304 Veterinary Medicine. 



such an attack possible. The Warm Summer Season has been 

 claimed to induce a greater number of cases, and doubtless ex- 

 posure to continuous heat, tends to prostrate the nervous system 

 and predispose to congestion, this fails to take into account the 

 still more important element of the rich spring and early sum- 

 mer pastures, where the already plethoric animal is left to feed 

 without stint, or the tempting red clover, alfalfa and other fodder 

 crops, rich in albuminoids, which are fed liberally in a succulent 

 condition. 



Chills in cold winter weather have been similarly invoked as 

 driving the blood from the surface to collect in internal organs, 

 including the brain. That chills do act in this way cannot be 

 denied, but there is no demonstration that any number of cases 

 have been materially affected by cold. 



Idiosyncrasy . Constitutional Predisposition. This must be al- 

 lowed, inasmuch as that it covers all those individual conditions, 

 functional and structural, which belong to the heavy milker, or 

 the animal with extraordinary powers of digestion and assimila- 

 tion. The same shows in the predisposition to a second attack 

 of an animal which has survived a first one. The structural 

 changes in the nerve centres, which occur in the primary attack, 

 leave traces, which render these parts more susceptible at the 

 next calving. In my own experience the violence of the disease 

 is liable to increase with successive attacks, so that a second or 

 third cannot be hoped to be as mild as was the former one. 



Cardiac Hypertrophy. Cagny draws attention to the fact that 

 in man and beast alike the heart undergoes hypertrophy during 

 gestation and, above all, during the later stages. In improved 

 breeds of cattle, and especially in milking breeds, a great de- 

 velopment of the whole circulatory system is seen, and a large 

 heart is a constant feature of this. This implies an increased 

 force of cardiac systole, an increased blood tension in the arteries 

 and capillaries, a condition which tells with special force on the 

 soft tissues of fhe brain, as the violent abdominal compression in 

 the expulsive efforts of parturition, tends to drive the blood from 

 the great vascular viscera situated back of the diaphragm. 



Parturition and the subsequent contraction of the womb and ex- 

 pulsion of the great mass of blood, must be accorded a prominent 

 place among causative factors. The disease is almost restricted 



