Veterinary Clinical Sciences - Research Publications
Now showing items 1-12 of 296
Synchrotron CT of an equine digit at the Australian Synchrotron Imaging and Medical Beamline.
(International Union of Crystallography (IUCr), 2021-11-01)
Laminitis is an extremely painful and debilitating condition of horses that can affect their athletic ability and even quality of life. The current gold standard for assessment of laminar tissue is histology, which is the only modality that enables detailed visualization of the lamina. Histology requires dissection of the hoof and therefore can only represent one specific time point. The superior spatial and contrast resolution of synchrotron computed tomography (sCT), when compared with readily available imaging modalities, such as radiographs and conventional CT, provides an opportunity for detailed studies of the lamina without the need for hoof dissection and histological assessment. If the resolution of histology can be matched or even approached, dynamic events, such as laminar blood flow, could also be studied on the microscopic tissue level. To investigate this possible application of sCT further, two objectives are presented: (i) to develop a protocol for sCT of an equine digit using cadaver limbs and (ii) to apply the imaging protocol established during (i) for sCT imaging of the vasculature within the foot using an ex vivo perfusion system to deliver the vascular contrast. The hypotheses were that sCT would allow sufficient resolution for detailed visualization to the level of the secondary lamellae and associated capillaries within the equine digit. Synchrotron CT enabled good visualization of the primary lamellae (average length 3.6 mm) and the ex vivo perfusion system was able to deliver vascular contrast agent to the vessels of the lamina. The individual secondary lamellae (average length 0.142 mm) could not be seen in detail, although differentiation between primary and secondary lamellae was achieved. This approaches, but does not yet reach, the current gold standard, histology, for assessment of the lamellae; however, with further refinement of this imaging technique, improved resolution may be accomplished in future studies.
Community Attitudes Reflect Reporting Rates and Prevalence of Animal Mistreatment
(FRONTIERS MEDIA SA, 2021-10-28)
Community attitudes toward the treatment of animals are important to understand for the development of intervention programs to prevent mistreatment. We aimed to investigate whether previously identified differences between local government areas (LGAs) in the rates of animal mistreatment reporting and prevalence were reflected by differences in community attitudes. In addition, attitudinal differences based on target species (dogs, cats, horses) and participant gender were considered. A representative telephone survey (N = 1,801) was conducted across six LGAs. Attitudinal themes included affection toward animals, valuing of animals, attitudes toward caring for own animals, and concern for the mistreatment of other animals. Factorial ANOVA was used to identify differences between high and low reporting LGAs, region types (regional, interface, metropolitan), and target species (cat, dog, horse). Respondents from high reporting LGAs demonstrated slightly more affection for animals F (1,1679) = 19.401, p < 0.001, ω p 2 = 0.011 and stronger subjective norms F (1,999) = 16.31, p < 0.001, ω p 2 = 0.015 than those from low reporting LGAs, but did not differ on the other variables. Participants in areas of high prevalence (regional areas) did not display lower levels of affection or concern for the mistreatment of animals as a whole, nor did they value animals less. However, regional differences were found for several items regarding caring for one's own animals: two behavioral beliefs and two control beliefs. Additionally various differences were found between the regions regarding the level of concern for mistreatment when broken down into the different species. Gender effects were also common. While the attitudinal results do reflect animal mistreatment prevalence and reporting rates, they also highlight the complexity of community attitudes. As such, interventions to prevent mistreatment must have clear targets including the audience, behavior, and species. Targeting smaller regions and thoroughly investigating their unique perspectives, challenges, and strengths are likely to be more effective than generic campaigns.
Association of Thoroughbred Racehorse Workloads and Rest Practices with Trainer Success
Understanding the relationship between the training practices of Thoroughbred racehorses and race performance is important to ensure advice given to trainers for injury prevention or management is practical and consistent. We assessed associations between intended volume and speed of gallop training (i.e., typical workloads for horses free of injury or other performance limiting conditions) and rest practices on official trainer career and previous season success rates (rate of wins and places, prizemoney per start). Sixty-six Australian Thoroughbred trainers were surveyed. Multivariable negative binomial regression models were employed for the outcomes career and previous season wins and places, and linear regression models for prizemoney per start. Intended training workload was not associated with prizemoney. Pre-trial total galloping distances (≥13.3 m/s) between 7500 m and 15,000 m were associated with a higher rate of career wins, and previous season wins and places per start (p < 0.05). Slow-speed (13.3-14.3 m/s) galloping distance to trial between 5000 m to 12,500 m was associated with higher rate of career placings per start, with reduced performance over 12,500 m (p = 0.003). Greater time between race starts was associated with a greater rate of previous season wins and prizemoney per start until three weeks between starts, with decline in performance thereafter (p < 0.05). Greater frequency of rest breaks was associated with greater prizemoney per start earnt in the previous season (p ≤ 0.01). These results suggest that modifications to training programs aimed at injury prevention, such as avoiding long galloping distances, should not adversely affect trainer success.
Low-grade gastrointestinal lymphoma in dogs: 20 cases (2010 to 2016)
OBJECTIVES: To report the clinical presentation, treatment and prognosis of dogs with low-grade gastrointestinal lymphoma. MATERIALS AND METHODS: Cases were solicited from the American College of Veterinary Internal Medicine Oncology Diplomate listserv. Medical records of dogs with low-grade gastrointestinal lymphoma diagnosed via a combination of histology and immunohistochemistry with or without analysis of polymerase chain reaction for antigen receptor rearrangement were included. Signalment, clinical signs, diagnostic test results, chemotherapy protocol, response to treatment, date of first progression, rescue therapies and date and cause of death or last follow-up visit were collected. RESULTS: Twenty cases were included. Males and small breed dogs were over-represented. Frequent clinical signs included weight loss, vomiting and diarrhoea. Most lymphomas were T-cell phenotype (95%), and epitheliotropism was commonly described (60%). Immunohistochemistry, polymerase chain reaction for antigen receptor rearrangement or both were frequently required for definitive diagnosis. Two dogs had resection of an intestinal mass, and all dogs were treated with chemotherapy; chlorambucil and prednisone were most commonly prescribed. Overall response rate was 70%, and median survival time was 424 days (95% confidence interval: 105 to 1206 days). CLINICAL SIGNIFICANCE: Low-grade gastrointestinal lymphoma appears to be a rare condition in dogs, and treatment with chemotherapy results in a high response rate and favourable survival times. Further study is needed to determine its prevalence in dogs with chronic enteropathies.
Accuracy and safety of pin placement during lateral versus dorsal stabilization of lumbar spinal fracture-luxation in dogs.
OBJECTIVE: To determine the accuracy and safety of pin placement for lateral vertebral stabilization to the reference dorsal stabilization. STUDY DESIGN: A randomized noninferiority trial. SAMPLE POPULATION: Twenty Greyhound cadaveric lumbar spines (L1-L6). METHODS: One hundred and fifty-nine lumbar vertebral pins placed in 80 vertebrae were assessed; these pins were distributed approximately equally between the dorsal and lateral approaches, and between 2 surgeons. Pin angle accuracy, bone purchase distance, and distances from pin to the spinal canal and the aorta were measured for each pin. RESULTS: The lateral approach was superior for pin angle accuracy and bone purchase. The mean angle of deviation was 15.3° with the dorsal approach and 7.0° with the lateral approach. The mean bone purchase was 16.7 mm with the dorsal approach and 22.2 mm with the lateral approach. Pins were placed at a mean of 2.3 mm from the spinal canal with the dorsal approach and 1.7 mm with the lateral approach. Pins were placed at a mean of 3.8 mm from the aorta with the dorsal approach and 8.0 mm with the lateral approach. The percentage of pins breaching the spinal canal was 14% with the dorsal approach and 19% with the lateral approach. Fourteen percent of pins placed via the dorsal approach breached the aorta, whereas no pins placed via the lateral approach breached the aorta. CONCLUSION: Relative to the dorsal approach, the lateral approach improves angle accuracy, bone purchase, and distance between pins, and the aorta and is noninferior with regards to the distance between pins and the spinal canal.
Biomechanical testing of the calcified metacarpal articular surface and its association with subchondral bone microstructure in Thoroughbred racehorses
BACKGROUND: Palmar/plantar osteochondral disease (POD) and third metacarpal/-tarsal condylar fractures are considered fatigue injuries of subchondral bone (SCB) and calcified cartilage due to repetitive high loads in racehorses. In combination with adaptive changes in SCB in response to race training, the accumulation of SCB fatigue is likely to result in changes of joint surface mechanical properties. OBJECTIVES: To determine the spatial relationship and correlation of calcified articular surface biomechanical properties with SCB microstructure and training history in the distal palmar metacarpal condyle of Thoroughbred racehorses. STUDY DESIGN: Cross-sectional study. METHODS: Third metacarpal condyles were examined from 31 Thoroughbred horses with micro-computed tomography (microCT). Hyaline cartilage was removed and reference point indentation (RPI) mechanical testing of the calcified articular surface was performed. Training histories were obtained from trainers. The association among indentation distance increase (IDI, an inverse RPI measure of toughness), and microCT and training variables was assessed using a mixed-effects generalised linear model. RESULTS: Untrained horses had higher IDI than horses that had commenced training (P<0.001). Death as a result of musculoskeletal bone fatigue injury (P = 0.044) and presence of POD (P = 0.05) were associated with higher IDI. The microCT variables connectivity density and trabecular pattern factor were positively (P = 0.002) and negatively (P<0.001) correlated with IDI respectively. MAIN LIMITATIONS: The application of RPI to the calcified articular surface is novel and there is a potential for measurement variability with surface unevenness. CONCLUSION: Commencement of race training is associated with altered material properties of the calcified articular surface in horses. Reduced articular surface material properties can also be detected in horses that have fatigue injuries of the distal metacarpus and at other sites in the skeleton. Measures of SCB connectivity and trabecular surface shape may be more important determinants of resistance to failure of the calcified articular surface than traditional measures such as SCB volume and density.
Elapid snake envenomation in horses: 52 cases (2006-2016)
BACKGROUND: Snake envenomation is a cause of morbidity and mortality in domestic animals worldwide. The clinical features of crotalid snake (pit viper) envenomation are widely reported and well described in horses but elapid snake envenomation is poorly characterised. OBJECTIVES: To describe the presentation, clinical and laboratory findings, treatment and outcome of horses with a diagnosis of elapid snake envenomation in Australia. STUDY DESIGN: Retrospective case series. METHODS: Medical records of horses with a diagnosis of elapid snake envenomation (2006-2016) at several university and private veterinary practices were reviewed. Inclusion criteria comprised one or more of the following: 1) observed snakebite, 2) positive snake venom detection kit (SVDK) result, 3) appropriate clinical response to treatment with antivenom or 4) supportive post-mortem findings. RESULTS: Fifty-two cases met the inclusion criteria. Most cases (94%) demonstrated clinical signs of neurotoxicity, characterised by generalised neuromuscular weakness. Associated neurologic signs included staggering gait, muscle fasciculations, recumbency, mydriasis, ptosis and tongue paresis. Concurrent clinically important conditions included rhabdomyolysis (50%) and haemolysis (19%). Of 18 urine samples evaluated with a SVDK, only three (17%) were positive. Overall survival was favourable (86%) among 49 horses who received antivenom. Eighteen surviving horses (43%) required more than one vial of antivenom. MAIN LIMITATIONS: Possible cases within the searchable database were not included if horses died acutely or responded to symptomatic treatment without receiving antivenom. CONCLUSIONS: Elapid snake envenomation is primarily a syndrome of neuromuscular weakness. Supportive anamnesis or an obvious bite site is rarely encountered. In endemic areas, this diagnosis should be considered for horses with generalised neuromuscular weakness, altered mentation, rhabdomyolysis and/or haemolysis; especially during spring and summer months. Diagnostic suspicion is best confirmed by response to treatment with antivenom.
Polypoid cystitis as a cause of haematuria in a pony mare
A 15‐year‐old pony mare was presented for investigation of haematuria of 2 weeks' duration. On cystoscopy, multiple small pedunculated soft tissue structures were observed on the bladder mucosa. Histopathological analysis of the masses was consistent with chronic polypoid cystitis. The polypoid lesions and associated haematuria resolved following prolonged antibiotic treatment. Polypoid cystitis has not previously been described in horses. This condition should be considered a differential for haematuria, requiring cystoscopy and biopsy to confirm a diagnosis.
In situ handheld three-dimensional bioprinting for cartilage regeneration
Articular cartilage injuries experienced at an early age can lead to the development of osteoarthritis later in life. In situ three-dimensional (3D) printing is an exciting and innovative biofabrication technology that enables the surgeon to deliver tissue-engineering techniques at the time and location of need. We have created a hand-held 3D printing device (biopen) that allows the simultaneous coaxial extrusion of bioscaffold and cultured cells directly into the cartilage defect in vivo in a single-session surgery. This pilot study assessed the ability of the biopen to repair a full-thickness chondral defect and the early outcomes in cartilage regeneration, and compared these results with other treatments in a large animal model. A standardized critical-sized full-thickness chondral defect was created in the weight-bearing surface of the lateral and medial condyles of both femurs of six sheep. Each defect was treated with one of the following treatments: (i) hand-held in situ 3D printed bioscaffold using the biopen (HH group), (ii) preconstructed bench-based printed bioscaffolds (BB group), (iii) microfractures (MF group) or (iv) untreated (control, C group). At 8 weeks after surgery, macroscopic, microscopic and biomechanical tests were performed. Surgical 3D bioprinting was performed in all animals without any intra- or postoperative complication. The HH biopen allowed early cartilage regeneration. The results of this study show that real-time, in vivo bioprinting with cells and scaffold is a feasible means of delivering a regenerative medicine strategy in a large animal model to regenerate articular cartilage.
Determination of testosterone esters in the hair of male greyhound dogs using liquid chromatography-high resolution mass spectrometry
The doping of greyhound dogs with testosterone is done in an attempt to improve their athletic performance, but such doping cannot easily be confirmed, especially in male dogs owing to the natural presence of endogenous testosterone. As testosterone is usually administered as its esters, their direct detection in hair would provide confirmatory evidence of the administration of a pharmaceutical product. This article demonstrates that the use of a liquid chromatography-high resolution mass spectrometry method with heated electrospray ionisation (HESI) combined with the use of amino solid-phase extraction (SPE) cartridges for sample clean-up, is suitable for the sensitive determination of propionate, phenyl propionate, isocaproate, decanoate, and enanthate esters of testosterone in greyhound hair. The method is linear over the range, 0.1 μg/kg-10 μg/kg, for all the testosterone esters analysed. The limits of detection (LOD) are 0.05 μg/kg for testosterone phenyl propionate, isocaproate, and decanoate, 0.025 μg/kg for testosterone propionate, and 0.25 μg/kg for testosterone enanthate. This method was applied to hair samples collected from male greyhounds before and after a single administration of a product containing several testosterone esters, each of which could be detected up to 100 days post-administration. The study also demonstrates that tail hair is the specimen of choice for the analysis of testosterone in dog hair and that washing of dogs does not impact the analysis of testosterone esters in hair. This method may be useful in racing regulation for the detection of illegitimate use of testosterone in all species.