New Zealand veterinary journal最新文献

Aims: To investigate the effect of injection of trace mineral supplement (TMS) 14-28 days before calving on white blood cell count (WBCC) and function, serum antioxidant capacity (SAC) and reactive oxygen species (ROS) in pasture-fed cattle after calving.

Methods: On each of two South Island, seasonally calving, pastoral dairy farms,1 month before dry-off, a random sample of 150 multiparous cows predicted to calve within 7 days of the herd's planned start of calving (PSC) were stratified on individual somatic cell count, age, breed and expected calving date. On each farm, 14-24 days before PSC, 60 selected cows were randomly assigned for TMS (Zn, Mn, Se, Cu) injection, and 60 were controls. All 240 cows were contemporaneously injected with hydroxocobalamin, and controls with Se. Blood samples were collected pre-injection and 3, 12 and 40 days after calving. Phagocytic activity, count and proportion of neutrophils, lymphocytes and monocytes, WBCC, ROS, SAC were measured. Plasma concentrations of Se, Cu and glutathione peroxidase (GPx) were monitored from a random subset of animals. Differences attributable to TMS were estimated using mixed-multivariable Bayesian analysis, expressed as mean and highest density interval (HDI).

Results: Three and 40 days after calving, TMS-treated cows had 0.36 (90% HDI = 0.00-0.77) x 10⁹ and 0.25 (90% HDI = 0.00-0.55) x 10⁹ fewer neutrophils/L. Neutrophils comprised 6 (90% HDI = 0-11)% and 4 (90% HDI = 0-8)% less of the WBCC, and the neutrophil count was 14 (90% HDI = 0-27)% and 9 (90% HDI = 0-18)% less than controls. However, 3 days after calving, there were 7 (95% HDI = 2-12)% more cells phagocytosing and 2,900 (95% HDI = 2,600-3,200) more bacteria ingested/cell. Twelve and 40 days after calving, TMS-treated cows had 0.65 (95% HDI = 0.17-1.17) x 10⁹ and 0.28 (95% HDI = 0.00-0.59) x 10⁹ more lymphocytes/L. Lymphocytes comprised 10 (95% HDI = 3-18)% and 5 (95% HDI = 0-9)% more of the WBCC, and the lymphocyte count was 30 (95% HDI = 11-51)% and 9 (95% HDI = 0-9)% more than controls. There were no meaningful differences in ROS, SAC, ROS/SAC, other white blood cells, or WBCC. Plasma Cu, Se and GPx concentrations were above recommended thresholds.

Conclusions: Pre-calving TMS injection was associated with differences in white blood cell population and function that may reduce the risk of disease.

Abbreviations: BHOB: Beta-hydroxybutyrate; GPx: Glutathione peroxidase; HDI: Highest density interval; MESF: Molecules of equivalent soluble fluorophore; OSi: Oxidative stress index; PSC: Planned start of calving; ROPE: Region of probable equivalence; ROS: Reactive oxygen species; SAC: Serum antioxidant capacity; THI: Temperature humidity index; TMS: Trace mineral supplement; WAIC: Widely applicable information criterion; WBCC: White blood cell count.

Aims: To describe rates of and reasons for culling and mortality of ewes between breeding and mid-lactation on New Zealand sheep farms; to investigate associations of these variables with farm demographic variables; and to describe rates of and reasons for culling of ewes at weaning.

Methods: Participants were a convenience sample of 34 farms from across New Zealand. Demographic data were initially collected for each farm via a questionnaire administered in-person to the flock owner or manager. During approximately 8 months from breeding to mid-lactation, ewe tally, culling and mortality data were collected and used to calculate various parameters related to flock performance and to investigate associations. During the main ewe-culling event at weaning, ewe-culling data were collected from 29/34 flocks participating in the study.

Results: There was considerable variation between flocks, but the between-flock mean replacement percentage was 29.2 (SD 5.0)%. Overall, a between-flock mean of 10.5 (SD 4.6)% of ewes presented for breeding were culled or dead/missing by mid-lactation and thus did not rear any lambs. Additionally, from 27 flocks that reported data on ewes' success at rearing lambs, a between-flock mean of 3.9 (SD 2.5)% of ewes that remained alive at mid-lactation failed to rear any lambs, resulting in an overall between-flock mean loss of 23.1 (SD 6.3) potential lambs per 100 ewes. Two-thirds of ewe mortalities between breeding and mid-lactation occurred during the lambing period. Model results showed flocks with higher pregnancy scanning percentages had lower rates of culling and mortality between breeding and mid-lactation. However, apart from farm contour, from breeding to mid-lactation there were no associations for culling and mortality with farm size, flock size, number of ewes per labour unit, whether ewe hoggets (7-9 months of age) were presented for breeding, or duration of the breeding period. A between-flock mean of 16.5 (SD 8.3)% of ewes present at weaning were culled, and among mixed-age ewes, the most common reasons for culling at this time were age, incisor teeth defects and udder defects.

Conclusions: To reduce unnecessary ewe culling and mortality, attention should be focused on maximising conception rates, ensuring judicious culling decisions, optimising body condition score, and identifying farm-specific causes of death over the lambing period to facilitate targeted intervention strategies.

Clinical relevance: Identifying why and when ewes exit flocks, and comparing it with the data presented here, will facilitate the development of flock-specific interventions to reduce ewe culling and mortality.

Aim: To assess whether the fluoride concentration in the humeri of first-lactation, 2-year-old dairy cows with a spontaneous humeral fracture is significantly different from that of first-lactation, 2-year-old dairy cows without a humeral fracture.

Methods: Two studies were conducted, the first with nine bone samples from 2-year-old, first-calving dairy cows with a humeral fracture (all from the Waikato region) age-matched with seven control bone samples from the Waikato, Bay of Plenty and Manawatū-Whanganui regions. The second study used 26 bone samples from 2-year-old, first-lactation dairy cows with a humeral fracture (from the Otago, Canterbury, Southland, West Coast, Waikato and Manawatū-Whanganui regions) age-matched with 14 control bone samples (all from the Manawatū-Whanganui region or unknown). Control bone samples were from first-lactation, 2-year-old dairy cows that did not have humeral fractures. Bone fluoride concentration was quantified for all samples.

Results: The median fluoride concentration of humeri from first-lactation, 2-year-old dairy cows with a humeral fracture was significantly higher than humeri from unaffected control cows in both studies. In Study 1, the median bone fluoride concentration was 599 (IQR 562.7-763.5) mg/kg from case cows and 296.6 (IQR: 191.2-391.7) mg/kg from control cows (p < 0.001), and in Study 2 the median bone fluoride concentration from case and control cows was 415 (IQR: 312.5-515) mg/kg and 290 (IQR: 262.5-410) mg/kg (p = 0.04) respectively.

Conclusions and clinical relevance: Although there are limitations to this study due to the unbalanced regional distribution of cases and controls, the results indicate that sub-clinical fluoride toxicosis may be linked to spontaneous humeral fractures in first-lactation dairy cows in New Zealand. Further research is required to determine if bone fluoride concentrations play a role in the pathogenesis of these fractures.

Aims: To assess the feasibility and safety of a locking cortical pearl plate system for the repair of lumbar vertebral fractures and luxation in cats using an ex vivo feline model.

Methods: This cadaveric study of the lumbar vertebral column (L1-L7) involved 28 Domestic Short-hair cats without vertebral column pathology. Surrounding soft tissue was removed, except for the paravertebral musculature, joint capsules, and ligaments associated with the L1-L7 vertebrae. To determine whether the application of a 2.0-mm, 69-mm-long, 12-hole locking cortical pearl plate (LCPP) and screws was feasible, the dimensions of the feline lumbar vertebral bodies (length, width, and height) were measured using CT imaging. Width and height were evaluated at five locations along the length of the vertebrae with implant corridors (cor 1-cor4) located in between. Following CT, plates were applied to the vertebral columns. After implantation, another CT scan was performed to evaluate plate positions, screw trajectories, screw implantation angles, and vertebral canal breaching. Implantation was classified according to the modified Zdichavsky scoring system for vertebral canal penetration and grade I and IIa defined as acceptable.

Results: A total of 371 screws were inserted into the lumbar vertebral bodies, and breaching occurred in 32 cases (8.6%), of which 29 (90.6%) were at L6 and L7. The median angle of inserted screws was 61.6° (min 53.4°, max 76.3°). Aside from one location, no significant angle deviations were observed between breaching (median 62.8°; min 53.4°, max 76.3°) and non-breaching (median 61.2°; min 53.8°, max 74.7°) screws. All 267 screws implanted in L1-L5 were graded I or IIa (acceptable). In contrast, low rates of acceptable implantation were achieved for L6 (52/60; 86.7%) and L7 (24/44; 54.4%), caused by clustering of breachings in corridor 3 of the two vertebrae.

Conclusions: Application of the LCPP immediately proximal to the transverse processes and ventral to the pedicles with a screw implantation angle of 60° is feasible and appears safe for L1-L5, resulting in a low number of vertebral canal breaches and a high rate of acceptable implantations.

Clinical relevance: The 2.0-mm, 69-mm-long, 12-hole LCPP can be considered an acceptable option for treating feline vertebral fractures and luxations of L1-L5. It cannot be recommended for use in corridor 3 of L6 or L7 due to the high risk of breaching the vertebral canal.

Aims: To investigate the effect of preservation by addition of yoghurt starter, potassium sorbate and citric acid on counts of aerobic bacteria, Lactobacillus spp., Streptococcus thermophilus and coliforms, Brix percentage, pH, protein, fat and anhydrous lactose concentrations at 0, 7 and 14 days after collection for colostrum stored at ambient temperature.

Method: Approximately 2 L of first milking colostrum was collected from 10 farms in the Waikato region. Following mixing, it was split into five 400-mL sub-samples and allocated randomly to a control (two sub-samples), or treatment with yoghurt, potassium sorbate, or citric acid preservative. Throughout the trial samples remained in the laboratory at ambient temperature with the lids slightly ajar, and were stirred daily for 15-30 seconds using a sterile spatula. Sub-samples were tested on Days 0, 7 and 14. On Days 0 and 14 aerobic bacteria (by aerobic plate count (APC)), Lactobacillus spp., coliforms and Streptococcus thermophilus counts, pH, Brix percentage, protein, fat and anhydrous lactose were measured. On Day 7 only bacterial counts were completed.The data were analysed using non-parametric clustered bootstrap sampling to estimate the effect of treatment, time, and their interaction on the outcome variables.

Results: Compared to control samples, on Day 7 the APC for potassium sorbate (1.0 (90% CI = 0.6-1.6) × 10⁸ cfu/mL) was approximately seven-fold lower than for yoghurt (7.3 (90% CI = 4.1-11) × 10⁸ cfu/mL), and approximately three-fold lower than citric acid (3.2 (90% CI = 0.2-4.3) × 10⁸ cfu/mL) remaining low to Day 14. All preservatives reduced coliform growth compared to control samples at Day 7 but growth was lower for potassium sorbate than the other preservatives. For Lactobacillus spp., at Day 7, samples with yoghurt preservative had greater counts than the other two preservatives. Potassium sorbate reduced growth of S. thermophilus compared to the other treatments, especially at Day 7, with 7-10 times fewer S. thermophilus per mL compared to the other three groups. All groups showed an obvious acidification over time, with very little variation within days and treatment groups. There was no evidence for change in fat or protein percentage over time regardless of treatment.

Conclusion and clinical relevance: Aerobic and coliform bacteria proliferate extensively in unpreserved colostrum. All preservatives decreased coliform counts compared to un-preserved colostrum, but potassium sorbate was more effective at decreasing both coliforms and aerobic bacteria than either yoghurt or citric acid.

Aims: To evaluate the prevalence of subclinical cardiomyopathy and cardiac mortality in a research colony of non-purebred cats, established as a model of the wider cat population in New Zealand.

Methods: All apparently healthy, compliant, non-pregnant, non-neonatal cats in the colony at the Centre for Feline Nutrition (Massey University, Palmerston North, NZ) underwent physical examination and echocardiography using a 4.4-6.2-MHz probe by a board-certified veterinary cardiologist. Cardiac phenotype was classified following current guidelines. Hypertrophic cardiomyopathy (HCM) phenotype was defined as an end-diastolic left ventricular wall thickness ≥ 6 mm. Colony mortality data from February 2012 to February 2022 was reviewed to determine cardiac mortality.

Results: Cats (n = 132; 65 females and 67 males) included in the study had a median age of 4.1 (IQR 3.0-8.0) years. Thirty-two (24%) cats had a heart murmur, and three (2%) cats had an arrhythmia. Echocardiography revealed heart disease in 24 (18.2%) cats, including 23 with an HCM phenotype and one with a restrictive cardiomyopathy phenotype. Of the cats with the HCM phenotype, 3/23 had systemic hypertension or hyperthyroidism or both, and these cats were excluded from the final diagnosis of HCM (20/132; 15.2 (95% CI = 9.5-22.4)%).Between 2012 and 2022, 168 colony cats died, with 132 undergoing post-mortem examination. Heart disease was considered the cause of death in 7/132 (5.3%; 95% CI = 2.2-10.6%) cats; five had HCM, one a congenital heart defect, and one myocarditis. The overall prevalence of death related to HCM in the colony during this period was 3.8% (95% CI = 1.2-8.6%). Three cats with HCM and the cat with a congenital heart defect died unexpectedly without prior clinical signs, while congestive heart failure was observed prior to death in two cats with HCM and the cat with myocarditis. Additionally, 30/132 (22.7%) cats had cardiac abnormalities but died for non-cardiac reasons.

Conclusions: Subclinical cardiomyopathy, specifically HCM, was common in cats in the colony. Given that the colony originated as a convenience selection of non-purebred cats in New Zealand, the true prevalence of HCM in the wider New Zealand population is likely to fall within the 95% CI (9.5-22%). The proportion of deaths of colony cats due to HCM was lower (3.8%) supporting the conclusion that subclinical cardiomyopathy may not progress to clinical disease causing death.

Clinical relevance: Veterinarians should be aware of the high prevalence of subclinical HCM when treating cats.

Abbreviations: CAM: Systolic anterior motion of the chordae tendineae; CFN: Centre for Feline Nutrition; HCM: Hypertrophic cardiomyopathy; LA/Ao: Left atrial to aortic ratio; LV FS: Left ventricular fractional shortening; LVIDd: Left ventricular internal diameters in end-diastole; LVIDs: Left ventr

Aims: To assess whether a whole-herd lameness score on a New Zealand dairy farm in spring could predict lameness prevalence on the same farm in summer (and vice versa) and whether a single-herd lameness score could be used to determine whether herd lameness prevalence was < 5% in both spring and summer.

Methods: Prevalence data (proportion of the herd with lameness score ≥ 2 and with score 3; 0-3 scale) from a study where 120 dairy farms across New Zealand were scored in spring and in the following summer were analysed using limits-of-agreement analysis. In addition, farms were categorised as having either acceptable welfare (lameness prevalence < 5% in both spring and summer) or not (lameness prevalence ≥ 5% in either spring or summer or both). The accuracy and specificity of a single, whole-herd lameness score at identifying herds with acceptable welfare were then calculated.

Results: The limits-of-agreement analysis suggests that 95% of the time, the prevalence of lameness in summer would be expected to be between 0.23 and 4.3 times that of the prevalence in spring. The specificity and accuracy of identifying a farm as acceptable on both occasions from a single observation were, respectively, 74% and 92% in spring, and 59% and 87% in summer.

Conclusions: A single, one-off, whole-herd lameness score does not accurately predict future lameness prevalence. Similarly, acceptable status (lameness prevalence < 5%) in one season is not sufficiently specific to be used to predict welfare status in subsequent seasons.

Clinical relevance: Whole-herd lameness scoring should be used principally as a means of detecting lame cows for treatment. A single whole-herd lameness score by an independent assessor should not be used to determine a herd's welfare status.

Aims: To determine whether evidence for infection with Theileria orientalis (Ikeda) could be identified in samples of commercial red deer (Cervus elaphus), horses, and working farm dogs in New Zealand.

Methods: Blood samples were collected during October and November 2019 from a convenience sample of red deer (n = 57) at slaughter. Equine blood samples (n = 50) were convenience-sampled from those submitted to a veterinary pathology laboratory for routine testing in January 2020. Blood samples, collected for a previous study from a convenience sample of Huntaway dogs (n = 115) from rural regions throughout the North and South Islands of New Zealand between August 2018 and December 2020, were also tested. DNA was extracted and quantitative PCR was used to detect the T. orientalis Ikeda major piroplasm surface protein (MPSP) gene. A standard curve of five serial 10-fold dilutions of a plasmid carrying a fragment of the T. orientalis MPSP gene was used to quantify the number of T. orientalis organisms in the samples. MPSP amplicons obtained by end-point PCR on positive samples were isolated and subjected to DNA sequencing. The resulting sequences were compared to previously published T. orientalis sequences.

Results: There were 6/57 (10%) samples positive for T. orientalis Ikeda from the deer and no samples positive for T. orientalis Ikeda from the working dogs or horses. The mean infection intensity for the six PCR-positive deer was 5.1 (min 2.2, max 12.4) T. orientalis Ikeda organisms/µL.

Conclusions and clinical relevance: Red deer can potentially sustain low infection intensities of T. orientalis Ikeda and could act as reservoirs of infected ticks. Further studies are needed to determine whether naïve ticks feeding on infected red deer can themselves become infected.

Case history: Over a period of 2 months in the spring and early summer of 2021, 13 cases of sudden death in cull ewes due to aortic rupture were diagnosed at a small number of New Zealand abattoirs.

Clinical findings: In 12/13 (92%) cases, a large blood clot was present in the thorax, and in one case the blood clot was seen in the tissues dorsal to the heart. There were no obvious signs of external trauma. The pluck (heart and lungs) or fixed aorta was submitted for histological examination in seven cases and in all of these, a tear in the aorta was found. Comparing the microscopic appearance of the proximal aorta in these seven cases to three clinically normal ewes from unaffected farms, the aortic wall thickness appeared thinner in the case ewes than the unaffected ewes. Subjectively, there was increased collagen in the tunica media in 3/7 and decreased elastin fibres in 5/7 case ewes compared to the control ewes. Further investigations on the index farm (where the first cases originated), found that the mean liver and serum Cu concentrations in 10 similarly aged, clinically normal ewes were within the normal reference range for New Zealand sheep. Similarly, the liver Cu concentrations of the seven case ewes were within the normal reference range.

Diagnosis: Aortic rupture due to an unknown aetiology.

Clinical relevance: Clinicians should be aware of this condition as a differential diagnosis for sudden death in older sheep and to assist the Ministry for Primary Industries in establishing the extent of this problem in New Zealand.

Case histories: The medical records of cats and dogs admitted to the Department of Small Animal Surgery of the Centre Hospitalier Vétérinaire Pommery (Reims, France) with a history of vehicular trauma or falls from the first floor or higher were screened for occurrences of a lower urinary tract (LUT) rupture. Signalment, reported injuries, diagnostic imaging findings, and blood test results were extracted from the medical records.

Clinical findings: A total of 585 animals were included in the study: 339 cats and 246 dogs. The overall prevalence of LUT rupture was 1.36% (8/585) and was 1.2% (3/246) in dogs and 1.4% (5/339) in cats. The most common site of rupture was the bladder (5/8 cases). All orthopaedic injuries were pelvic fractures and animals with pelvic fractures were 6.4 (95% CI: 1.67-24.41; p = 0.012) times more likely to incur urinary tract rupture than those without pelvic fractures. However, three cases had LUT rupture without associated orthopaedic injury. All affected patients had free abdominal fluid identified by abdominal focused assessment with sonography for trauma. Serum urea and creatinine concentrations were elevated in 5/8 cases of LUT rupture, and 4/8 cases were able to urinate.

Clinical relevance: Although LUT injury and pelvic fracture were significantly associated in this study, 3/8 cases of LUT rupture in this study had no orthopaedic injury and half retained the ability to urinate. Thus, lack of associated fractures and ability to urinate should not be used to rule out a LUT rupture. The possibility of bladder or urethral rupture should be considered in all patients with a history of severe blunt trauma.