# Ultrasound-Guided Celiac and Mesenteric Nerve Block in Dogs


## Key Takeaways

- The ultrasound-guided celiac and cranial mesenteric nerve block targets visceral afferent pathways originating from the stomach, liver, pancreas, and proximal duodenum, providing analgesia for conditions like pancreatitis and gastrointestinal neoplasia. This technique is distinct from abdominal wall blocks such as the transversus abdominis plane (TAP) block, which anesthetizes somatic pain.
- Key sonographic landmarks for this block include the origin of the celiac artery from the aorta, typically visualized in a sagittal or parasagittal plane, often described as a "seagull sign" when the celiac and cranial mesenteric arteries are imaged together. Echogenic needles are recommended for improved visibility, particularly with an in-plane insertion technique.
- Principal complications include intravascular injection, intraneural injection, and inadvertent puncture of adjacent viscera. Real-time ultrasound guidance is crucial for visualizing the needle tip, injectate spread, and adjacent vascular structures to mitigate these risks.
- Injectate volumes are extrapolated from cadaveric studies and current formularies, with a starting point of 0.2 to 0.5 mL/kg of local anesthetic (e.g., bupivacaine or ropivacaine) injected slowly. Perineural dexamethasone may be considered as an adjuvant to prolong analgesia, though species-specific evidence in dogs is limited.
- Patient selection is critical, contraindicating coagulopathy, local infection, hemodynamic instability, or hypersensitivity to local anesthetics. Dogs with profound hypovolemia or sepsis may be at risk of hypotension due to sympathetic blockade.
- Documentation should meticulously record procedural details, including patient information, indication, equipment used, injectate composition and volume, and post-block monitoring findings, adhering to professional imaging and practice standards.

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This article details the ultrasound-guided technique for celiac and mesenteric nerve blockade in dogs, a regional anesthesia approach for visceral pain management. The intended reader is a practicing veterinarian with working familiarity in ultrasound-guided injection procedures and small animal pain management. The article answers how to identify the relevant sonographic landmarks, select equipment, perform the block safely, and recognize complications, while distinguishing this technique from other abdominal wall blocks such as the transversus abdominis plane block.

The celiac and mesenteric plexuses carry nociceptive afferent fibers from the abdominal viscera, including the stomach, liver, pancreas, and proximal intestine. Blockade of these structures provides analgesia for conditions such as pancreatitis, gastrointestinal neoplasia, and visceral pain of non-surgical origin. The technique is performed percutaneously under real-time ultrasound guidance, allowing direct visualization of the needle, injectate spread, and adjacent vascular structures.

## At a Glance

| Parameter | Decision or Fact |
|---|---|
| Primary indication | Visceral pain from cranial abdominal organs, including pancreas, stomach, liver, proximal duodenum |
| Target structures | Celiac and cranial mesenteric plexuses, located periarterially around the celiac artery and cranial mesenteric artery |
| Imaging approach | In-plane needle insertion, real-time ultrasound guidance |
| Key sonographic landmark | Celiac artery origin from the aorta, visualized in a sagittal or parasagittal plane |
| Needle selection | Echogenic needles improve visibility, particularly at steep insertion angles |
| Injectate | Local anesthetic, volume based on patient size and current formulary reference |
| Adjuvant options | Perineural dexamethasone may prolong blockade, though evidence in dogs is extrapolated from human studies |
| Principal complication | Intravascular injection, intraneural injection, or inadvertent puncture of adjacent viscera |

## Anatomic Basis of the Block

The celiac plexus in dogs is a dense network of autonomic nerve fibers and ganglia surrounding the origin of the celiac artery from the abdominal aorta. The cranial mesenteric plexus lies caudal to the celiac artery, surrounding the cranial mesenteric artery. Together these plexuses convey sympathetic and visceral afferent fibers from the abdominal viscera. The afferent fibers travel with sympathetic pathways and enter the spinal cord through the splanchnic nerves and thoracic dorsal roots.

The celiac artery in the dog arises from the ventral aspect of the aorta at the level of the first lumbar vertebra, immediately caudal to the diaphragm. The cranial mesenteric artery originates approximately 1 to 2 cm caudal to the celiac artery. Both vessels course ventrally and slightly caudally from the aorta. The plexuses envelop these arteries, making the arterial walls the primary sonographic target for injectate deposition.

Ultrasound imaging in a sagittal plane through the cranial abdomen reveals the aorta as a long, anechoic tubular structure with hyperechoic walls. The celiac artery appears as a short branch arising from the ventral aortic wall, often described as a "seagull sign" when the celiac and cranial mesenteric arteries are imaged together in a single plane. The surrounding tissue appears moderately echogenic due to the retroperitoneal fat and connective tissue that envelop the plexuses.

## Comparison with Other Abdominal Blocks

The celiac and mesenteric nerve block targets visceral afferent pathways and should not be confused with abdominal wall blocks. The transversus abdominis plane block, for example, deposits local anesthetic in the fascial plane between the transversus abdominis and internal oblique muscles, anesthetizing the ventral branches of the thoracolumbar spinal nerves that supply the body wall. Anatomical studies in canine cadavers have demonstrated that the TAP block reliably stains the ventral branches of T11 through L2, providing somatic analgesia to the abdominal wall but not to the viscera. The subcostal oblique approach to the TAP block improves cranial abdominal wall coverage, staining T9 through T13 ventral branches in a high proportion of injections, but again does not address visceral pain.

For a patient with pancreatitis or other visceral pain syndromes, a celiac plexus block is the more appropriate regional technique. For a patient undergoing laparotomy, a combination of a TAP block for the body wall and a celiac plexus block for visceral structures may be considered. The two techniques are complementary instead of interchangeable.

## Equipment and Needle Selection

Ultrasound guidance requires a machine capable of real-time imaging with a curvilinear or microconvex transducer. Frequencies between 5 and 10 MHz are generally suitable for the depth of the celiac artery in most dogs. A linear transducer may be used in small or thin patients where the target lies within 3 to 4 cm of the skin surface.

Needle visibility is a critical determinant of procedural success. Studies comparing commercially available needles for ultrasound-guided regional anesthesia have shown that echogenic needles, which feature surface modifications that reflect ultrasound waves, are more visible than standard needles, particularly at steep insertion angles. One comparative study in Thiel cadavers found that an echogenic needle design provided the best visibility for ultrasound-guided regional anesthesia across multiple angles and planes of insertion. The same study identified the plane of insertion as an independent predictor of needle visibility, with in-plane insertions generally providing better visualization than out-of-plane approaches.

For the celiac plexus block, an in-plane approach with an echogenic needle is recommended. The needle should be long enough to reach the target from a dorsolateral or ventrolateral entry point, typically 5 to 8 cm in medium-sized dogs. Needle gauge is selected based on the viscosity of the injectate and the patient's size, with 22-gauge needles representing a common choice.

## Pharmacology of the Injectate

Local anesthetics used for this block should provide a duration of action appropriate for the clinical scenario. Bupivacaine and ropivacaine are commonly selected for their longer duration of action compared with lidocaine or mepivacaine. The volume and concentration of local anesthetic should be determined from current formulary and label references, as published dose ranges vary with patient size, body condition, and concurrent disease.

Perineural adjuvants may extend the duration of blockade. Dexamethasone has been studied as a perineural adjuvant in human regional anesthesia, with a randomized, double-blind, placebo-controlled trial demonstrating that perineural dexamethasone prolonged analgesia duration after sciatic nerve blockade compared with placebo. The same study did not find a significant improvement in the quality of recovery score with perineural dexamethasone compared with intravenous administration. Evidence for perineural dexamethasone in dogs is extrapolated from human studies, and the clinician should weigh the potential benefit against the lack of species-specific safety data.

## Safety Considerations and Imaging Standards

The celiac plexus lies in close proximity to the aorta, the caudal vena cava, and the kidneys. The needle path may traverse the peritoneal cavity, and inadvertent puncture of the stomach, duodenum, or pancreas is possible, particularly in patients with distended viscera or altered anatomy from mass lesions. Real-time ultrasound guidance reduces but does not eliminate these risks.

Intraneural injection is a recognized complication of peripheral nerve blockade. Experimental work in pigs has shown that nerve expansion seen on ultrasound during intraneural injection of local anesthetic produces histologic evidence of nerve injury, although functional deficits were not observed in that study. For the celiac plexus block, the target is a plexus instead of a discrete nerve, and the risk of intraneural injection is lower. However, the operator should still monitor for unexpected tissue expansion or resistance to injection and stop if either occurs.

Imaging standards for veterinary ultrasound practice are published by professional bodies such as the American College of Veterinary Radiology, which provides resources on diagnostic imaging practice and specialty standards. The operator should ensure that the ultrasound machine is maintained and that imaging settings are optimized for the tissue depth and patient body condition before beginning the procedure.

## Patient Assessment and Case Selection

The celiac and mesenteric nerve block is best suited to dogs with visceral abdominal pain arising from the pancreas, liver, biliary tract, stomach, duodenum, or proximal small intestine. Candidates include patients with acute pancreatitis, hepatic or biliary disease, gastric dilation without volvulus, and neoplastic infiltration of the cranial abdominal viscera. The block does not provide somatic analgesia, so dogs with concurrent parietal peritoneal pain, abdominal wall involvement, or orthopedic disease will require additional analgesic strategies.

Contraindications include coagulopathy, local infection at the puncture site, hemodynamic instability, and known hypersensitivity to amide local anesthetics. Severe abdominal distension with compromised respiratory mechanics may make the dorsal approach technically difficult and increases the risk of accidental visceral puncture. Dogs with profound hypovolemia or sepsis may not tolerate the sympathetic blockade that accompanies this block, because loss of vasomotor tone can precipitate hypotension. In these patients, defer the block until volume status is optimized or choose an alternative analgesic plan.

Patient positioning depends on the selected approach. The dorsal paravertebral approach is performed with the dog in sternal recumbency, which allows access to the sublumbar region and keeps the abdominal viscera ventrally displaced. The lateral approach uses lateral recumbency with the side of interest uppermost. Both positions require clipping and aseptic preparation of a wide region, extending from the caudal thoracic area to the mid-lumbar region. Sedation is usually necessary. A protocol that provides moderate sedation while preserving spontaneous ventilation is preferred, because the block is performed with the patient awake or lightly sedated in most clinical settings. Deep sedation or general anesthesia may be required for fractious patients, but this removes the ability to monitor for signs of intravascular injection or intraneural injection during the procedure.

## Ultrasound Landmarks and Needle Placement

The celiac and mesenteric ganglia lie adjacent to the aorta at the level of the celiac artery and cranial mesenteric artery origins. The celiac artery arises from the aorta just caudal to the diaphragm, typically at the level of the thirteenth thoracic to first lumbar vertebra. The cranial mesenteric artery originates 1 to 2 cm caudal to the celiac artery. Both vessels are readily identified with a microconvex or curvilinear transducer operating at 5 to 8 MHz in most dogs. A linear transducer at 10 to 15 MHz may be used in small dogs weighing less than 10 kg.

Begin with a transverse scan of the cranial abdomen to identify the aorta in short axis. The aorta appears as a pulsatile, anechoic, thick-walled structure ventral to the vertebral bodies. Follow the aorta caudally until the celiac artery is seen branching ventrally. Rotate the transducer to obtain a long-axis view of the aorta with the celiac artery emerging from its ventral surface. The cranial mesenteric artery is identified immediately caudal to the celiac artery origin. The ganglia are not consistently visible as discrete structures, so the target is the perivascular connective tissue surrounding these arterial origins.

Needle insertion uses an in-plane technique from the left or right side, depending on operator preference and patient positioning. The needle is advanced from lateral to medial, with the tip directed toward the perivascular space between the aorta and the origin of the celiac artery. A 22-gauge, 5 to 8 cm echogenic needle is appropriate for most dogs. Needle visibility is improved with echogenic needles, which have demonstrated superior ultrasound conspicuity compared with standard needles in cadaveric models. The angle of insertion should be kept as shallow as possible, ideally less than 45 degrees to the ultrasound beam, because steeper angles degrade needle visualization.

Aspirate before injection to exclude intravascular placement. Inject in small aliquots of 1 to 2 mL, observing for appropriate hypoechoic fluid spread around the arterial origins. The injectate should appear as an anechoic pocket surrounding the celiac and cranial mesenteric arteries. If the injectate is not visualized, stop and reassess needle tip position. Nerve expansion during injection is a warning sign of intraneural placement and should prompt immediate cessation and needle repositioning.

## Injection Volumes and Distribution

The volume of injectate required to achieve adequate spread around the celiac and mesenteric ganglia has not been established in controlled clinical trials. Extrapolation from cadaveric studies of abdominal wall blocks suggests that volumes of 0.2 to 0.4 mL per kg are commonly used for perivascular injections in dogs, but these data come from transversus abdominis plane blocks and do not directly inform celiac plexus dosing. Current formularies and regional anesthesia atlases should be consulted for recommended volumes and concentrations.

A single injection of 0.25 to 0.5 mL per kg of local anesthetic solution is a reasonable starting point for the celiac and mesenteric block. The solution should be injected slowly over 30 to 60 seconds with intermittent aspiration. If bilateral spread is desired, the injection may be repeated on the contralateral side. The total dose of local anesthetic must be calculated to remain below the systemic toxicity threshold for the selected agent, accounting for all other blocks or infusions the patient is receiving.

Bupivacaine 0.25% or ropivacaine 0.2% are commonly selected for their prolonged duration of action. The addition of dexamethasone as a perineural adjuvant has been shown to extend analgesia duration in peripheral nerve blocks in humans, but its efficacy and safety for visceral plexus blocks in dogs have not been specifically evaluated. The decision to add an adjuvant should be based on current evidence and formulary guidance instead of extrapolation from other species or block types.

## Monitoring and Complication Management

Continuous electrocardiography, pulse oximetry, and blood pressure monitoring are required during and after the block. The most immediate concern is intravascular injection of local anesthetic, which can produce arrhythmias, seizures, and cardiovascular collapse. Signs of systemic local anesthetic toxicity include agitation, muscle twitching, tremors, and progressive central nervous system depression. Hypotension may occur from sympathetic blockade even without intravascular injection, particularly in patients with preexisting hypovolemia or cardiac disease.

| Complication | Ultrasound Finding | Clinical Sign | Immediate Action |
| --- | --- | --- | --- |
| Intravascular injection | No perivascular fluid spread, injectate appears in vessel lumen | Arrhythmia, hypotension, seizures | Stop injection, supportive care, lipid emulsion per formulary |
| Intraneural injection | Nerve expansion during injection | Pain on injection, limb paresis | Stop injection, reposition needle |
| Visceral puncture | Needle tip within bowel lumen or solid organ | May be silent, peritonitis if unrecognized | Withdraw needle, reassess, consider antimicrobials |
| Retroperitoneal hematoma | Echogenic fluid accumulation near aorta | Pain, hypotension | Compression, monitoring, surgical consult if expanding |
| Hypotension from sympathetic block | No specific finding | Decreased blood pressure | Fluid bolus, vasopressor support |

Post-block monitoring should continue for at least 2 hours. Assess for signs of effective analgesia, including reduced abdominal splinting, improved posture, and decreased pain scores on abdominal palpation. The onset of analgesia typically occurs within 10 to 20 minutes. Failure to achieve analgesia within 30 minutes suggests incorrect needle placement or inadequate volume, and the block should be repeated or an alternative analgesic strategy employed.

## Documentation and Quality Assurance

Record the patient identification, indication for the block, positioning, transducer type and frequency, approach, needle gauge and type, volume and concentration of injectate, number of injection sites, and any adjuvant drugs. Document the ultrasound findings, including the visibility of the celiac and cranial mesenteric arteries, the appearance of the injectate spread, and any complications encountered. Include a description of the post-block monitoring period, pain scores, and the time to first rescue analgesia.

Standardized documentation supports outcome assessment and complication tracking. The [American College of Veterinary Radiology resources](https://acvr.org/) provide guidance on imaging standards and quality assurance that can be adapted to interventional procedures. Professional practice resources from the [American Veterinary Medical Association](https://www.avma.org/resources-tools) address documentation standards and complication reporting that apply to all interventional procedures.

The evidence base for ultrasound-guided celiac and mesenteric nerve blocks in dogs remains limited. Most published data derive from cadaveric studies of other abdominal wall blocks, and clinical outcome data for visceral plexus blocks are sparse. Clinicians should approach this technique with appropriate caution, document their outcomes, and contribute to the growing body of clinical experience. Where institutional protocols exist, they should be followed. Where they do not, the framework presented here provides a structured approach that can be adapted to individual patients and available equipment.

## Complications and Early Detection

The principal complications of celiac and mesenteric nerve blockade in dogs are inadvertent vascular puncture, intraneural injection, peritoneal injection, and systemic local anesthetic toxicity. Vascular puncture is the most immediately recognizable failure mode. The aorta and its major branches lie in direct proximity to the target plexus, and the needle path frequently crosses the vasa recta of the mesentery. Early detection relies on real-time observation of the needle tip during injection. Blood aspirated into the extension tubing before injection confirms intravascular placement, but negative aspiration does not exclude vessel wall puncture or delayed intravascular uptake.

Intraneural injection is a recognized hazard when the needle tip is advanced into or through the celiac ganglion. Experimental work in pigs has shown that nerve expansion visible on ultrasound during intraneural injection produces histologic injury, even when functional deficits are not immediately apparent [nerve expansion and histologic injury after intraneural injection in pigs](https://pubmed.ncbi.nlm.nih.gov/20216032/). The discriminating sign is circumferential swelling of the nerve fascicle during the first fraction of the injection. If this is observed, the needle should be withdrawn by 1 to 2 mm and repositioned before continuing.

Peritoneal injection occurs when the needle tip passes through the parietal peritoneum without entering the retroperitoneal space. The injectate is seen as an anechoic pool accumulating within the peritoneal cavity instead of as a discrete hypoechoic halo around the celiac artery. This is usually benign but reduces block efficacy. Systemic toxicity is the most serious late complication. Early signs include tremors, agitation, and sinus tachycardia, followed by hypotension and arrhythmias. Continuous electrocardiographic and capnographic monitoring during and for 30 minutes after injection is advised.

## Common Errors and Corrective Action

Less experienced operators most often misidentify the celiac artery as the cranial mesenteric artery. The celiac artery arises from the aorta at the level of the L1 vertebral body and courses cranially, whereas the cranial mesenteric artery arises slightly caudal and courses ventrally. The discriminating check is to trace the vessel to its origin from the aorta in a longitudinal plane before needle placement.

Needle visibility is a second common problem. Echogenic needles improve visualization at steep angles, but no needle is equally visible across all orientations [echogenic regional anesthesia needle comparison in Thiel cadavers](https://pubmed.ncbi.nlm.nih.gov/22390992/). The needle should be inserted in-plane and kept as parallel to the transducer face as possible. If the tip is lost, stop advancing and rotate the transducer or use a slight jiggling motion to reacquire the tip. Needle visibility is also influenced by the surrounding medium, so an anechoic field such as the retroperitoneal fat may obscure a poorly echogenic needle [ultrasound characteriztics of needles for regional anesthesia](https://pubmed.ncbi.nlm.nih.gov/17961844/).

A third error is injecting too rapidly. High injection pressure forces injectate along fascial planes of least resistance instead of around the plexus. Inject in 1 to 2 mL aliquots with a 2 to 3 second pause between aliquots, observing spread after each.

| Observation | Likely cause | Discriminating check |
| --- | --- | --- |
| Blood in extension tubing | Intravascular needle tip | Withdraw and redirect, re-aspirate |
| Nerve swelling during injection | Intraneural placement | Stop injection, withdraw 1 to 2 mm |
| Injectate pooling in peritoneal cavity | Peritoneal puncture | Confirm tip is retroperitoneal before injection |
| No visible spread around celiac artery | Incorrect vessel identification | Trace vessel to aortic origin |
| Poor needle tip visualization | Steep needle angle or non-echogenic needle | Reposition transducer or use echogenic needle |

## Limitations of the Evidence

The evidence base for ultrasound-guided celiac and mesenteric nerve blocks in dogs is limited to cadaveric anatomic studies and extrapolation from other regional techniques. No prospective clinical trials have compared this block with systemic analgesia alone in dogs. The transversus abdominis plane block literature, which is more developed, shows that cadaveric dye spread does not always predict clinical analgesic efficacy, and the same caution applies here [ultrasound-guided transversus abdominis plane block in the dog](https://pubmed.ncbi.nlm.nih.gov/21492393/). Expert opinion differs on the optimal injection volume, the value of a single injection versus multiple injections, and whether the block should be performed bilaterally as a routine. Some clinicians advocate a diagnostic block before therapeutic injection to confirm target coverage, while others proceed directly to therapeutic dosing. Neither position is supported by controlled data.

## Referral and Escalation

Referral to a veterinary anesthesiologist or a specialist in interventional radiology is warranted when the patient is obese, when abdominal effusion or mass lesions distort the normal sonographic anatomy, or when the operator cannot confidently identify the celiac artery after two attempts. Patients with coagulopathy, portal hypertension, or suspected retroperitoneal hemorrhage should not receive this block without specialist consultation. Laboratory evaluation of coagulation status is advised before the procedure in any patient with a history of bleeding or hepatopathy.

Regulatory reporting obligations vary by jurisdiction. In the United States, the [AVMA practice resources](https://www.avma.org/resources-tools) provide guidance on adverse event reporting and professional standards. International practitioners should consult the [WOAH terrestrial animal health standards](https://www.woah.org/en/what-we-do/standards/codes-and-manuals/terrestrial-code-online-access/) for welfare-related reporting expectations. Suspected adverse drug reactions involving local anesthetics should be reported to the relevant national pharmacovigilance program.

## Frequently Asked Questions

### How Should I Adapt the Block When Only a Basic Ultrasound Machine Is Available?

Machine capability affects needle visibility more than image quality. Needle visibility depends on insertion angle relative to the beam, with steeper angles reducing conspicuity regardless of transducer quality. Echogenic needles improve visibility at steep angles, and their benefit is most pronounced when imaging conditions are suboptimal. If only a standard needle is available, use a shallow in-plane approach, align the needle with the transducer face, and use small to-and-fro movements to identify the tip by tissue displacement. Hydrolocation, injecting a small volume of saline to confirm tip position, is a practical alternative when needle echogenicity is poor. The [ultrasound characteriztics of needles for regional anesthesia](https://pubmed.ncbi.nlm.nih.gov/17961844/) study demonstrates that needle design and angle interact with the surrounding medium, so expect reduced visibility in obese patients or when gas-filled bowel obscures the acoustic window.

### What Are the Cost and Resource Considerations for Adding This Block to Practice?

The incremental cost is modest once ultrasound equipment exists. Consumables include a regional block needle, local anesthetic, and optional adjuvants. Echogenic needles cost more than standard needles, and the [comparison study in Thiel cadavers](https://pubmed.ncbi.nlm.nih.gov/22390992/) found measurable visibility differences between brands, so trial a single brand before committing to inventory. Time is the larger cost. The procedure requires a second operator for monitoring, patient positioning, and aseptic preparation. For a practice performing one or two abdominal pain cases weekly, the setup time may not justify the block. For a referral or emergency practice managing pancreatitis or postoperative laparotomy pain regularly, the block reduces systemic analgesic requirements and may shorten recovery time. Start by offering the block to a defined case subset, such as pancreatic or hepatobiliary disease, and expand once the team is proficient.

### How Does This Block Compare with Epidural Analgesia for Cranial Abdominal Pain?

Epidural analgesia provides bilateral somatic and visceral blockade but has important limitations for cranial abdominal pain. The dermatomal spread of epidural injectate is unpredictable in dogs, and achieving blockade at the T9 to T13 segments requires large volumes that increase the risk of hypotension and hindlimb weakness. The celiac and mesenteric block is more targeted, sparing the pelvic limbs and bladder function. Recovery is faster and nursing care is simpler. The trade-off is that the celiac block does not cover the body wall, so a patient with a painful abdominal incision still needs a separate block such as the transversus abdominis plane block, which has been shown to stain the ventral branches of T11 to L3 in canine cadavers. For visceral pain without significant body wall involvement, the celiac block is the better choice.

### What Should I Record in the Medical Record After Performing the Block?

Document the indication, the ultrasound machine and transducer used, the approach, the needle type and gauge, the injectate composition and volume, and the number of attempts. Record the time of injection and the patient's heart rate, respiratory rate, and blood pressure before and after the block. Note the response to a standardized noxious stimulus, such as response to abdominal palpation, at 15 and 30 minutes after injection. Record any complication, including vascular puncture, hypotension, or signs of intraneural injection. The [American Veterinary Medical Association practice resources](https://www.avma.org/resources-tools) emphasize that procedure notes should allow a colleague to reproduce the technique from the record alone. Include a photograph or labeled still image of the needle position if your ultrasound machine supports image capture.

### How Do I Explain the Block to an Owner Who Is Anxious About Their Dog Undergoing Another Procedure?

Describe the block as a targeted injection that numbs the nerves carrying pain signals from the abdominal organs, similar to a dental block before a tooth extraction. Explain that the dog remains under general anesthesia for the injection, so there is no additional discomfort. State that the block reduces the need for systemic pain medication, which lowers the risk of sedation, nausea, and prolonged recovery. Be honest about the evidence base. The technique is supported by cadaveric studies of adjacent abdominal wall blocks and by extrapolation from human medicine, but large canine clinical trials are lacking. Mention that the block does not always provide complete pain relief and that the team will continue to monitor and adjust analgesics. The [MSD Veterinary Manual](https://www.msdvetmanual.com/) advises that client communication about procedural risk should be specific to the patient and the procedure.

### What Should I Do If the Patient Shows Signs of Pain Despite a Successful Block?

First, confirm the block was actually successful. Re-examine the ultrasound images to verify needle position and review the injectate volume against the patient's body weight. If the block appears technically correct, consider that the pain source may be outside the celiac and mesenteric distribution. The block does not cover the body wall, the diaphragm, or the retroperitoneal space. Reassess the patient for a surgical complication such as bile peritonitis, intestinal leakage, or pancreatitis progression. If the pain is visceral and the block failed, options include repeating the block with a higher volume, adding a systemic analgesic, or escalating to a multimodal plan. Do not exceed the maximum recommended dose of local anesthetic when repeating the block. If the patient required escalating analgesia within two hours of the block, document the failure and consider whether the original diagnosis requires revision.

## Related Clinical & Scientific Guides

* [MRI Monitoring of Brain Tumor Response to Therapy in Dogs](/knowledge/veterinary-medicine/diagnostic-imaging/mri-monitoring-brain-tumor-response-therapy-dogs)
* [Ultrasound-Guided Drainage of Abscesses in Small Animals](/knowledge/veterinary-medicine/diagnostic-imaging/ultrasound-guided-drainage-abscesses-small-animals)
* [Radiographic Monitoring of Total Hip Replacement in Dogs](/knowledge/veterinary-medicine/diagnostic-imaging/radiographic-monitoring-total-hip-replacement-dogs)


## References and Further Reading

- [Ultrasound-guided transversus abdominis plane block in the dog: an anatomical evaluation.](https://pubmed.ncbi.nlm.nih.gov/21492393/). 2011.
- [Ultrasound characteriztics of needles for regional anesthesia.](https://pubmed.ncbi.nlm.nih.gov/17961844/). 2007.
- [Echogenic regional anesthesia needles: a comparison study in Thiel cadavers.](https://pubmed.ncbi.nlm.nih.gov/22390992/). 2012.
- [The effects of perineural versus intravenous dexamethasone on sciatic nerve blockade outcomes: a randomized, double-blind, placebo-controlled study.](https://pubmed.ncbi.nlm.nih.gov/24686045/). 2014.
- [Nerve expansion seen on ultrasound predicts histologic but not functional nerve injury after intraneural injection in pigs.](https://pubmed.ncbi.nlm.nih.gov/20216032/). 2010.
- [Ultrasound-guided subcostal oblique transversus abdominis plane block in canine cadavers.](https://pubmed.ncbi.nlm.nih.gov/27232440/). 2017.
- [American College of Veterinary Radiology Resources](https://acvr.org/). American College of Veterinary Radiology.
- [MSD Veterinary Manual, Professional Edition](https://www.msdvetmanual.com/). MSD Veterinary Manual.
- [American Veterinary Medical Association Practice Resources](https://www.avma.org/resources-tools). American Veterinary Medical Association.

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> This article is educational professional reference material for veterinary audiences. It is not a substitute for veterinary diagnosis, individual clinical judgment, current product labeling, or applicable regulatory requirements.