Infections with weakly haemolytic Brachyspira species in pigs with miscellaneous chronic diseases

The prevalence of infections with different Brachyspira species was assessed in 202 pigs with various chronic herd problems using different methods. Twenty-seven pigs (13.4%) were positive for Brachyspira spp. with at least one of the methods used. The highest number of positives was identified with mucosal scraping-PCR (23), followed by PET-PCR (22) and bacteriological-biochemical analysis (15). With the exception of three cases of B. pilosicoli infections, only weakly pathogenic Brachyspira species were identified. The majority was B. murdochii, followed by B. innocens and B. intermedia. Concurrent infections with two or more Brachyspira species were common and accounted for 37.1% of the total. Presence of weakly haemolytic Brachyspira was associated with wasting and diarrhoea in a number of cases. This investigation shows that infections with weakly haemolytic Brachyspira spp. may contribute to colonic pathology in pigs with chronic herd problems and that mixed infections seem to occur more frequently than previously noticed.     

IN THIS ISSUE – May 2009

Australian poultry industries and highly pathogenic avian influenza  ▪  Diagnosis of canine splenic disorders  ▪  Dermatoses caused by immature Ixodes spp.  ▪  Seizures during medetomidine sedation and local anaesthesia  ▪  Inherited diseases of Holstein-Friesian cattle  ▪  Oral and topical triclabendazole  ▪  Double-outlet right ventricle in a filly     

Effect of Tibial Plateau Leveling Osteotomy on Femorotibial Contact Mechanics and Stifle Kinematics

Objective— To evaluate the effects of tibial plateau leveling osteotomy (TPLO) on femorotibial contact mechanics and 3-dimensional (3D) kinematics in cranial cruciate ligament (CrCL)-deficient stifles of dogs.
Study Design— In vitro biomechanical study.
Animals— Unpaired pelvic limbs from 8 dogs, weighing 28–35 kg.
Methods— Digital pressure sensors placed subjacent to the menisci were used to measure femorotibial contact force, contact area, peak and mean contact pressure, and peak pressure location with the limb under an axial load of 30% body weight and a stifle angle of 135°. Three-dimensional static poses of the stifle were obtained using a Microscribe digitizing arm. Each specimen was tested under normal, CrCL-deficient, and TPLO-treated conditions. Repeated measures analysis of variance with a Tukey post hoc test ( P <.05) was used for statistical comparison.
Results— Significant disturbances to all measured contact mechanical variables were evident after CrCL transection, which corresponded to marked cranial tibial subluxation and increased internal tibial rotation in the CrCL-deficient stifle. No significant differences in 3D femorotibial alignment were observed between normal and TPLO-treated stifles; however, femorotibial contact area remained significantly smaller and peak contact pressures in both medial and lateral stifle compartments were positioned more caudally on the tibial plateau, when compared with normal.
Conclusion— Whereas TPLO eliminates craniocaudal stifle instability during simulated weight bearing, the procedure fails to concurrently restore femorotibial contact mechanics to normal.
Clinical Relevance— Progression of stifle osteoarthritis in dogs treated with TPLO may be partly the result of abnormal stifle contact mechanics induced by altering the orientation of the proximal tibial articulating surface.     

Kinetics of substrate oxidation and hydrogen peroxide production by Mycoplasma mycoides subsp. mycoides Large Colony (LC) type and Mycoplasma mycoides subsp. capri

Mycoplasma mycoides subsp. mycoides Large Colony (LC) type is a pathogen of goats causing contagious agalactia and respiratory disease, found on all continents where small ruminants are kept. It shares close genetic characteristics with M. mycoides subsp. capri. Substrate oxidation by 22 strains of M. mycoides subsp. mycoides LC from nine countries was compared with that of eight strains of M. mycoides subsp. capri from five countries. There was considerable similarity in the substrates used, but substrate saturation coefficients (K_s) varied for different substrates. Substrate utilization patterns and K_s values did not (1) significantly differentiate the LC strains from each other, (2) show any correlation with geographical origin, or (3) distinguish the LC strains from the capri strains. These results support previous studies justifying the reclassification of these subspecies as a single species.     

日粮中蛋白质和纤维水平对仔猪生产性能和健康状况的影响

为了研究日粮的蛋白质和纤维水平对仔猪生产性能和健康状况的互作,特选择96头35日龄的仔猪（体重为9.11±0.60kg）,分32个栏饲养,每栏3头,分成4个日粮处理组,饲喂期21d。在设定的2×2因子处理中,4种日粮以大米、奶制品和大豆粕为基础配制,日粮蛋白质设两个水平（15.4%与19.4%,风干基）,纤维也设两个水平[低水平纤维（LF）为含5.3%中性洗涤纤维,高水平纤维（HF）为含7.15%中性洗涤纤维,风干基]。高水平纤维日粮组在基础日粮中添加了40g/kg的小麦麸和20g/kg的甜菜浆。每周测定动物生产性能,试验第1天和最后一天收集粪样进行微生物学分析,并且按1（液态）到4（硬实）的评分体系对粪便进行评分。在试验最后1d,每栏选1头猪采集血液,分析急性期反应蛋白（acute-phase protein）和主要急性期反应蛋白（major acute-phase prot）（即Pig-MAP）的含量,随后进行屠宰,对消化道（包括内容物）进行称重,并进行结肠组织学分析。饲喂高水平纤维日粮的仔猪具有较大的平均日增重（390g与457g,P≤0.001）和大肠重量（以占体重比例衡量为4.4%与5.4%,P≤0.05）。这与较高的短链脂肪酸浓度（尤其是乙酸和丁酸）、较少的大肠杆菌数量（每克粪便含7.77与6.86logcfu,P≤0.05）和较高乳酸杆菌与肠道细菌比（0.76与1.37,P≤0.05）是相符的。虽然日粮蛋白质水平没有改变猪的生产性能,但是20%的蛋白质水平提高（P≤0.05）了小肠（6.5与7.7）和大肠（3.8与4.3）的相对重量（占体重的百分比）。在大肠内,含20%蛋白质的日粮使仔猪杯状细胞数量增加（4.6/100与5.4/100μm;P≤0.05）,并使肠上皮内淋巴细胞数量减少（1.8/100与1.3/100μm;P≤0.05）。在健康状况方面,提高日粮纤维水平所产生的效果与日粮中的蛋白质含量有关。在含16%蛋白质的日粮中增加纤维水平可降低粪便评分值、增加抗生素治疗次数,然而在?     

Fine-Scale Spatial Genetic Structure in Perennial Grasses in Three Environments

Past research has shown that changes in grazing-resistance traits may be associated with genetic changes in plant populations. Little is known about spatial genetic relationships within plant populations (spatial genetic structure) and any grazing effects on these relationships. Here we present observations of the fine-scale spatial genetic structure in three grass species in semiarid environments (Arizona, Mexico, and Argentina). In each environment, populations of a dominant grass species were sampled from two sites with contrasting livestock grazing histories. Plant genotypes were described with the use of amplified fragment length polymorphism markers. In Arizona, populations of sideoats grama (Bouteloua curtipendula var. caespitosa Gould and Kapadia) differed in that one has never experienced livestock grazing, whereas cattle have grazed the other. In the other two environments, populations exposed to long-term heavy grazing were examined, along with those that experienced either moderate grazing (Mexico, blue grama [Bouteloua gracilis {Willd. ex Kunt} Lag. ex Griffiths]) or extended exclusion of livestock (Argentina [Poa ligularis Nees ex Steud.]). Based on independent analysis of each population, we observed no differences in average gene diversity between populations of each species. With the use of analysis of molecular variance we found slight but significant genetic differentiation between populations with different grazing histories in Arizona and Argentina. Significant genetic structure was present in all populations and indicated an inverse relationship between spatial and genetic distance. Interestingly, this relationship was most pronounced in the cattle-free sideoats grama population, suggesting larger genetic neighborhood areas in the absence of livestock. Less distinct differences in spatial genetic structure associated with grazing history were evident in the other two species. We hypothesize that livestock grazing may lead to increased homogeneity in genetic structure at the landscape scale. Effectively examining this hypothesis presents many experimental challenges.     

Review of diagnostic laboratory submissions of adult cattle 'found dead' in England and Wales in 2004

A total of 253 submissions from adult cattle 'found dead' in England and Wales were referred to the Veterinary Laboratories Agency in 2004. Carcases accounted for 54 per cent of the submissions and were of more diagnostic value than other types of sample. Whether the animals were beef or dairy, their distance from the laboratory and the number of deaths in the incident affected the likelihood of samples being submitted. The probability of reaching a diagnosis was influenced by the type of sample, the level of testing and the interval from sampling to receipt in the laboratory. Systemic disease was the most frequent cause of death in both dairy and beef cattle with hypomagnesaemia being the most frequent diagnosis (52 per cent) in beef cattle. In dairy cattle, 34 per cent of the diagnoses were for sporadic events, including haemorrhage and torsions of the digestive and reproductive tracts.