Use of a caudal intercostal block in horses undergoing surgery for colic

In humans and companion animals, regional anaesthesia is used in multimodal analgesic protocols for abdominal wall surgery. Benefits include earlier patient mobilisation and improved pain scores. Regional anaesthetic techniques for horses undergoing abdominal surgery could provide similar benefits and warrant investigation.

To evaluate the safety and efficacy of a caudal intercostal block for abdominal surgery (CIBAS) in horses undergoing surgery for colic.

Blinded, randomised clinical trial.

Horses (n = 22) undergoing exploratory celiotomy for colic were randomly assigned to receive CIBAS (1 mg/kg bupivacaine, 1 μg/kg epinephrine and 1 μg/kg dexmedetomidine), or an equivalent volume of saline (control). Recovery quality was assessed by blinded personnel using a semi-quantitative rubric. Pain scores for the first 24-h postoperatively were assigned by blinded observers trained to use validated composite visceral and facial pain scales. A Chi-square test for trend was used to compare recovery scores between groups, and an unpaired t-test was used to compare the area under the curve (AUC_0-24h) for composite pain scores between groups.

Horses receiving CIBAS had significantly better recovery scores than those in the saline group (median 3, IQR [3, 4] p = 0.05). CIBAS horses also had significantly lower AUC_0-24h pain scores (243.9; 95% CI [172.1, 315.8]) than horses receiving saline (331.1; 95% CI [233.9, 428.4] p = 0.0002).

Unstandardised anaesthetic protocols, use of a semiquantitative recovery score, CIBAS not tested for efficacy, and small sample size.

CIBAS is safe to perform. Horses that received CIBAS had significantly better recovery scores and significantly lower pain scores over the first 24-h postoperatively, compared to horses that received saline. Supplies to perform the block are inexpensive and accessible to most clinicians. CIBAS can be considered a safe option in horses undergoing exploratory celiotomy.