Intra- vs intermuscular injections in swine

Area of Science:

• Veterinary Medicine
• Pharmacology
• Animal Science

Background:

• Accurate drug administration via intramuscular injection is vital in veterinary medicine.
• Distinguishing between intra- and intermuscular deposition is essential for efficacy and safety.
• Pigs are a common model for studying injection techniques.

Purpose of the Study:

• To identify the optimal anatomical site for intramuscular injections in pigs.
• To evaluate the accuracy of intramuscular versus subcutaneous deposition in different injection sites.
• To compare the efficacy of various injection locations for drug delivery in swine.

Main Methods:

• Radiopaque test articles were injected into cervical, loin, and gluteal muscles of anesthetized pigs.
• Pigs were euthanized, frozen, sectioned, and X-rayed to visualize test article localization.
• Injection sites were scored based on intramuscular and subcutaneous deposition, and test article leakage.

Main Results:

• The loin area showed high scores for intramuscular location but frequent subcutaneous leakage.
• Cervical musculature injections, particularly perpendicular to the skin behind the ear, demonstrated minimal subcutaneous spread.
• The neck site was identified as the most reliable for achieving true intramuscular injection.

Conclusions:

• The injection technique and site significantly influence drug localization in pigs.
• Cervical injections perpendicular to the skin offer the highest accuracy for intramuscular drug delivery.
• This finding is critical for optimizing drug efficacy and minimizing adverse effects in swine.