Use of a Dog Abdominal Surrogate for Teaching Surgery
D. L. Holmberg, J. R. Cockshutt, and A. W. P. Basher
Drs. Holmberg and Cockshutt are from the Department of Clinical Studies, Ontario Veterinary College, Guelph, Ontario N1G 2W1. Dr. Basher is from the Department of Companion Animals, Atlantic Veterinary College, Charlottetown, P.E.I. C1A 4P3
Currently, in most veterinary institutions, surgical instruction involves the use of animals, either alive or as cadavers. Many veterinary faculty and students question the use of live animals for teaching surgery, and condemnation of this practice by animal welfare groups has been the focus of considerable public attention. This concern has also made it more difficult and expensive to procure animals for teaching purposes. To date, institutions teaching surgery have had three options: ignore public concerns; use cadavers; or use client-owned animals which are presented for recovery surgery. Fighting public opinion can lead to "bad press" for the institution and a number of legal suits have been filed against schools by students who feel that being forced to use live animals is a violation of their rights. Cadavers often have to be stockpiled for varying periods of time prior to their use. This requires freezer space and the thawed tissues are quite abnormal and aesthetically unpleasant. The integration of students into clinical surgery may be the ideal method of teaching but requires considerably more student contact time and larger faculty numbers than are available at most schools. The advanced type of referral case which is seen at most teaching hospitals is also generally considered to be inappropriate for training the novice surgeon.
Although there are some models currently on the market, plastic bones for teaching orthopedics and artificial skin for practicing suturing, there has been no model in general use for teaching abdominal surgery. We therefore developed our own dog abdominal surrogate for instructional exercises (DASIE) and evaluated its acceptance by the undergraduate students in the surgery training programs at the Ontario Veterinary College and the Atlantic Veterinary College.
Materials and Methods
Each DASIE consists of a hollow cylinder of laminated foam rubber and fabric with the ends plugged with a rectangular reinforcement block. The multiple layers of the outer shell are designed to be cut and sutured individually, much like the tissues of the canine abdomen. Colored threads are incorporated between the layers of the DASIE wall to simulate blood vessels that are transected by the skin and subcutaneous incision. These mock vessels can be grasped with hemostats and ligated. Within the cavity of the DASIE is a length of knitted tube that can be handled surgically like small intestine.
The DASIE was integrated into the undergraduate surgery laboratories at the Ontario and Atlantic Veterinary Colleges to teach abdominal draping, aseptic technique, the use of surgical instruments and the rudiments of tissue handling. Prior to the use of the DASIE, students were given the opportunity to practice these skills on a solid block of foam rubber. Following the DASIE laboratory the students performed abdominal surgery on live animals (dogs, sheep or goats). A second DASIE laboratory was performed by the students after their live animal experience.
Following completion of the second DASIE laboratory, a questionnaire was used to evaluate student acceptance of the teaching models. Students were asked to compare the foam block, DASIE and animal, and rate how useful each was for:
1. Learning sterile technique and general operating team roles;
2. Learning sterile draping, including the use of skin edge drapes;
3. Learning to cut tissue in layers to open a body cavity;
4. Learning the use and "feel" of surgical instruments;
5. Learning the control of hemorrhage by ligation of blood vessels;
6. Learning to handle and suture intestinal tissue;
7. Learning to close a body cavity by suturing tissue layers;
8. Learning suture patterns and to tie knots in suture material;
9. An overall learning experience.
Each learning objective was scored for each model; out of a possible five points 1 being the lowest or poorest learning experience and 5 being the highest or best learning experience.
Students were also asked if they agreed with the use of live animals for surgical instruction and were invited to comment, positively or negatively, on the use of the DASIE for teaching the surgery laboratory. The mean values for the responses to each question were calculated and statistical significance was determined by Chi square analysis.
A total of 116 students completed the questionnaire. Ninety-six percent of these students agreed with the use of animals for teaching surgery provided the animals were treated humanely. The results of the questionnaire are shown in Table 1. All mean values within each question were significantly different from each other (P<0.05). Question five (ligation of blood vessels) had fewer responses since only students from the Atlantic Veterinary College used DASIEs containing the artificial blood vessels.
Most comments made by the students were positive and related to what they perceived as reduced stress in the laboratory and their support of decreased animal utilization. Several suggestions were made regarding potential improvements in the design or manufacture of the DASIE. No negative comments were received.
Table 1. Summarized results of question 1-9. Respondents for all questions were from both Universities except "ligation of Blood vessels" which included only students from the Atlantic Veterinary College.
|Mean Learning Value *|
|Learning Objective||Foam Block||DASIE||Animal|
|2.||Use of Surgical Drapes||1.91||3.84||4.89|
|3.||Opening a Body Cavity||1.14||2.88||4.98|
|4.||Use of Surgical Instruments||2.64||3.97||4.73|
|5.||Ligation of Vessels||1.03||1.75||5.00|
|7.||Suturing Tissue Layers||1.18||3.04||4.96|
|9.||Overall Learning Experience||2.43||3.81||4.99|
* Respondents rated the learning value of each learning objective for each model on a scale of 1 to 5- 1 was low and 5 was high.
The results of the questionnaire confirm the impression of the faculty and staff who participated in the training sessions that the DASIE functioned well as an intermediate step between the single layer foam block and the animal. The multiple layers of laminated fabric and foam rubber respond to surgical instruments much like the tissues of the canine abdomen. The layered outer wall and internal tube of "bowel" permit students to practice the various suture patterns used clinically for abdominal, gastrointestinal and urogenital procedures. The "blood vessels" between the layers give the students practice at grasping and ligating specific points of tissue. Because the welfare and survival of the patient is not an issue, the use of the surrogate helps reduce the apprehension that most students feel when first attempting surgery on live animals.
Clean-up following the training exercise is minimized with the DASIE. Students have more time to learn proper surgical technique rather than spending a large portion of their laboratory period washing instruments. Students also have the option of borrowing or purchasing a DASIE to practice their surgical techniques outside the formal laboratory session.
The initial purchase price of a DASIE is approximately one tenth that of a conditioned research dog at our facilities. Because of its cylindrical shape, each surrogate can be rotated to allow six to eight incisions without affecting its teaching value. This multiple-use capability increases the potential cost savings.
As a surrogate, the DASIE was well received by students. We consider them to be an effective, low stress method of preparing for live animal surgery. Its use has reduced the need for animals in teaching abdominal surgery. This follows the philosophical trend of today's society in its demands for non-living teaching models. We suggest the use of an abdominal surrogate as an aesthetically acceptable alternative to live animal or cadaver surgery for some introductory surgical laboratories.
References and Endnotes
1. Rollin BE: Changing social ethics on animals and veterinary medical education. J Vet Med Educ 17:117-84, 1990.
2. Bauer MS, Glickman N, Glickman L, Toombs JP, Bill P: Evaluation of the effectiveness of a cadaver laboratory during a 4th-year veterinary surgery rotation. J Vet Med Educ 19:77-84, 1992.
3. Jennings PB: Alternative to the use of living animals in the student surgery laboratory. J Vet Med Educ 13:14-16, 1986.
4. DeYoung DJ, Richardson DC: Teaching the principles of internal fixation of fractures with plastic bone models. J Vet Med Educ 14:30-31, 1987.
5. Johnson AL, Harai J, Lincoln J, Farmer JA, Korvick D: Bone models of pathological conditions used for teaching veterinary orthopedic surgery. J Vet Med Educ 17:13-15, 1990.
6. Bauer MS, Seim HB: Alternative methods to teach veterinary surgery. Humane Innovations and Alternatives 6:401-404, 1992.
7. Johnson AL, Farmer JA: Evaluation of traditional and alternative models in psychomotor laboratories for veterinary surgery. J Vet Med Educ 16:11-14, 1989.