You must be speaking strictly in terms of monetary deflation. I could see dogecoin being deflationary as well, but in a "price deflation" sense.
Dogecoin could also become deflationary. If 6 billion dogecoins worth of value is created in a year and only 5 billion coins to match that increase in value, the economic value of goods created surpases that of the coins created. As a result, you have more goods chasing (relatively) fewer coins, increasing the value of the coin. In other words, less dogecoin gets you more stuff so you actually have (price) deflation.
In the US, during the stupidly-named "long depression" of the late 19th century, prices slowly dropped to about 60-65% of what they were at the start of the period while the total supply of money grew. That's because more goods were chasing (relatively) fewer gold-backed dollars. Monetary inflation coupled with price deflation.