Like other sources of stress, high heat and humidity can reduce an animal's response to vaccination. Summertime conditions also add challenges to keeping vaccines cool, especially when working large groups of heifers. Sam Leadley, calf and heifer management specialist with Attica Veterinary Associates, offers the following tips to help keep your vaccination program on track as the weather heats up this summer.

Step 1. Vaccinate as early as possible in the morning, when heat stress is lowest.

Step 2. Keep vaccines out of direct sunlight. Leadley suggests putting rehydrated vaccine back in the box to limit exposure to sunlight.

Step 3. Keep vaccines cool. Particularly during the summer, this does not include keeping them in your pockets or on the pickup seat. Instead, Leadley uses a frozen cold pack in a pail for small jobs or an insulated lunch box for larger tasks.

Step 4. Protect killed vaccines, too. Even if we put them back in the refrigerator, leaving killed products out in warm temperatures too long will reduce their effectiveness the next time.

Step 5. Use modified live vaccines within three to four hours of reconstituting them and discard leftover product. Most manufacturers say use within an hour.

Always consult with your veterinarian for specific recommendations for your operation. Refer to DCHA Gold Standards II for vaccination guidelines.

Source: Dairy Calf & Heifer Association