Ultrasound-guided parasternal injection in dogs: a cadaver study

Area of Science:

• Veterinary Anesthesiology
• Locoregional Anesthesia Techniques
• Canine Anatomy

Background:

• The distal parasternal intercostal space is a target for locoregional anesthesia.
• Ultrasound guidance offers precision in anatomical targeting for injections.

Purpose of the Study:

• To detail the ultrasound-guided technique for distal parasternal intercostal blocks in canine cadavers.
• To evaluate the distribution of two different volumes of methylene blue dye injected into the intercostal spaces.

Main Methods:

• A prospective cadaver study involving seven canine cadavers (12-34 kg).
• Ultrasound-guided injections of methylene blue dye (0.05 mL kg^-1 or 0.1 mL kg^-1) were performed in the distal parasternal intercostal spaces (second to seventh).
• Anatomical dissection was conducted to assess dye spread and intercostal nerve staining.

Main Results:

• Successful ultrasonographic landmark identification for injections.
• Low volume (0.05 mL kg^-1) injections consistently stained intercostal nerves across multiple spaces (36/36).
• High volume (0.1 mL kg^-1) injections showed variable multisegmental distribution, with occasional intrapleural staining.

Conclusions:

• Ultrasound-guided distal parasternal intercostal block with 0.05 mL kg^-1 dye effectively stained intercostal nerves in all canine cadavers.
• This technique may be a viable alternative to existing methods for locoregional anesthesia in dogs.
• Further clinical studies are recommended to validate and refine this technique.