If the tourniquet is placed properly and arterial (not only venous) blood flow is completely stopped, it can be safely kept for 2 hours without any lasting effect. Keeping the tourniquet for longer then 2 hours is likely to cause temporary nerve or muscle damage of the limb. Complications of prolonged tourniquet use (i.e. irreversible tissue fibrosis and consequent loss of limb) are likely to occur after 6 hours of the application.

Yes, modern high quality tourniquets, that consist of a sufficiently wide band and a tightening mechanism, are efficient in stopping the arterial blood flow, even on those parts of the limb where two bones are present (i.e. the forearm or calf).

A single tourniquet is not always sufficient to stop massive bleeding from the limbs, especially in the thigh area, for this reason, it may be necessary to use several tourniquets side by side to create a wide zone of tissue pressure. In addition, multiple limbs can be injured at once or there might be multiple victims. There are cases when the tourniquet breaks or deforms during the tightening process, especially if it is made of materials of poor quality.

There are tourniquets designs specifically for K9 dogs, however, if you do not have one, it is better to use a pressure bandage.. It will be more effective than a tourniquet for humans. A tourniquet designed for humans are too large for a dog.