This is the 11654th most frequent Russian word.
животном
"Животном" is the prepositional case of "животное," meaning "an animal."
In this sentence, "животном" is used in the prepositional case, referring to a singular animal about which something is being discussed.
Я прочитал интересную статью о животном.
I read an interesting article about the animal.
Here, "животному" is in the dative case, indicating the entity receiving help.
Мы помогли раненому животному.
We helped the injured animal.
The word "животном" in this instance is in the prepositional case, specifying the context under discussion regarding the animal.