Red, orange and white forms are the most toxic. Lantana is readily grazed by some cattle without apparent ill effect. Poisoning usually occurs when cattle are introduced to unfamiliar surroundings or when drought or flooding causes a loss of normal feed. Symptoms are loss of appetite and frequent urination, followed by constipation and dehydration. Diarrhoea with strong black smelling, black faeces may occur.
Affected animals show loss of colour.
Photosensitization then occurs with the skin becoming reddened and swollen. The affected skin dies and peels away. Ears may swell and droop. Veterinary treatment using activated charcoal in electrolytes can be used in severe cases. Affected animals should be kept in the shade with access to feed and water.