This is an interesting aside for Brewer's Yeast.
Years ago I read that feeding your pets Brewer's Yeast was a natural flea
repellant. Supposedly changed the taste of the pet or something and fleas
didn't like it.
My cat was allergic to fleas and would pull his fur out until he was
bleeding and bald, and would require a cortisone shot to stop his
scratching. Keeping in mind he was an indoor cat, too. Fleas come in off
people's shoes, and if you're in an apartment building, other animals can
bring them inside, blah blah blah.
I finally decided to give this Brewer's Yeast a try, since I was desparate.
First I tried mixing it in their food, but then I found if I just put it in
a dish, they'd eat it a little at a time right out of the dish.
I haven't had fleas in 18 years.
Can't prove it's the Brewer's Yeast, but I sure can't prove it isn't!