Indigofera spicata (creeping indigo) poisoning of three ponies.
Abstract: Three ponies continuously grazed a pasture containing an estimated 24% Indigofera spicata (wet weight basis) for 4-6 weeks in April and May 2004. They developed ataxia, paresis, depression, muscle fasciculations, dysphagia, ptyalism and halitosis. Two also developed corneal opacity. One pony recovered with supportive treatment, but the other two were euthanased and necropsied. Neuropathology was not present in either case, but both livers had periacinar and periportal lymphocytic infiltrations and hydropic degeneration of mid-zonal hepatocytes, with mild to moderate periacinar necrosis also evident in one. The I. spicata contained 2.66 mg 3-nitropropionic acid (3-NPA)/g dry matter and 1.5 mg indospicine/g dry matter. Indospicine, but not 3-NPA, was detected in serum from both of the euthanased ponies and indospicine was detected in heart, liver and muscle from the one pony in which this assay was performed. The clinical syndrome closely resembled 'Birdsville horse disease' caused by I. linnaei and was similar to that reported in horses poisoned by the closely related species I. hendecaphylla and to 3-NPA poisoning of other animals, including humans. 3-NPA is thought to cause this neurological syndrome. To our knowledge, this is the first authenticated report of I. spicata poisoning in grazing animals. We also report here the first published evidence that 3-NPA and indospicine exist in naturalised I. spicata in Australia and of the formation of indospicine residues in tissues of animals grazing paddocks infested with I. spicata.
© 2013 The Authors. Australian Veterinary Journal © 2013 Australian Veterinary Association.
Publication Date: 2013-03-11 PubMed ID: 23521099DOI: 10.1111/avj.12032Google Scholar: Lookup
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Summary
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The study discusses three ponies that grazed a pasture containing a high percentage of Indigofera spicata (a plant species) for several weeks and developed severe health problems, such as muscle weakness, depression, and dysphagia. While one pony recovered with support treatment, the other two were euthanized. Post-mortem reports showed damage in the livers but no problems in their neural systems. The study concluded that some of the toxins found in the plants were present in the ponies’ serum and tissues, pointing to Indigofera spicata poisoning as the cause of their illness.
Indigofera spicata exposure and its impact on ponies
- In April and May 2004, three ponies grazed in a pasture composed of roughly 24% Indigofera spicata plants, also referred to as creeping indigo. The ponies were exposed to the plant for about 4 to 6 weeks.
- The ponies developed several adverse health symptoms including ataxia (loss of full control of bodily movements), paresis (weakness of voluntary movement), depression, muscle twitching, difficulty swallowing, excessive salivation, and bad breath. Two of them also developed a condition known as corneal opacity.
- Only one pony recovered after receiving supportive treatment while the other two had to be euthanized. Post-mortem reports showed no neuropathology, but damage was observed in their livers. These damages were related to periacinar and periportal lymphocytic infiltrations and hydropic degeneration of mid-zonal hepatocytes. Mild to moderate periacinar necrosis was also evident in one of the cases.
Toxins in Indigofera spicata and their detection in ponies
- The I. spicata plants in the pasture contained 2.66 mg of 3-nitropropionic acid (3-NPA) per gram of dry matter and 1.5 mg of indospicine per gram of dry matter. Both substances are toxic and can cause a variety of health disorders in animals and humans.
- These toxins, specifically indospicine, were detected in the serum of the ponies. Except for 3-NPA, the toxins were also found in the tissues of the heart, liver, and muscles of one of the ponies.
- The symptoms presented by the ponies were similar to those associated with Birdsville horse disease caused by another species of Indigofera (I. linnaei) and in other animals, including humans poisoned by 3-NPA.
Significance of the study
- To the researchers’ knowledge, this is the first study to validate the poisoning of grazing animals due to feeding on I. spicata.
- This study signifies the first documented evidence of the presence of 3-NPA and indospicine in naturalized I. spicata plants in Australia.
- The research also demonstrates the formation of indospicine residues in the tissues of animals grazing in fields infested with I. spicata.
Cite This Article
APA
Ossedryver SM, Baldwin GI, Stone BM, McKenzie RA, van Eps AW, Murray S, Fletcher MT.
(2013).
Indigofera spicata (creeping indigo) poisoning of three ponies.
Aust Vet J, 91(4), 143-149.
https://doi.org/10.1111/avj.12032 Publication
Researcher Affiliations
- Biosecurity Queensland, Animal Research Institute, Yeerongpilly, QLD, Australia. selina.ossedryver@daff.qld.gov.au
MeSH Terms
- Animals
- Fatal Outcome
- Female
- Horse Diseases / diagnosis
- Horses
- Indigofera / poisoning
- Male
- Neurologic Examination / veterinary
- Plant Poisoning / diagnosis
- Plant Poisoning / veterinary
Citations
This article has been cited 2 times.- Ramadan MM, Dailey D. Trouble for Horses in Paradise: Toxicity and Fatality Resulting from the Consumption of Indigofera spicata (Fabaceae) on Oahu Island.. Vet Sci 2022 Jun 4;9(6).
- Sultan S, Giles C, Netzel G, Osborne SA, Netzel ME, Fletcher MT. Release of Indospicine from Contaminated Camel Meat following Cooking and Simulated Gastrointestinal Digestion: Implications for Human Consumption.. Toxins (Basel) 2018 Sep 3;10(9).
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