Sudden death of 16 of 100, 2 year old steers was reported to a local private practitioner on 27 Dec 2009. The cattle had arrived for agistment 10 days ago from Merriwa. The cattle had been vaccinated within the past 6-9 months. The animals were on a native grass pasture with no supplements, although there was concern they may have had access to a grain silo initially.
The private practitioner noted affected animals were ataxic, weak and scouring within 1-2 hours before death. On post-mortem examination he noted marked inflammation / ulceration of the abomasal and small intestinal mucosa, no evidence of grain in the contents and congestion of the liver, kidneys, spleen and rumen. Urinalysis showed 4+ protein and 2+ glucose.
Histopathology of the samples indicated a severe, peracute, multifocal necrotizing hepatitis and severe hyperacute medullary tubular necrosis of the kidney. The liver sample tested >1mg/kg arsenic which is considered positive.
With the positive arsenic result the private practitioner was happy for me to take over the investigation! I canvassed the vast knowledge of my rangers to see where on this property they would look if they suspected an old arsenic dump. I then went to the property to search for the source. There was evidence of the plastic bags spread out in the paddock with obvious signs of chewing and the owner noted that there had been plastic in the rumen of one of the necropsied animals. This plastic had a logo on it that looked like a fertiliser company. We then traced the plastic to an old open shed where more plastic and a very distinct garlic / chemical smell was permeating the shed. On digging up the soil in the corner of the shed where the bags had been, a white line could be seen in the soil. Samples were taken from both this area of the shed and also from the outside area next to the wall of the shed. This outside area appeared to have been 'swept clean' and the suspicion was that the steers had licked it continuously.
Soil arsenic levels came back as 2200 mg/kg and 1400 mg/kg for inside and outside the shed.