So-called primitive dogs such as dingoes and Basenjis retain the yearly estrus cycle. Basenjis are small, short-haired dogs with erect ears, tightly curled tails and graceful necks. Basenjis are also registered with the United Kennel Club. Basenjis are athletic dogs, and deceptively powerful for their size. Most 21st-century Basenjis are descended from ancestors that have tested clean. Basenjis typically weigh about and stand at the shoulder. Basenjis may not get along with non-canine pets. Basenjis share many unique traits with pariah dog types. Basenjis are highly prey driven and will go after cats and other small animals. Basenjis sometimes suffer from hip dysplasia, resulting in loss of mobility and arthritis-like symptoms.