What your pet shouldn't eatThere is a lot of discussion among dog owners regarding certain foods that are supposedly poisonous or not. When talking about potentially poisonous substances we should keep in mind the (in)famous father of toxicology, one Mr. Paracelsus of Switzerland and his famous saying “the dose makes the poison” (http://en.wikipedia.org/wiki/Paracelsus). Put another way, whichever substance you consider, it may be a poison in a large enough quantities. To turn it around, not every poison is poisonous if taken at a low enough dose. Here are just some of the more “controversial” foods our vets have been asked about in their professional careers.
This is the most asked about food in relation to its toxicity. The compound in chocolate that causes serious concern is called 'theobromine'. It is also known as 'xantheose' and is part of the methylxanthine group of chemicals, which includes the very well known caffeine (found in your morning coffee) and theophylline (found in your afternoon cup of tea). It is present in all kinds of chocolate, but in very different concentrations.
The basic rule to follow is the
more cocoa in the chocolate, the higher the levels of theobromine.
Plain or dark chocolates contain more cocoa than milk chocolates and
have 4.5-10x more theobromine in them. The amount of theobromine in
chocolate varies from one manufacturer to another, but a toxic dose
(the dose, where your pet may show signs of poisoning) for a 20kg dog
would be about 600-900g of milk chocolate and about 130-200g of dark
So giving your average collie a small piece of chocolate shouldn’t harm him, but you shouldn't give him a whole bar.
Theobromine/chocolate can cause problems in humans as well as dogs, but it takes higher doses to cause more than a bit of guilty conscience! This is because animals metabolize theobromine much more slowly than humans. Clinical signs of theobromine poisoning appear within 10 hours of ingestion and include vomiting, diarrhoea, excitability, irregular heart rhythms, and a slow heart rate. The vomiting and diarrhoea can cause a severe loss of body fluids (dehydration). Later stages of poisoning include epileptic-like seizures and even death. The term death by chocolate should not be taken lightly!
Dogs in particular may eat dangerous amounts of chocolate, especially around Christmas and Easter. However cats (especially kittens), horses and parrots are known to be very susceptible.
If you suspect that your dog has eaten a large quantity of chocolate (particularly dark/plain varieties), consider contacting your vet as soon as possible. Treatment can potentially save your dog’s life! This may include inducing your dog to vomit, limiting the absorption of the toxin by administering activated charcoal as an absorbent, and intravenous fluid therapy to prevent dehydration.
Grapes (including raisins and sultanas)
This may be becoming a bigger
problem in recent years with more reported cases every year. There
is a lot of potential danger with grape ingestion. Even small
quantities (9g - 18g) of grapes or raisins have been associated with
acute kidney failure in dogs and even death. The toxicity relates to
all products of the woody climbing vine (latin: Vitis
Clinical signs occur between 6 and 48 hours after ingestion. They include loss of appetite, vomiting, lethargy, shivering and increased water intake. The danger of grape toxicity is great, with high mortality rates. In many cases the owner will not even know their dog has eaten grapes.
What actually causes the poisoning is currently
unknown and there are many trials under way to try to shine light on
the problem. One of the possible culprits could be a toxin from a
fungus called a Mycotoxin, but so far nothing has been confirmed
As with chocolate poisoning you should contact your vet if you suspect your dog has eaten grapes or raisins. The therapy is supportive and quite similar to the one for chocolate poisoning.
Onions (including garlic, shallots, leeks and chives)
The toxicity relates to all plants from the latin
named Allium species but the most common plant that causes problem is
the onion (latin: Allium cepa). All parts of the plant, whether raw
or cooked, should be considered poisonous. The plant actually
contains several toxins but only one of them is the biggest cause of
problems as it causes a condition called a haemolytic
Clinical signs take one to five days to develop and include vomiting, diarrhoea, abdominal tenderness, loss of appetite and change in urine colour.
Treatment is, again, supportive, but in severe cases a transfusion might even be required. This poisoning is rarely fatal and dogs usually recover without any complications.
The exact cause of this toxicity
is, similar to grapes, unknown but the fungus toxin Mycotoxin is a
real suspect. These probably get onto the nuts during
Clinical signs include weakness, especially in the back legs, vomiting and elevated body temperature and start within 12 hours after intake. They recover after a day or two and the positioning is considered non-fatal.
Bread doughDue to the indiscriminate feeding habits of dogs they are most susceptible to bread dough related problems although other animals can also be affected. Bread dough is a two-fold problem: the warm and moist environment of the stomach acts like a great incubator for the yeasts in the dough and causes the dough to produce a lot of CO2 (carbon dioxide) that makes the dough rise. This can cause stomach distension and in severe cases gastric dilatation and torsion, which some of you will know is a very serious and often fatal condition.
The other side-product to a rising dough is ethanol (also known as the alcohol found in alcoholic drinks). Its results cause various degrees of alcohol intoxication and a condition called a "metabolic acidosis".
Bread dough poisoning can be fatal and is mostly because of the alcohol effects rather than the gastric torsion.
Treatment is not straight forward as the dough cannot be removed from the stomach with usual methods and in many cases a surgical removal might be needed. The effects of the metabolic acidosis can be treated with various medications and intravenous fluids.
Antifreeze (ethylene glycol)
All animals are susceptible to this poisoning, but it is most common seen in dogs and cats. The most common way of poisoning is ingestion of car antifreeze, solar panel coolant, some break and transmission fluids but here have been cases in cats where the animal was poisoned through skin absorption. The poisoning is unfortunately quite common, especially if there is no access to drinking water. An added problem is the quite sweet taste of the antifreeze and thus its inherent high palatability amongst dogs.
The minimum lethal dose of undiluted ethylene glycol is 1.4 ml/kg body weight in cats and 4.4 ml/kg in dogs. Please beware that younger animals may be more susceptible!
The clinical signs of intoxication vomiting, increased drinking and increased urination, decreased body temperature, seizures and even coma.
In case of ingestion you should contact your vet as medication needs to be started straight away, preferably within 12h of intake.
Cats are unfortunately very sensitive to different varieties of flowers from the lily family. Eating even a very small amount of leaves or flowers can be fatal as it causes severe kidney failure. It is sometimes enough for a cat to get her fur into contact with pollen (for example by rubbing herself against it) and then grooming herself and thus licking up and ingesting the pollen.
The exact poison in the lilies that causes these very dangerous problems has not yet been identified. Here are some of the lily species that are dangerous: Easter lily, Tiger lily, Japanese show lily, Rubrum lily, day lilies and various lilium hybrids.
Signs of poisoning you should watch out for are vomiting (can occur up to three hours after ingestion), salivation, loss of appetite, sleepiness. You should seek immediate veterinary assistance!
Unfortunately there is no antidote for this posioning and is often fatal. The veterinarian can help survival by intravenous fluids, clipping the cat's hair and vigorous washing.
Permethrin poisoning in cats is unfortunately still quite common and is in most cases due to owners mistakenly giving dog-only spot-on flea treatments to their cats. If you have applied a permethrin product to your cat seek veterinary assistance immediately!
Signs of poisoning are: muscle tremor (shivering), increased salivation, vomiting, weakness.
Unfortunately there is no antidote for this poisoning and can be fatal in severe cases. The poisoned needs to be given medication to relieve the muscle tremors and prevent an increase or decrease in the body temperature.
Xylitol is a popular sweetener in human food, but can cause a severe drop in an animal's glucose levels as it works similar to insulin.