<p>This study evaluated the population dynamics and ownerships of dogs and cats from the city of Jaguapitã, southern Brazil. The human to dog and cat ratios were 4.6 and 21.5, respectively. Comparatively more dogs (<em>n</em>=2,460) than cats (<em>n</em>=571) were within the households and there were significantly more male (55.8%; 679/1,217) dogs relative to females (44.2%; 538/1217). Most cats (69.2%; 180/260) did not received any antiparasitic medication, were not immunized against rabies (91.2%; 237/260) or any specific infectious disease (91.5%; 238/260). Less than half (40.8%; 106/260) of these was below oneyear-of age, but a significant number of cats was without any definite breed (81.2%; 211/260), and not spayed (93.5%; 243/260). Most dogs were of the mixed breed (69.5%; 846/1217), between one and four-years old (42.6%; 519/1217), and not spayed (96.3%; 1172/1,217). An elevated population of dogs received anthelminthic drugs (71%; 865/1,217), but most of these were not immunized against rabies (63.8% 777/1,217) or other infectious disease (58.6%; 713/1,217). Most (68.7%; 770/1,120) households were owners of a pet dog and/or cat; 54.4% (610/1,120) of these owned only dogs, 4.9% (55/1,120) were the owners of cats only, while 9.4% (105/1,120) owned pet dogs and cats. The results obtained are similar to those described in populated cities of Brazil and other countries. However, the free street access of pets associated with the reduced level of immunization against canine and feline infectious diseases coupled with the responsibility of ownership demonstrated by most residents make these animals highly susceptible to zoonotic and infectious diseases. Additionally, the free street access of unsprayed pets increases the risk of contact with other animals and the transmission of disease.</p>