Chondrodysplasia in Australian Dexter cattle

Objective To describe the occurrence of chondrodysplasia in Australian Dexter cattle.
Design A pathological and genetic case report.
Procedure Congenital lethal chondrodysplasia was studied in two female Dexter foetuses aborted mid to late gestation. Clinicopathological findings including histological changes in limb bones, and analysis of pedigree information were evaluated.
Results Characteristic features of congenital lethal chon-drodysplasia (Dexter bulldog) include abortion, disproportionate dwarfism, a short vertebral column, marked micromelia, a relatively large head with retruded muzzle, cleft palate and protruding tongue and a large abdominal hernia. Histological changes in limb bones are consistent with failure of endochondral ossification. Dexter chondrodysplasia is considered to be inherited in an incompletely dominant manner with the homozygous form producing the congenital lethal condition. A preliminary minimum estimate of heterozy-gote frequency is 19% within the registered Australian Dexter herd, based on analysis of the contribution of three obligate heterozygotes whose semen has been widely used by artificial insemination in Australia.
Conclusion Dexter chondrodysplasia is present in Australian cattle and further cases of the homozygous form, congenital lethal chondrodysplasia, are likely to occur.
Recommendation It is requested that spleen and liver tissue from bulldog foetuses and blood from their parents be collected to assist research into Dexter chondrodysplasia.     

Preliminary investigation of the effect of treating sheep during pregnancy with a vitamin A,D, E formulation on the incidence of vaginal prolapse

ABSTRACT

Aim: To determine if vitamin D₃ treatment reduced the incidence of vaginal prolapse in pregnant sheep on a North Canterbury sheep breeding property.

Methods: Pregnant ewes from a single farm were allocated to three treatment groups in May 2018. At this time, the first group (EarlyVitADE; n?=?512) received an I/M 1?mL dose of 500,000?IU/mL vitamin D₃, 60,000?IU/mL vitamin A, and 25?mg/mL vitamin E. This was repeated in July 2018, when the second group (LateVitADE; n?=?695) also received the same treatment. The third group (n?=?737) were untreated controls. All cases of vaginal prolapse on the property were recorded from pregnancy diagnosis in June 2018 until ewes were set-stocked in August 2018. The planned start of lambing was 10 August 2018.

Results: During the period of observation, vaginal prolapses were recorded in 3/699 (0.4%) 2-year-old ewes, and the odds of vaginal prolapse were not associated with treatment group in these ewes (p?>?0.3). Amongst ewes aged ≥3 years, during the same period, there were 6/333 (1.8%), 6/443 (1.4%) and 25/469 (5.3%) cases in the EarlyVitADE, LateVitADE and control groups, respectively. Compared to control ewes, the odds of vaginal prolapse were reduced in both the EarlyVitADE (OR?=?0.37; 95% CI?=?0.15–0.92) and LateVitADE (OR?=?0.25; 95% CI?=?0.10–0.62) treatment groups.

Conclusions and clinical relevance: In this preliminary study, administration of injectable vitamins A, D₃, and E to pregnant ewes reduced the incidence of vaginal prolapse during the period from pregnancy diagnosis to set-stocking on one North Canterbury hill-country farm. Due to the restricted data collection period, this investigation should be replicated to better quantify the repeatability of the observed treatment effect over the complete lambing period.     

Neurological diseases of ruminant livestock in Australia. III: bacterial and protozoal infections

Bacteria (including chlamydia) and protozoa can produce neurological disease in Australian ruminant livestock and the nature of the inflammatory and neuroparenchymal response is often suggestive of a particular aetiological agent. An overview of the clinicopathological features of infectious disease affecting the central nervous system (CNS) is followed by a discussion of important bacterial and protozoal infections in Australia. Each infectious disease is discussed in terms of classification and pathogenesis linked to clinical signs and gross and microscopic findings. The literature review is restricted to infectious conditions causing CNS disease in Australia. Sources include the Australian Veterinary Journal (over 50 years of articles), the quarterly newsletter of the National Animal Health Surveillance System and the Animal Health Surveillance Quarterly.     

Lesions in sheep following administration of a vaccine of a Freund's complete adjuvant nature used in the control of ovine paratuberculosis

CASE HISTORIES: Occurrences of adverse reactions in seven sheep flocks in Australia following vaccination against paratuberculosis where veterinary attention was requested are reviewed. All cases occurred within the 3-year period following commencement of use of a vaccine of a Freund's complete adjuvant nature, at a time when approximately six million doses of vaccine had been administered.

CLINICAL FINDINGS: In the first case, 26/58 (45%) Merino sheep vaccinated as adults had palpable tissue reactions at or near the site of vaccination; enlarged prescapular lymph nodes were palpated in 17 (29%), and nine (16%) sheep had both palpable lesions at the site of vaccination and enlarged prescapular lymph nodes. The reactions included caseous nodules up to 5.5 cm in diameter. In the other cases, fistulating or granulomatous wounds were occasionally found at the recommended site of injection behind the ear, and myiasis was rare. Occurrences of inappropriate choice of injection site were recorded, including injection into the axilla of two Merino rams, and lesions in the tissues of the maxilla and nose of almost 50% of 350 Border Leicester lambs. Four outbreaks of progressive paralysis due to injection into cervical musculature were reported, described as ‘OJD staggers’ by producers.

DIAGNOSIS: Granulomatous cellulitis and lymphadenitis associated with oil droplets typical of ‘oil granulomata’. Injection of vaccine into the dorsal cervical area resulted in progressive paralysis due to myonecrosis and suspected granulomatous leptomeningitis.

CLINICAL RELEVANCE AND CONCLUSIONS: Although lesions at and near the site of injection are common, adverse reactions to vaccination were rare and included mortality from cervical spinal injection, production losses from injection in the maxilla or axilla or if myiasis resulted, and potential marketing losses if animals or carcasses are discounted as a result of the lesions. Risk factors for adverse reactions included inadequate restraint of sheep, breed of sheep, experience of the operator, poor injection technique, and inappropriate placement of vaccine. Increasing attention to the proper restraint of animals, restricting vaccination to the recommended site behind the ear, careful placement of the vaccine into subcutaneous tissue to avoid drainage of vaccine material into tissues such as the spinal cord, and post-vaccination supervision to address welfare concerns should adverse reactions occur are recommended.     

兰州市尘暴过程中降尘粒度特征探析

通过对兰州市两次强度上有较大差异的尘暴样的采集、粒度分析及其与自然降尘样的对比研究,揭示出兰州市尘暴降尘粒度特性的一些细微特征。不论是自然降尘样还是尘暴样,皆以4～63μm的粉砂为主,说明粉砂粒级的颗粒是兰州地区自然降尘与沙尘暴所携带的主要组分;虽然含量甚微,但是尘暴样中存在近源低空气流所搬运的粒径(181.97～724.44μm)较大的粗颗粒物质。在粒径-体积百分含量曲线上,尘暴样基本上为三峰分布模式,区别于自然降尘样的双峰模式。同时,尘暴样具有向粗、细颗粒区间(尤其是细颗粒区间)延伸并富集的特点,尘暴强度越大,其延伸富集的程度也越明显,而且,随着尘暴强度的增大,其主峰的众数粒径呈减小趋势。