Biomedical subjects
M J Lindsey
Publications and source records attributed to M J Lindsey.
Treatment and control by vaccination of erysipelas in farmed emus (Dromaius novohollandiae).
OBJECTIVE: To study erysipelas in farmed emus and the treatment and control of the disease by vaccination. DESIGN: A retrospective study of field outbreaks in emus and challenge experiments in mice using field and vaccine strains of the organism. PROCEDURE: Outbreaks of the disease were described. Field strains of the organism were identified and tested by challenge experiments in mice against commercial vaccine strains. RESULTS: Erysipelas was characterised by sudden death in yearling emus. Deaths mainly occurred during the cold wet months. Mortalities of 6 to 10% were seen within the first 7 to 10 days of an outbreak. Clinical signs were uncommon but some birds exhibited lethargy and greenish diarrhoea. Necropsy findings included marked petechial haemorrhages on the serosal surface of the large intestine in particular, pericardial effusion and congestion and mottling of the liver. Treatment consisted of individual or mass medication with procaine penicillin, reduction of stress factors such as overcrowding, and spelling and rotation of paddocks. Isolates from two field outbreaks were identified as strain 21. Complete protection was provided by a commercial strain 2b vaccine against challenge by strain 21 field isolates in mice. Annual vaccination of birds at 4 weeks and again at 8 weeks of age appeared to control further outbreaks on farms where the disease had previously occurred and vaccination appeared to protect for at least 12 months.
Vaccination of dogs with multi-component vaccines.
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Vaxstrate: an anti-reproductive vaccine for cattle.
This paper describes the development of a vaccine for the prevention of pregnancy in female cattle. The vaccine is based on the established principle that antibodies to the hypothalamic releasing hormone, gonadotrophin releasing hormone (GnRH) block the action of GnRH on pituitary secretion of luteinizing hormone and follicle stimulating hormone, leading to gonadal atrophy in mammals. The vaccine comprises an immunogenic GnRH:ovalbumin conjugate formulated in a novel double adjuvant system and is administered in a two-dose treatment regimen. Field trials have confirmed efficacy and the product, Vaxstrate, has now been registered and commercialized.
Efficacy of ivermectin against nematodes of horses, including small strongyles resistant to benzimidazole.
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The efficacy of ivermectin against larvae of the screw-worm fly (Chrysomya bezziana).
An in vitro technique for screening systemic insecticides against larvae of the screw-worm fly, Chrysomya bezziana is described. Susceptibilities of screw-worm larvae of different ages to ivermectin (MK-933) were determined. Based on 24 h larval mortality, the LD50 of 1-,2-,3-,4- and 5-day larvae was 0.01, 0.02, 0.03, 0.2 and 0.4 ppm of ivermectin. LD50 based on adult emergence following treatment of 4- and 5-day larvae was 0.02 and 0.05 ppm. The LD99.9 for 4-day larvae based on 24 h larval mortality and adult emergence was 11.0 and 0.15 ppm respectively and for 5-day larvae, was 44.3 and 0.4 ppm respectively. Pen and field trials with cattle infested with screw-worm fly demonstrated the potential of ivermectin as a systemic insecticide. Dosages of 50, 100 and 200 micrograms/kg, of ivermectin administered subcutaneously to experimentally infested cattle gave complete control for 6, 12 and 14 days respectively. Ivermectin at 200 micrograms/kg caused 100% mortality of screw-worm larvae up to 2 days old at the time of treatment with 70, 64 and 21% mortality of 3-, 4- and 5-day old larvae at the time of treatment. The residual protection from a single dose of 200 micrograms/kg was 16 to 20 days. When bull calves were treated with ivermectin at a dose of 200 micrograms/kg at the time of castration and branding, none of the 77 treated animals sustained a screw-worm strike in the scrotal area compared with 47 strikes (44%) in the 106 control cattle.