Catarrh in sheep.

Catarrh or influenza in sheep occupies a unique position in livestock diseases in Australia. The condition, recognised in 1834, was the subject of government enquiries and the passing of special legislation for its control. Within 30 years it had disappeared. The identity of the condition was not determined then nor has it been identified in subsequent years. The purpose of the article is to review what was recorded about the disorder and to speculate on its nature.

The use of supplementary tests in the serological diagnosis of bovine brucellosis.

Comparative tests were carried out on serum samples using the Rose Bengal test (RBT), the complement fixation test (CFT), the antibovine globulin test (ABGT) by tube, plate and rapid variants, the mercaptoethanol test (MET) and the dithiothreitol test (DTT). Forty cows, from which Br. abortus had been recovered, gave strong reactions in all tests except for 2 cows in the SAT and 3 cows in the DTT Another group of 405 cows had not yielded Br. abortus on limited bacteriological examination. There was good correlation between the results of the CFT, RBT, tube ABGT, rapid ABGT and, to a lesser extent, the MET in cows with a CF titre greater than or equal to 16 or less than 4. In cows with CF titres of 8 the correlation was not as good while cows with a CF titre of 4 gave a wide range of reactions in these supplementary tests. A plate variant of the ABGT gave titres which were generally lower, by about 1 dilution, than those in the tube procedure. The results of the rapid ABGT correlated well with the results of the tube ABGT and the CFT in samples of high and low titre but not as well in samples of intermediate titre. The DTT gave titres which were usually lower than the corresponding MET titre. On the basis of the results obtained, tentative standards for the interpretation of the ABGT (tube) and MET were defined. It was concluded that these tests could be used to elucidate the status of a proportion of the cows which gave inconclusive results in the CFT.

Laboratory diagnosis of bovine tuberculosis.

Lesions of suspected bovine tuberculosis were examined by culture, histopathology and auramine-O (AO) stained smears and the findings correlated with field aspects of the disease. Of 642 lesions considered to be tuberculous, 62.0% yielded M. bovis and 4.5% other mycobacteria (OM). M. bovis and OM were recovered also from 0.6% and 3.6% respectively of 165 cattle which gave tuberculin reactions but had no visible lesions at slaughter. Of 262 lesions in which a histopathological diagnosis other than tuberculosis was made, 1.5% and 3.0% yielded M. bovis and OM respectively. All OM isolates tested belonged to the Mycobacterium-avium-intracellulare-scrofulaceum (MAIS) complex with a predominance of serotype 2. A good relationship was found between the recovery of mycobacteria and histopathology but examination of smears revealed 22.0% apparent false negatives. Apparent false negative culture results were also reported for 35.8% of lesions positive on histopathology and smear examination. The majority of herds yielding M. bovis contained reactors to the tuberculin test and many of these had lesions of tuberculosis. In contrast, herds yielding OM seldom contained reactors to the tuberculin test and rarely reactors with tuberculous lesions. The thoracic cavity was the main site of lesions from infections by M. bovis and OM.

The New South Wales mastitis control program. 2. Effect upon bacterial infections.

Bacteriological examinations were made on quarter samples from cows in 35 herds over a 3 year period to monitor the response in a mastitis control program. Initially, Staphylococcus aureus predominated in 32 of the herds and the mean herd prevalence was 26%. The control measures halved this rate but there was considerable variation in response between herds. The decline occurred rapidly and there was a significant reduction (P less than 0.01) by 3 months. Streptococcus agalactiae predominated in 3 herds and the overall infection rate was 4.9%. Control measures eliminated the infection completely from most herds but reinfection occurred in 2 herds. The greatest decline occurred in the first 6 months and was significant (P less than 0.05). The measures had little effect upon Str. uberis and Str. dysgalactiae which remained fairly consistently at low levels. Initially, strains of Staph. aureus resistant to penicillin were dominant in most herds. In a minority of herds strains resistant to streptomycin predominated and in these herds there was a concurrent resistance to penicillin. These patterns did not change greatly over the control period. Resistance by Str. agalactiae to streptomycin occurred in most herds at the start of the program.

Studies on nematode infections of beef cattle in New South Wales.

The occurrence and seasonal trends of nematode parasite infections in beef cattle on the Tablelands and North Coast regions of New South Wales are described, based on worm counts from 627 spring-born steers slaughtered at 2-monthly intervals from 6 to 24 months of age. The predominant parasites were Ostertagia ostertagi, Trichostrongylus axei and Cooperia spp. Large burdens of adult Ostertagia were seen in 12-month-old animals in late winter and early spring, and later in 18- to 20-month-old cattle in the following late summer and autumn. These infections often resulted in outbreaks of clinical parasitism. Massive numbers of inhibited early fourth stage larvae (EL4) also accumulated in the yearlings during their first spring, reached peaks in mid-summer and then declined. The possibility of their resumption of development to mature worms in the late summer and autumn period is discussed. Adult T. axei showed a similar seasonal trend to Ostertagia and may have increased the severity of outbreaks of clinical disease. Cooperia populations of EL4 and adult worms were highest in weaners during winter, but lower numbers thereafter indicated a strong resistance to re-infection. In addition, Haemonchus placei occurred frequently on the North Coast both as EL4 and adults in cattle of all ages up to 20 months. Of the other cattle nematodes, Oesophagostomum radiatum and Trichuris spp occurred in low numbers, mainly in weaners. Bunstomum phlebotomum and H. contortus occurred sporadically on the North Coast and Tablelands respectively. Intestinal Trichostronglyus spp, Oesophagostomum venulosum and Dictyocaulus viviparus were seen occasionally and Nematodirus spp were not seen. There was a poor relationship between worm counts and faecal egg counts. Cooperia spp dominated the egg counts, while those for other genera were generally low and did not reflect the relative abundance or seasonal changes in worm numbers.