Tinto Cao is one of the top five grape varieties used in the production of quality Port in the Douro Valley. The low-yielding variety is prized for the spice and bite it delivers to red Port. The name Tinto Cao means 'red dog', although there is little convincing evidence to explain its etymology. This is not the only wine grape name to refer to dogs; others include Esgana Cao (aka Sercial), and Etrangle Chien (Mourvedre), both of whose names translate as 'dog strangler'.
Tinto Cao is an old variety, but not ancient. It is also not particularly widely planted, despite how popular it is with winemakers. Its plantings represent just one per cent of the Douro's total vineyard area. It is also planted in Dao, where it may be produced as a blended or varietal dry red wine.
Over the centuries, winegrowers in the Douro have discovered that Tinto Cao is better suited to the region's less sunny sites, where the cooler mesoclimate helps showcase the variety's elegant floral aromas. When grown in such sites, Tinto Cao, with its strong tannins and acidity, provides longevity to the port blend, helping the wines to age gracefully for many decades.
Despite the dark hue of Tinto Cao grapes, the wines they produce are not as deeply colored as those made from the Douro's other principal grape varieties Touriga Nacional, Touriga Franca and Tinta Roriz.
A few Tinto Cao vines are planted in California where they are used in the production of port-style wines.
Synonyms include: Tinta Cao, Castellana Negra, Farmento, Teinta Cam.