Effect of oxytetracycline therapy on experimentally induced pneumonic pasteurellosis in lambs

Two groups of 10, specific pathogen free lambs were injected with a long acting oxytetracycline preparation at a dose rate of 20 mg/kg either 24 hours before or 24 hours after exposure to an aerosol of Pasteurella haemolytica. When compared with the response of similarly infected but untreated lambs, the effect of pretreatment was to postpone the appearance of clinical signs of pneumonia for four days and the deaths of five lambs for five to six days post infection, by which time seven untreated lambs had died. Treatment 24 hours after infection caused a rapid clinical recovery which persisted until six days after infection but two treated lambs died seven days after infection. Lung lesions in the group treated after infection were significantly less extensive than those in the untreated lambs.     

Three-step procedure for isolation of epithelial cells from the lungs of sheep with jaagsiekte

An efficient and reproducible technique is described for the isolation of transformed sheep pulmonary adenomatosis cells. It includes three basic steps: prolonged trypsinisation to kill fibroblasts, magnetic removal of macrophages and adherence to remove the rapidly adherent cells. The resultant preparations of lung cells were enriched to 96.6 per cent type 2 pneumocytes.     

Dorsal Nerve Root Origins of the Cutaneous Nerves of the Feline Pelvic Limb

The dorsal root origins of cutaneous nerves supplying the feline pelvic limb were determined electrophysiologically in 11 cats. Cutaneous nerves were surgically exposed and the presence or absence of an evoked potential in response to stimulation of individual dorsal roots was noted. The dorsal cutaneous branches of L3-L5 and S3, and the lateral cutaneous branch of L3 each arose solely from their parent spinal nerves. The L7, S1, and S2 dorsal cutaneous branches had multiple dorsal root origins. The lateral cutaneous femoral nerve originated from L3-L6 dorsal roots in 4 patterns of origin, and the saphenous nerve originated from L4-L6 dorsal roots in 2 patterns of origin. The lateral and caudal cutaneous sural nerves originated from L6-S1 roots in 2 and 3 patterns, respectively. The lateral and medial plantar nerves arose from L6-S2 roots in 4 and 2 patterns, respectively. The superficial and deep peroneal nerves originated from L6-S1 roots in 2 and 3 patterns, respectively. The caudal cutaneous femoral nerve or its branches arose from L7-S3 in 8 origin patterns. The dorsal nerve of the penis and the superficial perineal nerve arose from L7-S3 and S1-S3 roots, respectively, each in 4 patterns. A subtle correlation between plexus type and dorsal root origins of the cutaneous nerves was noted.     

The contribution of molecular biology to Mycobacteriumavium subspecies Paratuberculosis research

Molecular biology has contributed to our knowledge and understanding of the structure of Mycobacteriumavium subspecies paratuberculosis and has been particularly useful in determining those components that elicit immune responses in the host or discriminate M. avium paratuberculosis from other closely related environmental mycobacteria. As such, it has made a significant impact in the field of diagnosis, and has been instrumental in the development of specific and sensitive diagnostic tests. The next decade will see exciting new developments in paratuberculosis research as a consequence of substantial advances made in the construction of gene transfer systems in mycobacteria. These will provide opportunities for applying new strategies to determine the genetic basis for pathogenesis and the mechanisms of drug resistance and will offer new prospects for the rational design of efficient vaccines.     

Failure of a recombinant Babesia bovis antigen to protect cattle against heterologous strain challenge

Groups of cattle were inoculated subcutaneously with (i) a recombinant DNA-derived Babesia bovis protein (KaBbl-GZ) fused to beta-galactosidase and combined with adjuvants, or (ii) native beta-galactosidase (GZ) plus adjuvant, or (iii) adjuvant only or (iv) a live, attenuated B bovis vaccine. KaBbl-GZ was produced in the lambda gt11-amp3 system as a 5-10 kD babesial polypeptide linked to GZ. KaBbl has previously been shown to be an immunodominant antigen of B bovis, localised at the apex of the parasite, and present in a range of B bovis strains. High levels of GZ antibodies were observed in KaBbl-GZ and GZ inoculated cattle, but specific KaBbl antibodies could not be detected by ELISA. Five months after primary inoculation, all cattle were blood challenged with a virulent heterologous B bovis strain. Despite four inoculations with KaBbl-GZ, significant protection against the challenge was not observed.     

A PCR technique for the detection of Jaagsiekte sheep retrovirus in the blood suitable for the screening of ovine pulmonary adenocarcinoma in field conditions

Ovine pulmonary adenocarcinoma (OPA) is a naturally occurring contagious lung neoplasia caused by jaagsiekte sheep retrovirus (JSRV). Although no specific circulating antibodies against the virus can be detected in infected sheep, JSRV proviral DNA sequences can be found in peripheral blood leukocytes (PBLs) in clinically affected and in a proportion of in contact animals. In this study, existing hemi-nested PCR procedure is compared with a new one-step PCR technique that was developed to minimise potential DNA contamination and reduce sample and reagent handling. Different blood preparations were assessed and the best results were achieved on DNA prepared from buffy coat. The sensitivity of this PCR was lower in JSRV infected sheep without lesions of OPA than in clinically affected sheep, which indicate that this PCR may not be not fully appropriate for screening of individual sheep, but rather to provide results at flock level. This PCR is the only currently available blood test for detection of JSRV infected sheep and may be useful in epidemiological studies and in control programmes of OPA.     

Light intensity can influence plasma FSH and age at sexual maturity in domestic pullets

1. Shaver White and ISA Brown pullets were reared to 140 d in cage groups of 8 on a 10-h photoperiod of incandescent light and maintained at an illuminance of 3 or 25 lux, or transferred from 3 to 25 lux or from 25 to 3 lux at 63 or 112 d of age. 2. Plasma follicle stimulating hormone (FSH) concentration at 63 and 112 d was higher in both breeds for pullets maintained at an illuminance of 25 lux compared with 3 lux. After 2-4 d, and relative to constant-illuminance controls, plasma FSH increased significantly for ISA Brown transferred from 3 to 25 lux at 63 d and for Shaver White transferred at 112 d. Irrespective of genotype, plasma FSH for pullets given a decrease in illuminance at 63 or 112 d showed a tendency for less change than did constant-illuminance controls. 3. There was no significant difference in sexual maturity for ISA Brown maintained on 3 or 25 lux, but Shaver White pullets exposed to constant 3 lux matured later than those maintained on 25 lux. Shaver White matured later following an increase from 3 to 25 lux at 63 and 112 d, and earlier subsequent to a decrease from 25 to 3 lux at 112 d. ISA Brown pullets were not significantly affected by a change in illuminance at 63 or 112 d, though their responses were in the same direction as Shaver White. 4. Changes in plasma FSH in the 2- to 4-d period following a change in illuminance at 63 or 112 d were not significantly correlated with sexual maturity.