Dogs love to eat. They’ll consume anything that’s even remotely tasty and, with all the hazards in the average home, their eating habits can land them in hot water. Dog owners need to know what products, food and plants are potentially dangerous. It’s just as important to be able to recognize symptoms of poisoning so that care is sought early rather than later.

Antifreeze

The toxin that strikes most often and causes the greatest number of canine deaths is antifreeze. In a study among B.C. veterinarians, over 1,000 cases of confirmed antifreeze poisoning were identified in dogs and cats in one year. The actual numbers were probably much higher because many cases likely went undiagnosed. That was 20 years ago, and the problem is still seen regularly at veterinary hospitals.

Antifreeze tastes sweet. An inquisitive nose and tongue can easily find a little spill on the street or the garage floor. The lethal dose for dogs is six millilitres per kilogram, which translates to two tablespoons for a 10-pound dog and four ounces for a 40-pound dog. A lesser amount may not be lethal, but it could compromise kidney function.

The first symptom of antifreeze poisoning an owner would detect is a sweet odour on the breath coupled with nausea and vomiting. In just a few hours, this progresses to depression, trembling and an inability to stand.

Antifreeze contains ethylene glycol (EG), which is metabolized by enzymes in the body to oxalate, which then combines with calcium, forming crystals in the kidney tubules. The tubules become blocked, urine production stops, and the dog goes into acute kidney failure.

Treatment is aimed at blocking the metabolism of EG to oxalate. However, to be of any benefit, this must be done soon after ingestion of the toxin, before any oxalate is formed. Many dogs are seen too late to save them.

Antifreeze poisoning can be avoided in two ways. One is by being careful with antifreeze and preventing spills. The other, more effective way is to use the pet-friendly antifreeze propylene glycol, which is not toxic to dogs. All you need to do is ask your mechanic to put this in your car instead of EG. It costs a little more, but could save your dog’s life.

Chocolate

To us, chocolate is an indulgence. Dogs, on the other hand, metabolize chocolate differently, so it can be a poison. An ounce of unsweetened baking chocolate is potentially lethal to a 10-pound dog. It takes about 10 times as much regular (candy) chocolate to have the same effect because the toxins are not as concentrated.

The primary toxin in chocolate is theobromine, a potent cardiovascular and central nervous system stimulant. In the first four to six hours after ingestion, theobromine triggers vomiting, diarrhea and restlessness, as well as excessive urination and drinking.

With a higher dose, signs can escalate to hyper-excitability, muscle tremors, seizures, and increased heart rate and abnormal heart rhythm. Death can occur from cardiac and respiratory failure.

If you think your dog ate chocolate, induce vomiting then give repeated doses of activated charcoal. Once recovered, your dog should have no permanent effects from the poisoning.

Grapes and raisins

Just a few years ago, people gave these fruits to their dogs with no thought that they were dangerous. Now we know better. It seems that some dogs are highly sensitive to an unidentified toxin in grapes and their dried cousins, raisins.

The toxic dose varies considerably. It seems that, on average, a half pound (one-quarter kilogram) of grapes is dangerous for a medium-sized dog. However, there have been cases where the quantity is much less and we think that there is an ingrained susceptibility to it.

Grapes cause acute kidney failure and, like antifreeze, the prognosis depends on how quickly the dog is treated. Early signs must be spotted and treatment initiated as soon as possible. Damage to the kidney tubules can occur in 24 hours to a few days. A delay can be fatal.

Early symptoms of grape toxicity are vomiting and diarrhea, loss of appetite, depression and abdominal pain (the kidneys are sore). It follows the same course as EG poisoning.

Grape toxicity is treated by inducing vomiting, washing out the stomach, then giving activated charcoal to bind the toxin and prevent its absorption. The dog is also put on intravenous fluids to protect the kidneys and enhance toxin excretion.

Xylitol

This popular artificial sweetener is found in sugarless gum as well as toothpaste, beverages, cereals and baked goods. Harmless and very sweet-tasting to humans, it triggers a massive release of insulin in dogs that dramatically lowers blood sugar to life-threatening levels. The toxic dose of xylitol is 0.1 gram per kilogram. It takes only two sticks of gum to kill a large dog.

Within 30 to 60 minutes after ingestion, you will see vomiting, incoordination, depression and even seizures. Treatment is simple – it consists of intravenous glucose to boost blood sugar. This may be needed for up to 24 hours to counteract the lasting effects of xylitol.

Drugs – over-the-counter and prescription

Dogs sometimes get into medications people use on themselves. In some cases, the exposure is accidental; in other cases, owners intentionally give the medication to their dogs. These can be painkillers, anti-inflammatories and varied prescription drugs. Some medications are innocuous; others are fatal.

The problem is that dogs metabolize drugs differently than we do. For example, on a per pound basis, the toxic dose for ibuprofen (Advil®) for dogs is about the same as the normal dose for a person. Ibuprofen can trigger stomach ulcers and kidney failure. Similarly, the dose of acetaminophen is also much lower.
Before you give any medication to your dog, ask your veterinarian if it is safe. Similarly, if a dog gets into your pills, call your veterinarian or the poison control centre for advice on what to do.

Household plants

Plants may be beautiful, but some can be deadly. Poinsettias irritate the digestive tract, causing abdominal pain, vomiting and diarrhea. On the other hand, lilies can damage the kidneys. This is more of a concern in cats, but deserves mentioning.

If you keep plants in the home, find out if they are toxic. The ASPCA has a list of toxic and non-toxic plants on their web site. If a plant is a hazard, keep it out of your dog’s reach.

Onions and garlic

Both fresh and dried onions and garlic can be poisonous. The toxic dose for onions in dogs is about 25 grams per kilogram. This means that a pound of onions could kill a 40-pound dog. This does not have to be eaten in one sitting.

The toxic chemicals in these vegetables are organosulfoxide compounds, which damage the red blood cells and hemoglobin so that the cells break apart and are unable to carry oxygen. The result is anemia.

Dogs with onion poisoning are depressed, have red urine, abdominal pain, a high heart rate and rapid breathing. In severe cases, oxygen therapy as well as transfusions are necessary.

The key with poisonings is to prevent them. Take a little time to scour your home for hazards to your dog. If you are unsure about something, talk to your veterinarian.

A multi-published writer, Jeff Grognet, D.V.M., D.Sc.(Agr.), runs a veterinary practice in Qualicum Beach, B.C., along with his wife, fellow veterinarian Louise Janes, D.V.M.

Photo: Dean Palmer

(This article is a web exclusive for dogsincanada.com. To learn more about our print edition click here)