248 THE HORSE IN HEALTH AND DISEASE 



numbers of the characteristic bacilli will be found if the animal is 

 infected. 



As treatment is usually out of the question, much importance 

 attaches to the prevention of this disease. In addition to precau- 

 tions for guarding the food and water against contamination there 

 are a number of methods of producing immunity. The most 

 generally used method was developed by Pasteur. It consists in 

 two subcutaneous injections of attenuated cultures of the bacillus 

 of anthrax at an interval of twelve or fourteen days. The inocu- 

 lations must be repeated each year to keep the immunity of the 

 animal at a point sufficiently high to withstand natural infections. 



The blood-serum of animals rendered hyperimmune to anthrax 

 has been used both as a prophylactic and therapeutic agent. 

 When used in conjunction with the vaccine the chances for perfect 

 immunity without loss are greatly increased. 



TETANUS 



Tetanus is a typical acute, infectious disease of the nervous sys- 

 tem, characterized by spasmodic contractions of the muscles. It 

 is caused by the tetanus bacillus, a spore-forming, toxin-producing 

 organism that is naturally found in certain soils and plentifully in 

 the mold of horse manure. The horse possesses great susceptibil- 

 ity for virulent cultures. Infection occurs through wounds made 

 by fork-tines, nails, spUnters, or infected surgical instruments. 

 Strictly speaking, it is not a communicable disease, although pus 

 from an infected wound is nocuous. 



The period of incubation varies from two to five days. Then 

 the animal shows spasms of groups of body muscles. When those 

 of mastication are affected the jaws become immovable. This has 

 given rise to the term "lockjaw." The ears, tail, and limbs stiffen. 

 Chief among the diagnostic symptoms is the protrusion of the 

 membrane nictitans, or "haw," over the eyeball when the head is 

 raised. A stilty attitude is assumed and a stiff gait when in 

 motion. 



The mortality varies between 55 and 90 per cent. In mild 

 cases given prompt treatment recovery may be expected. Thorough 

 disinfection of the seat of infection is the first essential in treat- 

 ment. Quiet quarters and provision for comfort are of greater 

 importance than drugs. Injections with an antitetanic serum give 



