Japan's aging population and the higher cost of keeping dogs has likely contributed to the sliding number of pet pooches in the country, with cats overtaking them this year for the first time since an annual survey began in 1994, according to industry experts.

"The biggest reason behind the fall in the number of pet dogs is probably declining birthrate and graying population," said Tomoko Ishida, a 52-year-old public relations officer at major pet company Aeonpet Co.

She says more elderly people are giving up on dogs and keeping cats instead due to the perception that dogs require greater care because owners need to take them out for walks every day and are legally obliged to get them vaccinated.