A village farmer from Epukiro once called with the devastating news that he had lost about 20 of his valuable cattle. After thorough questioning about the symptoms, I asked him whether or not he had ever thrown or buried batteries somewhere in the field.
He was uncertain, therefore, I advised him to follow the animals when they go out to graze. While following them, the cattle stopped at a dumping site. After proper inspection, he discovered, amongst others, a lot of car batteries that must have been buried there for many years. He realised that the cattle were even refusing to move away from this “tasty” heap of sand full of batteries. Such mortality was not new to his animals, it finally hit him. The following day, he dropped the bombshell; ‘They have been savouring on batteries!’
The story lead to lead poisoning in cattle. In veterinary medicine, lead poisoning in other species (except dogs) is limited by reduced accessibility, more selective eating habits, or lower susceptibility.
How do cattle get lead poisoning? Cattle can drink engine oil, lick grease from machinery and chew on lead plumbing and batteries. I have heard of many reports of cattle that have been poisoned after eating soil on which used motor oil had been spilled. There is also lead in most paints, thus, if cattle happen to lick discarded paint containers or even discarded painted doors, chances of poisoning are high. Cattle that eat lead are likely to die. Even a small amount of lead is dangerous to cattle. A single vehicle battery left in a field can poison 10 to 20 calves. Other batteries used for those ‘old grandma radios’, you know, those brick-like ones that were once so popular, are also a danger if eaten by calves.
All animals with access to a source of lead are at risk but calves are most often prone to eat lead products because of their curious nature.
Signs of lead poisoning: Lead poisoning is associated with nervous symptoms. A farmer will notice that cattle grinding their teeth, bobbing their heads, or twitching their eyes or ears. Some animals may circle, press their heads or bodies against objects, or become uncoordinated and stagger. Muscle tremors, excitement, mania, blindness or convulsions may also be seen. Most often, the first signs are often depression, loss of appetite or occasional diarrhoea. Clinical signs range from the subtle to the dramatic and take from two days to three weeks to develop. Sometimes, you will find animals that have simply gone down or dead in the field. It is often difficult to distinguish lead poisoning from other diseases that affect the nervous system of cattle such as rabies.
A correct diagnosis is extremely important for identifying the problem and preventing a recurrence of the disease. This can be done during a post-mortem when the dead animal is opened. You might notice oil or lead particles in the stomach and intestines. If batteries were eaten, you would most likely find small lead wires (‘klein swart draaitjies’) in the stomach. What I have often found striking are the small black spots found on the abomasum (small stomach) walls; the walls always seem like someone had used a small cigarette to burn the stomach in different spots. Other non-specific changes in the tissues may be seen such as pale muscles and blood in various organs.
When one or two animals in a herd die or show signs of poisoning, other animals in the herd may also be suffering from lead poisoning. These animals may appear healthy but will grow poorly as a result of sub-clinical lead poisoning.
Can lead poisoning be treated? Treatment is complicated, costly and requires several days of therapy. Combined Calcium-EDTA and thiamine (vitamin B) treatment given IV or under the skin appear to produce the most beneficial response according to some vets. Apparently, the lead will bind to calcium in the blood and is not distributed as fast to cause harm. Personally, I have once tried treating two poisoned calves for days with every trick in the book but they still died. The only times I get it right are when animals suspected of being poisoned do not show signs of lead poisoning. Thus, my advice would be to concentrate rather on a valuable animal such a bull and call a vet for treatment. But in these cases, prevention is easier, cheaper and more effective than cure.
How to prevent lead poisoning: Lead poisoning of cattle can be avoided if a farmer practises good waste management on the farm. The following practices greatly reduce the risk of lead poisoning.
• Fence off any dumping site to prevent access of animals into them and go on a mission to clean them (existing dump sites) up. Service farm machinery in areas that are completely separate from animals. Do not leave petroleum products and engine or motor oils lying around or stored in open containers.
• Dispose of used batteries without spilling their contents. Do not leave batteries in the farmyard or field.
• Use lead-free paint on fences or other structures in areas accessible to livestock. Keep paint cans closed and do not discard them in areas accesed by livestock.
• Namibia is known for free-roaming cattle, thus, avoid holding animals in a yard for too long, it may be difficult to eliminate all toxic substances or to ensure that others take the same precautions.
Finally, it is beneficial to be knowledgeable about lead poisoning and informed about the hazard it presents to livestock. Discuss waste management practices with neighbours and other producers to develop a community awareness of the hazards to cattle from lead.