Sudden death due to aortic rupture in New Zealand sheep.

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.

Assessment of accuracy of liver fluke diagnostic tests using the gold standard of total worm counts.

In many regions of New Zealand liver fluke is endemic, infecting most grazing ruminants, including cattle, sheep, and deer. Restricting the economic losses and welfare costs associated with liver fluke relies on accurately identifying those animals with a production limiting infection. This has proven a difficult goal and although several antemortem quantitative tests are available, including faecal egg counts (FEC), serum ELISA and copro-antigen ELISA, none can be considered a gold standard test of liver fluke infection. The accepted gold standard test for fascioliasis is the total fluke count, which is both laborious and can only be completed at post-mortem. This study aimed to compare the performance of four liver fluke diagnostic tests, against the results of a gold standard total fluke count test. Two groups of cattle were selected, 29 culled mixed age beef cows (MAC) and ten 30-month-old steers. The cattle were blood sampled and faecal sampled prior to slaughter and their whole livers recovered post slaughter at the abattoir. Liveweight was also recorded at slaughter. After collection, each liver was weighed, scored for gross pathology, then serum, faeces and livers were frozen at -20 °C for later analysis. Faecal egg counts and F. hepatica copro-antigen ELISA tests were completed on the faecal samples and total fluke counts were completed on the livers. Fasciola hepatica antibody concentration in serum samples were quantified using a commercial ELISA test. Poisson regression models were built to model the association between each diagnostic test and the total fluke count, and a linear regression model was built to examine the relationship between each diagnostic test and live weight at slaughter. The median fluke count was significantly higher in MAC than steers (p = 0.01), and F. hepatica eggs were present in 100% steers and 66% MAC. There was a significant effect of copro-antigen ELISA value on total fluke count (p < 0.0001), with a coproantigen ELISA value = 20.1 predicting 10 flukes and a value = 44.8 predicting 30 flukes. There was also a significant effect of FEC on total fluke count (p = 0.002) but the R-squared value for this model was lower. There was no association between liver fibrosis score or antibody ELISA test and total fluke count (p = 0.95, p = 0.73, respectively). There was a significant effect of total fluke count (p = 0.03) on liveweight at slaughter, with liveweight falling 20.4 kg for each unit increase in loge (total fluke count). There was no effect of FEC (p = 0.11), antibody ELISA (p = 0.55) or copro-antigen ELISA value (p = 0.16) on liveweight at slaughter. Taken together, these results show that the coproantigen ELISA test is the better test for estimating the true liver fluke burden and that the number of flukes in the liver has a negative effect on cattle live weights at slaughter.

Theileria orientalis Ikeda infection detected in red deer but not dogs or horses in New Zealand.

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. ABBREVIATIONS: Cq: Quantification cycle; LOQ: Limits of quantification; MPSP: Major piroplasm surface protein; qPCR: Quantitative polymerase chain reaction.

The use of a Bayesian latent class model to estimate the test characteristics of three liver fluke diagnostic tests under New Zealand field conditions.

The liver fluke Fasciola hepatica is a trematode parasite of farmed livestock with worldwide distribution, causing chronic production losses and possible death from hepatobiliary damage. The effective management of liver fluke infection requires diagnostic tests which can accurately identify infected animals at both the individual and herd level. However, the accuracy of liver fluke diagnostic tests performed on individual New Zealand cattle is currently unknown. The aim of this study was to use a Bayesian latent class model (LCM) to estimate the test characteristics of three liver fluke diagnostic tests, the coproantigen ELISA, the IDEXX antibody ELISA and the faecal egg count. One hundred and twenty dairy cows each from two dairy farms were blood and faecal sampled in April 2021. The samples were transported to Massey University, Palmerston North, and the three diagnostic tests completed following the respective manufacturer instructions. A Bayesian LCM model, adapted from the original Hui and Walter 2 tests 2 populations model, was built to estimate the test characteristics of the three diagnostic tests in the two dairy herds. The model was implemented in JAGS using Markov chain Monte Carlo sampling. The first 30,000 iterations were discarded as burn-in, and the next 200,000 iterations were used to construct the posterior distributions. Uninformed priors, beta (1,1), were used as the prior distributions for the prevalence estimation and informed beta priors, based on published results, were used as the prior distributions for estimating the sensitivity and specificity of each diagnostic test. Model convergence was confirmed by inspection of trace plots and examination of the results of the Gelman and Rubin test. The results found that the coproantigen ELISA test was the most accurate for diagnosing liver fluke infection in individual animals with a sensitivity = 0.98 (95 % CI 0.95-1.00) and specificity = 0.95 (95 % CI 0.81-1.00) compared to the IDEXX antibody ELISA test, sensitivity = 0.39 (95 % CI 0.32-0.47) and specificity = 0.86 (95 % CI 0.75-0.96) or the FEC, sensitivity = 0.23 (95 % CI 0.17-0.30) and specificity = 0.92 (95 % CI 0.86-0.97). Based on these results clinicians should be encouraged to use the coproantigen ELISA test to diagnose liver fluke infection in individual cattle.

An outbreak of ischaemic teat necrosis in a dairy herd in Taranaki, New Zealand.

CASE HISTORY: In spring 2021, on a seasonally calving, pastorally based, Taranaki dairy farm, 12 first-calving heifers (≤ 30 days post-calving) developed similar dry, red to black, crusting lesions on the medial aspect of the teat udder junction extending down the medial teat. Some cows had multiple teats affected. Treatment was initially unrewarding and did not slow the progression of the disease. Overall, 8/12 cows recovered, and 4/12 cows were culled, with three of the cows culled after a teat sloughed and the fourth after surgical amputation of a teat. Outbreaks of the same condition, on the same farm but affecting fewer animals, occurred in spring 2022 (n = 6) and spring 2023 (n = 3). CLINICAL FINDINGS: An initial scab-like or crusting lesion progressed to resemble a thick eschar consisting of very dry and hard dead tissue. The unaffected areas of the teat felt normal but immediately under the dead tissue, there was a warm, firmer area consistent with an inflammatory reaction. Removing the scab led to profuse bleeding, with no visible bed of granulation underneath the scab. There was no leaking of milk in those cows that lost a teat, and no smell to the lesions themselves. Serology and virology ruled out the involvement of bovine alphaherpesvirus (BoHV-2) bovine gammaherpesvirus (BoHV-4), orthopoxviruses (cowpox) and parapoxviruses (pseudocowpox). Histopathology of an affected and surgically amputated teat showed multifocal erosion and ulceration of the epidermis, covered by a thick serocellular crust. In areas of ulceration, there were numerous neutrophils, and the dermis was expanded by granulation tissue with variable numbers of neutrophils, eosinophils, and lymphocytes around small blood vessels. DIAGNOSIS: Based on the similarity of the history, presentation, and histopathological changes to those described for a novel disease reported in the UK, a diagnosis of ischaemic teat necrosis (ITN) was made. CLINICAL RELEVANCE: If ITN is an emerging condition in New Zealand and becomes as prevalent as it has in the UK, clinicians will be confronted with a significant new welfare problem in dairy cows. Anecdotally, there have been reports of other ITN outbreaks in New Zealand, and the Ministry for Primary Industries would be interested in collating reports from other New Zealand veterinarians.

Ulcerative stomatitis associated with yellow bristle grass in New Zealand dairy cows.

CASE HISTORY: A line of 25 cull cows were all found to have ulcerative lesions of the tongue at post-mortem inspection in a New Zealand slaughter plant. A further 9 of 10 cows inspected at the farm of origin had similar oral lesions. There were no other clinical signs or indicators of ill-health observed at ante-mortem inspection in the abattoir or on the farm. The cows had been fed baleage for 3 weeks prior to slaughter, made from pasture in paddocks heavily contaminated with yellow bristle grass (Setaria pumila). CLINICAL FINDINGS: There was extensive and deep transverse linear ulceration in the lingual fossa immediately rostral to the torus linguae. At histological examination, full-thickness ulceration of the stratified squamous epithelium was observed with a bed of disorganised collagenous tissue and extensive mixed inflammatory infiltrate extending into the sub-epithelial connective tissue and skeletal muscle. Barbed plant fragments were embedded in both the superficial and deeper areas of inflammation. Detailed examination of the baleage also found that yellow bristle grass seedheads were present. DIAGNOSIS: Based on the presence of barbed plant material in the tongue and yellow bristle grass seeds in the baleage, a diagnosis of ulcerative stomatitis associated with yellow bristle grass was made. CLINICAL RELEVANCE: Clinicians should be aware of the potential for hay or baleage contaminated with yellow bristle grass to cause oral lesions in cattle.

Using weather data to predict the presence of Lucilia spp. on sheep farms in New Zealand.

Flystrike remains an important animal health issue on New Zealand sheep farms. To date no useful predictive tool to assist farmers to develop control options has been available. The aim of this study was to use National Institute of Water and Atmospheric Research (NIWA) virtual climate station data in New Zealand to develop a weather-based model to accurately predict the presence of Lucilia spp. on sheep farms throughout New Zealand. Three LuciTrap® baited fly traps were positioned on each of eight sheep farms throughout New Zealand (5 in the North Island and 3 in the South Island). The traps were put out for both the 2018-2019 and 2019-2020 seasons. They were emptied each week and the flies morphologically identified; with the counts of Lucilia cuprina and L. sericata combined as Lucilia spp. The count data for Lucilia spp. for each week of trapping was transformed into a binary outcome and a generalised linear mixed effects models fitted to the data, with farm as a random effect. The dependent variable was Lucilia spp. flies caught, yes or no, and the independent variables were mean weekly climate variables from the nearest NIWA virtual climate station to that farm. The model was trained on the 2018-2019 catch data and tested on the 2019-2020 catch data. A cut point was identified which maximised the model's ability to correctly predict whether Lucilia spp. were present or not for the 2019-2020 catch data, and the sensitivity, specificity, accuracy, and area under the curve (AUC) of the model calculated. The final model included just 3 significant variables, mean weekly 10 cm soil temperature, mean weekly soil moisture index, and mean weekly wind speed at 10 m. Mean weekly 10 cm soil temperature accounted for 64.7% of the variance explained by the model, mean weekly soil moisture index 34.7% and mean weekly wind speed at 10 m only 0.6%. The results showed that the predictive model had a sensitivity of 0.93 (95% CI = 0.80-0.98) and a specificity of 0.75 (95% CI = 0.62-0.85), using a cut point for the probability of Lucilia spp. being present on farm = 0.383. This model provides New Zealand farmers with a tool which will allow them to know when Lucilia spp. flies will likely be present and thus more accurately plan their interventions to prevent flystrike.

Farm management and husbandry practices associated with spontaneous humeral fractures in New Zealand dairy heifers.

AIMS: To use a farm-based survey to identify characteristics of the New Zealand dairy system associated with the risk of spontaneous humeral fracture in dairy heifers. METHODS: A questionnaire was designed and made available in print and online to collect information from dairy farmers and/or veterinarians, across New Zealand, about the management and nutrition of cows from birth to first lactation. Data were collected from July 2019 to March 2020 from farms that either had recorded (case farms) or not recorded (control farms) cases of humeral fractures in dairy heifers. RESULTS: A total of 68 completed questionnaires were returned, with 35 responses from case farms and 33 responses from control farms. Twenty-six responses (38%) were from the South Island (13 case farms and 13 control farms) and 38 responses (56%) were from the North Island (20 case farms and 18 control farms). For four questionnaires (6%) farm location was not given. Adjusting for the effect of age when calves accessed pasture, case farms had increased odds of having Holstein-Friesian Jersey crossbreed cows as the predominant breed (OR = 9.7; 95% CI = 3.1-36.0; p < 0.001). Adjusting for the effect of breed, allowing calves access to pasture a week later decreased the odds of being a case farm (OR = 0.68; 95% CI = 0.47-0.90; p = 0.006). CONCLUSIONS: Cows being Holstein-Friesian Jersey crossbreed was identified as a possible risk factor associated with spontaneous humeral fracture in dairy heifers in New Zealand. Given the small sample size, the likely multifactorial aetiology for humeral fractures, and the non-randomised survey, this risk factor, and the possible association between age at turn out and herd production with humeral fractures, all require further investigation.

The effect of parenteral vitamin B12 on the growth rate of dairy calves over the summer and autumn on seven farms from the Central Plateau, New Zealand.

AIMS: To investigate the effect of parenteral vitamin B12 supplementation on the growth rate of dairy heifer calves over the summer and autumn on seven farms from the Central Plateau of New Zealand, an area historically associated with low cobalt levels in grazing pasture. METHODS: This was a controlled clinical trial conducted on a convenience sample of seven farms with young female calves randomly assigned to three vitamin B12 treatment groups and followed through a grazing season. Two treatment groups received either monthly SC injections of a short-acting (SA) B12 formulation or 3-monthly injections of a long-acting (LA) B12 formulation and the third group received no treatment (NT). No additional parenteral vitamin B12 was given; however, all calves received additional cobalt (0.04-0.4 mg Co/kg liveweight) in the mineralised anthelmintic drenches given orally every month. Liveweight was recorded in December/January and at the end of the trial in May/June/July depending on farm. Pasture cobalt concentrations (mg/kg DM) were measured every month using 500-g herbage samples from 100-m transects in the area about to be grazed by the trial groups. RESULTS: There was evidence for a difference in growth rate between groups with mean final weight of 228 (95% CI = 212-243) kg for the LA groups, 224 (95% CI = 209-239) kg for the SA groups and 226 (95% CI = 211-241) kg for the NT groups respectively, (global p-value = 0.014). Calves given SA vitamin B12 were 3.77 (95% CI = 0.71-6.82) kg lighter than calves given LA vitamin B12 (p = 0.011). There was no evidence for a change in pasture cobalt concentrations (p = 0.32). CONCLUSIONS AND CLINICAL RELEVANCE: The results of this trial raise the question as to whether the routine use of vitamin B12 supplementation in young cattle from areas traditionally thought to be cobalt deficient is necessary, and further raise the possibility that vitamin B12 supplementation by repeated injection of SA products may negatively impact growth rates.

Downer cows: a reanalysis of an old data set.

AIMS: To compare the performance of two predictive models for the survival of downer cows. METHODS: The first model had been developed in 1987 using a dataset containing missing values, while the second, new model was developed on the same dataset but using modern data imputation and analytical methods. Missing data were imputed using multiple imputation by chained equations and a logistic regression model fitted to the imputed data, with survival or not as the outcome variable. The predictive ability of the model built on the imputed data was contrasted with the original prognostic model by testing them both on a second smaller but complete data set, collected contemporaneously with the development of the original model but from a different region of New Zealand. Sensitivity, specificity, accuracy, and cut point for the two models were calculated. RESULTS: The original 1987 model had a slightly higher accuracy than that of the new one with a sensitivity of 0.85 (95% CI = 0.72-0.94) and a specificity of 0.82 (95% CI = 0.7-0.91), using a cut point for the probability of survival = 0.313. CONCLUSIONS: The original prognostic formula published by Clark et al. in 1987 performed as well as a modern model built on an imputed data set. CLINICAL RELEVANCE: The use of a prognostic test based on the Clark model should remain an important part of the clinical examination of downer cows by New Zealand veterinarians.Abbreviations: AUC: Area under the curve; AST: Aspartate transaminase activity; CK: Creatine phosphokinase activity; GAM: Generalised additive model; NSAID: Non-steroidal-anti-inflammatory drugs; PCV: Packed cell volume.

Longitudinal study of the effect of sporidesmin toxicity on lamb production and serum biochemistry in a flock of 46 Romney ewes using a standardised measure of liver damage.

AIMS: To evaluate the effect of sporidesmin toxicity on production outcomes and serum biochemistry analytes in mixed age Romney ewes, using a standardised measure of liver damage. METHODS: This was a prospective longitudinal study following 46 mixed age Romney ewes from sporidesmin intoxication in April 2019, to slaughter 8 months later. The ewes were blood-sampled up to eight times, with a panel of serum biochemistry tests performed on the final six samples. However, only gamma-glutamyl transferase (GGT) activity was measured in the first two samples collected at the end of sporidesmin intoxication and 2 weeks later. Body condition score, ewe weight and production data were also recorded. Using a standardised liver score, based on histology of liver samples collected at slaughter, ewes were assigned to one of three liver disease categories (LDC); low, middle, and high. These were then used as the outcome or predictor variables for statistical analyses. Finally, two separate decision tree models, using recursive partitioning (RP), were fitted to the biochemistry data and to the GGT data collected at FE outbreak, to predict ewes in the low LDC. RESULTS: There was no evidence of a difference for the effect of LDC on ewe weight (p = 0.86) with ewes, on average, gaining weight to weaning. Weaning percent, lamb rearing percent and ewe flock efficiency were lower in ewes with high LDC, and scanning-to-weaning lamb loss was significantly higher in sheep with high LDC (p = 0.02). Serum activities of GGT and glutamate dehydrogenase and concentration of globulin were significantly lower in sheep with low LDC than in sheep with middle or high LDC (p < 0.05). However, there was no evidence of a difference for the effect of LDC on other biochemistry variables (p > 0.05). The final RP model for the biochemistry data categorised ewes as low LDC if their GGT was <122 IU/L, 3 months after sporidesmin intoxication, or if their GGT was <514 IU/L, <18 days after sporidesmin intoxication. CONCLUSIONS AND CLINICAL RELEVANCE: Sheep with gross and histological evidence of severe sporidesmin-induced liver damage were able to maintain or gain body weight, suggesting that sporidesmin intoxication alone is not causative of poor body condition. Similarly, many of the serum biochemistry tests were not associated with evidence of liver damage. Lamb production was reduced in ewes with evidence of severe liver damage and the decision tree model showed promise as a basis to select ewes for culling.

The role of sheep (Ovis aries) in maintaining Theileria orientalis Ikeda type infection.

Theileria orientalis is a tick‒borne intracellular parasite of red blood cells that causes severe and mild infections in various ruminants worldwide. To date there have been 11 types identified within this species, of which 4 types are presently found in New Zealand cattle. Since 2012, New Zealand has suffered a substantial epidemic of infectious bovine anaemia in both dairy and beef cattle associated with the Ikeda type. The speed at which the disease spread through the North Island suggested that other species could have been involved in transmission. The aim of a series of related experiments was to test the null hypothesis that sheep cannot maintain T. orientalis Ikeda type infection or infect ticks that feed on them. Several studies were conducted over 2 years to address this hypothesis which together showed that sheep can have detectable levels of T. orientalis Ikeda type infection in both the acute and chronic phase and that Haemaphysalis longicornis larvae can become infected when feeding on sheep. No anaemia, weight loss or clinical disease was recorded in the sheep in the acute phase of infection. The levels of infection recorded in the sheep were much lower than those found in cattle, consistent with the sheep being asymptomatic carriers of T. orientalis Ikeda type infection.

Isolates, antimicrobial susceptibility profiles and multidrug resistance of bacteria cultured from samples collected from sheep in New Zealand (2003-2016).

Aim: To describe the common species, antimicrobial susceptibility and multidrug resistance (MDR) of bacteria cultured from samples submitted to veterinary diagnostic laboratories from sheep in New Zealand between 2003 and 2016. Methods: Bacterial culture and antimicrobial susceptibility test data from June 2003 to March 2016 for animals identified as sheep were obtained from two commercial veterinary diagnostic laboratories in New Zealand. Submission information included animal signalment, geographic origin, specimen description, the organisms cultured, and where available, antimicrobial susceptibilities of the isolates. MDR was defined as any isolate with resistance to ≥3 antimicrobial classes. Results: There were 1,971 unique laboratory submissions, yielding 2,188 isolates. Of the 1,971 submissions, the most commonly represented breeds were Romney (933; 47.3%), Romney cross (264; 13.4%), and Coopworth (197; 10.0%), and there were more submissions from females (1,006; 51.0%) than males (184; 9.3%). Most submissions were from Canterbury (549; 27.9%), Southland (471; 23.9%), and Manawatu-Wanganui (272; 13.8%) regions. Other signalment data were inconsistently described. Submitted samples most commonly originated from the gastrointestinal tract (852; 43.2%), faeces (378; 12.1%), or liver (146; 7.4%). Of the 2,188 isolates, 1,771 (80.9%) were identified by species and 247 (11.4%) by genus, with the most common isolates being Salmonella spp. (880; 40.2%), Campylobacter spp. (408; 18.6%), Listeria spp. (140; 6.4%) and Yersinia spp. (113; 5.2%). Susceptibility results were available for 117/2,188 (5.3%) isolates from 51/1,971 (2.6%) submissions. No antimicrobial susceptibility data were available for Salmonella spp., Campylobacter spp., Listeria spp. or Yersinia spp. Overall for the isolates tested, susceptibility to the fluoroquinolones and tetracyclines was greatest, and MDR was found in 24/117 (20.5%) isolates. MDR was a more frequent finding for Enterococcus spp., Bacillus spp., and Proteus mirabilis, but was infrequent in isolates of Staphylococcus aureus, alpha-haemolytic streptococci, Escherichia coli or Enterobacter spp. Conclusions and clinical relevance: This is the first report on antimicrobial susceptibility and MDR for isolates from laboratory submissions from sheep in New Zealand. The low numbers of isolates submitted for antimicrobial susceptibility testing during the period studied mean that these findings provide limited insights into antimicrobial resistance in this population, and highlight the need to address significant gaps in our understanding of why veterinarians do not more frequently submit samples from sheep for bacterial culture and susceptibility testing. Abbreviation: AMR: Antimicrobial resistance; MDR: Multidrug resistance.

Sex Differences in Internalizing Symptoms and Amygdala Functional Connectivity in Neurotypical Youth.

Amygdala resting-state functional connectivity (rsFC) is altered in adolescents with internalizing disorders, though the relationship between rsFC and subclinical symptomatology in neurotypical youth remains unclear. Here we examined whether amygdala rsFC varied across a continuum of internalizing symptoms in 110 typically-developing (TD) youths 8 to 17 years old using functional magnetic resonance imaging (fMRI). We assessed overall internalizing symptoms, as well as anxious-depressed, withdrawn-depressed, and somatic complaints. Given known sex differences in the prevalence of internalizing disorders, we compared connectivity between males and females. As compared to males, females with greater internalizing, anxious-depressed, and somatic symptoms displayed greater connectivity with the cingulate gyrus, insula, and somatosensory cortices. In contrast, males with greater anxious-depressed symptoms demonstrated weaker connectivity with the subcallosal prefrontal cortex. Sex differences in rsFC in relation to symptom severity were evident for the whole amygdala and for two of its subnuclei (centromedial and superficial amygdala). Overall, results suggest that, for females, higher internalizing symptoms are associated with greater rsFC between the amygdala and regions implicated in emotional and somatosensory processing, salience detection, and action selection. Future longitudinal investigations are needed to determine whether this hyperconnectivity may confer resilience to, or pose risk for, the development of internalizing disorders.

The efficacy of toltrazuril treatment for reducing the infection intensity of Theileria orientalis Ikeda type in dairy calves.

The aim of this study was to test the hypothesis that toltrazuril administered at 4 weeks post-turnout reduces the infection intensity of Theileria orientalis Ikeda type in dairy calves and so prevents serious clinical disease in these animals at 2-3 months of age. Two groups of 40 dairy calves on two separate dairy farms in the Waikato were followed for 16 weeks post-turnout onto pasture. On each farm, 20 calves were randomly selected and orally treated with toltrazuril (15 mg/kg) at 4 weeks post-turnout, whilst the remaining 20 calves were left untreated. All 40 calves were blood sampled and weighed at 2, 4, 6, 8, 12, and 16 weeks post-turnout i.e. 6 samplings per calf. A random subset of 10 calves from each treatment group on each farm were faecal sampled at each visit. The blood samples were used to estimate the T. orientalis Ikeda type infection intensity and haematocrit for each calf and the faecal samples were used to estimate the number of coccidia oocysts per gram of faeces. Three linear mixed effects models, to evaluate the effect of toltrazuril treatment on infection intensity, haematocrit (HCT) and weight respectively were fitted to the data. No calves on either farm developed clinical theileriosis or coccidiosis and the three mixed effects linear models, controlling for the effect of farm and days from turnout, showed that there was no effect of treatment on infection intensity (p = 0.81), on HCT (p = 0.99) and on weight gain (p = 0.79). In conclusion, this study showed no evidence supporting the use of toltrazuril to control T. orientalis Ikeda type infection levels and prevent disease.

Effects of Theileria orientalis Ikeda type infection on libido and semen quality of bulls.

There is an epidemic in New Zealand of infectious bovine anaemia associated with Theileria orientalis Ikeda type, an obligate intracellular protozoan parasite. To establish whether T. orientalis Ikeda type infection adversely affects fertility of bulls used for natural mating, a randomised controlled experimental study was conducted. Ten of 17 2-year-old Friesian bulls that had not been previously infected with T. orientalis were infected with T. orientalis Ikeda type and then evaluations occurred during a 20-week period. There were semen and libido evaluations every 2 weeks, starting 4 weeks before the date of infection. In addition, there were blood collections, for haematocrit and infection intensity evaluations, rectal temperatures recorded, and bulls weighed three times weekly for 13 weeks after infection and then once weekly until completion of the study. Physical activity meters were also attached from Days 9-60 and 65-124 post-infection. The ten bulls were successfully infected with T. orientalis Ikeda type and this resulted in a decrease in HCT to about 0.25 by 70 days post-infection. There were no effects of infection on semen quality; however, during the acute phase of infection, when the infection intensity was rapidly increasing, the infected bulls took a longer time period for repeated mounting of females, and were less dominant in the herd social heiracrchy. In conclusion, although the transitory effects on libido could reduce conception rates, the overall effects of T. orientalis Ikeda type infection on bull fertility will probably be little.