I think I will have to have a nice loooooong conversation about this with Ellie's vet.
The poor girl... This is from
http://www.veterinarypartner.com/Content.plx?P=A&A=488
What is the LD50?
(lethal dose to 50% of population - this dose is typically available for lab animal species upon which the product has been tested. It is expressed in milligrams of drug per kilogram of animal body weight. The higher the number, the less toxic the product is)
Revolution: Oral LD50 is greater than 1600 mg/kg in the rat
Heartgard Plus, Iverheart Plus: Lethal dose to rats is 50 mg/kg
Sentinel and Interceptor: Symptoms of tremors and incoordination result at 19 times recommended dose
Revolution looks safer when you read this. The only drawback for me is that it doesn't kill roundworms or hookworms.