Plant poisoning is one of the causes of livestock fatalities in our farms and since there has been incidences of poisoning, it is only fit for a more in-depth discussion to be had about poisonous plants. Since we are just coming out of the winter season and graze and browse are at their lowest state opportunistic plants that are often poisonous are so plenty and as the range recovers, some of these plants are also sprouting.
There are various factors that favour or encourage the growth and multiplication of poisonous plants. These include:
- In general, poor grazing management means there are less different kinds of plants in the veld. But farmers should be most concerned about the loss of certain valuable plants, and their replacement with plants that have little or no value for people or livestock. This gives the less nutritious and poisonous plants an advantage and they gradually take over the veld.
- Some of these poisonous plants are invasive, parasitic and are intertwined with good, edible plants even hay hence making them difficult for the animals to differentiate.
- In addition to thorny plants, poisonous plants become more common as the condition of the veld deteriorates. For example Slangkop (Snake’s Head lily/Sekaname) causes diarrhoea, bloated abdomen, heart failure and sudden death in livestock. Some range plants are classed as poisonous plants because if they are eaten by livestock they may suffer from plant poisoning with symptoms ranging from diarrhea, vomiting, shallow breathing, paralysis and even death.
- Veld fires are also destructive. They kill other plants allowing poisonous plants to spread. So sometimes we should think of the repercussions of veld fires even controlled ones that we make trying to fight bush encroachment. We should always remember that when the rains come, these poisonous plants will be the only forage available hence many fatalities.
- As spring approaches much care should be taken as most poisonous plants are at their most toxic stage as this season is one where they are fast growing.
- Some perennial poisonous shrubs have well developed underground rooting systems e.g. Dichapetelum cymosum (Poison leaf/ mogau). This makes them well established and difficult to get rid of as the developed root system makes them drought resistant. Some are even able to store food for a long time hence their longevity in harsh times.
- Newly introduced grazing areas: if livestock is introduced to an unfamiliar territory, they are bound to graze/browse on harmful plants therefore it is vital to do a range survey before letting the animals roam that new territory.
- We should also know that there are some breeds that are more resistant to poisoning by plants. Animals indigenous to a place will be more hardy and resistant but exotic breeds would not be so lucky.
- General condition of animals also play an important factor:
- Stressed animals absorb poison faster e.g. Mogau
- Pregnant animals feed less discriminately and are therefore more prone to poisoning.
- Overgrazed pastures make animals eat poisonous plants as they do not have a choice.
- Deficiency of an essential element in the diet especially phosphorus makes the animal crave any plant
- Since there are few effective remedies for poisoning, it is better to try and prevent poisonous plants getting established in the first place through good veld management. There are many range plants in the wilderness that animals are exposed to and they are distributed countrywide. Farmers should ensure that livestock do not browse or graze in areas where these are found. Some examples are:
|Solanum incanumDichapetelum cymosum
|Thorn apple, nightshadePoison leaf
Rubber hedge plant
Wild striped cucumber
Source: Mushi et al. (1999), Kasozi et al. (1999)
This plants are troublesome and react differently once consumed by the animals. Therefore some reference and discussion in order to further understand these plants and how to handle the situation is necessary. More detail on common poisonous plants in Botswana, the main toxin in them, symptoms as well as possible aid can be read below:
||CLINICAL SIGNS OF POISONING
||TREATMENT AND CONTROL
|Pavetta harborii (Legonyana,gouisiekte)
||-Sudden heart failure
||-Chronic inflammation of the heart-No abnormalities at slaughter
|Urginea sanguinea (Sekaname,slangkop)
||– Inflamed gut-Diarrhoea and dehydration
– Muscle tremors
||-Activated charcoal 5g/kg and potassium chloride.
||-Flowers appear before leaves.-Flowers are poisonous.
||-Activated charcoal 5g/kg.-Give atropine for arrhythmia.
|Dichapetalum cymosum (Mogau)
||– Staggering– Restlessness
– Sudden death
||-Activated charcoal.-Delay watering.
||-Poisons the enzyme acotinase.-Arrests cellular respiration.
-Irreversible cardiac damage.
||-Difficulty in breathing.-Muscular Inco-ordination.
-Bright red mucous membranes.
||-Avoid feeding young wilted sorghum
||-Bitter almond smell from rumen.-Take rumen contents 1% mercuric chloride.
-Wilted, damaged young sorghum implicated.
|Solanum spp. (Tholatolwane)
||-Staggering, stiff gait-Unwilling to walk
||-Careful management of pasture
||-Breakdown releases vitamin D3.-Increases calcium levels in the blood causing tissue calcification.
|Brassica ssp. e.g. Rape, kale, cabbage
||-Goitrogens prevent uptake of iodine by thyroid gland.
|Cotton seed cake
||-Detoxify feed with 1% calcium hydroxide plusm0.1% ferrous sulphate
||-Damages heart muscle, slow poison(takes 1-3 months)
|Datura stramonium (Jimson weed)
||-Dry mouth, fast heart rate, blindness, and convulsions.
||-Damages the kidney.
|Amaranthus retroflexus (Pigweed)
||-Trembling, unsteady gait-Depression, diarrhoea
|-Nitrate and Nitrites
||-Fluid around kidneys. Degeneration of kidneys and brain.-Chocolate coloured blood.
||-Damages the liver.
|Ricinus communis (Castor oil bean)
Source: Mushi et al. (1999)
Possible treatment remedies for poisoning
- First thing that should be done when an incidence of poisoning arises is that livestock should be removed with immediate effect from the pastures with the poisonous plants. This is done so as to prevent any further poisoning to other animals that might come across the plants.
- Once the poisoned animals are identified, removal of any of the plants that are still in the mouth and not yet swallowed should be done…that is if it is possible.
- The most obvious and common yet efficient remedy is activated charcoal mixed water to make a suspension. Drenching the poisoned animals will help a lot.
- Drench with large doses of liquid paraffin which acts as a purgative.
- Treat the animals for shock.
- Identify the poisonous plant
- Provide large quantities of strong tea to the animal to prevent further absorption of the poison. It might seem an odd or bizarre measure to go to but the tannic acid in the tea will precipitate alkaloids from the poison and stimulate the animal’s body if it is depressed. But be careful with this remedy as it has to be done after confirming that the poisonous plant does not contain high levels of tannic acid, as if it does…then this would be more lethal.
- Another form of aid would be to give the poisoned animals substances to coat the lining of the stomach, soothing it thus relieving irritation. These substances are known as demulcents and they include a mixture of eggs, sugar and milk.
All in all these remedies are not prescribed by a veterinarian so it is advisable to contact your local veterinary office for further help and also to discuss and execute some of these remedy with your vet as some are likely to have serious side effects or rather unknown reactions. Therefore it is necessary to always contact a vet for thorough diagnosis.