There are many applications for use of rigid and flexible endoscopic instrumentation in examination of small animal patients. Rigid endoscopy will be discussed first in these seminar notes. Use of rigid endoscopes for performing laparoscopy (an excellent method for examination and biopsy of the liver, pancreas, and kidneys), vaginoscopy, urethroscopy and cystoscopy in female dogs and cats, rhinoscopy, thoracoscopy, arthroscopy, endoscopy in birds, reptiles, amphibians, and fish, and otoscopy is increasing as awareness of the myriad procedures that can be done with this type of instrumentation increases.

Clinical Applications of Rigid Endoscopy

Many veterinarians are not as well aware of the large number of applications for rigid endoscopy in their practice as they are for flexible GI endoscopy. Rigid endoscopy offers tremendous versatility. Modern rod-lens optical systems offer excellent light transmission, exceptional resolution and contrast, greater magnification than earlier model rigid telescopes, and a wide field of view. Rigid telescopes open up an enormous new field of minimally invasive diagnostic and therapeutic possibilities to veterinary practitioners.

While laparoscopy for examination and biopsy of the liver, kidneys, and pancreas has been a standard procedure in some university and specialty practices for over 20 years, there have been significant advances in other rigid endoscopy techniques in more recent years. The most significant advances include techniques in thoracoscopy, urethroscopy and cystoscopy in female dogs, arthroscopy, endoscopy in exotic animal species, and minimally invasive surgery. Laparoscopy is discussed in a separate section in this proceedings.

Cystoscopy, Thoracoscopy, and Arthroscopy

With rigid endoscopic instrumentation unparalleled views of the entire urethra and urinary bladder can be attained in female dogs and cats (narrow diameter flexible scopes are used for males). Urethroscopy/cystoscopy is the procedure of choice for diagnosis of ectopic ureter and neoplasia and routinely provides important clues in the diagnosis of patients with unexplained hematuria (e.g., small stones that were not identified with other diagnostic modalities can easily be seen at cystoscopy).Thoracoscopy provides very consistent results in the diagnosis of intrathoracic pathology and has been shown to be an excellent means of performing partial pericardectomy for dogs with pericardial effusion. Partial pericardectomy is performed using instrumentation passed through three small incisions, and patient recovery is more rapid than after thoracotomy. Instruments (telescope, grasper, scissors) are advanced and manipulated through cannulas which are placed through the body wall. Veterinary surgeons have developed excellent techniques for performing arthroscopic examination and therapeutic procedures of the shoulder, elbow, carpus, hip, stifle, and tarsal joints. Arthroscopy is clearly superior for diagnosis of bicipital tendon injuries and for complete exploration of the stifle joint. At arthroscopy intraarticular soft tissue and cartilage that is not apparent on radiographs can be examined under magnification. Visualization of most structures is better than with arthrotomy. Operative arthroscopic procedures include OCD lesion removal, removal of fractured coronoid process, bone chip removal, meniscectomy, partial synovectomy, and bicipital tendon resection. It is anticipated that over the next five years many more specialty and high-end general practices will begin to offer these and other rigid endoscopy techniques.

Minimally Invasive Surgery

Minimally invasive surgery is a collective term for surgical techniques designed to minimize the extent of an anatomic approach while maintaining precision and efficiency. In human medicine this began with laparoscopic cholecystectomy in 1988 and hundreds of thousands of procedures have now been performed world-wide. Veterinary surgeons have worked closely with physicians and industry in developing the tools and technology that have enabled many procedures to be developed and perfected. Although minimally invasive surgery is still in its infancy in veterinary medicine, it holds great potential and there are many advances to come. A textbook describing endoscopic surgical techniques for animal patients was published in 1998 (Veterinary Endosurgery, edited by Lynetta J. Freeman, DVM , published by Mosby-Year Book). Information described includes basic endosurgical techniques, minimally invasive hernia repair, and surgery of the gastrointestinal system, hemolymphatic system, reproductive system, urinary system, techniques for nondomestic animals, and arthroscopy.

Selection of Rigid Endoscopic Instrumentation

A majority of rigid endoscopic procedures can be performed with two scopes, a 2.7 mm 30-degree oblique viewing scope and a 5 mm forward viewing (0-degree) scope. The 2.7 mm scope is used for rhinoscopy, cystoscopy in female dogs, arthroscopy, avian and exotic species endoscopy, and can be used for laparoscopy in cats and small dogs. The 5 mm scope is ideal for laparoscopy of any size dog or cat. Ancillary equipment for performing rigid endoscopy includes a light source, insufflation unit for laparoscopic procedures, and a variety of operating instruments (biopsy forceps, palpation probe, grasping forceps, special sheaths for birds and reptiles, etc.). Use of a camera when performing rigid endoscopy is essential. The camera is attached to the eyepiece of the telescope and the endoscopist then views a significantly enlarged image on a video monitor. Most of the standard equipment, including light source, camera, and light guide cables can be used for all endoscopic procedures in a practice.

Overview of Flexible GI Endoscopy

Currently the most common flexible endoscopic procedures performed both in specialty and general practices are upper and lower GI endoscopy, mostly for the purpose of direct examination and biopsy of selected areas of the GI tract. Endoscopy is highly efficient in retrieval of gastric foreign bodies. There are many animals seen in private practices that could benefit from earlier diagnosis of gastrointestinal disorders, considering the large number of animals with intermittent or persistent symptom patterns that require biopsy of the GI tract as part of the process for determining a definitive diagnosis (e.g., chronic gastritis, inflammatory small bowel disease, colitis, irritable bowel syndrome, GI neoplasia). Indeed, it is much easier to convince a client relatively early in the diagnostic process to approve endoscopy for procurement of biopsies than it is if exploratory surgery (much more invasive) is the recommended method of obtaining tissue samples.

Selection of Flexible GI Instrumentation

Two very important considerations when evaluating equipment for purchase are optics quality and ergonomics (with respect to ease of handling and the maneuverability capabilities of the endoscope). Too often veterinarians purchase equipment of lesser quality because the (lower) price is more attractive. My advice is to buy excellent quality instrumentation and then spend whatever time and energy is necessary to become proficient in its use. Veterinarians will be able to do excellent work and will be much happier over the long term when using high quality instruments.

Many types of endoscopes are available. A standard endoscope for upper and lower GI endoscopy in dogs and cats should be a minimum of 100 cm long (working length) and have four-way distal tip deflection with at least 180-degrees upward deflection, water flushing, air insufflation and suction capabilities, independently locking deflection controls, an accessory (working) channel with a diameter of 2 mm or greater, and forward-viewing optics. The ideal diameter of the insertion tube for small animal general practices is 7.8 to 9.0 mm. Larger diameter scopes are available, but it is more difficult to advance them through the pylorus, especially in cats. The latest model endoscopes made specifically for animals have insertion tube lengths of 140 to 150 cm. These longer endoscopes are highly versatile as the extra length (compared to the standard size 100 cm length scopes that are used for upper GI endoscopy in people) provides sufficient length for the endoscope to be advanced to the small intestine in even the largest of dogs, while the diameter (7.9 to 8.5 mm range) is small enough to traverse the pylorus of most cats. The newer endoscopes are therefore quite useful as a single scope for performing all types of GI procedures in dogs and cats of any size.

Endoscopic Video Cameras and Accessories

Video is one of the most significant new endoscopic technologies. When the endoscopic image is displayed on a video monitor, the endoscopist is able to work more comfortably and share information during a procedure with any number of observers. A video image is produced by attaching a camera to the eyepiece of the endoscope. The endoscopist then views a significantly enlarged image on a video monitor. Other advantages of using video include the ability to document procedures in various forms (e.g., print, videotape, and slide) which can be enormously useful for client relations; medical records; and referral, teaching, or consulting purposes. High quality color prints documenting endoscopic findings can be provided to clients and referring veterinarians and used for inclusion in the patient's medical record.

Endoscopy Training Courses

The best way to become proficient in various endoscopic procedures is to participate in lecture and wet lab training courses. Getting "hands-on" experience under the supervision of experienced endoscopists can significantly shorten the learning curve and aid in the development of excellent technique. Textbooks and CD programs (www.Lifelearn.com)relating to endoscopy in small animal patients are also available. Attending several courses, rather than just one, to review and gain increased proficiency in techniques of interest is advised and well worth the financial investment involved.

References

1.  Chamness CJ. Endoscopic instrumentation. In Tams TR (ed): Small Animal Endoscopy. St. Louis, Mosby, 1999, pp 1-16.

2.  Sherding RG, Johnson S, and Tams, TR. Esophagoscopy. In Tams TR (ed): Small Animal Endoscopy. St. Louis, Mosby, 1999, pp 4696.

3.  Tams TR. Gastroscopy. In Tams TR (ed): Small Animal Endoscopy. St. Louis, Mosby, 1999, pp 97-172.

4.  Tams TR. Endoscopic examination of the small intestine. In Tams TR (ed): Small Animal Endoscopy. St. Louis, Mosby, 1999, pp 173-216.

5.  Willard MD. Colonoscopy. In Tams TR (ed): Small Animal Endoscopy. St. Louis, Mosby, 1999, pp 217-245.