Dallas Zoo officials say while they are still investigating the deaths of two giraffes last month, they have ruled out one zoonotic disease and adverse reactions to the COVID-19 vaccine.
Jessie, 14, and Auggie, 19, both died in October after experiencing liver problems, according to the zoo.
The zoo said it had not yet received the COVID-19 vaccine, so its side effects could not have impacted the animals.
The zoo tested food and vegetation in the giraffes' habitat and trimmed back the grazing areas. Animals are being let back into the habitat and the Dallas Zoo said they have no reason to believe the danger came from inside the enclosure.
Encephalomyocarditis was also ruled out as a possible reason for death.
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The Dallas Zoo is monitoring other hoofstock, including giraffes, to make sure they are not showing any strange symptoms by conducting regular blood draws and checking their liver enzyme levels. Zoo officials will continue to investigate and keep the public informed.