Giardia infection of cats and dogs in New Zealand

Giardia intestinalis is a pathogenic protozoan which infects humans and a wide range of animal hosts, including cats and dogs⁽¹⁾. However, the status of animals in New Zealand with respect to Giardia infection has not received much attention, so we undertook a preliminary study of cats and dogs in Palmerston North and Hamilton to determine the prevalence of infection, as indicated by the presence of cysts in faeces.     

Association between gestational age and bovine fetal characteristics measured by transcutaneous ultrasound over the right flank of the dairy cow

Objective   To determine bovine fetal characteristics significantly associated with increasing gestational age as measured via transcutaneous ultrasonography over the right flank.
Methods   The length of gestation at date of pregnancy diagnosis via transcutaneous and transrectal ultrasonography was determined for 224 dairy cattle by estimation from subsequent calving dates. A separate dataset was created for each measurable fetal characteristic (i.e. thoracic diameter, abdominal diameter, umbilical diameter, placentome length and placentome height) and risk factors significantly associated with gestational age at pregnancy diagnosis within each dataset, including the fetal characteristic, were identified.
Results   Abdominal diameter was the most frequently observed fetal characteristic and thoracic diameter was the least. Gestational age at pregnancy diagnosis (d) was significantly associated with fetal thoracic diameter (P < 0.01), abdominal diameter (P < 0.01) and umbilical diameter (P = 0.02) when measured via transcutaneous ultrasound. Within each model, sire breed, dam breed, dam age and/or calf sex were also significantly associated with gestational age. Gestational age at pregnancy diagnosis was not significantly associated with either placentome height or length (P > 0.05).
Conclusion   Fetal thoracic diameter, abdominal diameter and umbilical diameter were found to be significantly associated with gestational age between approximate days 73 to 190 of gestation. Transcutaneous ultrasonography may prove a useful method of estimating gestational age in the absence of accurate breeding records.     

A longitudinal study of veterinary students and recent graduates: 1. Backgrounds, plans and subsequent employment

Objective To examine factors that influence career choies by veterinary graduates.
Design Longitudinal study.
Population Students – 77 female and 77 males - who began studying veterinary science at The University of Queensland in 1985 and 1986.
Procedure Questionnaires were completed in the first and fifth year of the course, and in the second year after graduation. The data were arranged into an aggregated data set, then analysed using the SAS System for Windows.
Results These students chose veterinary science, many cases at an early age, because of their attitude towards animals rather than advice from other people. Most had extensive experience with animals, and many gained this in cities rather than on farms. Between half and two-thirds of them looked forward to a career in private practice when they were in first year. The proportion planning a career in private practice was highest for those who chose veterinary science before they were 12 years old. One-quarter of those in first year were undecided about what they would do after graduation. When they were surveyed in fifth year, most planned to enter mixed private practice at least initially. In fact, 59% entered mixed practice and 28% small animal practice. There were no significant relationships between prior experience with animals and either career plans or success in the job market. When asked in their second year after graduation, about half planned to continue in private practice over the longer term, and a quarter were undecided.
Conclusions The decision to study veterinary science is often made at a young age, and is influenced mainly by attitudes towards animals. The career path planned by the majority involves private practice, but for about a quarter the future is unclear, both when they enter the course and after they have worked as veterinarians.     

Effect of intravenous lidocaine on isoflurane MAC in dogs

Lidocaine decreases minimum alveolar concentration (MAC) of inhalational anesthetics. This study determined the influence of a low dose, 50 µg kg^?1 minute^?1 (LDI) and high dose, 200 µg kg^?1 minute^?1 (HDI) constant rate infusion of lidocaine on the MAC of isoflurane (I) in dogs. Ten mongrel dogs were anesthetized with I in oxygen and mechanically ventilated. End‐tidal anesthetic (Fe ′A) and CO₂ (Pe ′CO₂) concentrations were monitored at the endotracheal tube adaptor with an infrared gas analyzer calibrated before each experiment with a standardized calibration gas mixture designed for the analyzer. Pe ′CO₂ and body temperature were maintained within normal limits. Noxious stimuli included clamping the hindlimb paw (HC) and electrical current (50 V at 50 cycles second^?1 for 10 milliseconds pulse^?1) applied subcutaneously to the forelimb (FE) at the level of the ulna. After an initial equilibration period of at least 40 minutes at an Fe ′A of 1.7%, the Fe ′A was decreased to a value close to the estimated MAC for dogs. MAC was defined as the Fe ′A mid‐way between the value permitting and preventing purposeful movement. Following baseline MAC, a loading dose of 2 mg kg^?1 of lidocaine IV was administered over 3 minutes followed by the LDI, and MAC determinations for the combination started after 30 minutes of infusion. Once determined, the lidocaine infusion was stopped for 30 minutes and the dog maintained at the ETC that prevented movement without the lidocaine. Following this period, a second loading dose of lidocaine was given (2 mg kg^?1) over 3 minutes followed by the HDI, and the MAC determination procedure repeated after 30 minutes of infusion. Data were analyzed using an anova for repeated measures. MAC of I was 1.34 ± 0.035% (mean ± SEM) for both the FE and HC stimuli. The LDI significantly decreased MAC to 1.09 ± 0.043% (18.7% reduction) and HDI to 0.76 ± 0.030% (43.3% reduction). In conclusion, lidocaine infusions decreased the MAC of isoflurane in a dose‐dependent manner.     

Strategies for mastitis control: dry cow therapy and culling

SUMMARY The effects of three selection strategies for dry cow therapy on prevention of new infections and rate of antibiotic usage were compared. Quarter infection status of 1044 cows in 12 herds was determined by bacteriological methods at drying off, calving and three to five months into the following lactation. Cows that were uninfected at drying off were randomly allocated to treatment (whole udder, dry cow therapy) and non-treatment groups. Infected cows were randomly allocated to whole udder or infected quarter only treatments. The strategies compared were blanket treatment (treat all quarters of all cows), selective cow treatment (treat all quarters of any cow infected in one or more quarters) and selective quarter treatment (treat infected quarters only). Selective cow treatment was identified as the preferred strategy. Blanket treatment resulted in increased antibiotic usage (15.5 vs 6.4 tubes per infection eliminated) with no additional benefit, and selective quarter treatment resulted in a higher new infection rate (6.4%vs 3.9% quarters) in the dry period. The prevalence of infection within a herd at drying off had no influence on new infection rates in the dry period or early lactation. The cure rate after dry cow treatment (mean of 66%) decreased significantly with increasing age (P < 0.001). Cows infected in the previous lactation contributed over 76% of infections at calving and nearly 70% at mid-lactation. To lower the incidence of mastitis in a herd, a greater emphasis on culling of older infected cows and prevention of new infections during lactation is needed.     

Programs for surveillance and monitoring of antibacterial residues in Australia, 1989 to 1993

SUMMARY The development of a State-based confirmatory testing capability for antibiotic residues in meat in Australia has allowed the rapid feedback to producers failing to comply with antibiotic maximum residue limits. The identification of problem areas in various categories of livestock, and subsequent focused surveillance programs, has reduced the prevalence of antibacterial residues in both domestic and export meat products. Failure to observe withholding periods of antibacterial drugs after treatment is the most significant cause of non-compliance. In the period July 1991 to June 1993 the compliance rate for antibacterial residues for all species was 99.9%.     

The incidence and aetiology of clinical bovine mastitis on 14 farms in Northland,New Zealand

AIM: To estimate the incidence of clinical mastitis and the frequency of isolation of mastitis-causing organisms from clinical cases in one lactation season (July 2005 to May 2006) on 14 dairy farms from the Northland region of New Zealand.

METHODS: Cases of clinical mastitis were determined by trained farm personnel who recorded the identity of affected cows. Pooled milk samples from affected quarter(s) were aseptically collected by the farm personnel, for microbiology. Mean numbers of affected cows and quarters were compared at the population and farm level per 305 cow-days-at-risk (DAR).

RESULTS: One or more cases of clinical mastitis occurred in 559/3,765 (14.8%) lactating cows. The average incidence of clinical mastitis was 0.19 cases per 305 DAR. The incidence in rear quarters (56.2%) was 1.3 times (p=0.027) that of front quarters (43.8%). The incidence of clinical mastitis and numbers of affected quarters were signifi cantly infl uenced by the stage of lactation (higher in early lactation), age (higher in older cows) and farm. At the cow level, the most common isolates were Staphylococcus aureus (23.7%) and Streptococcus uberis (23.3%). No causative organisms were identifi ed in 19.9% of the samples. Each cow had an average of 1.8 quarters affected during a case of clinical mastitis.

CONCLUSIONS: This study demonstrated a higher incidence of staphylococcal clinical mastitis on dairy farms from Northland than has been reported in other regions of New Zealand.     

Loss of intraspecific aggression in the success of a widespread invasive social insect

Despite the innumerable ecological problems and large economic costs associated with biological invasions, the proximate causes of invasion success are often poorly understood. Here, evidence is provided that reduced intraspecific aggression and the concomitant abandonment of territorial behavior unique to introduced populations of the Argentine ant contribute to the elevated population densities directly responsible for its widespread success as an invader. In the laboratory, nonaggressive pairs of colonies experienced lower mortality and greater foraging activity relative to aggressive pairs. These differences translated into higher rates of resource retrieval, greater brood production, and larger worker populations.     

Strong enhancement of nonlinear optical properties through supramolecular chirality

A new approach to second-order nonlinear optical (NLO) materials is reported, in which chirality and supramolecular organization play key roles. Langmuir-Blodgett films of a chiral helicene are composed of supramolecular arrays of the molecules. The chiral supramolecular organization makes the second-order NLO susceptibility about 30 times larger for the nonracemic material than for the racemic material with the same chemical structure. The susceptibility of the nonracemic films is a respectable 50 picometers per volt, even though the helicene structure lacks features commonly associated with high nonlinearity. Susceptibility components that are allowed only by chirality dominate the second-order NLO response.