Yes, in small amounts — plain mozzarella is one of the milder cheeses a dog can taste. It sits relatively low in salt and lactose beside hard, matured cheeses, it is soft enough to tear without a knife, and its mild flavour makes it valuable in training, where a dog needs a reward worth working for. The portion discipline is the whole story: one small cube, cut into pea-sized pieces, or a few shreds torn from a ball is a full portion. Mozzarella is still cheese, which means fat and calories in a compact form, and a dairy-sensitive dog can still answer it with a loose stool.
Fresh Ball or Grated: Reading the Two Forms
Fresh mozzarella sold in liquid is mild, moist and comparatively gentle, but it is perishable, so serve a dog's pieces from a freshly opened ball and refrigerate the rest in its liquid rather than leaving the ball on a worktop. Low-moisture mozzarella, the firmer block or ready-grated kind made for cooking, keeps longer and portions neatly, yet it is usually a little saltier and more concentrated, so the same one-cube measure applies rather than a freer hand. Whichever form you use, plain is the condition: smoked mozzarella, garlic-and-herb varieties and marinated balls in seasoned oil are seasoned human food, and the flavourings, not the cheese, rule them out. Check grated bags for nothing more exotic than an anti-caking dusting, and refuse anything blended with other cheeses or spices.
The Pizza Trap
If mozzarella reaches your dog, it will usually be as pizza topping, and pizza is precisely where the answer changes. The cheese on a slice arrives with a fatty, salty crust, a tomato sauce that commonly contains onion and garlic seasoning, and toppings that range from fatty cured meats to onions themselves. Sharing a slice, a stuffed crust or the cheesy top layer is not sharing mozzarella in the sense this answer allows. If pizza is on your table, the dog's reward should come from the plain packet in the fridge, measured as its own portion, rather than being peeled off a slice. The same applies to mozzarella sticks and other breaded, deep-fried forms, where the coating and the frying fat do more harm than the cheese inside could ever do good.
Using Mozzarella in Training Without Overfeeding
Cut the one small cube into pea-sized pieces before a session and the portion stretches into a string of high-value rewards, which is the arithmetic that makes mozzarella genuinely useful: maximum motivation, one cube spent. Count those pieces as part of the day's food rather than an addition to it, and on a heavy training day, trim the next meal slightly to balance the cheese rather than letting rewards quietly stack. Tear string cheese into thin strands instead of offering the stick, because a whole stick invites a gulping dog to swallow a long, dense piece that is hard to manage. Store opened mozzarella in the fridge, respect the date on the packet, and discard fresh balls whose liquid smells sour. Weight is the quiet cost of cheese. Rewards used daily can undo a careful feeding plan within weeks, so mozzarella belongs to training days and special tasks rather than the everyday treat jar by the door. For a very small dog, halve the cube and count that half as the whole portion. In a household with several handlers, KinsLe Care Teams keeps the mozzarella rule in the shared feeding notes, so training rewards stay measured rather than improvised.