Chronological transition of necropsy cases of animals in Tokyo, Japan.

This research investigated the chronological transition in necropsy cases of animals in Tokyo, Japan, over a period of over 100 years, analyzing species, breed, age, and pathological diagnosis. The study suggested an increase in the variety and age of animals over time, as well as a decrease in infectious diseases and an increase in tumor cases.

Study Background and Methodology

• The study involved the investigation of necropsy records maintained at the University of Tokyo ranging from the year 1902 to 2021.
• A total of 3,137 cases were examined for various factors including the species of the animal, its breed, age, and the pathological diagnosis made post-necropsy.
• The period investigated was divided into three major sections: 1903-1914 (the Meiji-Taisho period), 1956-1969 (the Showa period), and 2006-2020 (the Heisei-Reiwa period).

Results and Findings

• The most necropsied animals varied over the different periods under consideration. Dogs and horses predominated in the early 20th century (Meiji-Taisho period), with dogs remaining significant and cats emerging in prominence during the Showa period. The data from 2006-2020 reflected a focus on dogs, cats, and exotic animals.
• The study registered an increasing variety in the species and breeds of animals being examined over time.
• The median ages of the animals at the time of death also changed with time, with dogs and cats surviving longer in the more recent periods.
• The patterns of disease reflected in the necropsy reports also evolved, with a decrease in viral, bacterial, and parasitic infections and a notable increase in tumor cases. The researchers suggest this shift may be linked to the prolonged lifespan of these animals.

Conclusion

• The record of necropsies in Tokyo, Japan, reveals transformations in animal life, both in terms of longevity and disease patterns, over the past century.
• These changes, such as the expanding diversity in species and breeds and the increased prevalence of tumors, may reflect broader social changes including increased variety in pet ownership and improvements in veterinary medicine and animal care.