In 2012 it was discussed to change the animal protection law, and "animal brothels" have been a topic in these discussions (also in 2010 and maybe even before).
2012-09 - Katharina Meyer (journalist of the Badische Zeitung) composed the article Gibt es Tierbordelle in Deutschland? (Do animal brothels exist in Germany?). She investigated where the statement (that animal brothels exist) was coming from and tried to find sources.
A primary source (Madeleine Martin, animal welfare officer of Hessen) claims that she was misquoted in the press. She claims that she never said that they would exist in Germany. But she doesn’t doubt that they do exist in Germany: she knows that they exist elsewhere¹, so it would be highly probable and logical that they do exist in Germany, too.
A professional association of veterinarians (Bundesverband praktizierender Tierärzte) supported a campaign/petition which claimed that farms exist where animals are kept ready, trained, and used for bestiality. The campaign’s spokeswoman (Astrid Behr) doesn’t think that it’s a rumor, as such things can be read in bestiality-related Internet forums. She claims to have photographs [but it’s not clear if these are about such farms, or about bestiality in general], but isn’t allowed to send them.
→ Katharina Meyer couldn’t find a single documented/concrete example of an animal brothel in Germany.
2012-10 - Dr. Thorsten Gerdes (judge of the State Court in Detmold) composed a statement as individual expert (on the topic of changing the animal protection laws) for the Bundestag. According to the archived copy (PDF), he wrote:
Das Argument, in Deutschland seien Tierbordelle denkbar,50 mutet mangels konkreter Fälle als eher theoretisches Szenario an, zumal § 17 TierSchG auch bereits in seiner jetzigen Form geeignet sein dürfte, einen derartigen Extremfall zu erfassen.
My rough translation:
The argument that animal brothels are conceivable in Germany seems to be a rather theoretical scenario, as there are no specific/concrete cases; especially since § 17 TierSchG in its current form should be suitable to cover such an extreme case.
→ Dr. Thorsten Gerdes didn’t know of a single documented/concrete example of an animal brothel in Germany.
2012-12 - A reform of the animal protection laws is decided, to come into effect on 2013-07-13. The new (and as of 2017 still current) law § 3 TierSchG explicitly covers bestiality: it’s illegal to use/train/provide animals for carrying out sexual acts if the animals are thereby forced to behave in a way that is not species-appropriate.
in 2012 there couldn’t be found proof that even a single animal brothel exists in Germany,
in 2013 the new animal protection law introduced (again) a law against bestiality,
and to this day there don’t seem to be any news reports about actual cases / proof.
- Could animal brothels exist in Germany? Yes. Illegal ones anyway, but possibly also legal ones (as § 3 TierSchG doesn’t forbid all kinds of bestiality).
- Is there proof that animal brothels exist(ed) in Germany? No.²
- Does the number of animal brothels in Germany currently increase? As we have no proof that even one animal brothel exists, it seems very unlikely, but we can’t know for sure, of course.
¹ Madeleine Martin claims that animal brothels exist in Scandinavia. Katharina Meyer checks this claim, too. The mentioned source points to Denmark (an article in 24timer). Back then, Denmark’s police and Denmark’s minister of justice said that they don’t know any cases.
² There are cases mentioned where animal owners take money to allow other persons to have sex with their animals, but it would be a bit of a stretch to call this brothels. Example: Sodomie: Die Dunkelziffer ist hoch (a private pet owner in their backyard)