An Assessment of the Epidemiology and Herd-Level Impact of the Fractured Humerus Epidemic in New Zealand Dairy Cattle, 2007-2015: Results from Four Studies.

A multi-method approach integrating data from four independent sources was used to describe some key features of the epidemiology and estimate the herd and within-herd incidence of fractured humeri in New Zealand dairy cattle for the period 2007-2015. The first dataset was from a national case series where cases of humeral fractures in dairy cattle were identified by veterinarians across New Zealand between the 2007/2008 and 2011/2012 lactation seasons. The second dataset was from a pet food company based in the Waikato region, which collated the number of casualty first- and second-lactation cows found to have a fractured humerus post-slaughter in the 2014/2015 lactation season, and the third dataset was a case series conducted by veterinarians employed in a Waikato veterinary business, also from the 2014/2015 lactation season. For the final dataset, 505 randomly selected New Zealand dairy farmers completed a phone survey on the incidence of non-responsive, non-weight-bearing forelimb lameness in first- and second-lactation cows in the 2014/2015 lactation season. Using the telephone survey results, the within-herd and herd-level incidence of cases for first- and second-lactation dairy animals was calculated. The national case series reported 149 cases of humeral fractures in 22 dairy herds; the pet food case series identified 61 cases from 41 farms; and the practice-based case series found 14 cases from 10 farms. Humeral fractures exclusively affected first- and second-lactation dairy cows and had a peak incidence between calving and early mating. The national telephone survey found that non-weight-bearing forelimb lameness requiring euthanasia of first- or second-lactation cows occurred in 11.7% of herds, with a mean within-herd incidence of 2.6% for first lactation cows and 2.8% for second-lactation cows for affected herds. These combined datasets demonstrate that humeral fractures in young, lactating dairy cattle are more common than previously suspected and that they occur nationally and over multiple years on some farms. Further work on this condition is urgently required in New Zealand to establish cost-effective management practices that will reduce unnecessary animal suffering and waste.

An idiopathic upper alimentary tract ulcerative syndrome in weaned dairy calves in Victoria, Australia.

An idiopathic clinical syndrome had been described in weaned dairy calves in the state of Victoria, Australia, where affected animals presented with diarrhoea, ill-thrift, enteritis and ulceration of the upper alimentary tract, with occasional oral/nasal ulcers. Between 7 November 2016 and 31 March 2019, 34 Victorian cattle herds were investigated, after each reported five or more weaned calves with diarrhoea and/or ill-thrift, or at least one calf with oral/nasal ulceration. Primary study objectives included the development of a detailed case definition for the clinical syndrome, termed upper alimentary tract ulcerative syndrome (UAUS) and the identification of potential causative virus(es) using metagenomics. A diagnosis of UAUS could not be made based solely on clinical signs and required histopathological assessment of post-mortem samples. Specifically, this included the identification of multifocal to coalescing areas of mucosal epithelial necrosis at all depths of the stratified squamous epithelium of the oesophagus, along with exclusion of bovine viral diarrhoea virus. Based on this case definition, twelve herds were diagnosed with clinical UAUS across the three dairying regions of Victoria, while thirteen were ruled UAUS-negative. The status of the nine remaining herds was unresolved due to a lack of required post-mortem samples. Metatranscriptomic analysis on oral swabs and oesopharyngeal samples from confirmed UAUS cases did not detect a virus common to the cross-sectional sample collection.

The racing pigeon (Columba livia domestica) industry in Victoria, Australia, and epidemiology of a novel Group A rotavirus outbreak.

A novel Group A rotavirus, first identified clinically in racing, feral and fancy pigeons in Western Australia, had spread throughout Australia by March 2017. In December 2016, the putative index case of rotavirus in racing pigeons in the state of Victoria was confirmed at a regional bird sale, with rapid spread to peri-urban Melbourne, the capital city. A survey sent to approximately 400 Victorian pigeon fanciers identified eight (of 85 respondents) with a confirmed rotavirus infection in their loft(s). If a fancier had purchased live birds, either from the regional sale or from another source, there was a 13%-38% increased likelihood of the loft subsequently being confirmed rotavirus-positive. An increased loft-level risk of rotavirus was also positively associated with the number of neighbouring lofts within a 5-km radius of a home loft. It was concluded that rotavirus was primarily transmitted beyond the Victorian index case through the movement of live birds into a loft, either deliberately through bird purchase and/or inadvertently through the entry of pigeons from neighbouring lofts. As pigeon racing inherently requires consistent contact between birds from different lofts, vaccination is recommended as a primary method of rotavirus control in this unique industry.

High seroprevalance of Neospora caninum in dogs in Victoria, Australia, compared to 20 years ago.

BACKGROUND: Canids are definitive hosts of the apicomplexan parasite Neospora caninum, the leading cause of abortion in cattle worldwide. For horizontal transmission from canids to occur, oocysts of N. caninum must be shed by the definitive host into the environment of susceptible intermediate hosts such as cattle. The purpose of this study was to determine the prevalence of N. caninum in canids in Victoria, Australia's leading dairy producing state. RESULTS: Neospora-like oocysts were observed in 8% (18/234) of faecal samples from wild dogs, domestic dogs and red foxes from Victoria, Australia. However, none tested positive for N. caninum DNA using a quantitative PCR. In a separate sample population, blood sera from 483 domestic dogs were tested for anti-N. caninum antibodies using competitive ELISA. A subset of cELISA samples were re-tested using indirect fluorescence antibody test (IFAT). A seroprevalence of 29.8% (144/483; 95% CI: 11.7-47.8%) was calculated when using cELISA; whereas it was 32.9% (27/80; 95% CI: 15.8-51.8%) using IFAT. Potential risk factors were evaluated using univariable analyses and then assessed in separate multivariable models. Using 'aged' dogs as a reference, the seroprevalence of 'adolescent' and 'adult' dogs was 88% (P = 0.05) and 91% (P = 0.08), respectively, indicating seroprevalence increases with age. There was a 19% higher likelihood of infection in rural locations (P = 0.10) relative to urban areas. Jack Russell Terriers had a 22% higher risk of a cELISA-positive result (P = 0.05) regardless of geographical location, age or sex. CONCLUSION: These results demonstrate that exposure to N. caninum in domestic dogs is widespread in Victoria, although faecal oocyst shedding is infrequent. Our results indicate increased N. caninum seroprevalance status in dogs over the past two decades. The results imply that dogs get either exposed to the infected meat more frequently or that vertical dam to foetus transmission is more frequent than previously thought. Our study calls for re-evaluation of historical N. caninum seroprevalance studies, because the attitude to dog diet changes.

Comparison of methodologies in determining bone marrow fat percentage under different environmental conditions.

The use of bone marrow fat percentage has been recommended in assessing body condition at the time of death in wild and domestic ruminants, but few studies have looked at the effects of time and exposure on animal bone marrow. We investigated the utility of bone marrow fat extraction as a tool for establishing antemortem body condition in postmortem specimens from sheep and cattle, particularly after exposure to high heat, and compared different techniques of fat extraction for this purpose. Femora were collected from healthy and "skinny" sheep and cattle. The bones were either frozen or subjected to 40°C heat; heated bones were either wrapped in plastic to minimize desiccation or were left unwrapped. Marrow fat percentage was determined at different time intervals by oven-drying, or by solvent extraction using hexane in manual equipment or a Soxhlet apparatus. Extraction was performed, where possible, on both wet and dried tissue. Multiple samples were tested from each bone. Bone marrow fat analysis using a manual, hexane-based extraction technique was found to be a moderately sensitive method of assessing antemortem body condition of cattle up to 6 d after death. Multiple replicates should be analyzed where possible. Samples from "skinny" sheep showed a different response to heat from those of "healthy" sheep; "skinny" samples were so reduced in quantity by day 6 (the first sampling day) that no individual testing could be performed. Further work is required to understand the response of sheep marrow.