PHTHIRIASIS. 781 



triangular head, armed with a tubulous haiistelhim. The other 

 species, belonging to the MaUopItaga, mandibular, or biting lice, 

 are entirely different, particularly in their head and thorax, the 

 former being distinctly quadrate, and furnished .with mandibles 

 and maxillae suited to their mode of life. These two species 

 are more apt to be found on horses neglected, or suffering from 

 poverty and privation ; while the inroads of the louse of the 

 domestic fowl are regulated largely by the condition of the 

 poultry -houses or roosts and their proximity to stables. They 

 attack horses of all classes, but seem to have a preference for 

 those which are in work and good condition, or probably they 

 have greater facilities for settling on such. 



Although horses may harbour in their coats a numerous 

 colony of varymg species of lice, it is only in particular 

 instances that much disturbance is witnessed. In some, how- 

 ever, the irritation and itching are most troublesome, proceed- 

 ing until well-marked traumatic abrasions of the skin or 

 papular and vesicular changes show themselves, the results of 

 this rubbing. 



In horses attacked by the poultry-louse, the Gonioctes 

 Burnetti, small and scattered spots of depilation occur over a 

 large surface of the body, this depilation being the result of 

 the occurrence over these circumscribed areas of a very minute 

 vesiculation. A similar condition may also show itself in 

 occasional cases of cutaneous irritation, where the insect is of 

 either of the species more common to the horse. As a rule, 

 however, the attack of the former is more sudden, its progress 

 more rapid, and the irritation — probably from the character 

 of the subjects affected — is more marked. 



Treatment. — It is easily understood that in those cases, which 

 are certainly not the commonest, where the pediculi are 

 conveyed from poultry, any attempt at the destruction of 

 those on the suffering horses themselves will be unavailing, 

 without the removal of the original cause, the destruction of 

 the lice in the poultry-roosts, or the removal of the larger 

 animals from their influence. In the application of either wash 

 or ointment the difiiculty is not that of being able to destroy 

 the insects, but of obtaining at the same time the destruction 

 of their eggs. Usually, the safest mode is that of repeated 

 applications of the parasiticides until the whole are destroyed 



