By Liz Hancock, District Veterinary Officer, Warrnambool
In April 2025, Agriculture Victoria investigated the sudden deaths of ducks in a backyard setup in south west Victoria.
While the deaths were caused by avocado (persin) toxicity, this case study provides a working example of how reports like this are urgently assessed to rule out an Emergency Animal Disease (EAD).
It all began when the Agriculture Victoria duty veterinarian received a call via the Emergency Animal Disease Hotline from a backyard poultry farmer reporting that 7 of their 18 ducks had died that day, all within minutes of each other.
The duty veterinarian asked the owner to carefully double bag all deceased animals and store them in a secure area, and keep all remaining live poultry isolated from wild birds until an investigation was done.
These initial steps help reduce the risk of disease spread while an investigation is underway.
The Agriculture Victoria on-call District Veterinary Officer (DVO) was notified, who went to the property to conduct a post mortem, collect information and samples to rule in or out Highly Pathogenic Avian Influenza (HPAI) and determine the actual cause of the deaths.
When the DVO arrived at the property, the owner of the poultry explained that 7 ducks had died in the past 24 hours. The ducks were co-housed with 10 chickens and 11 ducks, most of whom appeared clinically normal. There had been no prior illness in any poultry on the farm, and no dead wild birds had been seen.
Discussion with the owner uncovered that the last feed, approximately 6 to 7 hours prior to the deaths had included 6 whole avocados.
At this stage, a suspected diagnosis of avocado toxicity was made, and swabs and samples were collected and sent to Agriculture Victoria's Veterinary Diagnostics Laboratory at AgriBio for analysis.
Our pathologists at AgriBio performed a number of tests, including one to rule out HPAI.
Avocados are known to contain persin which is toxic to mammals and birds. Birds which have ingested it often show lethargy, difficulty breathing, loss of appetite, swelling around their neck and chest and sudden death.
Diagnosis is made by history of access to avocado and clinical signs in the duck. However, it can also be supported by tissue examination and testing, as this case was. Treatment involves supportive care only and is often unsuccessful and/or cost prohibitive.
This case shows how important it is to report sudden or unusual animal deaths promptly, even if the cause turns out not to be an emergency animal disease.
