I would think that this is not the case. When dumping the body in the mausoleum, it seemed that both Gnessier and Louise knew very well what they were doing. One interpretation could be that the other bodies have been dumped in a similar way, i.e. not at all fed to the dogs.

That's nothingI kept waiting for him to try and graft a dog's face onto her!

That's all they were used forskin grafting experiments. We're SHOWN what they did with the bodies of the girlsof which there were only two. Dumped in the river. People don't pay attention.

I also thought the dogs were used for medical testing.

The dogs were for medical testing. I believe this happened in real life (I'm sure I read it online somewhere at the time) in preparation for the world's first [partial] face transplant, performed in 2005 by a French surgeon in France.
But yeah, back to the movie you know, I never thought of that why not? It is the perfect cover up. You can save on dog food or other meat when you have an occasional body you want to dispose of discreetly. Remember though that
his whole driving force and motive was guilt and a desparate quest to repair (replace) his daughter's face and give her a chance to live. It was his henchwoman who was the real psychopathic one
.
"Oh look - a lovely spider! And it's eating a butterfly!"
''
,,

Yes, I actually thought that was what the doctor needed the dogs for.