Holding Power of Orthopedic Screws in Equine Third Metacarpal and Metatarsal Bones: Part I. Foal Bone

The holding power of orthopedic screws in the third metacarpal and metatarsal cadaver bones of foals that were aged from 1 to 14 days was tested. Comparative trials between screws inserted at the same site in contralateral bones from the same foal were performed to compare the holding power of 5.5 mm cortical and 6.5 mm cancellous screws in the metaphysis, and the holding power of 5.5 and 4.5 mm cortical screws in the diaphysis. A MTS servohydraulic tensile testing machine was used to perform screw pullouts at a displacement rate of 19 mm/sec. There was no significant difference between maximum holding power of 5.5 mm cortical screws and 6.5 mm cancellous screws in the metaphysis when expressed as kg per mm of bone width at the screw insertion site (p = 0.097) or as kg per mm of screw thread engaged in the bone (p = 0.17). There was no significant difference in holding power of 5.5 and 6.5 mm screws in the proximal versus distal metaphysis (p = 0.10). The 5.5 mm screws had significantly greater holding power than the 4.5 mm screws in the diaphysis (p = 0.0097). Fixation failure at screw pullout was always due to bone shear. In internal fixation in foal bone, the 5.5 mm screws may be a suitable alternative to 6.5 mm screws in the metaphysis. Use of 5.5 mm rather than 4.5 mm screws is recommended in the diaphysis because of greater holding power.     

Effect of ammonium sulphate and other additives upon the phytotoxicity of glyphosate to Agropyron repens (L.) Beauv

In several pot and field experiments additions of 1–10% w/v ammonium sulphate and/or 0.1–2.5% w/v surfactant increased the phytotoxicity to A. repens of sprays containing 0.2–0.5 kg/ha glyphosate. There were similar results with technical glyphosate-isopropylamine salt and formulated ‘Roundup’. Higher ammonium sulphate concentrations were sometimes antagonistic. Additions of ammonium sulphate without surfactant generally had less effect on phytotoxicity. While several surfactants increased glyphosate activity the order of effectiveness of these products varied according to whether or not ammonium sulphate was also present. When used alone, relatively hydrophilic non-ionic or cationic products had more effect. In mixtures with ammonium sulphate, however more lipophilic surfactants gave superior results. Ammonium sulphate (5%) with a lipophilic cationic surfactant (0.5% Ethomeen C12) enhanced the effects of very low volume controlled-drop applications as well as conventional medium volume sprays. In a field trial 0.25 kg/ha glyphosate applied with those additives in 20 l/ha of spray had as much effect on bud viability as l kg/ha applied conventionally.     

Survival of Mycobacterium avium subsp paratuberculosis in amitraz cattle dip fluid

OBJECTIVE: To determine the survival time of Mycobacterium avium subsp paratuberculosis in amitraz-based cattle dip fluid derived from an active dip site in northern New South Wales. PROCEDURE: Following inoculation of triplicate 5 L containers with faeces (0.5 g/L) from a clinical case of bovine paratuberculosis, samples collected up to 8 weeks after inoculation were examined by conventional and radiometric culture. M a paratuberculosis colonies were enumerated on solid media. RESULTS AND CONCLUSIONS: M a paratuberculosis survived in amitraz cattle dip fluid for up to 2 weeks, but not 3 weeks. Where 1% of solids in dip fluid is derived from a clinical case of paratuberculosis, dip fluid may contain viable M a paratuberculosis for at least 2 weeks. These findings have implications for the management of cattle dip sites.     

Hyperbaric oxygen used in the treatment of gas gangrene in a dog

Gas gangrene developed in the hindlimb of a dog after open reduction and stabilization of a compound femoral fracture. The condition occurred despite prophylactic ampicillin treatment and failed to respond to local irrigation and intravenous penicillin therapy. Three sessions of hyperbaric oxygenation were given. Used in combination with surgical drainage and high doses of intravenous penicillin, an excellent recovery was achieved.     

ISOLATION AND CHARACTERISATION OF BOVINE HERPESVIRUS MAMMILLITIS VIRUS AND ITS PATHOGENICITY FOR CATTLE

Ten viruses isolated from swabs and vesicular fluid collected from the teats of dairy cattle on 4 properties in Northern Victoria were identified as bovine herpes mammillitis (BHM) viruses by their physico-chemical and morphological properties and serological relationship to each other and a Scottish Strain of BHM virus. The viruses, isolated in bovine kidney and testicular cell cultures, produced cytopathic effects characterised by very large syncytia and eosinophilic intranuclear inculsion bodies. The intradermal inoculation of BHM virus into two cattle produced necrosis and ulceration of the skin of the teats about the area of inoculation and the development of serum neutralising antibody. After healing of the ulcers on day 37 after inoculation, the cattle were intravenously inoculated with corticosteroid for 6 days but BHM virus was not re-isolated from the teat skin or vaginal or nasal swabs.     

Identification of toxigenic Pasteurella multocida in atrophic rhinitis of pigs by in vitro characterisation

Toxigenic strains of Pasteurella multocida were readily differentiated from non-toxigenic strains by an agarose overlay method using bovine turbinate cells or bovine lung cells. Cells which were young and densely confluent were best suited to this assay. The incubation period required to distinguish toxigenic strains was dependent on the confluence of the monolayers, which was affected by the seeding rate, cell passage level and growth time prior to overlay. The agarose overlay method correctly identified 11 of 11 reference strains of Pasteurella multocida, and visible cytotoxic changes were present in the monolayers after 48 to 65 h. Outbreaks of the enzootic form of atrophic rhinitis in 2 New South Wales piggeries were associated with the isolation of toxigenic type D strains of P. multocida.