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Plant poisoning (old)
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| Introduction | Prevention - Control - Treatment | |||
| Some common poisonous plants | Information Source Links | |||
| General diagnosis of plant poisoning |
Introduction
- To let animals "learn" about a strange pasture without being poisoned, only put them on the new pasture for a short time each day . Than gradually increase the time they spend on it.
After very dry times, fires or when the pastures have been overgrazed, often the only plants that survive are poisonous plants with deep roots. The animals have than no other choice but to eat these plants which they normally avoid and they get poisoned.
- To avoid this, take extra forage to the animals if you can, while the pasture recovers.
Some common poisonous plants
Lantana
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There are various species of this plant which have poisonous effects to different species of livestock, the most common among them being the Lantana camara. It is a shrub with coarse, branched stems having small curved prickles, rough toothed leaves and flower heads of various colors which range from red, yellow and white. It is common in most tropical countries where it has been wide used as ornamental plant in gardens. It flourishes in grasslands and is not palatable to livestock. However it is sometimes ingested accidentally.
Signs of poisoning
Affected animals will show:
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Castor oil plant
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This is a blood poisoning plant occurring in most tropical areas. It is also called palma Christi. The shrub grows up to 3 meters high and has large palmate 3 or 5 pointed leaves. It has small yellowish flower and the seeds resembling engorged ticks with various markings on them. The seeds which are toxic if not treated are eaten by some tribes in Africa after special treatment i.e. soaking and boiling. Castor boil as them suggests is removed by pressing the seeds and the remaining cake is rich in ricin (a toxalbumen) which is the toxic principle. The cake sometimes gets mixed in animal feeds by accident thereby causing poisoning.
Signs of poisoning There is profuse watery diarrhea in all affected animals and cattle may die in convulsions
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Tribulus
It is a prostrate vine with yellow flowers having small spine fruits and burrs. It occurs through out the tropics mainly Australia, Asia, South America and Africa. It favors bush paths and is troublesome to pedestrians due to the fruits and burrs.
Signs of poisoning
Photosentisation, animals refuse to eat and drink, fever, edema of the limbs, blindness, jaundice, a purulent dermatitis and in the advanced stages asphyxiation and death. In South Africa it causes a condition called geeldikop (yellow thick head) with photosensitization.
In West Africa it appears most toxic during the humid season especially at the beginning of rains.
Oleander
Other names: Nerium oleander, Nerium Indicum, Ceylon rose, lovers' poisoin
This is a common shrub which grows up to 4 meters high and occurs throughout the tropics. It has numerous long stems growing from a common root. It has red compound flowers, and the leaves are dark green and are highly toxic.
Signs of poisoning
Vomiting, convulsions, diarrhea, colic and acute gastro enteritis
The solanines
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These are a group of the solanaceae family all likely to contain alkaloid which is toxic if taken in sufficient quantities. Members of the solanaceae family include: thorn apples, Datura species, Solanum species including the potato Solanum tuberosum, Solanum torvum, Solanum Incanum and Solanum nigrum (dealy night shade) among others.
Signs of poisoning Dullness, depression, increased pulse rate and respiration, nervousness, muscular tremors often followed by paralysis, drop in temperature, slowed pulse and respiration, relaxation of the sphincters, recumbency and death.
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The mimosine group
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A number of legumes such as Leucaena leucocephala are known to contain a toxic substance called mimosine which when eaten in large quantities may cause hair loss and may also affect the normal reproductive behavior.
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Mexican poppy-Argemone mexicana
This plant is widespread in the tropics and is known to be rich in toxic alkaloids. The seeds are particularly toxic and when mixed in grains and fed to animals will cause mortality. During drought, animals especially may feed on the plant and get poisoned.
Signs of poisoning
In all animals, there is intense capillary dilation leading to loss of fluid from the body tissues.
Milk weeds-Asclepias species
These plants are widespread in tropics and sub-tropical countries. Most species of the plant have large pods filled with floss. There toxic principle is a mixture of glycosides. When ingested by animals, they suffer gastro enteritis and heart conditions.
Signs of poisoning
Weakness, paraplegia, labored breathing, convulsions and death normally arising from respiratory failure.
Selenium accumulators or converters
These groups of plants are capable of taking up inorganic selenium and converting it into organic selenium thus making them available to other plants which are toxic when ingested by animals. They are of various genera some of them being:
Astragalus, Neptunia, Oonopsis, Xylorrhiza, and Stanleya
They thrive on soils that are rich in selenium and therefore are called selenium indicators.
Signs of poisoning
- In chronic selenosis they animals are dull, listless, lack appetite, emaciated and have rough coat.
- In acute form, they animals grind their teeth, salivate, show abdominal pain, some degree of paralysis and become bind condition called blind staggers.
General diagnosis of plant poisoning
- Careful examination of the whole of the contents of the alimentary canal to see if any parts of the plant can be seen may be indicative.
- Evidence of acute gastro enteritis coupled with parts of known poison plant can be conclusive.
- Death of animals recently introduced into an area where known poison plants exist can be considered as suspicious.
- Sporadic death at a particular time of the season in successive years when suspected poison plants are in bloom may arouse suspicion.
- Inspection of grazing areas will often show that poison plants have been grazed.
- In places where a good diagnostic laboratory is available, specimens from the alimentary tract of dead animals can be taken fore analysis.
Prevention - Control - Treatment
Prevention and control of plant poisoning
This involves removing the animals from the plants or the plants from the animals.
- In areas where animal husbandry is settled, the poison plants can be physically removed from the pastures.
- Do not graze animals where you know there are poisonous plants
- Feed animals well and healthy. They are much less likely to eat poisonous plants or scavenge for food and eat poisonous by mistake
- In pastoral and nomadic areas, rerouting of the animals away from the routes with known poison plants is a good control method.
Recommended treatment
Treatment of plant poisoning is never straight forward and is often symptomatic.
- Where toxins is a depressant, stimulants may be used and vice versa.
- Timely administration of purgatives is good in removing the poison from the alimentary canal and when treatment is delayed, it is better to treat symptomatically with sedatives and pain relieving drugs.
Information Source Links
- Barber, J., Wood, D.J. (1976) Livestock management for East Africa: Edwar Arnold (Publishers) Ltd 25 Hill Street London WIX 8LL. ISBN: 071310063X
- Blood, D.C., Radostits, O.M. and Henderson, J.A. (1983) Veterinary Medicine - A textbook of the Diseases of Cattle, Sheep, Goats and Horses. Sixth Edition - Bailliere Tindall London. ISBN: 0702012866
- Blowey, R.W. (1986). A Veterinary book for dairy farmers: Farming press limited Wharfedale road, Ipswich, Suffolk IPI 4LG
- Force, B. (1999). Where there is no Vet. CTA, Wageningen, The Netherlands. ISBN 978-0333-58899-4.
- Hall, H.T.B. (1985). Diseases and parasites of Livestock in the tropics. Second Edition. Longman Group UK. ISBN 0582775140
- Hunter, A. (1996). Animal health: General principles. Volume 1 (Tropical Agriculturalist) - Macmillan Education Press. ISBN: 0333612027
- Hunter, A. (1996). Animal health: Specific Diseases. Volume 2 (Tropical Agriculturalist) - Macmillan Education Press. ISBN:0-333-57360-9
- ITDG and IIRR (1996). Ethnoveterinary medicine in Kenya: A field manual of traditional animal health care practices. Intermediate Technology Development Group and International Institute of Rural Reconstruction, Nairobi, Kenya. ISBN 9966-9606-2-7.
- Pagot, J. (1992). Animal Production in the Tropics and Subtropics. MacMillan Education Limited London. ISBN 0-333-53818-8
- The Organic Farmer magazine No. 50 July 2009
