A Dog, a Horse and a Heart — Barbara Cartland

It is bad enough that the beautiful Manella's heartless uncle is threatening to sell her adorable English Setter, Flash and her beloved horse, Heron. 

But when he dashes all her hopes and dreams with a forced marriage to an aging, decrepit but rich Duke, she flees astride Heron with Flash at her heels to a rural village where she finds employment as the Marquis of Buckingdon's cook. 

Out of the frying pan and into the fire, she is embroiled first in a wicked poison plot and then highway robbery

And, as her trusty animals save the day and the dashing Marquis saves her life, Manella realises that she has now lost her heart.