A study of certain aspects of enteric and respiratory diseases of young calves on a dairy farm in the west of Scotland

Although several national surveys have established the extent of mortality in young calves, much less information is available on the precise cause of deaths and, more importantly, very little work has been done in an attempt to assess the economic loss and "set-backs" in development programmes that result from non-fatal disease problems. Without doubt, neonatal diarrhoea and calf respiratory disease are the most important problems in intensive calf rearing establishments. While a lot of clinical and laboratory investigations have been carried out into various aspects of calf diarrhoea, the relative importance of pathogens in the wider context of calf diarrhoea, is as yet undefined. Nonetheless, there is as yet no evidence to disprove earlier findings on the protective role of passively-acquired (colostral) immune globulins in neonatal diarrhoea. Compared with calf diarrhoea, much less information is available on respiratory diseases of indoor calves and, sadly too, there is a lack of general agreement as to nomenclature and classification. While many workers have, probably in despair, come to regard the problem as being of complex or multifactorial aetiology, a few others have attempted to separate it into distinct clinical and pathological entities. While it is true that the different "forms" of disease do occur during the course of an outbreak, there is no doubt that there are distinct syndromes and that there is need for further disease definition as a first step towards detailed investigations into these specific respiratory syndromes. The aim of this study was to define, as far as facilities and time permitted, the nature of a pneumonia problem which although not causing deaths, was nonetheless responding less to a hitherto effective treatment regime. However, the opportunity was taken to note and investigate all disease problems which arose during the abservation period, the most important of which was an outbreak of Salmonella dublin Infection. Apart from the outbreak of salmonellosis, no significant neonatal problems were encountered during the period of study. Against the acknowledged high morbidity and mortality rates from neonatal calf diarrhoea in the west of Scotland, this finding was Initially rather surprising but not in light of the high serum immune globulin levels attained by the calves and the high standard of care and hygiene on the farm. Another contributing factor in the reduction of the incidence of diarrhoea might have been the feeding of acidified milk substitute powder. Three cases of profuse persistent sweating were recorded on the farm. However, the exact cause of the sweating was not known. Three of five calves which developed enlarged joints during the period of study were slaughtered for detailed study. No particular organisms could be incriminated in the arthritis. During an outbreak of disease due to S. dublin, 11 of 45 calves were considered ill. Among the older (2-3 months old) calves no serious clinical signs were seen, however, the disease was more severe in the younger calves; it was characterised by dullness and tachypnoea in three 4-5 weeks old calves, and dullness, weakness, tachypnoea and high fever in 1-2 weeks old calves. Death occurred in a ten days old calf and another two weeks old calf was slaughtered in extremis. The respiratory problem for which advice was sought was found to be mild to moderately severe widespread coughing and tachypnoea. The presenting sign was coughing. However, In addition, an occasional calf became dull and pyrexic. A typical outbreak which occurred among a particular group of calves between November and December 1979 was studied in detail. On serological grounds, respiratory syncytial (RS) virus was incriminated in spite of the fact that what is currently considered to be the characteristic severe clinical and pathological findings associated with RS virus outbreaks were not observed. Understandably, doubts must still exist as to the agent responsible for the respiratory outbreak and the episode serves to emphasise the difficulties facing those who are involved in investigations into respiratory disease of indoor calves. Nevertheless, such studies must continue if this important problem is ever to be controlled by rational means