Blog by Dr Lindsay Marshall, Humane Society International
To artificially create an arthritic-like knee in a perfectly healthy dog requires an awful instrument known as the dropping tower. This device drops a 2 kg weight onto the bent hind leg of an anaesthetised dog – most commonly a beagle, but Labradors, golden retrievers and German shepherd dogs are also used for this. The beagle in the photo is about to have more than 2000 N of force applied to her flexed knee. To put this in some context, a person bench pressing 100 lbs uses around 450 N of force.