Indospicine toxicity in dogs

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.

Prior to a detection of indospicine in Victorian dogs in 2021, there had been only two other previously reported cases of consumption of horse or camel meat containing indospicine resulting in the illness and death of dogs, (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.

Consumption of contaminated fresh or frozen raw pet meat has been linked to previous occurrences of indospicine toxicity in dogs.

Is there a risk to people?

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.

Pets suffering from liver disease associated with indospicine toxicity do not pose a risk to people.

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.

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 also be reported to Agriculture Victoria on 136 186 or to your local Agriculture Victoria Animal Health and Welfare staff.

Case Overview – Victoria 2021

On 29 June 2021, Agriculture Victoria was advised of an unusual cluster of illness in dogs in the Bairnsdale area. In total, fourteen dogs were unwell and three had died over a two-week period. All of the dogs had been seen by local veterinary clinics and were suffering from severe liver disease. Affected dogs were previously healthy and vaccinated animals, and several different dog breeds of both sexes were affected.

By 27 September 2021, Agriculture Victoria had been notified of 68 dogs across Gippsland and around Melbourne, with severe liver disease and suspected indospicine toxicity; 26 of these dogs died.

A suite of tests were conducted to eliminate possible toxic and infectious causes. Testing included Ehrlichia canis, canine leptospirosis, and histology ruled out several other causes including blue-green algae toxicity. Indospicine, a plant toxin, was confirmed in tissue and blood samples from affected animals and fresh/frozen pet meat samples.

Indospicine toxicity had not previously been reported in Victoria but has been reported in northern Australia.

Agriculture Victoria worked closely with PrimeSafe and local pet food suppliers to identify the source of this toxin. After intensive investigations and testing the source of the toxin was traced to pet meat from a local knackery.

Interstate horses from an area where the toxic Indigofera plants are known to grow, were processed at the knackery and the meat subsequently used in fresh/frozen pet meat products.  These horses were likely to have consumed indospicine, which is a naturally occurring toxin and is impossible to detect without specialised laboratory tests. Testing of other horses from the same interstate property confirmed indospicine in their blood.

Remaining contaminated product was removed from sale and owners were advised to closely monitor the health of their pets if they had consumed fresh or frozen pet meat products within a certain date range. It has been reported that cooking doesn’t change the toxicity and in some cases the toxin can build up in a dog over time, resulting in delayed onset of illness.

Following the investigation and procedural changes at the local knackery, no further cases were reported.

This case highlights the importance of reporting unusual disease events to Agriculture Victoria and the benefits of local veterinarians, industry and government working together to ensure the ongoing health and welfare of our pets.

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