After all the suggestions about Web of Souls, which I knew weren’t right but sounded so close, I went through <PERSON>’s bibliography and found it! Web of the Chozen!
Plot of the Novel
The book Web fo the Chozen details the adventures over a period of several months of a lone starship scout, sent to travel the universe and find planets worth inhabiting. The scout, <PERSON>, discovers a planet called Petmos. He discovers the planet was previously colonized by a religious group called communards, yet he finds no traces of their colony.
<PERSON> lands on the planet, and a few hours later is attacked by a virus that transforms his physical body into a new shape: he now looks like one of the millions of herd animals he saw on the planet, a herbivore cross between a kangaroo and a mule, but with enormous bunny ears. <PERSON> then learns the horrible truth: the colonists were transformed into this new shape by the same virus, and call themselves 'The Chozen'. The colonists can still communicate, though sub-sonically, and one of their previous leaders, <PERSON>, takes him under his wing.
Unwilling to surrender to his new condition without a fight, <PERSON> reasons that the virus is not native to Petmos, but was engineered by <PERSON>: the AI supercomputer that navigated the colony ship to Petmos. 322
That colony ship is still in orbit around Petmos, and <PERSON> realized <PERSON> wants to use him, <PERSON>, to spread the virus to other colonized planets and transform other humans into Chozen.
Months pass, <PERSON> and <PERSON> go through a mating season, and with their eggs, they manage to escape the planet. They try and reason with <PERSON>, but when that fails, <PERSON> calls back to Earth for help. Earth’s response convinces him his previous employers see them and <PERSON> as a threat and will try to eliminate all of them, so he, <PERSON> and their two children, <PERSON> and <PERSON>, escape.
Finally they arrive at the solution for their dilemma: they would spread the virus themselves. That way, with all of humanity replaced by the Chozen, there would be no reason anymore for the humans to try and destroy them. The book ends after they successfully spread the virus on a colonized planet, proving their plan can work.
Thanks for all the suggestions!!
Plot from this website: https://www.academia.edu/26535797/Ecocritical_Look_on_The_Web_of_the_Chozen_by_Jack_L._Chalker 322