The Patterdale Terrier, or more correctly refered to as the the Fell Terrier, are used for the same purpose as Jack Russell Terriers - to be a working terrier that can follow it's quarry to ground. Physically they should posses the structure that allows them to do this type of work - most importantly being a narrow chest - but so many of the terriers sold as Patterdales in North America are no more able to go to ground than an Airendale.
Patterdale's are a bold and assertive terrier, more so than the JRT, without being aggressive towards other terriers on the hunt. A dog that is too interested in fighting with other terriers as is of little use in the field and far too many of these terriers are being bred as underground fighting dogs. A good working terrier must also be able to use it's brain and not go in and attack any quarry without some sense of self preservation. The Patterdale, while a working dog through and through, should remain biddable. Generally these terriers are more layed back in personality that the JRT, but in the field they are all business. They are a harder nosed terrier as opposed to a softer baying terrier. It is not recommended to keep a Patterdale simply as a pet as they do not do well in a non-working environment. They will not tolerate other small pets and should never be kept with cats, small rodents, etc.
