Experimental inoculation of Neospora caninum in pregnant water buffalo

The aim of this study was to characterize the pathogenesis of Neospora caninum in experimentally inoculated pregnant water buffalo (Bubalus bubalis). Twelve Mediterranean female water buffaloes ranging in age from 4 to 14 years old and seronegative to N. caninum by indirect fluorescent antibody test (IFAT) were involved. Ten females were intravenously inoculated with 10(8) tachyzoites of NC-1 strain at 70 (n=3) or 90 (n=7) days of pregnancy (dp). Two control animals were inoculated with placebo at 70 and 90 dp, respectively. Serum samples were obtained weekly following inoculation to the end of the experiment. Three animals inoculated at 70 dp were slaughtered at 28 days post inoculation (dpi), three animals inoculated at 90 dp were slaughtered at 28 dpi and the remaining four animals inoculated at 90 dp were slaughtered at 42 dpi. Fetal fluids from cavities and tissue samples were recovered for IFAT and histopathology, immunohistochemistry and PCR, respectively. Genomic DNA from fetal tissues was used for parasite DNA detection and microsatellite genotyping in order to confirm the NC-1 specific-infection. Dams developed specific antibodies one week after the inoculation and serological titers did not decrease significantly to the end of the experiment. No abortions were recorded during the experimental time; however, one fetus from a dam inoculated at 70 dp was not viable at necropsy. Specific antibodies were detected in only two fetuses from dams inoculated at 90 dp that were slaughtered at 42 dpi. No macroscopic changes in the placentas and organs of viable fetuses were observed. Nonsuppurative placentitis was a common microscopic observation in Neospora-inoculated specimens. Microscopic fetal lesions included nonsuppurative peribronchiolar interstitial pneumonia, epicarditis and myocarditis, interstitial nephritis, myositis and periportal hepatitis. Positive IHC results were obtained in two fetuses from dams inoculated at 70 dp and slaughtered at 28 dpi. N. caninum DNA was detected in placentas and fetuses from all inoculated animals. The pattern of amplified microsatellites from placental and fetal tissues resembled the NC-1 strain. Water buffaloes, like cattle, are susceptible to experimental inoculation with N. caninum at early pregnancy.     

Inhibited development of trichostrongylid worms in grazing cattle

Inhibition of development of gastro-intestinal trichostrongylid worms was studied using successive groups of tracer calves and groups of continuously grazed calves over one year in the Tully area of North Queensland lowland wet tropics. The results, assessed by means of worms from these calves recovered at necropsy 3 weeks after their removal from pastures, showed inhibition in the development of Haemonchus placei and Cooperia punctata at the early fourth stage at the approach to and during the relatively dry period in the area. Inhibition was however minor and inhibited larvae formed but only a small percentage of worm burdens in both categories of calves, indicating that they were not in any way of major epidemiological importance. It was suggested that the minor nature of inhibition was due to the mild climatic conditions which could not produce appropriate conditioning treatment, or caused only mild selection pressure for inhibition in the area.     

Inter-breed differences in equine forelimb kinematics at the walk

Linear, temporal and angular biokinematic characteristics of the forelimb at the walk in different breeds were determined, highlighting inter-breed differences. Twenty-three healthy stallions were used: ten Andalusians (AN), seven Arabs (AR) and six Anglo-Arabs (AA). Height at the withers was significantly different between groups (P < 0.001). Six trials per horse were recorded using a levelled video camera (sampling frame rate 25 frames/s), digitized and analysed using a semi-automatic movement analysis system. No statistically significant differences in speeds were recorded between breeds (P > 0.05). The only temporal parameter which was similar in the three breeds was the moment at which the hoof reached the highest point in its trajectory. The variables presenting the most significant differences were the percentages of deceleration and propulsion within the stance phase. ANOVA for angular variables showed that the greatest difference was in the range of angular movement of the carpal joint, being higher in AN, due to a lower minimum value. In the fetlock joint, the greatest difference was observed in minimum values, which differed in all three breeds. Significant inter-breed differences were also observed for maximum limb retraction, being lowest in the AN group, followed by the AA and AR groups. This finding was reflected in the angular range of motion, despite smaller differences in the degree of limb protraction; very similar values were reported in all three breeds. As regards the elbow joint, no inter-breed differences were observed in terms of minimum values, whereas differences were recorded for maximum and angular range of motion, higher values being displayed by the AR and AN groups than by AA animals. In conclusion, inter-breed differences may be determined in equine forelimb biokinematics at the walk. This study distinguished between AN, AR and AA horses.     

Heifers immunized with whole-cell and membrane vaccines against Tritrichomonas foetus and naturally challenged with an infected bull

The performance of a whole-cell vaccine and the other vaccine with cellular membranes of Tritrichomonas foetus applied to heifers naturally challenged by mating with an infected bull was determined. Forty heifers were divided into three groups: a control group (n=16) without immunizing, another group (n=12) immunized with whole cells (10(8)/dose) and a third group (n=12) immunized with cellular membranes (300 micro g of membranes/dose protein). The females were subcutaneously vaccinated at 3-week on two occasions and received a third intravaginal booster dose. After 3 weeks of the last vaccinal doses, the heifers were served by a T. foetus infected bull over 90-day period. The mean duration of infection for membrane-vaccinated heifers was 60 days +/-25, compared with 63 days +/-35.8 of infection for whole-cell-vaccinated heifers and 79 days +/-41.3 for control heifers. Calving rates were 6/12 for membrane-vaccinated heifers, 3/12 for whole-cell-vaccinated animals, and 2/16 for control animals. Fetal mortality rates were 3/12 for membrane-vaccinated animals, 4/12 for those vaccinated with whole cells and 10/16 for control animals. These reproductive parameters were significantly different (P<0.05) between heifers vaccinated with membranes and control heifers. The hemolytic test and enzyme-linked immunoabsorbent assay (ELISA) with T. foetus antigen showed that serum immunoglobulins peaked before and during the breeding period. The heifers vaccinated with membranes developed an important response during the critical period of fetal loss, second and third month of the breeding time, and another month after the same period. The ELISA method was more sensitive and more reliable than the hemolytic test for the evaluation of the systemic immune response in females infected and/or vaccinated with T. foetus.     

Influence of Training on the Biokinematics in Trotting Andalusian Horses

The aim of this study was to determine the influence of a 10-month training programme on the linear, temporal and angular characteristics of the fore and hind limbs at the trot in the Andalusian horse, using standard computer-aided videography. Sixteen male Andalusian horses were observed before and after training. Six strides were randomly selected for analysis in each horse and linear, temporal and angular parameters were calculated for fore and hind limbs. The training programme used here produced significant changes in kinematic parameters, such as shortening of stride length, and increase in swing duration and a decrease in hind limb stance percentage. No significant differences were recorded in the angular values for the forelimb joints. In trained horses, the more proximal joints of the hind limb, especially the hip and stifle, had a greater flexion while the fetlock showed a smaller extension angle. At the beginning of the swing phase, hip and stifle joints presented angles that were significantly more flexed. When the hind limbs came into contact with the ground, all the joints presented greater flexion after training.