Poisoning can occur on both indoor and outdoor systems but is most likely on smallholdings where there is a greater potential for exposure to poisonous substances.

Early and accurate diagnosis is the key, according to Richard Pearson of George Veterinary Group’s pig practice. “With any health problems in pigs, inclusive of poisoning, an accurate diagnosis should always be the starting point,” he says.

“There cannot really be any treatment without a diagnosis as you do not want to treat for the wrong thing.” If poisoning is suspected then it needs to be investigated and samples sent off for laboratory testing.

Common causes and symptoms

Mycotoxins are one of the most common forms of poisoning. “They can contaminate feed materials or bins but often the symptoms are vague,” says Mr Pearson. “Mycotoxin poisoning can cause slight reductions in production with pigs behaving slightly off from normal, which means it can be quite hard to diagnose.”

Bulk bins and augers are a particular danger, according to Richard Evans of Bishopton Veterinary Group.

“If the fungi become warm and wet they are more likely to produce the dangerous toxins, and if bins or augers are not regularly cleaned out, these can build up.”

In 2014, ergot was a particularly prominent form of mycotoxin poisoning as the right weather conditions meant it could proliferate in certain cereals.

“If ergot bodies are present when the crop is harvested, it can get into the feed and straw. Larger feed companies would always test for this and most agronomists can check for it before harvest,” says Mr Pearson. If it does reach pigs then it can cause dry gangrene to the extremities such as the ears, tail and hooves, as well as patches of skin.

Zearalanone is another common form of mycotoxin poisoning. “It emulates oestrogen and so can often be difficult to notice in pregnant sows,” says Mr Evans.

“It can become apparent once the piglets are born as it causes swollen vulvas, splayed legs and under-developed muscles.” After farrowing it can cause prolapsed uterus and rectum, and is a major cause of prolapsed rectums in growing pigs.

A large dose of the mycotoxin Vomitoxin can make pigs sick within 10 minutes of consumption, with small doses putting them off of their food. “If pigs don’t like eating something, it can be down to mycotoxins being present,” says Mr Evans.

Alcohol poisoning can be caused when pigs are fed on brewing waste. “Brewing grains can continue to ferment which can lead to them having high levels of alcohol in them,” says Mr Pearson. “Once consumed by pigs, it can cause similar effects to alcohol in humans. It can be quite debilitating for them and doesn’t happen that infrequently.”

Salt poisoning or water deprivation is a result of pigs not having access to enough water. “This can be down to water deprivation or feed containing high levels of salts without sufficient water to compensate,” says Mr Pearson.

Wet rations can be one of the culprits as they can be high in salt. “This, combined with marginal water and high temperatures can bring on meningitis-like symptoms as it affects the central nervous system.” Water should be administered slowly, otherwise it could make symptoms worse and result in death.

Coal tars in the form of phenols and cresols can be found in paints, disinfectants and old clay pigeon targets. “Pigs will search these out and they can cause liver damage and subsequent mortality,” says Mr Pearson.

Gas poisoning is relatively rare but can be caused by a build up of carbon dioxide, carbon monoxide or hydrogen sulphide in buildings. “It is reasonably rare as sheds are so well ventilated with good air control now.”

Medication poisoning from antibiotics or vaccinations is also extremely rare. “All pharmaceuticals are rigorously tested before being licensed for use on animals and have extremely high safety ratings, so it is incredibly rare that they will cause problems,” says Mr Pearson.

Plant poisoning can occur from a number of plants and is mostly likely to happen on outdoor systems or smallholdings. Dr Georgine Crawford, senior policy advisor for the National Animal Disease Information Service, says that hemlock and bracken are the most common forms of poising they are alerted to.

Bracken can cause acute heart failure with lung oedema, while hemlock is extremely toxic in small doses. It affects the nervous system and causes congenital deformities in piglets, and can result in death within hours.

Other plants to watch out for include foxglove, cocklebur, henbane, ivy and laburnum.

Prevention and treatment

Treatment must be tailored to the specific type of poison, although more often than not it will be too late to treat the animal by the time a problem has been identified. Prevention is therefore more important than cure.

Vet advice is crucial to help avert problems, says Mr Pearson. “Most vets would be pleased to have a conversation on poisons and if need be, can suggest further advice from colleagues or nutritionists.”

It is also advisable for farmers to be aware of the site they are using for pigs, he adds. Knowing what to look for and checking land and removing potential sources of poison before putting pigs on it will help to minimise risks.

Buying feed from a reputable merchant, and regularly testing it should reduce the risk of mycotoxins, as will being vigilant with storage and feeder cleanliness.

“I have experienced a range of different poisonings as vet, but in all forms, poisoning in pigs is thankfully relatively uncommon.”

September 2015