Gypsy pollution code (marimÃ©) taboos extend to animals from the edibility of certain types of meat to pet ownership. Cruelty to animals is prohibited and they may only be killed for food. The German Sinti consider eating horseflesh a serious offence, as do other tribes. The exclusion of horsemeat has more to do with respect than to marimÃ©, since the horse has been so important to the Roma's mobility and survival in the past. Dogs and cats are considered polluted because of their unclean living habits. Roma consider cats particularly unclean because they lick their paws after burying their feces. The critical concern, as with dogs licking themselves, is that the uncleanness of the external world may defile the purity of the inner self if it is permitted to enter the body through the mouth. Cats are also a sign of impending death to many tribes. If a cat sets foot in a house, trailer or automobile, a purification ceremony may be required. Dogs are also unclean, but to a lesser extent. Dogs are tolerated outside the house because of their value as watchdogs. Owls are considered portents of death, just as with many non-Roma groups. In some tribes, the owl's cry is considered very bad luck, or bibaxt. For this reason, owls are avoided as food or pets.