Source

Here are some other instances of oral sex in non-humans - but we don’t have enough data to say whether it occurs regularly during sex:

There are few observations of fellatio in non-human animals. Oral sex was found as a play behaviour between juvenile males or between juvenile female and juvenile male bonobos Pan paniscus.

Schürmann observed that a female orangutan, Pongo pygmaeus, often interrupted copulation for a short while, manipulating her mate’s penis with her hand, licking it or putting it in her mouth before mounting again. It is plausible that this female’s behavior increased male arousal.

In general, many animals may lick genitals before and after copulation, for example, the male of ring-tailed lemur, Lemur catta, often licks the genitals of the female in order to judge whether she is in oestrous, and after copulation, he also licks his penis.

Both male and female Livingstone’s fruit bats (Pteropus livingstonii) also licked the genitals of their partners during heterosexual interactions.

However, because of the limited details provided, we do not know whether fellatio occurs during copulation in these species.