Perivascular wall tumour presenting as pastern mass in a Standardbred gelding

A 2-year-old Standardbred gelding was referred for a mass on the palmaromedial right front pastern which was accompanied by progressively worsening lameness. The mass was firm to palpation and covered by normal skin. Ultrasonographically, a smooth encapsulated mass was present, medial to the flexor tendons and palmar to the neurovascular bundle. Because of a poor prognosis for future athletic performance without surgical or chemotherapeutic intervention and economic constraints preventing further diagnostics and treatment, the horse was euthanised. Post-mortem magnetic resonance imaging, histopathology and immunohistochemistry revealed the mass to be a perivascular wall tumour, the first record of such a neoplasia in the horse.     

Stress and glycemic responses to postprandial interval and feed components in exercising horses

Six Thoroughbred geldings were used in a Latin squaredesign to determine the effects of three feeding regimens and two postprandial intervals on stress parameters during rest, exercise, and recovery. Each horse was randomly assigned to one of six treatments on six sampling days. The three feeding regimens consisted of a fasting regimen in which no feed was offered, or an isoenergetic (4.1 Mcal DE) meal of either corn or alfalfa. One or 4 h after feeding, a standardized exercise test (SET) was imposed on all horses. The SET consisted of three 10-min periods each of saddling, walking to the arena, and warm-up (walking and trotting), followed by three bouts of progressively more intense galloping at heart rates of 130–140 (10 min), 150–160 (10 min), and 170–180 bpm (5 min), respectively. Blood was sampled via jugular catheters from 0630 to 1500, including the 55-min SET. Analysis of variance by repeated measures within either the 1- or 4-h protocol showed no differences between dietary treatments for glucose concentration; differences due to sampling time were shown for concentrations of glucose, lactate, cortisol, α₁-acid glycoproteins (AGP), and the neutrophil to lymphocyte ratio (N:L). In both the 1- and 4-h protocols, glucose concentrations decreased precipitously in cornfed horses at the onset of the SET, but rebounded at the termination of the galloping. Plasma glucose concentrations in fasting and alfalfa-fed horses decreased slightly and then gradually increased throughout the SET. Serum cortisol and plasma lactate concentrations did not differ (P >.05) between dietary treatments, but increased concentrations were detected during the SET in both the 1- and 4-h protocols. The AGP concentration and N:L did not differ (P>.05) due to dietary treatments; however, AGP concentrations marginally increased (P<.10) from prefeeding to early recovery during the 1-h but not the 4-h protocol. The N:L increased (P<.05) in response to exercise; elevated values were detected in early recovery.     

Effects of cross-tying horses during 24 h of road transport

Transportation stress has been implicated as a predisposing factor to respiratory disease in horses. Cross-tying horses individually in stalls is common practice for transporting show and racehorses, but horses also travel in small groups or individually without being restricted by tying. The objective of this study was to compare physiological responses of horses travelling cross-tied or loose during 24 h of road transport. Ten horses were used in a cross-over design consisting of two 4 day trials. In the first trial, 6 horses were cross-tied, while 2 pairs of horses were loose in enclosed compartments. Treatments were reversed in the second trial. Baseline samples were collected on Day 1, horses transported on Day 2, and recovery data collected on Days 3 and 4. Blood samples were collected daily at 0800, 1100 and 2000 h. The mean responses in all horses of serum cortisol, lactate, glucose, alpha1-acid glycoprotein, and total protein concentrations, packed cell volume (PCV), white blood cell (WBC) counts and aminotransferase and creatine kinase were was elevated significantly from baseline during the 4 day study. The response of white blood cell counts, neutrophil to lymphocyte ratios and glucose and cortisol concentrations was significantly elevated in the cross-tied compared to the loose group during transport and recovery. This study supports the recommendation of allowing horses during long-term transportation to travel loose in small compartments, without elevating their head by cross-tying.     

Impact of Endocrine‐Disrupting Chemicals on Reproductive Function in Zebrafish (Danio rerio)

The prevalence of endocrine‐disrupting chemicals (EDCs) in the aquatic environment has been associated with the wide detection of alterations in the development and physiology of vertebrates. Zebrafish, as a model species, has been extensively used in toxicological research. In this review, we focus on recent published evidence of the harmful effects of EDCs on reproductive function in zebrafish, including skewed sex ratio, immature gonads, diminished sexual behaviour, decreased sperm count, reduced spawning and fertilization. These impairments mostly result from disruption to sex‐steroid hormones induced by endocrine disruptors. We also discuss other effects of exposure to EDCs. In EDC exposure research, despite incomplete assessments of altered gonad histopathology and sexual behaviour, these present potential effective biomarkers or pathways for evaluating the reproductive function in zebrafish on EDC exposure. To date, the pernicious effects of some EDCs on the reproductive performance in laboratory zebrafish are well understood; however, similar alterations remain for further determination in wild‐type fish and more kinds of EDCs. More studies should be performed under established scientific regulatory criteria to investigate the impact of EDCs on reproduction in zebrafish. Moreover, further research is required to explain the definite mechanism of sexual differentiation, which helps in understanding the shift of sexual phenotype with EDC exposure.     

The prevalence of itchmite, Psorergates ovis, among sheep flocks with a history of fleece derangement

An investigation of sheep flocks in the main sheep raising areas of New South Wales showed that the itchmite Psorergates ovis was frequently associated with fleece derangement. In 26 of the 41 flocks examined, P. ovis was the only ectoparasite detected. P. ovis and the sheep body louse Damalinia ovis, were found in 5 flocks. No external parasites were found on sheep examined from the 10 remaining flocks. The type of fleece derangement most frequently recorded was rubbing which in some cases was combined with areas of chewed fleece. Among flocks, there were positive relations between the prevalence of fleece derangement and prevalence of itchmite or scurf and between itchmite count and mean scurf score. Within flocks, itchmite infested sheep or sheep with scurf had higher prevalences of fleece derangement than sheep on which no mites or no scurf were found. Itchmite infested sheep had a higher prevalence of scurf than those with no detectable mite infestation. There were no significant differences in itchmite populations or fleece derangement between untreated flocks and flocks treated with synthetic pyrethroids, organophosphates or arsenic and rotenone.     

Chlamydiosis in workers at a duck farm and processing plant

SUMMARY An outbreak of chlamydiosis was Investigated in workers at a duck farm and processing plant during winter 1989. Chlamydia psittaci was isolated from ducks, but there was little evidence of clinical chlamydiosis in the ducks. Serological tests showed that 76% of workers had been exposed to Infection, 12% recently, 16% had not been exposed and 8% had inconclusive test results. There was a strong association (P < 0.05) between years of employment and exposure to Infection. Infection appeared to be contracted during the first year of employment. Measures were Implemented to reduce shed contamination and control rodents and wild birds. At the same time, ducks were medicated, the processing plant was modified, work practices were altered and workers were advised about chlamydiosis to reduce the risk of human infection.