropexy in dogs. Vet Surg. 2009;38:738–746.

2.  Spah CE, Elkins AD, Wehrenberg A, et al. Evaluation of two novel self-anchoring barbed sutures in a prophylactic laparoscopic gastropexy compared with intracorporeal tied knots. Vet Surg. 2013;42:932–942.

3.  Takacs JD, Singh A, Case JB, et al. Total laparoscopic gastropexy using 1 simple continuous barbed suture line in 63 dogs. Vet Surg. 2017;46:233–241.

4.  Coleman KA, Monnet E. Comparison of laparoscopic gastropexy performed via intracorporeal suturing with knotless unidirectional barbed suture using a needle driver versus a roticulated endoscopic suturing device: 30 cases. Vet Surg. 2017;46:1002–1007.

5.  Shaver SL, Mayhew PD, Steffey MA, et al. Short-term outcome of multiple port laparoscopic splenectomy in 10 dogs. Vet Surg. 2015;44:71–75.

6.  Mayhew PD, Sutton JS, Singh A, et al. Complications and short-term outcomes associated with single-port laparoscopic splenectomy in dogs. Vet Surg. 2018. doi: 10.1111/vsu.12752.

7.  Wright T, Singh A, Mayhew PD, et al. Laparoscopic-assisted splenectomy in dogs: 18 cases (2012–2014). J Am Vet Med Assoc. 2016:248:916–922.

8.  Pelaez MJ, Bouvy BM, Dupre GP. Laparoscopic adrenalectomy for treatment of unilateral adrenocortical carcinomas: techniques, complications and results in seven dogs. Vet Surg. 2008;37:444–453.

9.  Naan EC, Kirpensteijn J, Dupre GP, et al. Innovative approach to laparoscopic adrenalectomy for treatment of unilateral adrenal gland tumors in dogs. Vet Surg. 2013;42:710–715.

10.  Mayhew, PD, Culp WTN, Hunt GB, et al. Comparison of perioperative morbidity and mortality rates in dogs with non-invasive adrenocortical masses undergoing laparoscopic versus open adrenalectomy. J Am Vet Med Assoc. 2014;245:1028–1035.

11.  Pitt KA, Mayhew PD, Steffey MA, et al. Laparoscopic adrenalectomy for removal of unilateral non-invasive pheochromocytomas in 10 dogs. Vet Surg. 2015;45:070–076.

12.  Mitchell JM, Mayhew PD, Culp WTN, et al. Outcome of laparoscopic adrenalectomy for resection of unilateral noninvasive adrenocortical tumors in 11 cats. Vet Surg. 2017;46:714–721.


Speaker Information
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Philipp D. Mayhew, BVM&S, MRCVS, DACVS
Department of Surgical and Radiological Sciences
University of California
Davis, CA, USA

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