PARTURIENT PARESIS— MILK FEVER 161 



Occurrence. — The disorder is common among cows, espe- 

 cially valuable dairy cows, which are heavy feeders and deep 

 milkers. It usually occurs at the acme of lactation and in 

 cows that are well bred and in prime condition. Thin cows 

 or very fat cows do not seem predisposed. When delivery 

 has been difficult, parturient paresis is less apt to occur than 

 when the birth has been easy and the expulsion of the after- 

 birth prompt. 



Primipara are very rarely attacked. Usually it occurs in 

 cows from the third to the fifth calving. 



Etiology. — The causes of parturient paresis are unknown. 

 The following theories have been suggested : (a) auto-intoxi- 

 cation from the uterus or udder resembling ptomaine poison- 

 ing; (b) it may be an anaphylactic phenomenon or (c) an 

 anemia of the brain, the result of the sudden blood flow to the 

 udder or in consequence of a vasomotor collapse. 



Symptoms. — The symptoms usually begin twelve to forty- 

 " eight hours after delivery. A few cases are recorded where 

 the attack came on during or even before the birth. The prin- 

 cipal symptoms are a suddenly developing general motor and 

 sensory paralysis, with loss of consciousness. After showing 

 some symptoms of languor, weakness, and staggering gait 

 the cow lies down. She may regain her feet but arises with 

 difficulty. Finally she becomes completely paralyzed and 

 unconscious. Often the patient is found lying bn her sternum 

 with her head thrown around against the flank, the muzzle 

 resting close to the udder. In other cases she lies flat on her 

 side. The respirations are slow and deep, the temperature 

 normal to subnormal. From the nostrils a lymph-like fluid 

 is discharged. Besides these general symptoms those of 

 specific paralyses of the cranial nerves occur, especially the 

 oculomotor, trigeminal, glossopharyngeal, vagus, hypoglossus, 

 and sometimes the opticus. 



The oculomotor paralysis is expressed by drooping of the 

 upper eyelids (ptosis) and dilatation of the pupil; the tri- 

 geminal paralysis leads to sinking of the lower jaw; the 

 glossopharyngeal paralysis leads to dysphagia; the vagus 

 paralysis produces inactivity of the muscles of the larynx, 

 leading to stenotic, noisy respirations. It also increases the 

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