
The domestic dog is the first species, and the only large carnivore, known to have been domesticated. Especially over the past 200 years, dogs have undergone rapid phenotypic change and were formed into today's modern dog breeds due to artificial selection by humans. These breeds can vary in size and weight from a 0.46 kg (1.0 lb) teacup poodle to a 90 kg (200 lb) giant mastiff. Phenotypic variation can include height measured to the withers ranging from 15.2 centimetres (6.0 in) in the Chihuahua to 76 cm (30 in) in the Irish Wolfhound; color varies from white through grays (usually called "blue") to black, and browns from light (tan) to dark ("red" or "chocolate") in a wide variation of patterns; coats can be short or long, coarse-haired to wool-like, straight, curly, or smooth.[131] The skull, body, and limb proportions vary significantly between breeds, with dogs displaying more phenotypic diversity than can be found within the entire order of carnivores. Some breeds demonstrate outstanding skills in herding, retrieving, scent detection, and guarding, which demonstrates the functional and behavioral diversity of dogs. The first dogs were domesticated from shared ancestors of modern wolves, however the phenotypic changes that coincided with the dog–wolf genetic divergence are not known.[26]
The breed with the shortest lifespan (among breeds for which there is a questionnaire survey with a reasonable sample size) is the Dogue de Bordeaux, with a median longevity of about 5.2 years, but several breeds, including miniature bull terriers, bloodhounds, and Irish wolfhounds are nearly as short-lived, with median longevities of 6 to 7 years.[64]
^ Jump up to: a b Thalmann, O.; Shapiro, B.; Cui, P.; Schuenemann, V.J.; Sawyer, S.K.; Greenfield, D.L.; Germonpre, M.B.; Sablin, M.V.; Lopez-Giraldez, F.; Domingo-Roura, X.; Napierala, H.; Uerpmann, H.-P.; Loponte, D.M.; Acosta, A.A.; Giemsch, L.; Schmitz, R.W.; Worthington, B.; Buikstra, J.E.; Druzhkova, A.; Graphodatsky, A.S.; Ovodov, N.D.; Wahlberg, N.; Freedman, A.H.; Schweizer, R.M.; Koepfli, K.- P.; Leonard, J.A.; Meyer, M.; Krause, J.; Paabo, S.; et al. (2013). "Complete Mitochondrial Genomes of Ancient Canids Suggest a European Origin of Domestic Dogs". Science. 342 (6160): 871–874. Bibcode:2013Sci...342..871T. doi:10.1126/science.1243650. hdl:10261/88173. PMID 24233726.
Experienced pet stylists hired from outside the company must complete a personal skill evaluation by a Petco Certified Pet Stylist or Grooming Salon Leader, as well as four weeks of safety and pet grooming operations training. They must also complete and pass a technical skills assessment within 14 days of hire. If the candidate does not pass the technical evaluations, they must complete Petco's 12-week Pet Stylist Apprentice & Certification program and retake the skills assessment.