It is assumed that attacks on grazing animals are caused large carnivores. The size of the large carnivores population can be most precisely estimated on basis of faeces collection and the analysis of DNA in the faeces. Due to the increasing number of the two most common predators, bears and wolves, we have to protect grazing animals against their predation. Several types of protective agents are known, e.g. tactile, mechanical and chemical deterrents, use of guard animals, human presence or sheep's electronic collars. The most popular protection devices in Slovenia are the electric fences and protection with animals, with shepherd dogs. Electric fences are often not as effective as we wish. In addition to the fact that the electric fence is too low or that it allows the wolf to crawl under the wires, the most common error is the unsteady or too low voltage, and the errors in the grounding, causing the beast to not receive a large enough electric impulse that will repel it. The effectiveness of shepherd dog increases with the number of dogs. Furthermore, the effectiveness of shepherd dogs depends also on the proper training of the dog. The number of shepherds in Slovenia is very low, although this is the most efficient protection method, as the beast are feared by the human presence. Other methods of protection with various repellents or animals are, in principle, less effective than protection with electric fences or a shepherd dog, while protection of sheep with electric collars was not yet been extensively investigated.