Hi! Welcome to the horse forum. I wish it were under better circumstances.
Yes! I have seen hooves slough off. And yes, it can be from an infection. But, It is more likely to be because the hoof has died from a lack of blood supply.
It is usually caused by gangrene -- the necrosis or death of the hoof. There are different kinds of gangrene -- wet, dry and gas gangrene. In the horses I have seen lose hooves, the blood supply had been lost in one or both arteries on the sides of the pastern at or above the coronet. This can be caused by a deep cut that severed the artery or some kind of wire or rope got hung up around a lower leg long enough to destroy the blood supply, laminitis and founder was severe enough to destroy the blood supply or an infection from a deep puncture wound literally 'killed' the hoof from the inside out.
Lameness is not always real severe. Infection can be very severe depending on how much of the hoof is dead and how much is alive enough to be infected. Dry gangrene has no pus and the affected hoof just sloughs off leaving a dry, nearly dead black coffin bone exposed that is also dying. [Think diabetic person that has to have a leg or foot amputated.] Other cases of gangrene cause a severe cellulitis, extreme fever and the horse can die from the toxins produced by the infection. These infections are usually caused by an anaerobic bacteria related to Tetanus. The bacteria is Clostridium Perfrengens. It produces gas as it multiplies and is responsible for gas gangrene. Wet gangrene causes a lot of pus, a horrible smell and usually is home to thousands of maggots.
The one thing they all have in common is that the lower leg will smell very bad a good while before it sloughs, particularly if there is an open or running sore or abscess. If there are flies around, there will frequently be maggots or screw worms in the wound. The only time you would not smell it before hand would be if the blood supply was lost without an open wound of any kind until it sloughed. But, I'll bet it smelled really bad after it sloughed.
I hope this explains how a hoof can appear to just be there one day and slough off the next without a drop of blood. There just had to be trauma or some disease process that caused the hoof to die first.
Last edited by Cherie; 09-24-2012 at 11:00 PM.