At first I took this for a photograph of a painting of a dog, but I believe in fact the portrait of the dog, and the carpet it lies on, is photographic; it is just the background that was painted. And with some blurring of the lines along the back of the dog where photo and illusion meet, yielding a very atmospheric and painterly portrait of a clearly much beloved pet. With Howard & Co.'s Plattsburgh, NY printed on the back of the cabinet card--all of the photographs and records for which I can find date to the 1860s and 70s, so an early one I believe, c. 1870s.
6 3/8" x 4 1/4". General spotting to the card, a bit of wear around the edges of the photograph, and a couple of small stains to the carpet in the photo, looks like blue ink, in foreground.