The Humane Society of Southern Arizona holds rattlesnake-avoidance classes for dogs at 5 and 7:30 p.m., Friday, April 2. Dogs between the ages of 10 months and 10 years are eligible. $70 per dog, which includes one follow-up session, if it is necessary. Registration is required. Call 321-3704, ext. 147, or visit www.hssaz.org for more information.