Human beings are not the only ones living longer in Japan.

Dogs and cats are living an average 13.2 years and 11.9 years respectively, a survey showed Wednesday.

This was an increase of 50 percent for dogs and a massive 2.3 times for cats over the past 25 years.

The rise is attributed to changes such as better vaccinations, according to the Tokyo University of Agriculture and Technology and the Japan Small Animal Veterinary Association.

It is also attributable to more pets being kept indoors, given better food and getting treated when they develop medical problems, they said.

Mixed-breed dogs live longer than purebred ones while female cats have longer lives than males, said Haruka Yanagawa, a student at the university who analyzed the data.

Further improvements may lie ahead.

"The life span of cats may increase as the rate of vaccinated cats is still low at the moment," said Hideki Hayashidani, an associate professor at the university.

Previous surveys of pets' life expectancy were conducted in 1990, 1994 and 2002. The latest survey covered 5,977 dogs and 3,288 cats that died in 192 Japanese veterinary hospitals during 2014.

In 1990, the average life span of dogs stood at 8.6 years, while that of cats was 5.1 years.

The death rate caused by infectious diseases fell to about 2.5 percent in 2014 from around 30 percent in 1990 for dogs and to about 12 percent from roughly 25 percent for cats.

Vaccination coverage of dogs was at about 82 percent, while that of cats stood at around 54 percent.