Observations on the indirect transmission of virulent ovine footrot in sheep yards and its spread in sheep on unimproved pasture

SUMMARY: Virulent ovine footrot was transmitted accidentally to a group of 23 adult Merino sheep (flock B) after holding for 1 hour in sheep yards, which earlier the same day had contained another flock (flock A) with < 1% prevalence of sheep with footrot lesions. Sheep in flock B were rendered susceptible to virulent footrot by grazing 600 mm high unimproved pasture dominated by paspalum ( Paspalum dilatatum ) and kangaroo grass ( Themeda australis ) during warm, humid and wet weather. In addition to moisture, interdigital abrasions caused by the pasture might have predisposed the interdigital skin to infection with Dichelobacter nodosus .     

Assessment of the potential toxicity of a poison for rabbits, pindone (2-pivalyl 1, 3 indandione), to domestic animals

The toxicity of pindone, a rabbit poison, to horses, cattle, goats, chickens, dogs and cats was investigated, using extension of prothrombin time (PT) as an index of poisoning. The daily dose of pindone, administered for 5 days, ranged from 0.3 mg/kg for dogs to 2.5 mg/kg for chickens. This range of dose rates was considered to be indicative of the worst possible case that could arise following a campaign of baiting for rabbits. Although significant elevations in PT (more than double baseline values) were noted in all species other than horses, clinical signs of anticoagulant poisoning were not observed in any of the species tested. From the observed PT, cattle and cats appeared to be the most susceptible, and horses the least susceptible, to pindone toxicity. The half-lives of the elevated PT were calculated as 3.1 days for cattle, 2.8 days for goats and chickens, 1.9 days for horses and dogs and less than one day for cats. It is proposed that these half-lives can be used as a guide for determining the duration of treatment of pindone-affected animals.     

Restriction-endonuclease analysis of Australian isolates of Leptospira interrogans serovar hardjo from cattle with agalactia and abortion

SUMMARY Polyacrylamide gel electrophoresis and agarose gel electrophoresis were used to resolve restriction endonuclease digests of 20 Australian isolates of Leptospira interrogans cultured from urine samples of cattle with agalactia and abortion. The restriction endonuclease profiles of 19 isolates closely matched the profiles of L interrogans serovar hardjo subtype hardjobovis reference strains. The remaining isolate had a different restriction profile from subtype hardjobovis and subtype hardjoprajitno reference strains and was serologically identified as serovar pomona. Silver staining of polyacrylamide gels gave enhanced resolution of restriction fragments compared with the traditional method of ethidium bromide staining of agarose gels.     

Photosensitisation and crystal-associated cholangiohepatopathy in sheep grazing Brachiaria decumbens

Two outbreaks of photosensitivity and jaundice in sheep grazing the grass, Brachiaria decumbens. In West Java in 1983 and 1983 and 1990 are described. Aggregates of acicular clefts and crystals were present in bile canaliculi, bile ducts, Kupffer cells, hepatocytes and in kidney tubules. The number of crystals increased with the length of exposure to the plant and sheep that died had the largest accumulations. These crystalline structures have been reported before in this syndrome, but are similar to those seen in Tribulus terrestris and Panicum spp toxicities.     

Investigations into the toxicity of Echium plantagineum in sheep: 1. Field grazing experiments

A field grazing trial was undertaken to monitor the health and production of crossbred sheep grazing pasture where Echium plantagineum constituted a considerable proportion of the available forage. The trial, conducted for 19 months over successive grazing seasons, demonstrated a significant difference in production, with sheep on the E. plantagineum pasture being lighter and growing less wool compared with sheep on Echium-free pasture. No mortalities involving pyrrolizidine alkaloid poisoning were recorded in sheep grazing E. plantagineum, although there was histological evidence of moderately severe liver damage associated with high liver copper concentrations in at least one sheep following the grazing of large quantities of the plant.     

Experimental evidence that tryptamine alkaloids do not cause Phalaris aquatica sudden death syndrome in sheep

The acute toxicity for sheep of 3 alkaloids that occur in Phalaris acquatica was examined by intravenous and oral administration. The lowest tested dose rates that produced clinically observed signs were, for 5-methoxy dimethyltryptamine, 0.1 mg/kg body weight intravenously and 40 mg/kg orally; for gramine, 10 mg/kg intravenously and 500 mg/kg orally; and for hordenine, 20 mg/kg intravenously and 800 mg/kg orally. All induced the clinical signs observed in the nervous form of phalaris toxicity, but none induced the cardiac, sudden death, syndrome.     

Fertility of sows mated on different days of the week

The farrowing rates resulting from matings on different days of the week were determined for a 2800-sow intensive piggery in both 1983 and 1984. The results showed that sows mated early in the week achieved a significantly higher farrowing rate than sows mated late in the week (P less than 0.0001). During the seasonal (summer to autumn) infertility period, Wednesday matings resulted in a poor farrowing rate whereas for the rest of the year farrowing rates following Wednesday matings were similar to those for Sunday Monday and Tuesday matings. Consistent results were obtained for data from both years. It is proposed that the stress of regrouping unmated sows on Wednesday to accommodate newly weaned sows is responsible for this decrease in fertility. This study illustrates how detailed analysis of farrowing rates on a day of mating basis can identify a problem which is otherwise masked by weekly data.