Predator urines do repel some wildlife pests, according to proceedings of a symposium sponsored by the U.S. Department of Agriculture that considered the effectiveness of repellents in wildlife damage control. Based on the USDA proceedings, using kitty litter as a repellent might be worth a try. Bobcat urine was among the substances shown to repel woodchucks and voles in orchards. However, all urine is not the same. The most repellent urine for herbivores is from predators fed a 100% meat diet. Urine from fox farms probably comes from foxes eating largely a "dog food," which has a considerable non-meat basis.
As you know, many Internet sources sell products containing or simulating predator urine as nuisance animal repellents. Some of them may package the product in the vials you mention.
Repellents rarely work as effectively as people would like. Repellents, including predator urines, do not remain effective indefinitely. Frequent applications may be needed, especially after heavy rain and as new growth appears on the plants. Don't use repellents on or around plants destined for consumption.
Also use predator urines with caution and protective equipment. Avoid breathing urine vapor and spilling urine on unprotected skin. They are "urine" and may contain germs that can result in an infection.
The best and most effective way to protect a garden from rabbits is to install fences. Details on construction can be found at the link below.
While trapping is also an option, it is very difficult to trap rabbits during the summer as you will be competing with too many other food sources.
Online Resources:
Rabbit Control Techniques
