2l6 CLINICAL VKTERINARV MKDICINE AND SURCKRY. 



The blood and affected organs may contain various microbes, but 

 none of those at present isolated can be regarded as the specific agent 

 of influenza. That remains to be discovered.* 



Diagnosis is easy. The sudden appearance, rapid aggravation of 

 symptoms, extreme depression, and the ocular symptoms constitute the 

 principal indications. Any doubts which might at first exist are soon 

 dissipated by the rapid spread of disease to large numbers of fresh 

 subjects. In less than a fortnight one half or two thirds of the animals 

 in a large stable may be attacked. 



The disease can be distinguished from contagious pneumonia and 

 from the pneumo-enteritis said to be produced by bad fodder. 



Contagious pneumonia is recognised by the predominance of pul- 

 monary symptoms ; the rapidity of breathing from the outset ; the 

 slighter depression ; the absence of epiphora ; the yellowish colour and 

 moderate injection of the conjunctiva, and the slow extension of the 

 epidemic. The embarrassing cases are those where infection is of a 

 mixed character, — influenza and contagious pneumonia, for instance, 

 being both present in one stable. 



The existence of pneumo-enteritis is usually announced by some- 

 what alarming symptoms, but in general the onset is less striking and 

 the contagion less active than in influenza. The conjunctiva is less 

 swollen, and lacks the violet or mahogany colour. If the colour, 

 appearance, and smell of the hay and oats leave nothing to be desired, 

 if they are clean, have been well got and carefully stored — if, in a word, 

 they are of excellent quality, pneumo-enteritis may be placed out of the 

 question. It is always easy to distinguish influenza from sore throat, 

 or bronchitis affecting a number of animals. 



The prognosis is usually favourable, but varies according to the 

 character of the prevailing outbreak, the time of 3'ear, and the animals' 

 surroundings. When the disease seizes on a locality from which it has 

 long been absent, more animals are lik-ely to succumb than in large 

 towns where it exists, so to speak, permanently. This year we have 

 seen little but benign cases which developed regularly and rapidly. 

 All our cases of simple influenza recovered, but the mortality is some- 

 times severe, varying between i and 15 per cent., the medium being 



* M. Lignieres isolated and cultivated a microbe which he termed the cocco-baciHiis, and 

 which he regarded as the specific cause of influenza in the horse. He states that " inocu- 

 lation of a horse with a culture of this microbe produces most characteristic symptoms of 

 influenza." Suitably attenuated and inoculated into a healthy horse it produces no grave 

 symptom and affords immtmity. By vaccinal inoculation in the horse a preventive and 

 <-urative serum was obtained. 



