Verdict: No, dangerous
Pizza is dangerous for dogs and should not be fed to them. It contains multiple ingredients like garlic, onions, high fat, and dairy that can cause severe gastrointestinal upset, pancreatitis, red blood cell damage, or even life-threatening conditions like GDV. If your dog eats pizza, especially a significant amount or one with toxic toppings, contact your veterinarian immediately.
Garlic and onions contain N-propyl disulfide, which can cause oxidative damage to red blood cells. High fat content can lead to pancreatitis. Lactose in cheese can cause gastrointestinal upset in lactose-intolerant dogs. Yeast dough can expand in the stomach and produce ethanol. Many seasonings are irritants.
garlic, onions, cheese (lactose), high fat, yeast dough, various seasonings