While the Clostridium tetani bacteria is normally found in the feces of most species of farm animals, Clostridium botulini thrives on dead and dying plant and animal tissue. Both bacteria can live in the environment for years. When a clostridium bacteria finds its way into a wound, the pus and dying tissue provide an ideal environment for growth. As the bacteria thrives and multiplies, toxins are released that travel through the peripheral nerves, eventually reaching the spinal cord. There the toxin interferes with normal activity at nerve junctions and, in the case of tetanus, causes a generalized muscular rigidity.
Botulism results in a neuromuscular paralysis.
That said, tetanus has become less common in the United States because of a good annual vaccination program and timely boosters. Nevertheless, the disease, which is more common in the warmer southern states, has a poor prognosis. Small ruminants like sheep will lay on their side with all of their limbs stiff. Eventually the toxin moves far enough up the spinal cord to cause respiratory paralysis and death. Also, if any medical procedures such as castration or tail-docking are needed, they must be done using good sterile technique.