Pathogenesis of infectious bronchitis virus in vaccinated chickens of two different major histocompatibility B complex genotypes

Infectious bronchitis (IB) disease progression in vaccinated chickens after challenge was evaluated in a single commercial line of layer chickens presenting two different major histocompatibility complex (MHC) B complex genotypes. MHC B genotypes were determined by DNA sequence-based typing of BF2 alleles. In total, 33 B2/B15 and 47 B2/B21 chickens were vaccinated with an Ark-type IB virus (IBV) attenuated vaccine and challenged with Ark-type IBV field isolate AL/4614/98 14 days later. Additional chickens of both genotypes served as unvaccinated/challenged and unvaccinated/nonchallenged controls. Clinical signs, histopathologic analysis, detection of IBV genomes in tears, and IBV-specific immunoglobulin A (IgA) in tears were used to evaluate disease progression and immune response. The incidence of IBV respiratory signs was significantly higher in B2/21 than in B2/B15 MHC genotype birds. However, neither the severity and duration of respiratory signs nor the severity and incidence of histologic lesions differed significantly with MHC genotype. The levels of IBV-specific IgA in tears of vaccinated and challenged chickens did not differ significantly between MHC genotypes. IBV genomes were present in the tears of vaccinated and challenged birds, and the incidence of detectable IBV genomes did not vary significantly with MHC B genotype. From an applied perspective, these results indicate that vaccinated commercial outbred chickens with these MHC genotypes are equally resistant to IBV.     

Comparison of mandibular motion in horses chewing hay and pellets

REASONS FOR PERFORMING STUDY: Previous studies have suggested that temporomandibular joint (TMJ) kinematics depend on the type of food being masticated, but accurate measurements of TMJ motion in horses chewing different feeds have not been published. HYPOTHESIS: The temporomandibular joint has a larger range of motion when horses chew hay compared to pellets. METHODS: An optical motion capture system was used to track skin markers on the skull and mandible of 7 horses as they chewed hay and pellets. A virtual marker was created on the midline between the mandibles at the level of the 4th premolar teeth to represent the overall motion of the mandible relative to the skull during the chewing cycle. RESULTS: Frequency of the chewing cycles was lower for hay than for pellets. Excursions of the virtual mandibular marker were significantly larger in all 3 directions when chewing hay compared to pellets. The mean velocity of the virtual mandibular marker during the chewing cycle was the same when chewing the 2 feeds. CONCLUSIONS: The range of mediolateral displacement of the mandible was sufficient to give full occlusal contact of the upper and lower dental arcades when chewing hay but not when chewing pellets. POTENTIAL RELEVANCE: These findings support the suggestion that horses receiving a diet high in concentrate feeds may require more frequent dental prophylactic examinations and treatments to avoid the development of dental irregularities associated with smaller mandibular excursions during chewing.     

Incisional complications following exploratory celiotomy: does an abdominal bandage reduce the risk?

REASONS FOR PERFORMING STUDY: Post operative complications following exploratory laparotomy can be potentially life-threatening, increase post operative morbidity and result in an increase in the length of hospitalisation of the affected individual. No study has evaluated the efficacy of specific strategies to reduce the incidence of post operative incisional complications. HYPOTHESIS: The use of an abdominal bandage following colic surgery through a celiotomy incision would significantly reduce the prevalence of post operative incisional complications. METHODS: A controlled, randomised clinical trial to test the hypothesis was devised. Horses eligible for inclusion in the study were assigned randomly either to the study or control group following recovery from general anaesthesia. Any post operative incisional complications occurring during hospitalisation were recorded. Long-term follow-up was obtained via telephone questionnaires. Absolute risk reduction (ARR) and number needed to treat (NNT) were calculated. Multivariable analyses were conducted for all outcomes of interest. RESULTS: There was an ARR of the likelihood of developing a post operative incisional complication of 45% when using compared to not using an abdominal bandage in the post operative period. Therefore, it would be necessary to treat 2.2 horses with an abdominal bandage in order to prevent one horse developing any post operative incisional complications. CONCLUSIONS: Although incisional complications continue to be a problem following an exploratory celiotomy for colic, the proportion of horses affected was significantly reduced by use of a bandage. POTENTIAL RELEVANCE: Using an abdominal bandage following an exploratory laparotomy may help reduce the prevalence of post operative incisional complications, and prevent the development of potentially life-threatening complications.     

The aetiology of generalized alopecia in young calves

The objective of this study was to test for correlations between alopecia and ruminal drinking in young calves. 331 calves up to an age of 31 days were tested for evidence of generalized hair loss daily during their stay in the clinic. Incidence of diarrhoea and the results of ruminal fluid and blood analysis were compared between the groups with and without alopecia. Calves with alopecia showed a significantly higher incidence of diarrhoea and of ruminal acidosis persisting for at least 24 hours. Blood analysis revealed significant differences in degree of acidosis, in concentrations of D-lactate, urea, and creatinine in serum as well as in the activities of glutathione peroxidase, aspartate amino transferase, and creatine kinase. Alopecia in calves is correlated to longer periods of diseases, which are known to be accompanied by the production of D-lactate in the gastrointestinal tract, such as diarrhoea and ruminal drinking. The question, whether alopecia is due to formation of toxic substances or to deficiency of essential substances can not be answered.     

Molecular cloning of a Mycoplasma meleagridis-specific antigenic domain endowed with a serodiagnostic potential

A recombinant phage library harbouring Mycoplasma meleagridis (MM) genomic DNA fragments was generated in the bacteriophage lambda gt11 expression vector. The library was screened for expression of MM specific antigens with a polyclonal antiserum that had been preadsorbed with antigens of the most common unrelated avian mycoplasma species. A 49-amino acid antigenic domain unique to MM was isolated, expressed in Escherichia coli, and its serodiagnostic potential was demonstrated. An antiserum raised against this MM-specific antigenic domain recognized a cluster of seven membrane-associated MM proteins with molecular masses ranging from 34 to 75 kDa. Overall, this study resulted in the identification of a potent serodiagnostic tool and revealed the complex antigenic nature of MM.     

Multiplex real-time PCR for the detection and differentiation of equid herpesvirus 1 (EHV-1) and equid herpesvirus 4 (EHV-4)

A multiplex real-time PCR was designed to detect and differentiate equid herpesvirus 1 (EHV-1) and equid herpesvirus 4 (EHV-4). The PCR targets the glycoprotein B gene of EHV-1 and EHV-4. Primers and probes were specific to each equine herpesvirus type and can be used in monoplex or multiplex PCRs, allowing the differentiation of these two closely related members of the Alphaherpesvirinae. The two probes were minor-groove binding probes (MGB) labelled with 6-carboxy-fluorescein (FAM) and VIC for detection of EHV-1 and EHV-4, respectively. Ten EHV-1 isolates, six EHV-1 positive clinical samples, one EHV-1 reference strain (EHV-1.438/77), three EHV-4 positive clinical samples, two EHV-4 isolates and one EHV-4 reference strain (EHV-4 405/76) were included in this study. EHV-1 isolates, clinical samples and the reference strain reacted in the EHV-1 real-time PCR but not in the EHV-4 real-time PCR and similarly EHV-4 clinical samples, isolates and the reference strain were positive in the EHV-4 real-time PCR but not in the EHV-1 real-time PCR. Other herpesviruses, such as EHV-2, EHV-3 and EHV-5 were all negative when tested using the multiplex real-time PCR. When bacterial pathogens and opportunistic pathogens were tested in the multiplex real-time PCR they did not react with either system. The multiplex PCR was shown to be sensitive and specific and is a useful tool for detection and differentiation of EHV-1 and EHV-4 in a single reaction. A comprehensive equine herpesvirus disease investigation procedure used in our laboratory is also outlined. This procedure describes the combination of alphaherpesvirus multiplex real-time PCR along with existing gel-based PCRs described by other authors.     

Detection of Mycobacterium avium subsp. paratuberculosis in ovine faeces by direct quantitative PCR has similar or greater sensitivity compared to radiometric culture

The aims of this study were to develop a new real-time quantitative PCR (QPCR) assay based on IS900 for detection and quantification of Mycobacterium avium subsp. paratuberculosis (MAP) DNA in faeces, and to use this to detect infected sheep. Both the C and S strains of MAP were detected by the QPCR assay, and no cross reactions were detected with 51 other species of mycobacteria including 10 which contained IS900-like sequences. One copy of IS900 fragment cloned into plasmid pCR2.1 and 1 fg of MAP genomic DNA were consistently detected, while in spiked faecal samples the detection limit was 10 viable MAP per gram of ovine faeces. A total of 506 individual ovine faecal samples and 27 pooled ovine faecal samples with known culture results were tested. The QPCR assay detected 68 of 69 BACTEC culture positive individual faeces and there was a strong relation between time to detection in culture and DNA quantity measured by QPCR (r= -0.70). In pooled faecal samples, QPCR also agreed with culture (kappa=0.59). MAP DNA was detected from some culture negative faecal samples from sheep exposed to MAP, suggesting that the QPCR has very high analytical sensitivity for MAP in faecal samples and detects non-viable MAP in ovine faeces. None of the faecal samples from 176 sheep that were not exposed to MAP were positive in QPCR. This is the first report of a direct faecal QPCR assay that has similar sensitivity to a gold standard radiometric culture assay.     

Interpretation of serum antibody response to Anoplocephala perfoliata in relation to parasite burden and faecal egg count

REASON FOR PERFORMING STUDY: Increased knowledge is needed to assist in the interpretation of presently available diagnostic techniques for infection by the tapeworm Anoplocephala perfoliata in horses. HYPOTHESIS: The suggested cut-off level of an A. perfoliata specific ELISA may not adequately reflect the actual infection level. Hence, faecal egg counts may be a more useful diagnostic test for individual horses than previously reported. METHODS: Eighty-four horses admitted for slaughter at a Danish abattoir were examined for the presence of A. perfoliata. The number of tapeworms, their stage of development and gross pathological mucosal lesions were recorded and compared with serum antibody responses and faecal egg counts. Faecal egg counts were determined in samples from A. perfoliata infected horses using a semi quantitative centrifugation/flotation technique. Blood samples collected at slaughter were analysed by ELISA to determine serum antibody levels against A. perfoliata 12/13 kDa excretory/secretory antigens. RESULTS: Macroscopically visible tapeworms were detected in 24 (29%) of the horses. The overall sensitivity of the faecal egg count was found to be 0.46; however, if the detection limit was increased to above 20 tapeworms, sensitivity increased to 0.89. There was a correlation of 0.71 between worm burden and egg count. The antibody levels correlated significantly with infection intensity despite a wide variation among horses with similar levels of infection. The optimal cut-off value was determined using receiver operating characteristic analysis. If cut-off was chosen at optical density (OD) = 0.7, sensitivity was 0.68 and specificity 0.71. CONCLUSIONS: Both diagnostic methods were capable of revealing potentially pathogenic infections, with the faecal egg count being more applicable on the individual horse level. POTENTIAL RELEVANCE: In the population of Danish horses investigated the serum ELISA test should be interpreted such that horses in need of anti-Anoplocephala treatment have an OD = 0.7 or above.     

The clinical utility of the right lateral intercostal ultrasound scan technique in dogs

When performing abdominal ultrasonography in dogs, the right aspect of the liver, porta hepatis, right kidney, right adrenal gland, pancreas, and duodenum are often not fully visible from a ventral, or subcostal, approach. The right lateral intercostal plane is an alternative approach that allows evaluation of these structures. This report provides multiple case examples that demonstrate the sonographic anatomy via the right intercostal approach. Other cases are included to demonstrate indications for this approach. Animals in which the right intercostal approach may prove most useful include large- and giant-breed dogs; deep-chested dogs; dogs with gas distention of the stomach, duodenum, and colon; dogs with microhepatia; and those with abdominal effusion and pain.