The weather in Lithuania has been unusually hot for July, reaching 30 degrees Celsius, although this is not quite close to the country's record summer temperature.
The male tiger Miglis, 19, died first. He was later followed by the tigress Taiva, which was four years younger. An autopsy of the two animals showed that they had been suffering from heart disease.
Alvydas Jakevicius, the head of Kaunas Zoo, denied the assumption that the tigers had died as a result of negligent care.
"It happened in midsummer. The original information that appeared in the Lithuanian press, that both tigers died on the same day, is incorrect. The difference between the male's and the female's deaths was two weeks. We watched the symptoms of their disease for about a year," Jakevicius told The Baltic Times.
"Heat is a great danger for tigers who have heart disease, as it is for people," Erika Samulyte, the zoo's senior veterinary surgeon told Kauno Diena daily.
Her colleague Virginija Mikutaviciene, head of the predators department at the zoo, agreed. "An unbearable heatwave coincided with the old age of the animals."
She denied that the tigers' deaths were directly caused by the heat. They were simply very old, she told The Baltic Times. The previous old age record for a tiger in Lithuania was 17 years.
"I pity Miglis very much. He was born free in Siberia. Now, to buy another tiger in Russia would be too expensive for us. We specialize in the rearing of Amur tigers. We used to have about 80 of them in our zoo," Mikutaviciene said.
"The expense of keeping a male tiger can be judged from the animal's daily ration. It eats about eight kilograms of animal feeding meat and drinks half a liter of milk. It gets one egg daily and a set of vitamins necessary to keep him healthy under zoo conditions."
The offspring of the deceased couple, Mirgis, who is three years old, now awaits a spouse. She should be carefully selected, so as to get a pure and healthy Amur cub, and this will not be easy.
Since the deaths, Kaunas Zoo is left with only four tigers.