780 Parturient Paresis. 



after difficult ones (according to statistics collected in Bavaria 

 out of 129 cases of illness 120 of the births were normal and 

 easy), still cases also occur now and again after difficult partu- 

 ritions. Hess further noticed that milk fever occurred only in 

 such cows as went to full term or five to fifteen days beyond it. 



A part that must not be undervalued is further played by 

 the kind and mode of the feeding. Well-nourished cows chiefly 

 become affected, especially those that are fed intensively to- 

 wards the end of the period of gestation, as well as very greedy 

 cows, especially those that have been dry for several weeks. 



Most authors state that cows that are kept in the barn 

 almost constantly are most susceptible to the disease, but Tapken 

 could not determine any difference in this respect. 



Finally some cows may be said to have an individual pre- 

 disposition for attacks which occur at several subsequent par- 

 turitions (Roll). 



Other\vise the illness arises in connection with the birth 

 and indeed in most cases within the first three days, sometimes, 

 however, somewhat later, or during or before parturition, yet 

 never before the establishment of milk secretion (Hess, how- 

 ever, has never seen the onset of parturition paresis before or 

 during birth in 170 carefully observed cases). 



According' to statistics collected by Jensen in 1107 cases, 4.24% occurred before 

 birth and the remainder after birth; of the latter 2.53% began after 1 to 3 hours, 

 3.9% after 3 to 6 hours, 13.09% after 6 to 12 hours, 14.27% after 12 to IS hours, 

 27.37% after 18 to 24 hours, 10.29%, after 24 to 30 hours, 8.40% after 30 to 36 hours, 

 3.70% after 36 to 42 hours, 6.77% after 42 to 48 hours, and 5.42%, after more than 

 48 hours. Hess did not observe any cases more than 96 hours after parturition, al- 

 though there are records in literature where the disease was said to have occurred 

 much later, as long as 10 days after parturition (Harms) ; but such cases may have 

 been confounded with other diseases as is suggested by the investigations of Guille- 

 beau and Hess. 



The opinions as to the nature of the illness are numerous, 

 Init only hypothetical; some have no scientific foundation what- 

 ever, and are consequently untenable. Even those hypotheses 

 which have more or less foundation do not throw a clear light 

 on the etiology and nature of the disease. 



Cerebral anemia is often assumed to be the cause of the symptoms of 

 parturient paresis. This could arise from too powerful contractions of 

 the uterus (Franck), or according to another view from an increased 

 flow of blood to the udder, the effect of which would be accentuated by 

 the milk secretion or the loss of tissue fluid caused thereby (hyposero- 

 hemia [Bredo] ). In support of this hypothesis, on the one hand, the 

 very favorable results of pumping air into the udder have been men- 

 tioned, and on the other hand also a few cases of rupture of the womli 

 with hemorrhage, where symptoms similar to those of milk fever could 

 be sho-wTi. It is believed by many that the udder and the blood vessels 

 situated between the abdominal walls and the udder, are capable of 

 containing about half the total quantity of blood in the body (Nelke, 

 Keim). 



The authors consider this hypothesis untenable for the following reasons: 

 Marek did not succeed in producing milk-fever-like symptoms by very copious bleeding 

 after calving. In one cow 30 hours after a normal calving 21%, and in another 36 



