Hello,
If you use Bittrex or Coinmarketcap, you should get the price of Dogecoin next time your exchange rates refresh.
Do you get prices for other cryptocurrencies?
You can use the debug view in Admin -> Wallets -> Exchange rates -> Exchange rates to inspect what data is loaded.
If you are viewing exchange rates via the [wallets_rates] shortcode, note that you can only display exchange rates for currencies that you have enabled coin adapters for.
kind regards