First of all, that was really funny!
have to eat vegetarian dog food
because they're allergic
to meats. Usually, what happens is this. People start their puppy
out on, say, "Chicken and Rice" dog food. The puppy starts picking at his fur and chewing big sores
onto himself, turns out he's allergic to his food. So his owners switch him to Lamb and Rice, which is more hypo-allergenic
than chicken. Of course, it's not completely
hypo-allergenic, so his skin and fur don't recover and he's still itchy and miserable. So they switch him to something a little more weird, like, Rabbit and Potato. The symptoms
decrease, but they don't go away. Eventually, once one has exhausted all the possible meat-inclusive dog foods, one has to resort to a vegetarian formula.
Sometimes dogs with Irritable Bowel Syndrome
or colitis have to go on vegetarian food formulas too, so they can stop having screaming diarrhea
every time they eat.
Although I'm sure there are also some die-hard vegan
folk who abjectly refuse to have any meat products in their homes at all and if it's 'good enough for them it's good enough for their dog!' too.