I am working on a project for a history class and my topic was the bubonic plague. I was researching when I came across multiple articles that claimed Pope Gregory IX - leader of the Roman Catholic Church in the 1230s - issued a papal bull called the Vox In Rama that implied cats were demonic creatures and thus decreased the number of cats in Britain. This caused the rat population to increase and ultimately led to the widespread of the bubonic plague. I am unsure if this information is historically correct or not.
Vox In Rama was aimed at satanism in Mainz. ( https://museumhack.com/black-cats-black-death/ )
the proximate cause of the Black Plague was the medieval economic over extension and collapse. This left a large concentrated low calorie marginal population with poor reserves. This was of course exacerbated by war and misrule attendant upon economic collapse. See the greater plague resistance in areas sparsely settled due to a lack of economic boom in the 1200s: Poland.
the obvious immediate cause of disease couldn’t have been regulated by rat reduction through catting for the predatory relations described in comments. Ratting was best done by experts with small dogs. Given the variety of densities of ratting quality expectable across Europe, and the strong link between plague resistance and low population / economic complexity, ratting doesn’t seem to have had an effect historically.
The text of the bulla (in Latin), with references to secondary literature, can be found here:
I have skimmed this and not found anything prohibiting the keeping of cats and ordering their destruction, but maybe I have overlooked something. (Correction is welcome). But the main thing is that before reaching the Catholic countries in Western Europe the Black Death ravaged the Near East and the Balkans, regions where the Pope had no say. It is thus anachronistic to blame the plague on the Pope.