Static statistics for dogs in three areas, Matsudo city of Chiba Prefecture, Nerima-ku and Hachioji city of Tokyo Metropolitan, were constructed by using dog registration data in 1986 and 1988. The following results were obtained.
1. The Number of registration dogs in Nerima, Hachioji and Matsudo were 5493, 14446 and 8824, respectively. Population density (No. of people/km²), the average number of dogs per people (No. of dogs/No.of people × 1, 000), the average number of dogs per household (No.of dogs/No. of households × 1, 000) and dog population density (No. of dogs/km²) were 14078.4, 17.7, 46.4, and 249.7 in Nerima, 3226.9, 33.4, 96.8, and 107.7 in Hachioji and 7175.6, 24.2, 73.4, and 173.4 in Matsudo, respectively.
2. The proportion of males was about 60% and was much greater than that of female in three areas. The ratio of male to female in dogs at birth (male/female × 100) calculating by using Japan Kennel Club registration data was 101.5. Therefore, high proportion of males to females seems to be due to artificial selection.
3. The proportion of mongrel dogs was larger than that of purebred dogs in three areas. However, the different proportion of mongrel dogs were observed among three areas, and seems to reflect social, economical and educational level of people in each area.
4. The figure of age distribution in three areas showed pyramidal style. In all areas, the percentage of dogs in each age interval decreased gradually with age over 5 years of age.
5. The percentage of spayed males and castrated females in Hachioji were 24.6% and 4.4%, respectively. The difference of the percentage of castration among breed was not observed. However, the difference of the percentage of spaying between mongrel (35.5%) and purebred dogs (11.6%) was observed. The percentage of spayed female increased with age. These results suggest that spaying was associated with increased life expectancy for female dogs.
6. The results obtained in the present study may provide useful informations for future studies.

View full abstract