Researchers speculated that a substance in mother’s milk might be responsible for the state of relaxation newborns experience after nursing. This inspired the discovery of a unique milk-derived protein, alpha-casozepine, with proven calming properties. Alpha-casozepine promotes a sense of relaxation and contentment.

The manufacturer's directions for use:

Zylkene capsules can be administered orally, or opened and mixed with a meal. Use as recommended by your veterinarian.

Short-term use: Use Zylkene for 1–2 days before a planned event or change in environment. Some animals may need earlier administration (5–7 days).

That said, a Company spokesman told us they strongly recommend you purchase a minimum of 6 packets, and use 2 per day for the 2 days prior to your event and 2 on the day of your event.  Using less may not yield the results you are looking and hoping for.