North American Veterinary Licensing Examination (NAVLE) Practice Test

What is expected to happen when lidocaine is injected into the dorsal pedal vein of a cow with a tourniquet placed mid-cannon bone?

1. Anesthesia distal to tourniquet

2. Bradycardia with gradual tourniquet removal

3. Anesthesia only from mid-pastern to the toe

4. Cessation of atrial fibrillation after tourniquet removal

The correct answer is: Anesthesia distal to tourniquet

When lidocaine is injected into the dorsal pedal vein of a cow, particularly with a tourniquet placed mid-cannon bone, the expected outcome is that anesthesia will occur in the region distal to the tourniquet. This is due to the local anesthetic effectively blocking nerve conduction in the area supplied by the nerves distal to the tourniquet. In this scenario, the lidocaine becomes concentrated in the blood flow distal to the tourniquet, allowing it to exert its anesthetic effects on the tissues in that specific area, which includes the foot and lower limb structures. This makes the choice appropriate because the action of the tourniquet enables localized anesthesia by preventing the rapid systemic absorption of lidocaine, thereby allowing for effective pain control while performing procedures on the distal limb. The other outcomes such as bradycardia with tourniquet removal and cessation of atrial fibrillation after tourniquet removal are not directly related to the impact of lidocaine in the bloodstream or the intended use of the drug in this specific context. Furthermore, anesthesia localized only from mid-pastern to the toe does not fully encompass the expected results since the focus is on the entirety of the area supplied by the nerves below the tourniquet, not just that specific