Question: Are  Great Pyrenees and Terceira Mastiff both dog breeds?

Context paragraphs:
Mastiff: Mastiff type means a large molosser dog.  The term "mastiff type" has been used synonymously with the term "molosser".  For example, the bulldog breeds, the Great Dane, the mountain dogs, the pit bulls and even smaller dogs such as the Boston terrier, may be considered "mastiff types" in this broad sense.  The descriptive term, mastiff type, should not be confused with the breed, the Mastiff.  All breeds are individual and should be referred to by their breed name to ensure correct identification.

Alpine Mastiff: The Alpine Mastiff is an extinct Molosser dog breed, the progenitor of the St. Bernard, and a major contributor to the modern Mastiff (through such dogs as "Couchez"), as well as to other breeds that derive from these breeds or are closely related to them.  M.B. Wynn wrote, "In 1829 a vast light brindle dog of the old Alpine mastiff breed, named L'Ami, was brought from the convent of Great St. Bernard, and exhibited in London and Liverpool as the largest dog in England."  William Cavendish, 5th Duke of Devonshire, is believed to have bred Alpine Mastiffs at Chatsworth House.

Barbado da Terceira: The Barbado da Terceira is a medium-sized dog, with a volumous and robust look.  The Barbado da Terceira is the most recently recognized Portuguese breed.  The Portuguese Kennel Club (CPC) recognized it, on a provisional basis, on November 2004; it is not yet recognized by The Fédération Cynologique Internationale (FCI).  It is a population native to the Azores Islands, in particular the Terceira Island.

Great Pyrenees: The Pyrenean Mountain Dog, known as the Great Pyrenees in North America, is a large breed of dog used as a livestock guardian dog.  It should not be confused with the Pyrenean Mastiff.

Shōnen to Inu: Shōnen to Inu (少年と犬 ) is a Japanese manga written by Akira Itō and illustrated by Yoshihiro Takahashi.  The manga was re-issued in 2001 under the name Ginga no Inutachi [Shōnen to Inu] Remix (銀牙の犬たち [少年と犬] リミックス ) .  It has six different stories about six different dog breeds: Golden Retriever, Shiba Inu, Siberian Husky, German Shepherd, Labrador Retriever and Great Pyrenees.  All stories are mostly about the relationships between the dogs and a boy or a young man.

Vulnerable Native Breeds: Vulnerable Native Breeds are a group of dog breeds originating in the United Kingdom and Ireland, and identified by The Kennel Club (KC) as having annual registration numbers of 300 puppies or fewer.  The need for such a list was first identified in June 2003, with research conducted by the KC to identify the extent of the vulnerability and viability of each breed.  It was a joint project, with the KC working with the British and Irish Native Breeds Trust, later to be known simply as the Native Dog Breeds Trust.  The breeds on the list have been promoted at events such as Discover Dogs and Crufts, and by asking that owners of these breeds mate their dogs rather than having them spayed.

Pyrenean Shepherd: The Pyrenean Shepherd (known in France originally, and also in non-AKC registries such as the UKC, as the Berger des Pyrénées, and in Spain as the Pastor de los Pirineos) is a medium-small breed of dog native to the Pyrenees mountains in southern France and northern Spain, bred since at least medieval times for herding livestock, especially sheep.  It worked as an active herder together with the Great Pyrenees, another mountain dog, which acted as the flock's guardian.

Terceira Mastiff: The Terceira Mastiff (Portuguese: ] ) is a landrace Portuguese dog breed, also known as the Rabo Torto ("rabo"=tail, "torto"=curled/twisted).  Neither the Fédération Cynologique Internationale nor the local Clube Português de Canicultura has officially recognized it.  It is a remarkable ancestor to both the Cão Fila de São Miguel and the Fila Brasileiro .  This breed is fully different from the Barbado da Terceira

English Mastiff: The English Mastiff is a breed of extremely large dog (often known simply as the Mastiff) perhaps descended from the ancient Alaunt and Pugnaces Britanniae, with a significant input from the Alpine Mastiff in the 19th century.  Distinguishable by enormous size, massive head, and a limited range of colours, but always displaying a black mask, the Mastiff is noted for its gentle and loving nature.  The lineage of modern dogs can be traced back to the early 19th century, but the modern type was stabilised in the 1880s and refined since.  Following a period of sharp decline, the Mastiff has increased its worldwide popularity.  Throughout its history, the Mastiff has contributed to the development of a number of dog breeds, some generally known as Mastiff-type dogs, or, confusingly, just as "Mastiffs".

Dogue de Bordeaux: The Dogue de Bordeaux, Bordeaux Mastiff, French Mastiff or Bordeauxdog is a large French Mastiff breed—and one of the most ancient French dog breeds.  A typical brachycephalic molossoid type breed, the Bordeaux is a very powerful dog, with a very muscular body.  This brawny breed has been put to work in many different capacities, from pulling carts and hauling heavy objects, to guarding flocks and, historically, the castles of the European elite.

Supporting paragraphs: Great Pyrenees Terceira Mastiff
Answer: yes