While I couldn't find a specific, free PDF resource titled "Atlas de Artrologia del Perro," there are several online resources and academic databases that offer access to veterinary anatomy and arthrology resources, including:

If you're interested in accessing a free PDF resource on canine arthrology, I recommend searching online academic databases, veterinary information networks, and open-access textbooks. Additionally, you can try contacting veterinary schools, research institutions, or professional organizations, such as the American Veterinary Medical Association (AVMA), to inquire about available resources.