MALIGNANT HEAD CATARRH OF THE OX 367 



The disease has not been transmitted by inoculation. It 

 does not spread by contact. In some stables, as noted, it 

 exists for years, appearing each spring and fall and in time 

 causing considerable losses. 



Young, fat cattle (one- to three-year-old steers) are most 

 often attacked. One attack does not produce immunity 

 against subsequent ones. A given animal may suffer suc- 

 cessive attacks a few weeks or months apart. 



Symptoms. — The period of incubation is from twelve hours 

 to two days. 



The disease usually begins with symptoms of fever (104° to 

 107° F.). The surface temperature is unevenly distributed, 

 the poll of the head hot, the muzzle hot and dry. The fever 

 drops on the second or third day. Before death it becomes 

 subnormal. 



Nervous Symptoms. — The head is held low or rests on the 

 manger. In some patients on the second or third day there 

 is marked stupor, the animal lying on the ground unconscious. 



In other patients there is excitement, the animal bellowing, 

 rearing, and plunging. Locomotion is difficult, the gait un- 

 certain and staggering. Twitching of the muscles of the neck, 

 shoulders and body may occur. Epileptiform spasms have 

 been observed. The excitability of the patient is increased by 

 such external influences as bright sunlight, sudden noise, etc. 



The eyes on the first or second day show conjunctivitis, 

 which may extend to the cornea causing keratitis. There is 

 photophobia and profuse lacrimation. The cornea becomes 

 turbid or "milky," the clouding beginning at the periphery. 

 Iritis and cyclitis are also observed, the anterior chamber 

 being filled with yellow exudate. The episcleral bloodvessels 

 are congested. From the fibrinous iritis the animal is often 

 blind. 



The Respiratory Tract. — There is at first a thick, viscid, 

 purulent, later more fibrinous nasal discharge, mixed with 

 blood, which finally becomes discolored and fetid. The 

 croupous masses forming in the larynx narrow its lumen, 

 cause noisy dyspnea, and at times distressing cough. The 

 sinuses of the head may become filled with exudate and the 

 horn core inflamed, leading to the horns becoming loose. In 



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