Why are poisonous plants important?

 When is plant poisoning most likely to occur?

Animals usually avoid poisonous plants.

Generally poisoning occurs when:

 Which factors contribute to plant poisoning?  

There are plant/veld factors and animal factors, which contribute to the likelihood of plant poisoning occurring.

 Plant factors

Animal factors

Most important plant poisonings in South Africa

In cattle

  • Cardiac glycosides (for example, tulp and slangkop )
  • Seneciosis
  • Gifblaar
  • Gousiekte
  • Lantana  
  • Diplodiosis  

In goats and sheep

  • Geeldikkop
  • Vermeersiekte
  • Cardiac glycosides (for example, tulp and slangkop)
  • Seneciosis
  • Gousiekte
  • Diplodiosis  

 Effects of poisonous plants in animals

Nervous signs

Restlessness, sensitivity to sounds and touch, high-stepping, difficulty in walking, muscle tremors, aimless wandering, staggering, stumbling, pushing against objects, star-gazing, blindness, convulsions, paralysis.

Digestive signs

Animal stops eating, salivation, dehydration, fluid from the mouth and nose, vomiting, stomach pains, stomach stops working, constipation, diarrhoea, swollen belly.

In dead animals large quantities of fluid or gas in the gut may be visible, changes in colour and smell of the gut contents, reddening of areas of the gut, bleeding.

Urinary signs

Little or no urine production, swelling of the belly with fluid, change in colour of the urine and the urine may contain crystals (small stones) and the animal drinks a lot.

In dead animals crystals in the kidney, swollen, wet kidneys filled with fluid, large and pale kidneys, change in shape of the kidneys and bleeding may be observed.

Reproductive signs

Difficulty in giving birth, poorly developed or large udder, enlarged belly, enlarged vulva, suppressed milk production, abortions, deformed young, oversized or weak young, males not interested in mating, repeated breeding.

Heart signs

When the heart is affected, an animal may drop dead suddenly, for example, when it is chased or when drinking water.

The animal tends to stand with its head in a low  position and the stomach tucked in. It sometimes grinds its teeth or groans, and the heart rate increases. Bloat, diarrhoea and weakness of the hindlegs can also occur.

In the dead animal you may notice pinpoint or larger areas of bleeding, lungs swollen with fluid, fluid in the chest cavity, around the stomach and in the sac around the heart, froth in the windpipe and a heart that is enlarged, flabby or pale.

Respiratory signs

Increased breathing rate, difficult breathing, animal grunts when breathing, frothing at the mouth.

In dead animals fluid and gas in the lungs, signs of infection in the lungs (pneumonia), and froth in the windpipe may be apparent.

Blood and blood-component signs

Pale, yellow, bluish or brownish colour of membranes, green-tinged faeces, listlessness, animal stops eating, animal will bleed easily, red-wine to coffee-coloured urine.

In dead animals you may notice ulcers in the stomach, bleeding, and pale, yellow, blue or brown colour of the carcass.

Signs of bones and teeth

Itchiness and reddening of skin, scale or crust formation, rough coat, thick fluid on the skin, seeds stuck onto hair, wool or skin, sunburn, especially on white areas and muzzle, hair or wool loss, animals seek shade, feet are warm and painful to the touch, hoof grows outwards and turns up, difficulty in walking.

Some of these skin signs occur because of liver damage.


Signs of bones and teeth

Uneven teeth, mottled or black teeth, animal shifts weight from one leg to the other, stiffness, bones fracture easily.

Liver signs

Vomiting, weight loss, yellow discoloration of membranes, swelling of the belly with fluid, sunburn, swelling of the face, sore feet.

In dead animals you may notice yellow colour of the carcass, bleeding in the body, fluid in the chest and abdomen, hard and small liver, intense reddening of the liver, soft and swollen liver, swollen gall bladder.

How do you know if your animals have been poisoned?

Can plant poisoning be treated?

How to prevent plant poisoning


For further information about recognising poisonous plants in your area, and about preventing and treating poisonings in your animals, speak to your animal health technician or state veterinarian 
or contact 
Animal Health for Developing Farmers
ARC-Onderstepoort Veterinary Institute
Private Bag X05
Onderstepoort 0110 


Information provided by
Animal health for Develping Farmers Programme

ARC-Onderstepoort Veterinary Institute
Private Bag X5


Compiled by Directorate Communication, National Department of Agriculture
in cooperation with ARC-Onderstepoort Veterinary Institute

Printed and published by National Department of Agriculture
and obtainable from Recource Centre, Directorate Communication,
Private Bag X144, Pretoria 0001, South Africa