Study suggests single-site flank block may simplify bovine anesthesia
Bottom line
Single-site ventral distal paravertebral block at either L1 or L2 effectively anesthetized the bovine paralumbar fossa in a blinded, randomized crossover study in healthy Holstein steers, according to a new JAVMA report by investigators at North Carolina State University. The study evaluated a simplified, single-injection approach using 2% lidocaine, rather than the multiple injections typically required for distal paravertebral anesthesia. In conference proceedings that appear to match the published work, both L1 and L2 approaches anesthetized the paralumbar fossa in 6 of 7 steers, while the L1 approach was more likely to stain the T13 nerve, suggesting somewhat broader cranial coverage. (wcvaa-2025.com)
Why it matters: For bovine practitioners, the appeal is practical: a single-site technique could reduce procedure time, needle passes, and handling compared with traditional multi-injection flank blocks, while still achieving usable regional anesthesia for standing flank procedures. That said, the evidence base is still early and small, and the work was done in 5-month-old healthy steers under experimental conditions. Existing literature still frames distal paravertebral anesthesia as a block of T13, L1, and L2, and flank anesthesia in cattle remains a space where clinicians balance reliability, tissue distortion, speed, and field conditions. (wcvaa-2025.com)
What to watch: Watch for follow-up studies in adult cattle, clinical surgical cases, and head-to-head comparisons with standard distal or proximal paravertebral techniques before this becomes a routine field recommendation. (2025acvimforum.eventscribe.net)
Key facts
- Study type
- Blinded, randomized crossover study
- Species
- Healthy Holstein steers
- Sample size
- 7 steers
- Intervention
- Single-site ventral distal paravertebral block at L1 or L2
- Drug
- 2% lidocaine plus methylene blue
- Dose
- 6 mg/kg
- Main finding
- Both L1 and L2 anesthetized the paralumbar fossa in 6 of 7 steers
- Additional finding
- L1 stained the T13 nerve more often than L2, 6 of 7 versus 1 of 7
A new JAVMA study suggests that a single-site ventral distal paravertebral block may be enough to anesthetize the bovine paralumbar fossa, potentially simplifying a procedure that traditionally requires multiple injections. The work, led by Madeline Butterfield, Lydia Love, and Earl G. Ford, tested single injections at L1 or L2 and found both approaches produced successful flank anesthesia in most steers studied. (wcvaa-2025.com)
That matters because paralumbar fossa anesthesia is foundational for standing bovine flank surgery, including procedures such as laparotomy and cesarean section. Conventional options include line blocks, inverted-L blocks, and proximal or distal paravertebral techniques, each with tradeoffs. Paravertebral blocks are often favored because they avoid injecting anesthetic directly into the incision site, but they can be technically demanding and typically involve blocking multiple nerve branches across T13, L1, and L2. (skat.ihmc.us)
In the conference abstract corresponding to the published study, seven healthy Holstein steers were enrolled in a randomized, blinded crossover design. Each steer received a ventral distal paravertebral block with 6 mg/kg of 2% lidocaine plus methylene blue at either L1 or L2. Investigators assessed anesthesia with needle-prick testing along a standard paralumbar fossa incision line, then later characterized staining of the T13, L1, and L2 spinal nerves by dissection. Both L1 and L2 injections anesthetized 6 of 7 steers, but T13 staining was much more frequent with the L1 approach, 6 of 7 versus 1 of 7 at L2. (wcvaa-2025.com)
The findings build on a broader line of work from the same research group around bovine regional anesthesia. In prior JAVMA research, investigators compared lidocaine alone with lidocaine-xylazine mixtures for distal paravertebral anesthesia in dairy cattle, and later reported that adding xylazine could prolong block duration in steers. More recent abstracts also suggest continued refinement of paravertebral techniques, including comparisons of 3-site versus 4-site distal blocks and additive strategies for proximal blocks. Taken together, the field appears to be moving toward techniques that are not just effective, but also more durable and easier to perform in practice. (pubmed.ncbi.nlm.nih.gov)
Direct outside commentary on this specific paper was limited in the material available online, but the broader professional conversation is active. An ACVIM Forum session in 2025 on paralumbar fossa anesthesia highlighted “latest updates on nerve block methods” and framed the area as one of ongoing practical refinement for cattle practice. That’s consistent with the interest this study is likely to generate: if a single-injection technique can reliably cover the flank, it could be attractive for ambulatory and production-animal settings where efficiency matters. (2025acvimforum.eventscribe.net)
Why it matters: For veterinary professionals, the promise here is operational as much as pharmacologic. A single-site ventral distal paravertebral block could mean fewer injections, less time at the chute, and potentially less variability tied to repeated needle placement. It may also preserve one of the main advantages of paravertebral anesthesia over line infiltration, namely less distortion of tissues at the surgical site. Still, clinicians should be cautious about overgeneralizing. The study population was small, consisted of young healthy steers, and measured experimental anesthesia success rather than outcomes in real-world surgical patients such as adult dairy cows undergoing cesarean section or exploratory laparotomy. (wcvaa-2025.com)
Another practical consideration is coverage. Traditional teaching emphasizes blockade of T13, L1, and L2 for reliable paralumbar fossa anesthesia, and this study’s staining data suggest the L1 approach may better capture T13 than L2. That could matter in procedures where cranial flank desensitization is especially important. In other words, the simplified approach looks promising, but exact injection site selection may still influence how dependable the block is across the full surgical field. (wcvaa-2025.com)
What to watch: The next step is clinical validation: larger studies in adult cattle, direct comparisons with standard distal and proximal paravertebral blocks, and outcomes tied to actual standing surgeries will determine whether this technique stays an interesting experimental advance or becomes a practical new standard in bovine anesthesia. (2025acvimforum.eventscribe.net)