A study of the effects of Marek's disease in a broiler flock

In a flock of 17000 broilers, characteristic Marek's disease (MD) paralysis, accompanied by increased mortality occurred during the fourth week of the flock's life. Cytolytic lesions and atrophy in the bursae of Fabricius, and the severity of lymphocytic infiltration of nerves, livers, proventriculus and brain are suggestive of the involvement of MD virus of greater pathogenicity than has been encountered previously in New Zealand.     

A study of the effects of Marek's disease in a broiler flock

In a flock of 17000 broilers, characteristic Marek's disease (MD) paralysis, accompanied by increased mortality occurred during the fourth week of the flock's life. Cytolytic lesions and atrophy in the bursae of Fabricius, and the severity of lymphocytic infiltration of nerves, livers, proventriculus and brain are suggestive of the involvement of MD virus of greater pathogenicity than has been encountered previously in New Zealand.     

Longitudinal study of the spread of ovine Johne's disease in a sheep flock in southeastern New South Wales

OBJECTIVE: The aim of this study was to apply whole flock testing over time to determine the prevalence, distribution and spread of infection in a recently infected flock, with a view to planning intervention strategies for disease control. PROCEDURE: Serology, pooled faecal culture (PFC) and histology were used to determine the distribution and persistence of infection in a sheep flock in south east New South Wales between 1997 and 2002. Partial flock testing was done up to June 2000, after which annual whole flock testing, using PFC was performed. RESULTS: Faecal shedding of M a paratuberculosis was not detected in home-bred sheep until 7 years after the introduction of infected sheep in 1993. For at least 7 years there was clustering of infection and shedding within two age groups only. The infected groups appeared to have been exposed to infection (mycobacterial contamination) at an early age (<12 months) and commenced shedding at 5 years of age or older. Groups that were exposed to contamination as adults did not shed detectable amounts of M a paratuberculosis during the study period. CONCLUSION: Clustering of detectable infection in age groups of sheep that were exposed as lambs was a feature on this farm, providing indirect evidence of finite duration of survival of M a paratuberculosis on pasture and the influence of age on the susceptibility of sheep to develop detectable M a paratuberculosis infection. Spread of infection occurred very slowly and was probably related to the long incubation period (exposure to shedding interval) of 5 years observed on this farm. The findings suggest that partial flock culling, selective grazing management and vaccination could lead to a reduction in mycobacterial contamination on farm to a level at which patent infection no longer occurs. Better understanding of disease spread within flocks over time through flock profiling using PFC will help in devising surveillance strategies (including testing protocols for market assurance testing) to detect infected flocks where there has been clustering and slow spread of infection.     

A longitudinal study to evaluate the diagnostic potential of a direct faecal quantitative PCR test for Johne's disease in sheep

A longitudinal study was carried out to evaluate the diagnostic potential of the previously developed direct faecal real-time quantitative PCR (QPCR) assay (Kawaji et al., 2007) for the detection of Mycobacterium avium subsp. paratuberculosis (MAP) infected sheep. Of the 58 sheep, 38 were orally inoculated with MAP, while 20 controls were maintained separately from the infected group throughout the trial. All animals were tested by QPCR, faecal culture and serum ELISA pre-inoculation and at 4, 8 and 13 months post-inoculation, and were necropsied at 13 months post-inoculation. Eighteen out of 38 inoculated sheep were detected by QPCR to be shedding MAP in faeces at 4 months post-inoculation, while only one sheep was positive in faecal culture at this time point. At 8 months post-inoculation, MAP DNA was detected in faeces of all inoculated sheep by QPCR, while MAP organisms were isolated from only 34% of the inoculated animals by faecal culture. The QPCR results for faecal samples that were collected at necropsy demonstrated that faecal QPCR was more sensitive than culture of intestinal tissues for MAP. The QPCR assay was confirmed to be a sensitive and specific ante-mortem diagnostic test for MAP in sheep, circumventing faecal culture which is a less sensitive and highly time consuming test. Quantification of MAP DNA in faeces by QPCR may provide immediate information to estimate the stage of the infection as well as the risk of transmission from infected animals.     

A longitudinal study on the acceptance and effects of a therapeutic renal food in pet dogs with IRIS‐Stage 1 chronic kidney disease

Currently, nutritional management is recommended when serum creatinine (Cr) exceeds 1.4 mg/dl in dogs with IRIS‐Stage 2 chronic kidney disease (CKD) to slow progressive loss of kidney function, reduce clinical and biochemical consequences of CKD, and maintain adequate nutrition. It is unknown if dietary interventions benefit non‐azotemic dogs at earlier stages. A prospective 12‐month feeding trial was performed in client‐owned dogs with IRIS‐Stage 1 CKD (n = 36; 20 had persistently dilute urine with urine specific gravity (USG) <1.020 without identifiable non‐renal cause; six had persistent proteinuria of renal origin with urine protein creatinine (UPC) ratio >0.5; 10 had both). Ease of transition to therapeutic renal food and effects on renal biomarkers and quality of life attributes were assessed. Dogs were transitioned over 1 week from grocery‐branded foods to renal food. At 0, 3, 6, 9, and 12‐months a questionnaire to assess owner's perception of their pet's acceptance of renal food and quality of life was completed. Renal biomarkers, including serum Cr, blood urea nitrogen (BUN), and symmetric dimethylarginine (SDMA), and USG and UPC ratio were measured. Of 36 dogs initially enrolled, 35 (97%) dogs were transitioned to therapeutic renal food. Dogs moderately or extremely liked the food 88% of the time, ate most or all of the food 84% of the time, and were moderately or extremely enthusiastic while eating 76% of the time. All renal biomarkers (Cr, BUN, and SDMA) were decreased (p ≤ .05) from baseline at 3‐months, and remained decreased from baseline at 12‐months in dogs completing the study (n = 20). Proteinuria was reduced in 12 of 16 dogs (p = .045) with proteinuria. Owners reported improvement in overall health and quality of life attributes, and hair and coat quality (all p < .01). In summary, dogs with IRIS‐Stage 1 CKD readily transition to renal food. Decreasing serum biomarker concentrations and reduction in proteinuria suggest stabilized kidney function.