Hippos step up for important jab

15 December 2021

After months of training, the Hippopotamuses at Werribee Open Range Zoo have achieved a huge healthcare milestone - stepping up to voluntarily receive their annual tetanus immunisation.

Werribee Open Range Zoo Animal Training Coordinator, Kelly Hobbs, said the positive interaction with the giant beasts will now allow vaccinations to be integrated into the hippos’ annual proactive healthcare routine.

“This is the very first time we’ve been able to successfully ask our hippos to accept their vaccinations voluntarily. They have taken to the new process wonderfully thanks to the strong bonds with our keepers. After all, they’re very big animals, and it’s a very small needle.”

The complex behaviour is built upon existing proactive healthcare training, including recall training, where keepers ask the hippos to move from one area of their habitat to another, and station training, where the hippos have learned to voluntarily stand still on a weigh station.

Traditionally, immunisations for the 1400-kilogram mammals would be administered under anaesthetic, so this complex behaviour promotes positive animal welfare by increasing the animals’ choice and control, reducing stress and maintaining the hard-earned trust between the animal and keepers.

Ms Hobbs said the training process was a long journey of small steps.

"We want the hippos to voluntarily accept their tetanus vaccinations,” Ms Hobbs said. “We first asked them to move to an area where we could start safely desensitising them to our touch. We then got them used to different tools, such as a capped or blunt needle. And, finally, we provided them with a nice treat for positive reinforcement.”

Tetanus is a serious infection caused when Clostridium tetani bacteria, which naturally occurs in soil and mud, enters the body through wounds or abrasions. The large, semi-aquatic mammals spend around 16 hours each day submerged in water or wading through shallows, where the bacteria can proliferate.

Zoos Victoria’s animal training programs use the most positive and least-intrusive approaches to proactive healthcare for animals of all shapes and sizes.

The Common hippopotamus is under serious threat in the wild from illegal poaching and habitat destruction. Population numbers are now estimated at just 125,000.

The hippos at Werribee Open Range Zoo are part of a regional breeding program to maintain an insurance population in the fight against extinction.