After the beer has been through the primary fermentation process, yeast and sugars are added and the beer is bottled. The yeast and sugars naturally carbonate the beer as a secondary fermentation process takes place in the bottle itself. This gives the beer a higher gravity level and alcohol content. Bottle-conditioned beer has a shelf life of several years, whereas cask-conditioned beer should be consumed within three months. Hair of the Dog Brewing Company is one of the local breweries that use this process.