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Vet on call: Watch out for datura plant, an animal killer

Friday December 13 2019
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Dairy cattle feed in a farm in Siaya County. Poisonous plants, (including inset) once identified in the farm, should be removed. PHOTO | JOSEPH MUGACHIA | NMG

By DR JOSEPH MUGACHIA

Last week I travelled to Elgeyo Marakwet County for a family function, which offered me a deserved time off from my daily professional work.

We were all impressed with our daughter who had settled well in the community and could now speak the local language sufficiently.

In my address to the gathering, I pointed out that Kenya shall eventually be united by matrimony, economic activities, religion and the full awareness that all human beings are created equal.

A participant, who recognised me as the writer of this column, seized the moment and asked if a certain plant with deep green leaves and white flowers is poisonous to cattle, sheep, goats, horses, poultry and humans. We later chatted and he confirmed that his animals had died after feeding on the plant.

I did not know the plant would ambush me on my way back to Nairobi. We were around Sachang’wan when my phone rang.

A neighbour in Nairobi who farms in Murang’a was on the line and said he had lost four valuable dairy cows in four weeks. The animals had died suddenly at different times but the cause of death had not been determined.

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Though I’m not his doctor due to the distance, he had called me because another animal had dropped dead the previous evening hours after feeding. One other cow was unable to stand and he was concerned the deaths could continue.

He had wanted me to visit his farm, but I was far away, I informed him as much, but none of his regular doctors was available. I recalled the African saying that a rat will pass near you when your hands are empty.

My calls to three doctors and four paravets were unfruitful. We agreed I would visit the farm the following day. The farmer later called me to discuss with one of the doctors who had reached him.

The doctor had called the farmer, visited the farm and wanted to share his findings so that we could compare notes.

SHOWN SIMILAR SIGNS

Dr Kamau told me the dead animal had shown signs of nervous toxicity and bloating before suddenly dying. The signs included difficulties in breathing and uncoordinated movement. He was informed the other cattle that had died had shown similar signs.

From the history given, he suspected the animals had died of plant poisoning. To further investigate, he went to the section of the farm where the feed the dead animal had eaten was obtained.

The culprit was there, waiting to be identified. He saw a lot of datura plants on the farm, and some had been harvested together with the napier grass fed to the cattle the previous day.

He was able to see the datura stubs left on the farm. The farm workers told him they did not know the datura plant or that it is poisonous to cattle.

“From these findings, I’m convinced the cattle have been dying of datura poisoning,” he concluded. I agreed.

Datura plants are common globally in dry temperate, tropical and subtropical regions. The plant is believed to have originated from Mexico and spread to the rest of the world. All datura species are poisonous, with Datura stramonium as the most prevalent.

Common names of the plant that include devil’s trumpet, devil’s weed and devil’s bells signify its ominous nature. It’s also known as Jimson’s weed and thorn apple.

Datura contains potent alkaloid toxins, mainly atropine, hyoscyamine and hyoscine, also called scopolamine. The plant has been used both in traditional medicine and witchcraft.

I recall when I reported in Lamu, my first duty station, a local traditional healer prescribed datura smoke for my congested chest due to an allergic reaction. I declined and went to hospital as I clearly understood the plant’s toxicity.

Datura thrives in fertile soils. Livestock manure from dry lands like Kajiado has contributed to wide dispersal of the plant to the highland farm areas like Kandara, where the manure is in great demand due to soil exhaustion.

IDENTIFY POISONOUS PLANTS

All parts of the plant are poisonous, but the seeds and flowers have the highest toxin concentration. Livestock avoid eating the plant even in dry periods.

Most poisoning occurs due to inadvertent inclusion of the plant or its seeds in harvested forage and grains or malicious poisoning.

I recall the most serious case of datura poisoning I’ve seen was in Kiambu about 25 years ago. A worker maliciously mixed datura with napier grass and chopped it for the cattle, killing 15 cows on one weekend. He then disappeared, never to be seen again.

There was also a case of a farmer who poisoned his four animals to get insurance compensation. He dropped the claim when my investigation diagnosed datura poisoning. I’ve seen many cases of accidental poisoning.
It is difficult to treat datura poisoning because animals tend to die suddenly. The poison acts by slowing the nerves that control stomach and intestinal movement, thus causing bloat.

It also disrupts the heart rhythm and paralyses nerves that control respiration. Finally, it acts on the brain, causing hallucinations, uncoordinated movement, depression, collapse and death.

I advise livestock farmers to always identify poisonous plants on their farms with the help of their animal health service providers.

The plants once identified should be removed. Those who grow cereals and other food and feed crops should always make sure that poisonous plants and their seeds do not enter the human and animal food chains.

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