Photos courtesy Phil Zeltzman, DVM Although many colleagues use local blocks routinely, one body part is all too often neglected—the testicle. Yet, intratesticular blocks are easy, cheap and effective. They have been shown to lower inhalant anesthesia requirements during castration, thereby improving the patient’s cardiovascular and respiratory status, and also lead to a lower pain score after surgery. Performing an Intratesticular Block All you need is lidocaine, bupivacaine, a syringe and needles. The patient is in dorsal recumbency, anesthetized, clipped and scrubbed. Aseptically draw up the lidocaine first, then the bupivacaine, and place a new needle on the syringe. Stabilize one testicle with one hand and place the needle into the cranial third of the testis, going from the caudal pole to the cranial aspect of the testicle, so you are inserting the needle along the long axis of the testicle. As you approach the cranial pole of the testicle, you will be close to the spermatic cord, which will be stimulated by your hemostat or your ligature. Aspirate to verify you are not in a blood vessel. Inject less than half of the volume of the syringe as you slowly draw it back. You should feel quite a bit of resistance, as the testicle is a dense organ to begin with. Replace the needle, and rinse and repeat with the second testicle. A fraction of the local anesthetic drugs can be saved to block the skin incision (incisional block). Your favorite castration technique can be performed about 5 minutes after the block is injected. This is the time is takes for the local anesthetic drugs to diffuse into the spermatic cord. This has been shown with 1 radioactive lidocaine.1 This gives you time to scrub in, gown up, glove up and get your instruments ready. Intratesticular block in a dog. What the Studies Show One double-blinded study2 compared the results of using lidocaine versus saline in dogs. Dogs who received lidocaine had a significant lower heart rate and mean arterial pressure intraop. They received fewer rescue doses of opioids peri- and postoperatively. They had decreased pain scores compared to the placebo group. No adverse effects were noted. A similar double-blinded study3 was performed on cats. Lidocaine was injected intratesticularly and subcutaneously. The results were comparable to those of the dog study; the heart rate and mean arterial pressure increased less in cats with a local block. Another study1 showed that injecting bupivacaine and giving an epidural provided fairly comparable analgesia. Pain scores were lower after surgery in dogs who received the block. Again, intratesticular blocks are easy, cheap and effective. They belong to the multimodal analgesia protocol of any progressive practice. So kick your patient care up a notch, and use testicular blocks! Dosages, Characteristics 1 mg/kg lidocaine: has a rapid onset (5 to 10 minutes) but a short duration of action (1 to 2 hours) 1 mg/kg bupivacaine: has a slower onset time (15 to 30 minutes) but a longer duration of action (3 to 12 hours) Materials Needed Two or three 0.5- to 1.5-inch, 22- to 25-gauge needles • One 1- to 3-milliliter syringe 2 percent lidocaine 0.5 percent bupivacaine Cost Breakdown According to Dr. Bob Stein, founder and webmaster of the Veterinary Anesthesia & Analgesia Support Group (vasg.org), your cost for an intratesticular block with lidocaine and bupivacaine should be around: 14 cents for an 11-pound (5 kg) patient 71 cents for a 55-pound (25 kg) patient $1.55 for a 121-pound (55 kg) patient Add a few pennies for the syringe, and this goes to show you that cost should not be a limiting factor. References TE Perez et al. “Effects of intratesticular injection of bupivacaine and epidural administration of morphine in dogs Intratesticular block in a cat.undergoing castration.” JAVMA 2013; 242(5):631- 642. V Huuskonen et al. “Intratesticular lidocaine reduces the response to surgical castration in dogs.” Vet. Anaesth. Analg. 2013; 40(1):74-82. ER Moldal et al. “Intratesticular and subcutaneous lidocaine alters the intraoperative haemodynamic responses and heart rate variability in male cats undergoing castration.” Vet. Anaesth. Analg. 2013; 40(1):63-73. Dr. Phil Zeltzman is a board- certified veterinary surgeon and author. His traveling practice takes him all over Eastern Pennsylvania and Western New Jersey. Visit his website at DrPhilZeltzman.com, and follow him at facebook.com/ DrZeltzman. Kelly Serfas, a certified veterinary technician in Bethlehem, Pa., contributed to this article.
