New Zealand veterinary journal最新文献

Aims: To estimate prevalence and incidence of intramammary infections (IMI) using herd test somatic cell counts (SCC) or quarter-level microbiology in a single pasture-based, seasonal calving dairy herd.

Methods: Over four seasons (2010/11-2013/14) milk samples were collected for microbiology from quarters of all cows at four times; calving, MID1 (mean 116 (SD 21) days in milk (DIM)), MID2 (mean 204 (SD 21) DIM), and at drying off (DO; mean 266 (SD 30) DIM). SCC was determined every 1-4 (median = 2) weeks. Quarters were defined as having a new IMI if a bacterium was isolated that was not present at the preceding milk sampling and a cow was defined as having a new IMI where one or more quarters had a new IMI. Cows were defined as having a new high SCC where SCC increased to ≥ 200,000 cells/mL. Binary logistic regression and Poisson models were used to estimate prevalence and incidence rate (IR) of new infections. Cow-level IR estimates from bacteriology and SCC were compared using χ² analyses, and the sensitivity and specificity were estimated for SCC to estimate IR, assuming bacteriology was the gold standard.

Results: The prevalence of cows with a high SCC was 12.7 (95% CI = 12.3-13.1)% and quarter-level prevalence of IMI was 10.7 (95% CI = 10.2-11.1)%. The unadjusted IR for a new cow-level high SCC was 2.2 (95% CI = 2.0-2.4)/1,000 cow-days and for a new quarter-level IMI was 0.82 (95% CI = 0.71-0.95)/1,000 quarter-days at risk. Prevalence and IR were associated with DIM (p < 0.001), age (p < 0.001), and season (p < 0.001). The agreement between the IR based on herd test SCC and microbiology at cow-level was 77.1% (p < 0.001), with the level of agreement highest in mid-lactation. The sensitivity and specificity of an increase in SCC were 29.8% and 88.9%, respectively.

Conclusions: Prevalence and IR varied by season, age and DIM. While the IR estimates differed between estimates based on a high SCC at the cow-level, and quarter-level microbiology, the level of agreement was 77% suggesting utility of cow-composite SCC data as a mastitis monitoring tool. However, the sensitivity of incidence based on elevated SCC was only approximately 30% relative to quarter-level microbiology as the gold standard.

Clinical relevance: This study provides the first estimates of prevalence and incidence of IMI in pasture-based dairy cows.Abbreviations: DIM: Days in milk; DO: Dry Off; EMM: Estimated marginal mean; IMI: Intramammary infection; IR: Incidence rate; NAS: Non-aureus staphylococci; SCC: Somatic cell count; TAR: Time at risk.

Case history: Two dogs, a 10-year-old male Siberian Husky cross and an 11-year-old male Cocker Spaniel were referred to a specialist veterinary hospital in Melbourne, Australia, for treatment of metastatic anal sac apocrine gland adenocarcinoma (ASAGAC) and concurrent hypercalcaemia (concentration of ionised calcium in serum > 1.5 mmol/L) of malignancy.

Clinical findings: Case 1 had a left anal sac mass approximately 5.5 cm in diameter, enlarged sub-lumbar lymph nodes palpable on rectal examination and a concentration of ionised calcium in serum of 2.45 (reference range 1.2-1.32) mmol/L. Soft tissue opacities suspicious for metastatic pulmonary nodules were observed on thoracic radiographs. CT of Case 2 revealed bilateral anal gland masses (left: 4.7 × 3.2 cm; right: 2.8 × 2.1 cm) and a large, ill-defined, intrapelvic mass (7.0 × 6.0 cm) encompassing the medial iliac and internal iliac lymph nodes and intimately associated with the aortic blood vessels. Cytology of fine-needle aspirates of the anal gland masses of both dogs was consistent with ASAGAC. The owners of both dogs declined surgical intervention and medical management with toceranib phosphate was initiated in the gross disease setting.

Treatment and outcome: Toceranib was initially administered at a dose of 2.5 mg/kg orally every other day in both dogs. Due to side effects from this medication, including hypocalcaemia, the dosing schedule was adjusted to Monday, Wednesday, and Friday with a dose range of 2.25-2.5 mg/kg. Both dogs remained alive, Case 1 after 519 days and Case 2 after 477 days, and were normocalcaemic at the time of writing. Both dogs experienced resolution of hypercalcaemia of malignancy while being treated with toceranib alone: hypercalcaemia was controlled for a total of 12 months in Case 1 and 15 months in Case 2. During treatment the anal sac mass of Case 1 remained approximately 5 cm in diameter and the sub-lumbar lymph node remained subjectively stable though no objective measurements were taken. Case 2's anal sac masses and intrapelvic lymph node mass subjectively reduced in size based on palpation.

Clinical relevance: This case series highlights two instances where toceranib monotherapy effectively managed hypercalcaemia of malignancy secondary to metastatic ASAGAC. Despite the presence of extensive macroscopic neoplastic disease, both dogs achieved durable control of hypercalcaemia with toceranib treatment.Abbreviations: ASAGAC: Anal sac apocrine gland adenocarcinoma; cRECIST: Canine response evaluation criteria in solid tumours; HHM: Humoral hypercalcaemia of malignancy; OST: Overall survival time; PFS: Progression-free survival; PTH: Parathyroid hormone; PTHrP: Parathyroid-related hormone peptide; RTK: Receptor tyrosine kinase; TKI: Tyrosine kinase inhibitor.

Case history: Between June 2017 and April 2019, three captive tuatara from a zoological facility in the South Island of New Zealand were found unwell and admitted to veterinary care. One other tuatara from the same facility was found dead from misadventure in May 2019.

Clinical findings: All three unwell tuatara showed clinical signs of lethargy, mucous membrane pallor, and dehydration, with haematoma formation/swelling in dependent parts of the body. Fine needle aspiration and cytology of the swellings showed common features of peripheral blood, with variable other cytological findings. Haematology confirmed marked anaemia in Case 1 (PCV 5%; reference range 22-53%) and Case 2 (PCV 1%) and suspected mild anaemia in Case 3 (PCV 27%). Case 1 died 6 weeks after initial presentation, whereas Cases 2 and 3 died soon after presentation.

Pathological findings: Post-mortem examination showed general pallor of soft tissues in the three tuatara with clinical signs of coagulopathy. There was haemorrhage in the bladder wall of Case 1, while Cases 2 and 3 had haematomas (subcutaneous in Case 2 and peri-oesophageal in Case 3). The pathological diagnosis in Case 4 was death by asphyxiation following burrow collapse. Retrospective analysis showed brodifacoum was present in liver tissue at a concentration of 0.26 mg/kg in Case 3, and in skeletal muscle tissue at concentrations of 0.019 mg/kg in Case 2 and 0.035 mg/kg in the non-clinical case (Case 4).

Diagnosis: The clinical signs and post-mortem findings were consistent with anticoagulant poisoning in three tuatara, and tissue concentrations of brodifacoum demonstrated exposure in three animals, including one animal with no clinical signs of coagulopathy (Case 4). Definitive diagnosis was prevented, however, by inconsistent toxicology testing and a limited understanding of toxicity thresholds in reptiles in general, and tuatara specifically.

Clinical relevance: This case series suggests that tuatara are susceptible to anticoagulant poisoning and this has implications for both the captive management of tuatara, and also the use of rodenticides in tuatara habitat, such as offshore islands and mainland sanctuaries.

Abbreviations: AR: Anticoagulant rodenticide; LD50: Median lethal dose; SGAR: Second generation anticoagulant rodenticide.

Current paradigms and practices impede the ability of practitioners to fully utilise clinical pathology results from blood and other body fluids to recognise and manage disease in veterinary patients. These issues include analyser bias, the suitability of population reference intervals, and "grey areas" around individual results. Analyser bias gives rise to different results for the same sample determined on different analysers (even of the same model at commercial laboratories). Such bias is often not accurately accounted for by using reference intervals specific for the different analysers. The ideal solution would be harmonising analysers so that results are equivalent regardless of the analyser they were determined on. Without harmonisation, results from different analysers should not be compared. Population-based reference intervals may not reflect the local population and, for most analytes, are much wider than an individual patient's normal fluctuation of results. This means that clinically relevant changes that remain within the population reference interval may be missed. Rather than assessing results in relation to a patient's cohort, results can be assessed in relation to a patient's prior results, expected analyser variation and expected physiological fluctuation. Such fluctuations are known as biological variation. Biological variation enables individualised reference intervals to be determined from prior results obtained when a patient is clinically stable. Such reference intervals are not yet readily available; however, assessing prior results and comparing them to expected variation (see Supplementary Tables 1 and 2) to recognise the significance of any change could be used as an interim measure. A single laboratory result represents a range of possible values. This range is known as dispersion and is also determined from biological and analyser variation. Dispersion creates grey areas around individual results and thresholds such as reference interval limits and staging of disease. Therefore, any threshold should not be taken as definitive and apparent changes may be within expected physiological fluctuation and therefore not significant.This review assesses the background and science behind these issues and offers ideal solutions for how they may be addressed in the future and practical approaches that can be immediately incorporated by clinicians into daily practice. Addressing these issues can help improve clinical pathology acuity and thus improve outcomes for veterinary patients.Abbreviations: CKD: Chronic kidney disease; CV_A: Analyser variation; CV_G: Inter-individual (group) variation; CV_I: Intra-individual variation; HSP: Homeostatic set point; IRIS: International Renal Interest Society; RCV: Reference change value; SDMA: Symmetric dimethylarginine.

Aims: To describe the spatio-temporal patterns of leptospirosis case counts in sheep and cattle in New Zealand, and to assess their association with climate variables indicative of flooding and surface runoff. As livestock are a major reservoir of Leptospira spp. and an important source of zoonotic transmission, understanding these patterns is critical for informing livestock and public health interventions in the context of climate change.

Methods: Confirmed cases of bovine and ovine leptospirosis from January 2011 to December 2023 were extracted from the Ministry for Primary Industries' Animal Health Surveillance programme. Climate data was sourced from the National Institute of Water and Atmospheric Research. Using the χ² test and Poisson regression models, the association between district-level case counts and four climate indices were examined: seasonal mean rainfall, seasonal frequency of extreme rainfall, seasonal mean soil moisture, and seasonal frequency of estimated surface runoff.

Results: Findings indicated an average of 13 confirmed cases for sheep annually, with notable surges in 2017 (34 cases) and 2023 (36 cases), aligning with extreme climate events. Poisson regression models for sheep leptospirosis identified significant associations with extreme rainfall (incidence risk ratio (IRR) = 5.03; 95% CI = 1.18-21.45), mean rainfall (IRR = 1.25; 95% CI = 1.15-1.36), surface runoff (IRR = 1.09; 95% CI = 1.04-1.15), and soil moisture (IRR = 1.03; 95% CI = 1.02-1.03). Cattle leptospirosis was positively associated with surface runoff (IRR = 1.06; 95% CI = 1.02-1.10) and soil moisture (IRR = 1.01; 95% CI = 1.00-1.01). Associations with extreme rainfall (IRR = 1.46; 95% CI = 0.49-4.31) and mean rainfall (IRR = 1.07; 95% CI = 1.00-1.14) were not statistically significant.

Conclusions: The outcomes of this study provide new evidence linking extreme rainfall, surface runoff, and other climate variables with increased leptospirosis case counts in sheep, with less pronounced but notable associations in cattle. These findings highlight the vulnerability of livestock to climate-driven disease pressures and suggest that future extreme weather events may increase the risk of leptospirosis outbreaks. This has important implications for targeted vaccination, surveillance, and public health preparedness in flood-prone rural regions of New Zealand.

Abbreviations: ICC: Intra-class correlation coefficient; IRR: Incidence risk ratio; MPI: Ministry for Primary Industries; NIWA: National Institute of Water and Atmospheric Research.

Aims: To describe the pathophysiology caused by ballistics applied to the head of stranded cetaceans that required euthanasia and use this information to infer the likely welfare implications of these real-life euthanasia events.

Methods: Post-mortem computed tomography (PMCT) imaging was conducted on six cetacean carcasses of five different species that were submitted for dissection following ballistics euthanasia. No animals were euthanised for the purpose of this study. All data were collected opportunistically at stranding events where euthanasia was a priori deemed necessary by the Department of Conservation (DOC) in partnership with indigenous Māori (iwi). The cranial damage assessed included osseous lesions at entry and exit wounds, intracranial bone fractures and intracranial projectile fragments. Potential welfare implications were inferred based on the likelihood of instantaneous insensibility occurring due to direct physical disruption to the brainstem. Additionally, basic stranding data were collected from DOC incident reports including whether animals were refloated prior to the decision for euthanasia. We also gathered information from the marksperson involved on how the ballistics method was employed, equipment used, and animal insensibility assessed at each stranding event.

Results: PMCT results suggest that two animals were likely instantaneously insensible, three had a moderate chance of being instantly insensible and one had a low chance of instantaneous insensibility. In one case, the marksperson reported a faster time to insensibility/death than was judged likely to have occurred from PMCT. In only two cases were the criteria for verifying insensibility reported as being checked. The likelihood of instantaneous insensibility occurring was affected by shot placement/aim and characteristics of the projectile used.

Conclusions: Euthanasia is a critical option for severely compromised cetaceans. While most animals examined were probably rapidly insensible following shooting, cranial trauma and thus confidence in the efficacy of ballistics seemed to vary with shot placement, aim, equipment and cranial anatomy.

Clinical relevance: Verification of insensibility immediately following shooting, by assessing reflex responses as recommended, is crucial to ensure humane emergency management. PMCT provides an effective non-destructive tool to validate field methods for assessing the efficacy of euthanasia.

Aims: To describe the morphology and prevalence of teat and udder pathology of New Zealand dairy ewes.

Methods: A repeated cross-sectional study was conducted on 20 commercial New Zealand dairy sheep farms over the 2022-2023 season. Approximately 15 randomly selected ewes were examined on each farm in early, mid, and late lactation. Four udder morphology measures were scored on a 5-point scale: depth (1 = pendulous, 5 = compact udder), suspension (ratio of width at abdominal attachment to height, 1 = low, 5 = high), gland separation (1 = zero, 5 = maximum separation), and teat placement (1 = distally located, vertically oriented, 5 = laterally located, horizontally oriented teats). Teat length and width were measured, and the presence of supernumerary teats, asymmetry, visible teat/udder inflammation, and lesions were recorded. Teats and glands were palpated for consistency, gland-nodules, teat canal thickening, and patency, and teat ends scored for hyperkeratosis. Teat and gland-level pathological variables were converted to ewe-level scores. The presence of involuted, non- or minimally lactating glands was recorded. Data were analysed using descriptive statistics.

Results: Across the three visits, 893 observations were made on 882 unique ewes. Mean teat length and width were 27.5 (95% CI = 27.2-27.7) and 15.8 (95% CI = 15.7-15.9) mm. Udder depth, separation, suspension, and teat placement had modal scores of 4, 3, 3, and 3 respectively, and varied across visits and age groups. Asymmetrical udder prevalence was 39% (95% CI = 35.5-42%) overall and increased with age (27% for 1-year-olds, 38% for two-year-olds, 43% for mixed age ewes). Supernumerary teats were observed in 15% (95% CI = 13-17.9%) of ewes. There was between-farm variation in all udder morphology variables. Ewe-level prevalences of teat end hyperkeratosis (any degree of severity), gland/teat inflammation, lesions, palpable defects, and involuted glands were all < 6%.

Conclusions: Morphological observations resembled those from overseas dairy sheep. Teat dimensions, udder depth, separation, suspension, teat placement, and presence of supernumerary teats varied between farms. Udder depth, separation, and suspension scores decreased with age, while teat placement score and the prevalence of asymmetry increased with age. Teat and udder pathology were rare.

Clinical relevance: This is the first systematic study of teat and udder morphology and pathology in New Zealand dairy ewes. The data will be useful for farmers and industry partners, providing a comparison with their own flocks, identifying areas for improvement, and informing and contrasting with future studies.

Aims: To assess whether herd-level lameness prevalence can be estimated on New Zealand dairy farms, by scoring the first, middle, or last 100 cows in the milking order. In pasture-based herds, whole herd locomotion scoring requires an assessor outside the milking parlour throughout milking. If sufficiently predictive, sampling a proportion of the herd based on milking order, could reduce the costs and time of welfare assessments.

Methods: Six pasture-based, spring-calving, dairy farms in the Manawatū region of New Zealand were conveniently selected. Visits occurred at approximately 6-week intervals between October 2021 and May 2022. Cows were scored using the DairyNZ lameness score (0-3). The assessor tallied cows as they left the parlour and recorded the milking order of those with a lameness score ≥ 2. Data were analysed to determine the association between farm, visit and the proportion of lame cows in the first, middle, and last 100 cows, and the agreement between the prevalence of lame cows in those groups and from whole herd scoring.

Results: Across all visits, 263 lame cows were recorded. Of these, 40.7% were in the last 100, 25.9% in the middle 100, and 14.4% in the first 100. Farm, visit and their interactions with group were all statistically significant (p < 0.001). While, overall, the last 100 cows had the highest proportion of lame cows, this pattern varied across farms and visits, Limits-of-agreement plots showed that as herd prevalence increased, agreement between the prevalence in each sample group and herd prevalence worsened. When herd prevalence exceeded 5%, only the middle 100 sampling group had a limits-of-agreement < 5%.

Conclusions: Variations across farms and seasons in the proportion of lame cows in each part of the milking order lead to variations in the accuracy of predicting overall lameness from such samples. Based on limits-of-agreement, observing the middle 100 cows is likely to be the most accurate sample, but is still likely to be of limited value on New Zealand dairy farms, especially as a single, one-off measurement.

Clinical relevance: On New Zealand dairy farms, locomotion scoring the middle 100 cows in the milking order as part of a welfare assessment would reduce costs and time but would not produce an accurate estimate of whole-herd lameness prevalence. However, it may be useful as a screening tool in herds routinely locomotion scoring throughout the year.