Avet at your clinic is preparing to perform a punch biopsy of a dermal mass in a cat under local anesthesia. he asks you to add epinephrine to his lidocaine before administering the local anesthetic. what is the rationale for adding epinephrine?

To increase the duration of effectiveness of local anesthesia.

Explanation:

Local anesthesia is best effective when its rapid absorption in systemic blood vessels is prevented.  Diffusion of anesthesia along with blood reduces the period for which it is active. Epinephrine is a vasoconstrictor and does not allow the local  anesthesia to diffuse rapidly. Concentrating the  anesthesia locally increases the duration for which it is active.