The Great Dane is one of very few breeds rated 5/5 for cost, and the figures back it: $200–400 a month against the Malamute's $150–300, with a first year of $3,000–5,000 against $2,000–4,000.
Food is the obvious component. A 150 pound dog eats a great deal, and a giant-breed puppy needs a formulation with controlled calcium and a specific calorie density to avoid accelerating growth — the wrong food is genuinely a health risk in the first eighteen months, not just an expense.
The less obvious costs are the ones weighed by the kilogram. Parasite prevention, antibiotics, anaesthesia, pain relief and sedation are all dosed by body weight, so every routine event costs more. A dental under general anaesthetic on a Dane is a bigger procedure with more drug and more risk than the same job on a 90 pound Malamute. Insurance premiums for Danes are among the highest of any breed because of the cardiac, orthopaedic and cancer history.
Then there is the equipment. Crates, beds, ramps for the car, gates, harnesses and boarding fees all step up a tier at Dane size, and some boarding kennels either decline giant breeds or surcharge them.
The Malamute has one cost the Dane does not: grooming. At 4/5 grooming and 5/5 shedding against the Dane's 1/5 and 3/5, the Malamute needs an undercoat rake two or three times a week and possibly professional de-shedding twice a year. The Dane needs a rubber mitt occasionally and nothing else. That is real, but it does not close a gap of $50 to $100 a month in the other direction.