Lisle W. George

Mycoplasma Otitis in California Calves

A retrospective study of Mycoplasma otitis in California calves submitted for necropsy between 1993 and 2002 was conducted to characterize the demographic features of the disease and the pathologic findings associated with infection. Sixty-one confirmed cases of Mycoplasma otitis were identified among 20,525 necropsied cattle. All affected animals were calves, ranging in age from 2 weeks to 4 months and with a median age of 1.5 months. Ninety-two percent of the cases were dairy breeds. A higher percent of necropsied calves with Mycoplasma otitis were males (0.45%) than females (0.23%). The proportion of cases that had Mycoplasma otitis increased from 1993 to 2002, and there was a significant (P < 0.05) seasonal distribution, with the highest proportion in the spring and the lowest in the summer months. Infections involved both the middle and inner ear and were characterized by a suppurative inflammatory response with extensive bony involvement. Three species of Mycoplasma were isolated from the ears: M. bovis, M. bovirhinis, and M. alkalescens. Concurrent pneumonia occurred in 47 cases (77%), and Mycoplasma was isolated from the lungs of 30 of those cases. The increasing proportion of Mycoplasma otitis cases in the past 10 years emphasizes the importance of identifying risk factors that could be modified to lower the incidence of this disease in calves.

Evaluation of the toxicity of Adonis aestivalis in sheep

To determine the toxicity of Adonis aestivalis (adonis) in sheep, adult Suffolk ewes were administered 1 per cent bodyweight adonis via surgically placed rumen cannulas in an acute, high-dose toxicity study, and 0.2 per cent bodyweight daily in a two-week, low-dose toxicity study. The ewes received cardiac examinations before dosing, 24 and 48 hours after dosing with 1 per cent bodyweight adonis, and after continuous low-dose administration. All the ewes administered adonis had transient sinus arrhythmias after receiving 1 per cent bodyweight adonis. Two of the three ewes had transient reduced fractional shortening after administration with 1 per cent bodyweight adonis; the same two ewes had reduced fractional shortening after the low-dose treatment regimen. No gross or microscopic lesions were seen when the ewes were examined postmortem at the end of the study.

Evaluation of the Toxicity of Adonis Aestivalis in Calves

Toxicosis of Adonis aestivalis is well documented in horses, but little is known of its toxicity in cattle. A. aestivalis (summer pheasants eye) was collected over multiple years, under different growing conditions, and at various stages of maturity, dried, and administered to calves to evaluate the toxicity of A. aestivalis in cattle. Four 300-lb Holstein, and 2 90-lb, preruminating Jersey calves were administered 1% body weight of ground A. aestivalis via a stomach tube and monitored for clinical signs for 2 weeks and 1 week, respectively. The Holstein calves were then fed 0.2 to 1% body weight A. aestivalis daily for 4 to 5 weeks. The Holstein calves had transient, mild cardiac abnormalities during the feeding trial. Mild, transient gastrointestinal and cardiac signs were noted in the preruminating calves. No gross or microscopic lesions were seen on necropsies performed at the end of the study. Based on the results of this study, cattle do not appear to be as susceptible to toxicosis from A. aestivalis as other species, such as horses and pigs.

Neurologic Examination of the Ruminant

In this article, the neurologic examination of ruminants is reviewed. The proposed approach is simple, although thorough and methodical. The bovine veterinary practitioner should be able to efficiently assess the nervous system to rule out a primary neurologic disorder. Simple observations and procedures are suggested to allow evaluation of the nervous system. The appropriate method and interpretation are reviewed as well as the danger of misinterpretation.

Flow cytometric determination of peripheral blood lymphocyte subpopulations and haematological values in the neonatal calf

Non-vaccinated Holstein female calves, 3–31 days old (n=106) were examined in order to determine peripheral blood lymphocyte subpopulations and haematological values. The relative populations of lymphocytes were determined using flow cytometry. Monoclonal antibodies were used to identify BoCD2+, BoCD4+, BoCD8+, B-cells,γ/δ T-cells, and monocytes/neutrophils, respectively. Complete blood counts were also determined. Calves were stratified into four groups by age (days): group A = 3–7 days, group B = 8–14 days, group C = 15–21 days and group D = 22–31 days. Group A calves had 30%–70% lower numbers of all lymphocyte subtypes compared to older calves. Group B calves had significantly lower numbers of B-cells than calves in group D, but were not different from group C. Calves in groups B and C had significantly lowerγ/δ T-cell counts than calves in group D. All other group comparisons of lymphocyte subtypes and the ratios of BoCD4+ to BoCD8+ T-cells were not significantly different.Calves in group A had significantly lower white blood cell counts than older calves and had significantly lower lymphocyte numbers than group C and D calves. Calves in group D had significantly higher lymphocyte counts than younger calves. Groups A and B had significantly higher neutrophil to lymphocyte ratios than groups C and D. Absolute numbers of monocytes, eosinophils and basophils were not different among any of the groups. Group A calves had significantly lower red blood cell counts than older calves. Calves in groups A and B had significantly higher mean corpuscular haemoglobin (MCH) and mean corpuscular volume (MCV) values than calves in group C. Group C calves also had significantly higher MCH and MCV values than calves in group D. Significant differences in haemoglobin, haematocrit and mean corpuscular haemoglobin concentration values were not apparent among any of the four groups. In this cross-sectional study we observed that older calves consistently had higher numbers of all subtypes of peripheral blood lymphocytes, compared to younger calves.