This vintage real photo postcard features two brindle terriers. They appear to be Jack Russell terriers. They are beautifully posed. This postcard was published by Valentine & Sons as part of their Real Photo Animal Series (no.RP.18). The Valentine and Sons printing company was founded in Dundee, Scotland in 1851. The founder was James Valentine (1815-1879). The company became the leading manufacturer of picture postcards in Scotland. After James died, his two sons operated the business. The company was purchased by John Waddington Limited in 1963, In 1980, the Valentine business was bought by Hallmark Cards. In 1994, the company ceased operations. This card was printed in Great Britain. (SOLD)
THE CABINET CARD GALLERY 
The believe dogs featured here in this wonderful postcard are Smooth Fox Terriers.
Thanks for the identification.