Mucosal In Mild Form May Be Fairly Common

Press, Volume XCVIII, Issue 28920, 13 June 1959, Page 9

Mucosal In Mild Form May Be Fairly Common

According to Jarrett, an overseas worker on mucosal disease, the mild or sub-clinical form is probably widespread and escapes recognition. The ulcers in the mouth are small in> number and the other symptoms are less severe. Scouring and reduced milk yield may be of only one or two days’ duration and the animal recovers.

This is reported in the most recent issue of the “New Zealand Agriculturalist,” which also notes that preliminary studies of Underdahl and others have indicated that antibodies are commonly found in animals from herds having no previous history of the disease. Mucosal is defined as a disease of cattle characterised by erosions nf mucous membranes and hemorrhages from these erosions, fever, intense diarrhoea, marked reduction of appetite! wasting and dehydration. Cattle of all ages appear to be susceptible but the majority of reported cases have involved animals within the age group of

about three to 18 months. The first symptom, although it may easily be missed, is a sudden rise in temperature followed by the development of small erosions or ulcers on the mucous .membranes of the muzzle, mouth and tongue. There is acute diarrhoea, the faeces beifig of normal odour but of a greenish colour, and containing considerable amounts of mucus and blood, and there is evident straining and pain on defecation. Affected animals are dull and depressed, appetite is absent, and they show a pronounced reluctance to graze in a normal fashion.

Ulcers or erosions resembling those in the .mouth cavity occur also throughout the length of the alimentary tract, involving the oesophagus, rumen abomasum and intestines. In severe cases, which terminate fatally in usually from three to 10 days, death appears to be due to the severe dehydration which follows persistent diarrhoea and is preceded by rapid wasting of the animal’s tissues. In some cases there is lameness arising from erosion of th 6 skin between the digits but these foot changes will not be detected unless the space is carefully washed. The observations of many authorities, who have contributed to the literature on this subject, suggest that only a few animals in a herd are usually affected, but of those which do contract it almost all will die.

On the point of infectivity, the journal says that the literature is singularly confusing and indeterminate. Several workers have attempted to transfer the disease from affected to healthy animals by solutions prepared from ulcerated lesions or by administering blood or spleen emulsion. Failure to reproduce the disease has been reported by some workers and success by others.'

Thus Nielsen and others, Swope and Luedke and Schipper and Eveleth were unable to transmit the disease by inoculation of lesion material or by direct contact, thereby supporting in some measure the suggestion contained in a report by Olson and Hoerlein that infectivity is slight. These workers have recorded that in an outbreak of mucosal disease in a herd of 223 calves, 24 died, but shortly afterwards 53 new calves were brought into the herd and none developed the disease despite ' continuous contact with affected animals for more than four months.

On the other hand, Hoag and others report success in transmitting the virus of mucosal disease by inoculating spleen and blood filtrates into calves, provoking a mild form of the disease. Since older cattle and very young calves did not become infected they suggested that the stress of weaning may have increased susceptibility to the disease. Underdahl and others claim to have isolated and cultivated the virus obtained from the tissues of cattle with the disease. They report that the virus is inactivated by temperatures above 50 degrees Centigrade for 15 minutes. Further, Jarrett in the United Kingdom reports having carried out more than 100 experimental transmissions of mucosal disease using blood, spleen and faecal preparations from affected ’ animals. He found that the virus was resistant to freezing and to storage for 16 months at minus 1 40 degrees centigrade.

The “Agriculturalist” ends on the note that there is no doubt as to the seriousness of the disease. Some reports from the United States and Australia suggesting that in those countries mucosal was not viewed with the same gravity as in New Zealand were possibly due to it having been confused with malignant catarrh and virus diarrhoea, neither of which were comparable with mucosal disease in its lethal effects nor presented the same peril to the animal industry.