In conclusion being an atavism, PSC could have had some functional importance during evolution when non-bred female wolves had to nurse other females' litters (Jochle ,1997). PSC is now a frequent phenomenon in domestic dogs and although its exact frequency is not known, it is estimated to be around 50±75% (Johnston ,1980). Due to the variability among non-pregnant bitches,some dogs in mid and late metaoestrus can express symptoms (overt PSC) whereas others may have no signs at all (covert PSC). This syndrome usually initiates with behavioural changes, such as restlessness, anorexia, decreased activity, aggression, licking of the abdomen ,nesting, mothering inanimate objects, adopting other bitches' puppies. Next, follow the physical
