Indospicine toxicity in dogs

Update 17 August

Pet meat samples have tested positive for the indospicine toxin which caused the recent cluster of liver disease and dog deaths in Victoria.

Fresh or frozen raw pet meat sourced from Maffra District Knackery between May 31 and July 3 should not be fed to dogs. All pet meat products fitting that description should be considered a risk. The toxin builds up in dogs over time, so even if a pet hasn’t been sick so far, it doesn’t mean the food is safe. Cooking the meat does not remove the risk. If you have concerns, please consult your pet food provider to understand where your fresh meat came from and when it was sourced from the processor

Contact a vet immediately if you are concerned or recognise signs in your pet such as a sudden loss of appetite, lethargy or jaundice in a previously health animal, particularly after eating pet meat.

Situation summary

As of 17 August 2021, Agriculture Victoria was aware of 68 dogs across Gippsland and around Melbourne, with severe liver disease; 24 of these dogs have died.

Background

On 29 June 2021, Agriculture Victoria was advised of fourteen cases of illness, and the death of three other dogs, in the Bairnsdale area in the previous two weeks. All the dogs had been seen by local veterinary clinics and were suffering from severe liver disease. Affected dogs were previously healthy and vaccinated animals; greyhounds were over-represented in the case series, but many different dog breeds of both sexes were affected.

Initially, Agriculture Victoria provided advice to the private veterinarians who had been treating the dogs and facilitated testing of samples from deceased dogs.

  • Samples from affected dogs were provided by their attending private veterinarians and submitted to Agriculture Victoria’s diagnostic network. Testing was undertaken for canine leptospirosis (using PCR), and Ehrlichia canis. All returned negative results.
  • Histopathology results on affected dogs showed a consistent pattern of hepatic toxicity and minimal changes to other tissues.
  • The investigation considered causes including infectious disease, poisoning (including environmental, accidental, malicious, or blue green algae) or contaminants in feed.

Initial investigations revealed that the unwell dogs had consumed fresh pet meat supplied by a nearby knackery and sourced from local retailers. A meat sample provided by an owner was tested for the fungal toxin aflatoxin and was negative.

Because of the apparent but circumstantial link between the illness in the dogs and the pet food, PrimeSafe was advised.

Agriculture Victoria then contacted all the veterinary clinics in the area to advise them of the situation and ascertain if they too had seen similar cases recently. Regular contact has been maintained with the local private practitioners and detailed histories about the dogs were collected from owners.

A case-control study was initiated to help identify potential risk factors associated with the observed cluster of canine liver disease cases. Forty owners of affected dogs and 115 owners of unaffected ‘controls’ were surveyed with information collected on dog demographics and health, a complete dietary history including identification of all food and water sources, and any household or environmental exposures to a range of potential liver toxins. A total of 46 different exposure variables were considered. The study found that feeding meat originating from the Maffra District Knackery was the only variable associated with liver disease in dogs.

Testing on blood and liver samples from affected dogs, supplied with permission from their owners by their private veterinarian, and undertaken at the Queensland Alliance for Agriculture and Food Innovation (part of the University of Queensland), confirmed the presence of indospicine in all samples (reported 21 July). All these dogs had consumed pet meat either directly purchased from the Maffra District Knackery as part of regular, direct sales to dog owners or from retail outlets that on-sell product sourced from Maffra District Knackery.

Testing at the Queensland laboratory (reported 27 July), indicated that samples of dog food provided by owners of affected dogs, contained indospicine at varying levels. The samples had been purchased from different retailers but with Maffra Knackery as a common primary source of the pet meat.

Indospicine toxicity has not previously been reported in Victoria but has been reported in northern Australia (see references below).

Indospicine is a natural toxin occurring only in Indigofera plant species, including the Australian native species Indigofera linnaei. These perennial legumes are resistant to drought and are palatable to grazing livestock including cattle, horses and camels. Indospicine accumulates in the tissues (including muscle) of animals grazing Indigofera, and these residues persist for several months after exposure.

Dogs are particularly sensitive to indospicine with reports in past decades of liver disease and mortalities in dogs after eating indospicine-contaminated horse or camel meat.

The line of enquiry centered on the incorporation of horse meat in the knackery pet food products.  Horses from the Northern Territory where the Indigofera plant is known to grow are considered the most likely source of the contaminated meat. Specifically, twenty-six horses originating from the Northern Territory in an area where the toxic Indigofera plants are known to grow, were transported into Victoria on 16–17 May 2021 and 15 were reportedly processed by the Maffra District Knackery in late May and early June 2021. The flesh from these horses may have contained indospicine, which is a naturally occurring toxin and is impossible to detect without specialised laboratory tests.

Meat speciation testing undertaken by Intertek, South Australia, indicated that seven out of seven pet food products supplied by pet owners but said to be sourced from the Maffra knackery, or their retail outlets in June and July 2021 contained beef and horse and kangaroo meat, including two the owners understood to be at that time to be only kangaroo meat. Six of these samples were shown to contain indospicine.

Conclusion

Indospicine toxicity is consistent with the illness seen in the dogs and other possible causes of the illness have consistently been ruled out. Indospicine has been found in serum and liver samples from affected dogs and multiple pet meat samples eaten by the dogs. The meat had a common origin (the Maffra Knackery). Horse meat was detected in these pet meat samples.

Background

A cluster of 68 dogs suffering from liver disease was investigated across Bairnsdale, Latrobe Valley and Melbourne. Clinical signs ranging from mild elevations of liver enzymes on blood tests through to severe hepatic (liver) disease and death were seen in these cases.

A suite of tests has been conducted to eliminate possible toxic and infectious causes. Indospicine, a plant toxin, has been confirmed in tissue and blood samples from affected animals.

Agriculture Victoria worked closely with PrimeSafe and local pet food suppliers to identify the source of this toxin.

What is indospicine?

Indospicine is a naturally occurring hepatotoxin (toxin that causes liver damage) found in plant species from the genus Indigofera.

These plants are generally high in protein and palatable to livestock. Indospicine residues accumulate in the tissues of grazing animals such as cattle, camels and horses, and can persist in tissues for several months after exposure.

Dogs are particularly sensitive to indospicine when it is consumed in meat products from grazing animals containing this naturally acquired plant toxin. The resultant liver damage can cause a range of clinical signs from mild illness to serious hepatic (liver) disease, leading to death.

There have been two previously reported cases of consumption of horse or camel meat containing indospicine resulting in the illness and death of dogs in 1984 and 2009.

Indigofera sp. are widely distributed across tropical and subtropical regions. In Australia, 65 species have been recorded of which I.linnaei is the most prevalent across central and northern Australia and is known to contain high levels of indospicine. They are a hardy, drought-resistant plant that flourishes during the wetter months in the subtropics.

What are the signs of indospicine toxicity in dogs?

Indospicine toxicity in dogs can present with a range of non-specific clinical signs. The severity of disease may be related to the amount of toxin consumed, the duration over which the toxin was fed (i.e. fed on one day or over several days/weeks) and/or other concurrent health issues that may contribute to the illness.

Clinical signs are often related to underlying liver damage from the toxin and may include:

  • loss of appetite
  • lethargy
  • jaundice
  • abdominal discomfort
  • vomiting
  • elevated liver enzymes on a blood test

Some cases of toxicity will cause severe liver damage resulting in death.

There is no specific treatment for indospicine toxicity which relies on generalised supportive therapies such as intravenous fluids, non-specific medications, and liver and gut protectants.

How can I reduce the risk of exposure?

Indospicine is a naturally occurring toxin that is impossible to detect without specialised laboratory tests.

Meat from camels and horses previously grazing on Indigofera sp. in northern Australia is known to pose a risk to dogs.

Fresh or frozen raw pet meat sourced from Maffra District Knackery between May 31 and July 3 should not be fed to dogs. All pet meat products fitting that description should be considered a risk. If you have concerns, please consult your pet food provider to understand where your fresh meat came from and when it was sourced.

Is there a risk to people?

Dogs are especially susceptible to indospicine toxicity and the current risk is to dogs. Pets suffering from liver disease associated with indospicine toxicity do not pose a risk to people. There are no indications of any risk to human health nor of human food safety issues associated with these cases to date.

Pet meat must comply with the Australian Standard for the Hygienic Production of Pet Meat. There are strong food safety regulatory controls to prevent pet meat entering the human food supply.

Research shows that people have a relatively low susceptibility to indospicine toxicity, and FSANZ advise that they are not aware of any reports of adverse effects in humans due to the ingestion of toxins such as indospicine via meat consumption.

What if I suspect indospicine toxicity in my dog?

Pet owners are advised to contact your local veterinarian for medical assessment and advice if your pet is unwell.

Suspect cases of indospicine toxicity can be reported to Agriculture Victoria on 136 186 or to your local Agriculture Victoria Animal Health and Welfare staff.

References

Fitzgerald, L. M., Paul, A., Fletcher, M. T., Mansfield, C. S., and O'Hara, A. J. (2011). Hepatotoxicosis in dogs consuming a diet of camel meat contaminated with indospicine. Australian Veterinary Journal 89 (3) 95-100

Hegarty, M.P.; Kelly, W.R.; McEwan, D.; Williams, O.J.; Cameron, R. (1988) Hepatotoxicity to dogs of horse meat contaminated with indospicine Australian Veterinary Journal 65 (11)337–340

Netzel, G., Palmer, D.G., Masters, A.M., Tai, S.Y., Allen, J.G., and Fletcher, M.T. (2019). Assessing the risk of residues of the toxin indospicine in bovine muscle and liver from north-west Australia. Toxicon 163 48-58

Page last updated: 17 Aug 2021