Flunixin Meglumine Is Superior to Meloxicam for Providing Analgesia after Surgical Castration in 2-Month-Old Goats

Abstract

Farm animals are exposed to various painful procedures during their productive lives, making it necessary to implement anesthetic and analgesic protocols. However, there are few studies evaluating the effectiveness of these drugs. Our objective was to compare the analgesic effects of two nonsteroidal anti-inflammatory drugs (NSAIDs): meloxicam (MEL) and flunixin meglumine (FLU), in goat kids subjected to surgical castration under local anesthesia. Anglo-Nubian goat kids (60 days old) were allocated into two groups: MEL (n = 9), and FLU (n = 8), each administered 5 min before starting castration. All had been previously subjected to local anesthesia with lidocaine, injected bilaterally into the testes, plus subcutaneous in the scrotal raphe. Pain sensitivity was evaluated using the von Frey monofilaments test. Reactions were recorded before castration (M0), immediately after castration (M1), and once-daily for three consecutive days post-castration (M2, M3, and M4, respectively). Pain assessments were conducted in three body regions: at four points of the scrotum (dorsal and ventral; left and right lateral; R1); medial region of the pelvic limb, gracilis muscle (R2); and hypogastric region of the abdomen (R3). MEL goats had considerably greater pain reaction in R1 and R2 over time, mainly in M2; therefore, FLU was a more effective analgesic than MEL, resulting in less pain reaction.

Keywords: Anglo-Nubian goat kids; animal welfare; non-steroidal anti-inflammatory drugs; pain; von Frey monofilament test.

Figure 1

Body regions assessed (R1 = at four points of the scrotum (dorsal and ventral; left and right lateral); R2 = medial region of the pelvic limb (gracilis muscle); and R3 = hypogastric region of the abdomen.) and moments of von Frey filament test assessments (M0 = pre-castration, M1 = immediately post-castration, M2, M3 and M4 = 1, 2, and 3 days after castration, M4, respectively).

Figure 2

Mean force values (g) ± standard deviation of the von Frey filament test obtained in goat kids subjected to a surgical castration procedure under anesthesia and receiving analgesic protocols with meloxicam (MEL: 0.5 mg/kg⁻¹ IM) or flunixin meglumine (FLU: 1.1 mg/kg⁻¹ IM). Assessments were performed just before castration (M0), just after castration (M1), 1, 2, or 3 days after castration (M2, M3, and M4, respectively), in three body regions: (A) scrotum (average of four points), (B) hypogastric region of the abdomen, and (C) gracilis muscle. Notes: Lowercase letters indicate significant differences over time (M0 vs. M1 vs. M2 vs. M3 vs. M4) within the same treatment group (FLU and MEL) and each body region (A: Scrotum, B: Hypogastric region of abdomen, and C: Gracilis muscle). Capital letters represent significant differences between treatments (MEL vs. FLU) within each body region.