I have a vague recollection of having seen a movie on T.V. many (many) years ago (early to middle 1960s) about a cruel prison warden who kept these fierce hounds as guard dogs. I recall that the prisoners were mistreated, perhaps they were political prisoners, and, at times tortured, and, perhaps, fed to the dogs. I also recall that their blood was sometimes drained, and, perhaps consumed by the warden (none of this is very clear to me and given the time, none of this would have been explicitly shown). I recall the film had a Mexican or Spanish setting, but this may be my own childish interpretation of the uniforms of the guards (I was a child, and may have misread the setting).
However, the conclusion was something that has frightened me for years, even though it was an off-screen event: the warden, fleeing from some disruption in the prison (perhaps a revolt, I cannot recall), is torn to death by his own dogs. His shrieks and the dogs' howls were quite vivid and terrifying, "blood-curdling" as goes the cliché.
Perhaps this is why I am, to this day, so wary around dogs.
UPDATE: It seems Joe D. (with assistance from Leonard Maltin) has answered his own question with 1958's BLOOD OF THE VAMPIRE…
It might be the "Blind Alleys" segment of Tales From The Crypt (the 1972 anthology movie, not the TV series). It doesn't take place in a prison, but rather a cruel "care center." A synopsis from Wikipedia: Major William Rogers (Nigel Patrick), the new director of a home for the blind, makes drastic financial cuts, reducing heat and rationing food for the residents, while he lives in luxury with Shane, his German Shepherd. When he ignores complaints, the blind residents exact revenge by constructing in the basement a maze of narrow corridors lined with razor blades. They starve the Major's dog, place the Major in the maze's center, release the dog and turn off the basement lights.
Naturally, when the lights go out, you don't see what happens…but you hear some bloodcurdling mayhem.
There's also the possibility that we're talking about El Perro, AKA A Dog Called…Vengeance, from 1976, starring Jason Miller (The Exorcist): A political prisoner in a South American dictatorship escapes and is pursued throughout the country by a bloodthirsty dog.
Another possibility: 1978's Mean Dog Blues with George Kennedy as a vicious prison warden who uses prisoners to train his equally vicious dogs…but I don't know much about that one.
Unavailable on DVD, A Dog Called…Vengeance and Mean Dog Blues can be torrented from Cinemageddon.org (registration required). Tales From The Crypt is there too, but also available on DVD along with its sequel, for cheap.
Thanks for great guesses Grokenstein, but none of those seem to be it.
Joe emailed this:
Joe emailed again (and this time, with an answer!):
And to answer Joe's closing question… I say PUPPETS!
Incredibly, Blood Of The Vampire is the latest review at StompTokyo! Chock full of nice color pics and plenty of text (cough)! http://www.stomptokyo.com/badmoviereport/reviews/B/blood-of-vampire.html