There are several options for heartworm preventatives.
 
1) Heartgard for small dogs, 0-25 pounds
2) Heartgard for small cats, 0-5 pounds.
3) Interceptor for small dogs, 0-10 pounds
4) Revolution for large cats, 5-15 pounds or
5) diluted ivomec. 20 to 200mcg/kg
 
Hope that helps,
Jerry Murray, DVM
[Posted in FML issue 3745]