The online magazine Slate sent out this tweet June 23:
The Oxford English Dictionary‘s first citation for “dog’s breakfast,” from the Balleymena (Ireland) Observer, 1892, also provides a definition: “In a lump like a dog’s breakfast, said of a heterogeneous heap of things.”
It is very much a Britishism, but more of a NOOB than I would have expected. It has appeared in the New York Times–attributed to or written by Americans–seven times since 2010, the first in a quote from Supreme Court Chief Justice John Roberts, who called court rulings on jury instructions “a dog’s breakfast of divided, conflicting, and ever-changing analyses.” The most recent occurred in a review of the HBO series “Vinyl” this past February, referring to a character who is “president of American Century Records, which has a dog’s breakfast of an artist roster: Grand Funk Railroad, Donny Osmond, Savoy Brown, Robert Goulet, and their biggest act, Led Zeppelin.”
Slate’s use of the phrase was appropriate–the author of the article called Simmons’ show “a mess.” If only the magazine had left things there. Instead, a mere four days later, it sent out this tweet:
That was a misuse of “dog’s breakfast”; all the article really said about the industry was that it isn’t doing well. But the tweet committed an even worse journalistic sin: repeating yourself.
notoneoffbritishisms.com 
Ahhh… the dog’s breakfast. Ben is quite right in his definition. However, it is not to be confused with the dog’s dinner. My grandmother used to say: “Look at you, all dressed up like the dog’s dinner!” I also believe (possibly erroneously) that the phrase ‘it’s the dog’s bollocks’ as in ‘it’s fabulous’ comes from the dog’s dinner, rather than the breakfast, illustrating the UK’s insistence on creating a ‘rudity’ out of a perfectly polite, if obscure, well-used phrase.
Actually Catherine, I think (also possibly erroneously) “dog’s bollocks” is a newspaper printing term referring to the start of a list, as in :-
To say something is a dog’s breakfast or a dog’s dinner or someone has made a dog’s dinner or a dog’s breakfast of something means a mess or a muddle. But dressed up like a dog’s dinner means to have dressed up in a smart or showy way which draws comment as from Catherine Rose’s grandmother.
I’d always assumed that ‘dog’s bollocks’ was a later extension of the 1920s ‘bee’s knees’, ‘cat’s pyjamas’, and similar phrases. A quick web search suggests that may be true, or it may have originated as a typographic symbol (‘:-‘).
I learned this term in the late 70s while playing euchre or cribbage. Cousins from Saskatchewan referred to a terrible hand as a dog”s breakfast. My mother from the Ottawa valley, in Ontario, called the name thing a mess of pottage. Thanks for background on this.