Local and Regional Anesthesia for Gastrointestinal Surgery in Dogs: Are We Blocking All the Pain?

By Steve Mehler, DVM, DACVS

Gastrointestinal surgery can be among the most painful procedures performed in small animal practice. Whether we are performing an exploratory laparotomy, gastrotomy, enterotomy, or intestinal resection and anastomosis, effective perioperative analgesia is essential.

Systemic opioids are frequently the foundation of pain management for these patients. However, regional anesthesia offers an opportunity to reduce nociceptive input, decrease some systemic anesthetic requirements, and potentially improve postoperative comfort.

But there is an important distinction that is sometimes overlooked:

Blocking the abdominal wall is not the same as blocking the intestines.

Understanding that difference is essential when selecting regional anesthetic techniques for gastrointestinal surgery.

Understanding the Two Major Sources of Abdominal Pain

Abdominal surgery produces both somatic and visceral nociception.

Somatic Pain

Somatic nociception originates from structures such as the skin, subcutaneous tissues, abdominal musculature, and parietal peritoneum. It is typically well localized and transmitted through segmental spinal nerves. A ventral midline laparotomy creates substantial somatic nociceptive input as the surgeon incises and manipulates the abdominal wall. Regional techniques such as transversus abdominis plane (TAP) blocks, rectus sheath blocks, and local incisional infiltration primarily target this component.

Visceral Pain

Visceral nociception arises from structures such as the stomach, intestines, mesentery, and visceral peritoneum. It is associated with stimuli including distension, traction, ischemia, and inflammation. Visceral afferent pathways differ from those supplying the abdominal wall. Much of the nociceptive input from the gastrointestinal tract travels through autonomic-associated afferent pathways before entering the spinal cord.

Consequently, a technically successful abdominal wall block does not necessarily provide meaningful visceral analgesia.

This becomes particularly relevant during intestinal manipulation, mesenteric traction, or gastrointestinal resection.

1. Incisional Local Anesthetic Infiltration

Local anesthetic infiltration is among the simplest and most accessible regional analgesic techniques. Local anesthetics such as lidocaine, bupivacaine, or ropivacaine may be administered into tissues surrounding the planned incision or during wound closure, depending on the clinical situation and selected protocol.

These medications block voltage-gated sodium channels, interrupting propagation of action potentials along peripheral nerves.

Potential Advantages

Incisional infiltration is relatively straightforward, inexpensive, and does not require specialized ultrasound equipment. When administered before surgical incision, it can reduce nociceptive transmission associated with tissue injury.

Its limitations include variable distribution, finite duration of action, and the inability to reliably address visceral nociception. Injection into highly vascular tissues can also increase systemic absorption.

Clinical consideration: Incisional infiltration can be a valuable component of multimodal analgesia, but it should not be considered sufficient analgesia for an enterotomy or intestinal resection.

2. Transversus Abdominis Plane (TAP) Blocks

The TAP block has become an important regional anesthetic technique for abdominal surgery in dogs. The technique involves depositing local anesthetic within the fascial plane between the internal oblique and transversus abdominis muscles.

Thoracolumbar nerves contributing to abdominal wall innervation travel within or near this plane.

Ultrasound guidance allows the clinician to identify relevant muscular layers and observe local anesthetic distribution.

Depending on the approach, injection sites, and distribution of anesthetic, TAP blocks may provide analgesia to portions of the ventral and lateral abdominal wall. However, a single injection does not necessarily provide complete coverage of a long ventral midline incision.

What Does the Evidence Show?

A particularly interesting randomized study published in 2025 compared three approaches in dogs undergoing laparoscopic ovariectomy:

● Ultrasound-guided TAP block

● Ultrasound-guided quadratus lumborum block

● No regional block

The researchers evaluated cardiovascular responses to different surgical stimuli.

For abdominal wall incision, the proportion of dogs demonstrating a defined cardiovascular response was 70% for the no block group, 20% for the quadratus lumborum group, and 0% for the TAP block group. These results suggest that TAP blocks can effectively attenuate nociceptive responses associated with abdominal wall incision. However, neither regional technique eliminated cardiovascular responses associated with pneumoperitoneum or ovarian traction. This is an important observation.

A TAP block may provide effective somatic analgesia while leaving clinically relevant visceral nociceptive input intact. The study also highlights several limitations that should be considered before applying its findings to gastrointestinal surgery.

First, the study evaluated dogs undergoing laparoscopic ovariectomy, not intestinal surgery.

Second, cardiovascular responses are indirect measures of nociception rather than direct measurements of conscious pain. Finally, the study was relatively small, and its findings should not be interpreted as demonstrating that TAP blocks eliminate all incisional pain. Nevertheless, it provides a useful physiological demonstration of the distinction between somatic and visceral nociception.

Clinical Application in GI Surgery

For a stable dog undergoing exploratory laparotomy, a properly performed TAP block may be a valuable component of perioperative analgesia. However, during enterotomy, gastrotomy, or intestinal resection and anastomosis, the patient may still experience significant visceral nociceptive stimulation despite an effective abdominal wall block.

The TAP block should therefore be considered an adjunct to systemic analgesia, not a replacement for it.

3. Rectus Sheath Blocks

The rectus sheath block is another regional technique particularly relevant to ventral midline abdominal surgery. Local anesthetic is deposited within the rectus sheath, generally between the rectus abdominis muscle and its posterior fascial boundary where anatomically present. The objective is to anesthetize terminal branches of segmental nerves supplying the ventral abdominal wall.

For procedures involving a ventral midline laparotomy, this technique may provide useful somatic analgesia.

However, its distribution is limited by the relevant anatomy, and coverage can vary with injection location and local anesthetic spread. As with TAP blocks, rectus sheath blocks do not reliably provide visceral analgesia.

TAP Block Versus Rectus Sheath Block

The choice depends on the surgical incision and desired distribution of analgesia.

TAP blocks target nerves within the lateral abdominal wall fascial plane, whereas rectus sheath blocks target terminal nerve branches supplying the ventral abdominal wall.

For a midline laparotomy, a rectus sheath block may be anatomically appealing.

However, there is insufficient procedure-specific canine evidence to conclude that one technique consistently provides superior postoperative analgesia following intestinal surgery.

Technique selection should therefore be based on anatomy, surgical approach, patient factors, and clinician experience.

4. Quadratus Lumborum Blocks

Quadratus lumborum (QL) blocks have received increasing attention in veterinary regional anesthesia. These techniques involve ultrasound-guided deposition of local anesthetic in fascial planes associated with the quadratus lumborum muscle.

Depending on the approach and spread of anesthetic, QL blocks may affect nerves supplying the abdominal wall and potentially produce a broader distribution of analgesia than some TAP approaches. There has also been interest in whether certain QL approaches might influence visceral nociception through spread toward paravertebral structures. However, this possibility should not be interpreted as established, consistent visceral blockade in dogs.

The 2025 Fumanelli study is particularly relevant because QL blocks did not eliminate cardiovascular responses to ovarian traction or pneumoperitoneum.

This illustrates why proposed anatomical mechanisms must be distinguished from demonstrated clinical outcomes. Current evidence does not establish that QL blocks reliably provide complete visceral analgesia during canine gastrointestinal surgery.

5. Epidural Anesthesia

Neuraxial anesthesia offers a different approach to perioperative analgesia.

Epidural administration of local anesthetics and selected opioids can modify nociceptive transmission at the spinal level.

Depending on the medication, dose, injection location, and extent of distribution, epidural techniques may affect somatic and visceral nociceptive pathways.

However, the extent of analgesia cannot be assumed from the fact that an epidural was administered.

Why Epidural Spread Matters

A conventional lumbosacral epidural does not automatically provide sufficient cranial distribution to anesthetize the entire abdomen. The spinal segments involved in upper abdominal and gastrointestinal nociception are more cranial than those typically targeted for pelvic limb procedures. Drug distribution can vary substantially among patients. An epidural technique appropriate for pelvic limb surgery may therefore provide inadequate analgesia for an upper abdominal procedure.

Hemodynamic Considerations

Epidural local anesthetics can produce sympathetic blockade and vasodilation, potentially contributing to hypotension.

This is particularly relevant in dogs undergoing emergency gastrointestinal surgery.

Patients with intestinal obstruction, perforation, septic peritonitis, or severe gastrointestinal fluid losses may already have compromised cardiovascular function.

Additional hypotension could further impair tissue perfusion. Other concerns include coagulation abnormalities, infection at the injection site, and patient-specific contraindications. Epidural opioids have different physiological effects from epidural local anesthetics, and their risks and expected analgesic distribution should not be considered interchangeable.

Clinical consideration: Neuraxial techniques may be valuable in selected abdominal surgery patients, but they require careful attention to the desired dermatomal coverage, hemodynamic status, and drug selection.

6. Intraperitoneal Local Anesthetics

Intraperitoneal administration involves delivering local anesthetic into the abdominal cavity. This approach has been investigated in dogs undergoing procedures such as ovariohysterectomy. The proposed mechanism includes local effects on nociceptive pathways associated with the peritoneal surfaces. Unlike TAP or rectus sheath blocks, intraperitoneal administration is not specifically designed to anesthetize abdominal wall nerves.

However, it should not be assumed to produce complete visceral analgesia.

The effectiveness of intraperitoneal local anesthetics may depend on drug selection, concentration, total dose, distribution, contact time, and the type of surgical procedure.

What About Intestinal Anastomoses?

This is an area where caution is appropriate. Evidence obtained from healthy dogs undergoing elective reproductive surgery cannot automatically be extrapolated to patients with intestinal perforation, compromised bowel viability, or fresh gastrointestinal anastomoses. Potential concerns include systemic absorption, effects on injured tissues, and uncertainty regarding direct exposure of healing intestinal structures to particular formulations or concentrations.

There is insufficient high-quality clinical evidence to establish an optimal intraperitoneal local anesthetic protocol specifically for canine intestinal resection and anastomosis.

Therefore, routine application in these patients should not be justified solely by studies involving elective ovariohysterectomy.

7. Regional Anesthesia Does Not Replace Multimodal Analgesia

The fundamental goal of multimodal analgesia is to address nociception through complementary mechanisms. For gastrointestinal surgery, this may include systemic opioids, appropriate local or regional anesthesia, and other analgesic adjuncts selected according to the patient’s condition. Full mu-opioid agonists such as fentanyl, methadone, or hydromorphone are commonly important components of analgesia for major abdominal procedures. Although opioids can decrease gastrointestinal motility, this concern must be balanced against the consequences of inadequate analgesia.

Regional techniques may reduce some systemic anesthetic or analgesic requirements, but opioid-sparing effects demonstrated in elective procedures should not automatically be extrapolated to critically ill intestinal surgery patients.

NSAIDs require particular caution when gastrointestinal integrity, renal perfusion, or cardiovascular stability is compromised. Additional adjuncts may be considered based on the patient’s condition and the available evidence. Importantly, effective analgesia requires ongoing postoperative assessment rather than relying exclusively on the technique selected before surgery.

8. How Would I Approach Different GI Surgical Patients?

There is no single regional anesthetic technique appropriate for every gastrointestinal surgical patient.

Stable Dog Undergoing Exploratory Laparotomy

For a hemodynamically stable patient, an ultrasound-guided abdominal wall block may be a reasonable component of multimodal analgesia. A TAP block, rectus sheath block, or incisional infiltration may be selected according to the incision and available expertise.

Systemic analgesia remains necessary, particularly if significant gastrointestinal manipulation is anticipated.

Dog Undergoing Enterotomy or Gastrotomy

These procedures involve both abdominal wall injury and manipulation of gastrointestinal structures. A successful abdominal wall block may decrease somatic nociception but will not reliably address the visceral component. Systemic analgesia remains essential throughout surgery and recovery.

Dog Undergoing Intestinal Resection and Anastomosis

These patients may experience substantial nociceptive input from intestinal and mesenteric manipulation in addition to the abdominal incision.

The presence of bowel compromise, contamination, or systemic illness may further complicate analgesic selection. An abdominal wall block may still be beneficial, but it should not be viewed as comprehensive analgesia. Particular care is warranted when considering techniques that may affect cardiovascular function or involve direct exposure of compromised intestinal tissues to local anesthetic.

Dog With Septic Peritonitis or Hemodynamic Instability

In these patients, maintaining perfusion and cardiovascular stability is critical.

Regional anesthesia should be selected according to the patient’s current physiology, not simply the surgical procedure. A technique that is appropriate in an otherwise healthy elective surgical patient may introduce additional risk in a hypovolemic or septic dog. The risks of sympathetic blockade, systemic local anesthetic toxicity, and altered drug handling deserve particular consideration.

9. Safety Considerations

Local and regional anesthesia are not risk-free. Local anesthetic systemic toxicity can produce neurological and cardiovascular complications, including seizures, arrhythmias, and cardiovascular collapse.

Risk depends on factors such as drug selection, total dose, injection site vascularity, inadvertent intravascular administration, and patient physiology.

When multiple regional techniques or local infiltration sites are used, the cumulative local anesthetic dose must be calculated.

Additional safety considerations include appropriate monitoring, aseptic technique, ultrasound-guided needle placement when indicated, and readiness to manage complications. Clinicians should also recognize that technically successful needle placement does not guarantee complete or predictable sensory blockade.

10. What Does the Evidence Still Need to Answer?

Despite growing interest in regional anesthesia, important questions remain unanswered for canine gastrointestinal surgery.

We need prospective studies specifically evaluating dogs undergoing enterotomy, gastrotomy, and intestinal resection and anastomosis.

Ideally, these studies would compare clinically relevant outcomes such as postoperative pain scores, rescue analgesic requirements, gastrointestinal recovery, hemodynamic complications, and hospital length of stay. We also need better evidence regarding the safety and effectiveness of regional techniques in dogs with septic peritonitis, hypovolemia, and compromised intestinal tissue. Studies involving elective ovariectomy and ovariohysterectomy provide useful foundational information, but they cannot answer every question relevant to major gastrointestinal surgery.

Conclusion: Treat the Abdominal Wall and the Viscera

Local and regional anesthesia can be valuable components of perioperative analgesia for gastrointestinal surgery in dogs. TAP blocks, rectus sheath blocks, and incisional infiltration can address somatic nociception arising from the abdominal wall.

Neuraxial and intraperitoneal techniques offer additional possibilities, but their effectiveness and safety depend on the approach, medication, and patient.

The 2025 randomized study comparing TAP and quadratus lumborum blocks provides a useful reminder that attenuating responses to an abdominal incision does not necessarily eliminate nociception from visceral manipulation. For dogs undergoing gastrointestinal surgery, effective pain management requires recognition of both components. The goal is not simply to block the incision. It is to provide comprehensive, individualized analgesia throughout surgery and recovery.

References

1. Fumanelli A, et al. Comparison of ultrasound-guided transversus abdominis plane block, quadratus lumborum block, and control in dogs undergoing laparoscopic ovariectomy. Frontiers in Veterinary Science. 2025.

2. Portela DA, Otero PE. Regional anesthetic techniques for abdominal surgery in dogs and cats. In: Grimm KA, Lamont LA, Tranquilli WJ, Greene SA, Robertson SA, eds. Lumb and Jones’ Veterinary Anesthesia and Analgesia. 6th ed. Wiley-Blackwell; 2024.

3. Campoy L, Read MR, eds. Small Animal Regional Anesthesia and Analgesia. Wiley-Blackwell; 2013.

4. Steagall PVM, Robertson S, Simon B, et al. 2022 ISFM consensus guidelines on the management of acute pain in cats. Journal of Feline Medicine and Surgery. 2022;24(1):4–30.

5. Mathews K, Kronen PW, Lascelles D, et al. Guidelines for recognition, assessment and treatment of pain. Journal of Small Animal Practice. 2014.

6. Grubb T, Sager J, Gaynor JS, et al. 2020 AAHA anesthesia and monitoring guidelines for dogs and cats. Journal of the American Animal Hospital Association. 2020.

Clinical note: This review summarizes available evidence and physiological considerations. It is not a validated procedure-specific regional anesthesia protocol. Local anesthetic dosing, contraindications, and technique selection must be individualized. Bibliographic details and primary study findings should be verified against the original publications before formal publication.