Three female lions at Tokyo's Tama Zoological Park have died from suspected heat-related illnesses as Japan grapples with a severe summer heatwave. The zoo reported that the animals suffered from dehydration and multiple organ failure, pointing to the extreme temperatures as the likely cause.

Mugi, a three-year-old lioness, showed a loss of appetite on July 19 and was unable to stand the following day. Despite efforts by zoo staff to provide ventilation, water, and medical treatment, she died on July 28. Ichigo, an 11-year-old lioness, died on July 31, followed by Luena, a 15-year-old, on Sunday.

Autopsies revealed systemic dehydration and multiple organ failure in all three lions. While definitive causes of death await test results, zoo officials stated that heat stress is a suspected factor. "This is the first time we've experienced anything like this," a zoo representative told the BBC. "Last year was also hot, but none of our lions fell ill like this."

Two other male lions and one female are reportedly still unwell and unable to stand, receiving fluids and medication. The zoo indicated that some of these animals are showing signs of improvement, and four lions that had previously shown signs of illness have since recovered. Six other lions remained in good health and will be moved to a private enclosure with air conditioning and industrial fans.

Experts suggest that the high humidity accompanying the heatwave makes it difficult for lions to regulate their body temperature. Unlike humans who sweat, lions expel heat by panting, a process less effective in humid conditions. A sudden spike in temperatures in mid-July may have also prevented the animals from acclimating to the extreme heat, according to Hideaki Karaki, a professor of veterinary medicine at the University of Tokyo.

Tama Zoo, home to approximately 260 species, has suspended its lion exhibit and safari bus service due to the heatwave impacting the animals. This incident occurs as over 43,000 people nationwide have been hospitalized for heatstroke this summer, prompting the government to issue heat warnings and advise residents on staying cool.