AHVLA: Rodenticide Poisoning in Backyard Flock

UK - Among the main points of the Monthly Scanning Surveillance Report for April 2011, just published by AHVLA, are the deaths of two backyard bantams that had escaped and are thought to have had access to rodent poison.
calendar icon 15 June 2011
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Broilers and Broiler Breeders


Rickets was diagnosed in two flocks of 10-day-old organic broilers with a history of lameness and also in a flock of 17-day-old broilers. Findings at PME were of moderate to marked reduction of bone strength and widening of the tibio-tarsal growth plates. Histological examination of undecalcified sections of growth plates stained by Von Kossa's method confirmed osteodystrophic changes consistent with hypophosphataemic rickets with failure of mineralisation of the newly formed columns of hypertrophied chondrocytes. It transpired that the organic birds had inadvertently been given a breeder ration, for birds in lay, with the usual high calcium content probably causing mineral imbalance and a relative phosphorus deficiency in the rapidly growing broilers.

Septic arthritis

Septic arthritis was diagnosed in two batches of 29- and 35-day-old broilers from one farm, submitted with a history of lameness. Necropsy revealed a creamy to crumbly exudate affecting mostly the hock joints and also the tendons in the smaller birds. Moderate to heavy growths of E. coli were cultured in the older broilers whereas Staphylococcus aureus was cultured from the 29-day-old birds.

Backyard Flocks

Rodenticide poisoning

Winchester investigated rodenticide poisoning of two bantam chickens that had been found dead. The affected bantams were in one of a group of pens, and the birds had escaped from their pen. The bantams in the remaining pens which had not escaped were unaffected. Free blood was present in the peritoneal cavity and there were also haemorrhages within the muscles adjacent to the stifle joints. Detailed examination of the crop and gizzard contents showed they were well-filled with cereal grains and other feed, and a blue-tinged grain was visible in the crop of one of the birds. The source of the rodenticide was identified and removed. Risk assessment identified no threat to the human food chain.

Infectious laryngotracheitis

Sutton Bonnington diagnosed Infectious laryngotracheitis in a free-range layer hen from a backyard flock of 42 birds where eight birds had ongoing signs of respiratory disease, including dyspnoea and tracheal rhales. At necropsy blood clots and catarrhal exudate were present in the tracheal lumen. There was diffuse pulmonary oedema and congestion.

Ducks and Geese

Duck viral enteritis (DVE)

Preston diagnosed two outbreaks of suspected DVE. In one of these, 14 out of 34 ducks died and a further two were affected with green diarrhoea. Necropsy of a Muscovy-type bird revealed severe diphtheritic oesophagitis, enteritis and cloacitis, and signs of enteritis were seen in a Mallard-type bird.

In the other outbreak, there were four deaths in a group of five Muscovy ducks. Signs of severe diphtheritic enteritis were seen in one of the casualties. It was reported that at both premises the birds had access to ponds which were also populated by wild Mallard – likely carriers of the virus.


Slight increase in mortality in a submission of three-day-old red-legged partridges from a total flock of 8,000 was attributed to E. coli septicaemia and yolk sac infection. Profuse growths of E. coli were obtained from yolk sac and liver samples.

Further Reading

- You can view the full report by clicking here.

Further Reading

- Find out more information on the diseases mentioned in this article by clicking here.
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