Interventional radiology (IR) and interventional endoscopy (IE) use various imaging modalities to allow guided therapeutics. Traditionally, imaging and endoscopy have been used for diagnostic purposes. This specialty uses images to guide interventions and are therefore at once diagnostic and therapeutic. IR and IE offer minimally invasive treatments for a variety disorders. Small to no incisions, decreased pain, shorter anesthesia times, faster recovery and few post-operative limitations are some of the advantages. In some cases, IR and IE can be used when no good standard of care options are available (for example transjugular coil embolization of an intrahepatic shunt that cannot be reached in surgery, chemoembolization of nonresectable tumors). IR and IE also offer lots of interesting options for exotic, zoo and farm animal patients.

The main disadvantages of IR and IE are the advanced materials and technical expertise required to perform many of the procedures. An initial large investment is necessary to start offering IR and a steep learning curve exists. Therefore, limited availability for some of these procedures has been problematic in veterinary medicine. As the demand grows, training of professionals and availability will likely increase. A dedicated textbook and society (Veterinary Interventional Radiology and Interventional Endoscopy Society, www.viries.org) exists.¹ The society’s mission is to promote training and research in IR and IE. Veterinary IR and IE has primarily focused on the development of procedures for the urinary tract, respiratory tract, and the vascular system.

Urinary Tract/Endourology

Endourology refers to the specialty of urology in which endoscopes, fluoroscopy and other instruments are used to access, under direct visualization, structures inside the urinary tract. The entire urogenital system can be accessed from the vulva, through the urethra, into the bladder, up the ureter and into the renal pelvis. As opposed to traditional surgery, access is most commonly achieved through natural orifices and the procedures are done internally either without or with minimal external incisions. The following algorithm can be used to aid in the decision-making process.

Figure 1. Decision making algorithm in the evaluation of a patient with urinary tract disease (VIN editor note: Figure not available at time of publication).

Some upper urinary tract interventions that will be presented: percutaneous nephrolithotomy, ureteral stenting, subcutaneous ureteral bypass, extracorporeal shock wave lithotripsy. Some lower urinary tract interventions that will be presented: intracorporeal lithotripsy, urethral stenting, laser ablation of ectopic ureters, laser ablation of bladder/urethral masses, percutaneous cystolithotomy, hydraulic occlude, cystoscopic urethral bulking agents.^2,3

Respiratory Interventions

The respiratory system can be readily accessed by endoscopy in most dogs and cats. Laser turbinectomy, nasopharyngeal stenting, tracheal and bronchial stenting will all be discussed.¹

Vascular Interventions

The central venous and arterial systems are readily accessible through access to the femoral artery/vein, jugular vein or carotid artery. The portal vein can be accessed in the presence of portocaval shunting. The treatment of vascular occlusions (thrombectomy, angioplasty, stenting) will be discussed.^4,5

Other Species

IR and IE procedures can often be done in farm animals under sedation and an epidural, thus avoiding general anesthesia. Zoo animals can greatly benefit from the short recovery times and lack of post-operative care. Reptiles can be treated through their natural orifices thus avoiding prolonged incision site recovery and avoiding cutting the plastron in turtles and tortoises. Ureteroscopy and lithotripsy in pigs, goats, horses, guinea pigs and ferrets will be presented along with tracheal and ureteral stenting in ferrets and rabbits.^6,7

References

1.  Weisse C, Berent A. Veterinary Image-Guided Interventions. Ames, IA: Wiley-Blackwell; 2015.

2.  Dunn M, Berent A. Chapter 124. Interventional urologic therapies. In: Textbook of Veterinary Internal Medicine. 8th ed. Elsevier. 2016:466–417.

3.  Butty E, Vachon C, Dunn M. Interventional urology. Vet Clin Small Anim. 2019;49:287–309.

4.  Dunn M, Scansen B. Interventional radiology management of vascular obstruction. Vet Clin Small Anim. 2018;48:819–841.

5.  Dunn ME. Thrombectomy and thrombolysis: the interventional radiology approach. J Vet Emerg Crit Care. 2011;21(2):144–150.

6.  Coutant T, Dunn M, Montasell X, Langlois I. Use of percutaneous cystolithotomy for removal of urethral uroliths in a pot-bellied pig. Can Vet J. 2018;59:159–162.

7.  Coutant T, Dunn M, Maccolini E, Langlois I. Cystoscopic-guided lithotripsy for the removal of a urethral stone in a guinea pig. J Ex Pet Med. 2019;28:111–114.