The Dallas Zoo announced Friday night that Subira, a 24-year-old silverback gorilla, died.
Zoo officials said Subira had recently developed a cough, but colds are common for gorillas this time of year.
Pathology results later revealed Subira's cause of death to be cardiovascular disease.
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The zoo said in a release "Heart disease is the number one cause of death for male gorillas, which is why our males receive regular wellness checks, including bimonthly heart rate tests as well as a more intensive ultrasound procedure every three years. We have also been working with the Great Ape Heart Project, based at Zoo Atlanta, for the last 10 years to stay at the forefront of causes, research, and preventative measures we can take when it comes to our great apes' heart health. Subira's last heart ultrasound was conducted in 2018 and showed no signs of heart disease, and his latest heart rate measurements had all been normal, which makes his passing all the more sudden and tragic."
The release went on to say "Given his cough, we also were incredibly sensitive to concerns about COVID-19. The CDC has not received any reports of animals becoming ill from this disease, and we have no reason to believe that any of our animals are at risk. Out of an abundance of caution, we worked with local and state officials and were able to confirm earlier this week that Subira was NEGATIVE for novel coronavirus."