Most of the time, they are harmless and happen in healthy people free of heart disease. However, some abnormal heart rhythms can be serious or even deadly. Having other types of heart disease can also increase the risk of arrhythmias.
The internet meme doge is the Shiba Inu breed of dog. The Shiba Inu breed is native to Japan. Shiba is Japanese for Brushwood and Inu is Japanese for dog. The original person who caused the doge meme sensation actually didn't understand very much English.
As to the extent that Latinate words such as  Dogo  or  Dogge  may be translated as mastiff, molosser breeds such as the Dogo Argentino and Dogo Canario may also be considered mastiffs. However, these terms may refer not only to breeds called mastiffs in English, but also to Bulldogs and pit bulls.