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Why is it important?

Humans can actually tolerate a wide range of different chemicals, many of which are highly toxic to our pets. Add to this the list of substances that are poisonous to humans too, and you've got a massive list of potential hazards to your dog! In this factsheet, we're just going to outline some of the most common poisonings that we see in dogs - what they are, what the symptoms are, and how to minimise the risk.

Rat Poison (coumerins)

The commonest rat baits in use are the anticoagulants, based on the blood thinner warfarin. They work to prevent the rat's blood from clotting, so that they bleed to death. The trouble is, if a dog eats enough, the result is the same! Typically, symptoms don't show up for several days after eating the poison, and include bruising, a rash on the skin or gums, bleeding from the mouth or nose, bloody faeces or vomit, weakness, pale gums, and collapse. If not treated, it is often fatal. If you suspect your dog may have eaten some rat bait, bring them in and we'll get them to throw it up before it causes a problem! There is, fortunately, an antidote, but affected dogs are often very sick and need intensive care and sometimes blood transfusions.

Slug Pellets (metaldehyde)

Metaldehyde slug pellets are a really nasty poison. If eaten by dogs, they rapidly cause twitching, then tremors, then severe seizures that can be very difficult to control. If prolonged, these seizures result in brain damage that may be permanent; more often, they are fatal. The only treatment is hospitalisation, medical treatment to control the seizures - this often involves keeping the dog under anaesthetic for several days - and controlling their body temperature, which tends to rise uncontrollably. Unfortunately, even with every treatment option, the prognosis isn't good, so we strongly advise you NEVER to use metaldehyde slug pellets in your garden.

Antifreeze (ethylene glycol)

This is a common cause of illness in cats, but it also affects dogs, because it tastes so sweet (some animals have even been known to chew into containers to get at it). In the dog's body, it causes symptoms similar to drunkenness (wobbliness, excitement and then sleepiness). However, about 24 hours later, it results in sudden-onset kidney failure, with the dogs being unable to produce urine normally, despite severe thirst. If we can begin treatment before the kidneys start to fail, we can give an antidote and use intravenous fluids to help support kidney function; if not, the prognosis is guarded. Whenever possible, always make sure you only use pet-safe antifreeze; if you do use ethylene glycol, and you notice any missing, get your dog checked out by one of our vets as soon as possible.

Chocolate (theobromine)

A great treat for us - but potentially fatal to dogs! The active ingredient is theobromine, which in low doses causes vomiting and diarrhoea; higher doses cause excitation, muscle tremors, and heart problems, and may even result in seizures. Unfortunately, many dogs love the taste of chocolate, so make certain you keep it safe and sound, well away from marauding pets! If they do break into the chocolate box, the best solution is to call your vets for advice. Some types of chocolate are less dangerous than others (white chocolate, for example, is safer than milk, and dark is the most dangerous of all), but if there's any doubt, the vet will probably ask you bring the dog down to the practice to induce vomiting to empty their stomach.

Human painkillers (e.g. aspirin, paracetamol, ibuprofen)

This is something that comes up over and over again - sometimes due to dogs stealing tablets and eating them, but more often because well-meaning but ill-informed owners try to medicate their animals with human drugs. DO NOT DO THIS! Dogs do not tolerate this family of drugs as well as humans do and are usually smaller too, so even a half a human dose is generally a massive overdose for a dog! These drugs can cause a range of symptoms, including stomach ulcers (causing bloody vomit and diarrhoea), kidney failure, damage to the red blood cells and swelling of the head and face, as well as liver damage. They can easily be fatal, and treatment can be very difficult. Bottom line - keep dogs away from human medicines!

Raisins, currants, grapes etc.

Although safe for humans, vine fruits (grapes, currants, raisins, and anything they're in such as mincemeat, cakes, puddings etc) are potentially highly dangerous to dogs. The exact mechanism isn't well understood, but it results in acute kidney failure. Unfortunately, the toxin isn't consistent - some dogs can eat half a bunch of grapes with no effects and then a month later eat two or three raisins and die of renal disease. The best treatment is prevention - don't allow dogs to eat any grapes or raisins!

Artificial Sweetener (Xylitol)

Xylitol is found in a lot of diet baking products, chewing gum, and some brands of low calorie peanut butter. In dogs, it triggers a catastrophic fall in blood sugar levels, resulting in abnormal behaviour, collapse, seizures and death. If caught quickly enough, affected dogs can be saved with intensive care and blood glucose stabilisation, but many will die before treatment can be sought. Many people feed peanut butter in toys, or to help get tablets down, but if you do - make sure it doesn't contain this lethal ingredient!

Rotten food (tremorgenic mycotoxins)

If your dog raids the dustbins, eventually they'll come across something properly rotten. However, not only can this cause a stomach upset, it can be really dangerous. Mycotoxins are fungal waste products that cause toxicity in humans and animals. Tremorgenic mycotoxins are present in some mouldy foods, in silage and compost, and can also occur in mouldy fallen fruit and nuts. Onset of symptoms is usually within 30 minutes, but sometimes up to 3 hours. Common signs include vomiting, irritability, wobbliness, muscle tremors, excitation, accelerated heart rate and breathing, panting, rolling eyes and dilated pupils. In severe cases, tremors, fitting, convulsions, coma and even death may occur. To keep your dog safe, keep them out of the dustbin!


Many nuts are mildly poisonous to dogs, but in most cases vomiting and diarrhoea are the only likely effects. However, some are more dangerous.Macadamia Nutsare particularly dangerous, and just two or three nuts may affect many different body systems. The symptoms are therefore very wide-ranging, and may include weakness, depression, vomiting, diarrhoea, wobbly legs, tremors, and/or increased body temperature.Salted Peanutscan also be particularly dangerous, causing Salt Poisoning (thirst, abnormal behaviour, convulsions and potentially brain damage). If your dog gets into the nuts, the vet needs to know exactly what they've eaten so they can treat the dog effectively!

In conclusion...

If you think your dog may have eaten anything on this list - or anything else that might be nasty - call your vet RIGHT AWAY. Don't wait until they start showing symptoms - by then it might be too late.