Australian Veterinary Journal最新文献

Background: Bovine respiratory disease (BRD) is the most economically important disease affecting feedlot cattle. While viral pathogens are initiating agents, bacterial coinfections exacerbate disease severity. Vaccines for Pasteurella multocida and Histophilus somni are not commercially available in Australia.

Methods: This trial evaluated the efficacy of a single-dose autogenous vaccine targeting P. multocida and H. somni, administered intramuscularly at induction, on carcase characteristics, feed conversion efficiency and health performance in feedlot cattle.

Results: Vaccinated cattle showed a 6.20% lower prevalence of subclinical BRD than controls (16.50% vs. 22.70%), corresponding to a 27.31% lower likelihood of subclinical BRD with vaccination. Vaccinated cattle exhibited improved performance, with a 2.86% increase in average daily gain, a 0.50% increase in hot standard carcase weight, a 0.81% increase in loin eye muscle area and a 2.68% increase in dry matter intake compared with controls. Vaccinated cattle showed lower odds of lung consolidation compared with controls (odds ratio [OR] = 0.73), indicating a 27.00% reduction in the likelihood of consolidation. Similarly, vaccinated cattle showed a 35.50% reduction in pleurisy scores relative to controls (OR = 0.65). Despite slightly higher feedlot costs, vaccinated cattle achieved a higher total end value and higher gross profit margins with a cost-benefit ratio of 6.95.

Conclusions: Given the overall reduced BRD incidence during the study period, the observed results may be influenced by pathogen prevalence, vaccine dosage, timing, route of administration and environmental factors. While the single-dose vaccine improved subclinical disease outcomes and growth performance, further studies, including a two-dose vaccine trial, are required to assess the full potential of the anamnestic immune response.

A 2-year-old female spayed British Shorthair cat presented for investigation of chronic small intestinal diarrhoea, which was determined to be attributable to ionised hypercalcaemia. A cranial mediastinal mass was identified on computed tomography; median sternotomy was performed, and the mediastinal mass was excised. Histopathology, including immunohistochemistry, diagnosed the mediastinal mass as being remnant thymic tissue. Subsequent follow-up 10 months postoperatively showed restoration of normocalcaemia and concurrent resolution of gastrointestinal symptoms. To the authors' knowledge, this is the first case to report remnant thymic tissue as a cause of hypercalcaemia. This case report aims to describe the clinical presentation, computed tomography description, histopathological findings and treatment outcome of a thymic remnant causing hypercalcaemia in a cat.

Five dogs diagnosed with and treated for Ixodes holocyclus tick paralysis were successfully weaned from mechanical ventilation (MV) to high flow nasal oxygen therapy (HFNOT). All dogs were mechanically ventilated primarily for hypoventilation for a median time of 80 h (36–113 h). Concurrent conditions included aspiration pneumonia (n = 3) and laryngeal paralysis causing upper airway obstruction (n = 3). Median duration of HFNOT was 4 h (0.5–24 h) before either de-escalation to traditional oxygen therapy (TOT) or discontinuation from oxygen support. Reported complications included superficial corneal ulceration (n = 2), thrombophlebitis (n = 2), gastric ileus (n = 3), urinary tract infection (n = 2) and postventilator seizures (n = 1); however, none were associated with HFNOT. One dog developed a pneumothorax during MV, which was managed with continuous suction via bilateral thoracostomy drains but was not noted to progress with HFNOT. Nasal prong placement was well tolerated in all but one dog, requiring transition to TOT after 1 h of HFNOT. All dogs survived to discharge. Although not recommended in the initial management of hypoventilation, in this case series HFNOT was successfully used as a weaning strategy for dogs ventilated with recoverable neuromuscular disease. This is the first reported use of HFNOT after MV in dogs, specifically with tick paralysis.

Background: The emergence of Ehrlichia canis in northern Australia in 2020 has reshaped the landscape of tick-borne diseases in dogs, particularly in rural and remote communities where the brown dog tick (Rhipicephalus linnaei) is endemic. Despite the rapid spread of ehrlichiosis and reported impacts on dog health, its prevalence remains poorly understood. This study aims to provide baseline data on the epidemiology of E. canis in Australia by determining its seroprevalence in dogs from a remote Northern Territory community.

Methods: In a cross-sectional study, an enzyme-linked immunosorbent assay (ELISA) assessed the point seroprevalence of E. canis in community dogs. A door-to-door census was undertaken to quantify resident dogs and obtain information on signalment and clinical signs. Canine serum samples were evaluated for seroreactivity to E. canis at the state reference laboratory.

Results: Of the 48 dogs present in the community, 44 (91.2%) were included in the serosurvey. ELISA testing found a point seroprevalence of 52.3% (95% CI: 36.7% to 67.5%) for E. canis. Seropositive dogs were mostly asymptomatic and had similar body condition scores to seronegative dogs.

Conclusions: This study documents a high point seroprevalence of E. canis in dogs from a remote Australian community. There was no significant correlation between serostatus and gender, body condition or the presence of clinical signs. These results underscore the need for further research to understand the clinical significance of seropositivity in asymptomatic dogs and highlight the need for a locally validated diagnostic test to support field-based surveillance and management of ehrlichiosis in Australia.

This study appraises recent research to critically evaluate knowledge on the factors that influence decisions around the release of rehabilitated koalas to fire-affected home sites. Availability of koala release sites could be compromised at times in the future by the increasing incidence of large and intense bushfires due to climate change. In addition, factors such as the fragmentation of koala habitat and increasing urbanisation impose other threats to the long-term survival of the released koala. Our investigation is conducted as a Critically Appraised Topic (CAT) with eight papers selected to be appraised. We highlight three key areas that affect koala rehabilitation and release to fire-affected home sites - the resilience of the koala in recovery, the adaptation ability of the koala upon release and the components of the fire-affected habitat. The evidence shows that the koala is a good candidate for release given that burnt koalas are resilient in rehabilitation and many can recover and then adapt quickly to their release site. Findings from this study indicate that, when the release site is affected by fire, the conditions that are more favourable for koala release are low severity of fire impact, greater distance from urban areas, connection to unfragmented habitat and previous management of predators. These findings can inform wildlife release and rescue as well as government planning and urban development.

This study presents a retrospective analysis of clinical records data from koalas presenting for treatment following the large-scale bushfire event on Kangaroo Island 2019-2020. The aim of the study was to identify prognostic factors for koalas affected by bushfire. Koalas (n = 199) were grouped based on their burn status in combination with their burn bandaging requirement at triage; those with no burns, with burns that did not require bandaging and with burns that did require bandaging. Overall, 59.8% of koalas had positive outcomes, but this reduced to only 13% of koalas in the most severely affected group (burns that were bandaged). Negative outcomes were found to be associated with several factors, including the timing of presentation, with the worst affected animals presenting in the first 2 weeks of the operation. Also, an increasing number of bandage changes during hospitalisation led to increasingly negative outcomes, with no positive outcomes beyond three bandage changes. In addition, clear associations were found with patterns of burns on feet, with only 4% positive outcomes for animals with all 4 feet burnt. All bandaged koalas with severe dehydration had negative outcomes and body weights decreased over time for hospitalised animals from the most severely affected bandaged burn group. Mild serum sodium concentration elevation at triage was the only clinically significant blood abnormality for koalas with bandaged burns. Overall, this study identified key prognostic factors, particularly bandaging requirements and the number of feet burnt, that will enable more effective decision-making at triage and improve animal welfare outcomes.