Tetanus sometimes occurs in the absence of any noticeable wound. It may be in such cases that the seat of the infection is a slight abrasion of the skin, or the lining membranes of the respiratory and digestive tracts. The tetanus bacillus is a slender, spore-producing bacterium. The spore is located at one end of the rod in the form of a round head, that gives the organism a pin shape, hence the name of pin bacillus. It is very resistant to outside conditions and the action of the chemical disinfectants. It is because of its ability to resist the action of disinfectants and the fact that it develops best when protected or covered by the tissues and wound secretions, that this disease so often follows ordinary wound treatment.
Note the rigid, tense position of the muscles.]
From a few days to several weeks may lapse from the time of infection with the germs until the development of the stiffness and spasms. Sometimes the wound by which the organism has entered the tissues has healed before the symptoms of tetanus are manifested. In case the symptoms develop a few days after the inoculation the disease is severe or acute in form, and less violent or subacute if the symptoms are manifested after the second week. The above statement does not hold true in all cases, but it may be considered true in a general way.
Of the domestic animals the horse is the most commonly affected. The symptoms shown by this animal are very characteristic. Any person that has had the opportunity to see and examine a horse suffering from tetanus should have no trouble in recognizing the disease in other animals.
=The Characteristic Symptom= is the spasmodic contraction of the muscles. This may vary in the different individuals, depending on the susceptibility of the animal and the quantity of poisonous toxin present in the system. There is at first a slight stiffness of the muscles of the back, neck, head, and limbs, and the animal is more nervous than common. A noise in the stable or a slap with the hand may increase the stiffness and contractions temporarily. The contracted condition of the muscles of the eye, are, perhaps, the most noticeable early in the disease. These muscles pull the eyeball backwards, the fatty cushion is pressed on and the third eyelid protrudes, covering at times from one-third to two-thirds of the front part of the eye. In the severe form of the disease the muscles feel hard, especially those of the back and neck, and the animal moves with difficulty. In addition to the muscular symptoms, the respiration and pulse beats are quickened and the body temperature higher than normal. The evidence of suffering from the contracted condition of the muscles is very marked, and, unless supported in some way, the animal may fall to the floor. If the symptoms develop a few days after infection, the animal usually dies. The acute form is very fatal, but in the mild or subacute form the chance for making a recovery is good.
