A range of poisons – some obvious and others hidden – can be found on farms. Story and photos by Karen Trebilcock.

Before Christmas, the death of a South Otago dog after licking leftover milk replacer made headlines.

The Labrador cross named Oscar was found panting and dragging its legs before being rushed to the vets, but it was too late.

The owner said he never realised milk powder could kill a dog. And who would?

It’s just milk powder right?

Wrong. Like so many other products we use on our farms they can be deadly if fed to the wrong animal.

Poisons are hidden everywhere.

What likely killed Oscar were the coccidiostats often included in calf, lamb, chicken, dairy and even rabbit feeds which are used to reduce the risk of the parasitic infection.

They come under different names including Bovatec®, Rumensin®, Deccox® and Cycostat® and the feed must clearly state on the label that it should only be fed to the species it’s intended for.

As well as your family dog, horses, donkeys, alpacas and llamas can also die after eating it.

Be careful too with Rumensin used for bloat prevention and as a growth promoter for cattle.

It contains monensin which is one of a group of drugs called the ionophores and is deadly to all animals with one stomach instead of four.

Even washing out a Rumensin container to reuse it won’t mean you have got all of it out as the plastic can absorb it.

Chicken food, unless it is feed grain, will have a warning on the bag not to feed to ruminants. This isn’t because it is poisonous for them, but because it contains non-dairy animal protein, or was made in a mill where animal protein is used.

Feeding animal protein to cows is what caused the outbreak of mad cow disease (BSE) in the United Kingdom in the 1980s and 1990s.

A good rule is only give the product to the animals which are pictured on the label and make sure all the rest of the animals on your farm can’t access it.

Then there is fertiliser. Phosphate also contains fluoride and too much is deadly.

Paddocks grazed too early after superphosphate has been spread can result in fluoride poisoning. It can cause damage to kidneys, liver, lungs, the nervous system and ultimately lead to death.

Applying too much molybdenum, the clover enhancer, can also be deadly and unlike phosphate a good shower of rain won’t fix it.

Urea is not much better.

Cows can eat a certain amount but it’s easy for it to become toxic.

If too much is consumed it is converted into ammonia in the rumen and enters the bloodstream. If the liver can’t cope then it affects the brain and the lungs. Early signs are cows wobbly on their feet, aggressive behaviour, salivating, bloating and difficulty breathing.

A North Island farm found this out when it used a plastic container, which had held urea but had been well washed afterwards, to top up water troughs on a hot summer afternoon.

Even with vets called quickly when they realised something was very wrong, more than 120 cows of the herd of 600 died.

They treated it by stabbing the rumen as if for bloat, removing as much of the rumen contents as possible and pouring in about five litres of vinegar to neutralise the ammonia.

The lesson is, only use containers for their intended purpose, then send them to the recyclers.

Another past headline-maker was the death of about 100 cows in Southland after fodder beet was planted on land that had been used by a shooting club.

The soil was contaminated with lead pellets and when the fodder beet paddock was fed during the winter the cows ingested enough lead to either kill them or require them to be euthanised.

Their carcases had to be disposed of at a site approved by the regional council so they could not further enter our or anything else’s food chain.

If in doubt, before planting winter crops, soil should be tested to make sure there is nothing there that shouldn’t be.

DDT is on that list as it wasn’t until 1989 it was completely banned. Levels of the widely used insecticide for grass grub and porina moth are slowly falling but traces can potentially still affect milk and meat products.

Owners of farms that once ran sheep should also know where the sheep dip site was.

At one time sheep had to be dipped or sprayed by law with insecticides such as lindane, dieldrin and arsenic to stop lice and other parasites in the wool.

Arsenic was used in footbaths to stop footrot and copper and zinc still are.

These are not the places where you should raise your calves, grow your winter crops, and especially not your own veges.

Add to that list old buildings, or where they once were. Lead was added to paint until the early 1980s to hasten drying time and increase durability. Unfortunately calves and cows like to lick or chew wood with lead paint and it can quickly kill them.

Lead paint testing kits are at most hardware retailers and are cheap and easy to use. Google ways to safely remove lead paint if you find it.

But our use of poisons is not so last century.

Cattle have died from arsenic poisoning after grazing where tanalised timber was burnt.

And then there are plants. Be aware that ragwort, macrocarpa, rhododendron, camellia, foxgloves and lilies, unripe acorns, avocado, oleander, ngaio, tutu, poroporo and a whole lot more are poisonous to cattle. If you suspect your cows have eaten any of these call your vet quickly as there are some treatments that can minimise symptoms and stop your cows dying or aborting.

Always check paddocks, especially after a strong wind, if the trees are nearby and if your cattle graze next to gardens, ensure the fences keep them away from any shrubs.

Make sure garden clippings are never dumped over the fence for your cattle to eat. Often neighbours mean well but let them know just how deadly their habit can be for your cows.

Most food waste (except non-dairy animal protein because of the risk of BSE), can be fed to cows such as apples and even lollies but don’t feed them stone fruit as the stone contains cyanide which is released when crushed.

Even mouldy hay can kill your cattle, although in one case it led to a lifesaving discovery for humans.

When cows in Wisconsin ate mouldy sweet clover hay in the mid-1930s, scientists realised the cows were dying because the fungus growing on the hay was stopping their blood from clotting.

It’s how the blood thinner warfarin, used by many following a heart attack, was found.