Symptoms. Diagnosis. 23 



frontal sinuses and in those at the base of the horns ; sometimes, 

 also in the antrum of Highmore and in the nasal cavities. They 

 are strongly adherent to the mucosa which here shows small 

 roundish depressions and in their neighliorhood catarrhal 

 changes. Exceptionally the brain and its membranes liecome 

 invaded and likewise exceptionally the larvae are found in tlie 

 pliarynx and larynx. They get there usually only after the 

 death of the animal, but may exceptionally get there during life 

 and cause death by suffocation. 



Symptoms. Since the larvae cause irritation of the mucosa' 

 of the head only after maturity or after their migration, sj'nip- 

 toms become manifest only in spring or in early summer. The 

 disease usually begins with the mild symptoms of an acute nasal 

 catarrh, which increases in intensity within the next weeks. 



The first and most constant symptom is nasal secretion, 

 frequently unilateral, at first clear, serous or seropurulent, 

 later purulent; or possibly hemorrhagic. The animals fre- 

 quently sneeze and blow and throw out an abundant secretion, 

 occasionally also some larvae. At the same time, the sheep rub 

 their noses on their front legs, on neighboring objects and 

 on the ground, so that the parts around the nose sometimes 

 become denuded and subsequently edematous. The head is low- 

 ered from time to time, then suddenly elevated, bent energetic- 

 ally backward or laterally ; the gait is staggering and uncertain. 

 Simultaneous catarrh of the conjunctiva leads to profuse lacri- 

 mation. The mature larvae leave the nasal cavities after one 

 to two weeks, and the nasal and conjunctival catarrh then dis- 

 appear. 



In a minority of cases the catarrhal symptoms are com- 

 plicated by signs of excitement and depression. The gait of 

 the sick animal becomes markedly disturbed; they raise their 

 feet high, stagger with the hind legs and repeatedly fall down. 

 There is depression of high degree and gratiRg of the teeth, 

 rolling of the eyes, and occasionally forced movements toward 

 one side (Gilis) arc observed. In such cases death usually 

 occurs within five to eight days, exceptionally within three to 

 four days after the first symptoms l)ecome manifest. 



The intensity of the symptoms and the eourse of the disease depend largely 

 \ipon the nnndier of larva\ They may be present in small uumljers and they may, 

 npon their migration, not ]uodnce any other symjitoms except those of a catarrji. 

 The location of the larviv also has some influence upon the clinical picture. The 

 invasion of the ethmoid bone, or the involvement of the meninges, or the migration 

 of the larva^ into the cranial cavity, bring about serious nervous phenomena; 

 nervous symptoms may sometimes develop on account of the affection of the 

 frontal sinuses. 



Diagnosis. The rare cases with forced movements may 

 be confounded with giddiness of sheep. This, however, affects 

 almost exclusively young animals, and forced movements 



