It’s that time of year when, at least in our household, the tradition
of Christmas includes waistline-altering meals and treats of all
descriptions.
Among these are chocolates, which can be harmful to dogs if eaten in
sufficient quantities. Most of us have heard that chocolate can be bad
for dogs, but do you have to rush your dog to the veterinarian if it
eats a chocolate or two?
Chocolate’s toxicity comes from methylxanthines, specifically
theobromine and caffeine, and levels vary with the form of chocolate.
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In most chocolates, theobromine is the predominant toxic compound and
caffeine is present in much lower amounts.
Theobromine toxicity affects primarily the gastrointestinal, nervous
and cardiovascular systems.
Within a few hours after ingestion, the dog may be restless and may
vomit or have diarrhea. There may be increased thirst and increased
urination. There would likely be increases in heart rate, respiration
rate and temperature. Advanced signs include agitation, weakness,
seizures, coma and death, usually from cardiac failure.
How much chocolate is toxic?
Toxicologists measure the toxicity of compounds in terms of its LD50,
or lethal dose 50, which is the amount of the agent needed to be lethal
to 50 percent of the animals exposed.
The reported LD50 of theobromine is as low as 100 milligrams per
kilogram. As with many agents, severe and life threatening clinical
signs may be seen well below the LD50 in chocolate toxicity.
How much your dog would have to eat to show clinical signs depends on
what type of chocolate was eaten, how much was eaten and how much your
dog weighs.
Mild clinical signs may occur in animals that eat 20 mg per kg of
theobromine, severe signs at 40-50 mg per kg and seizures are likely at
60 mg per kg. This means it would be potentially lethal for an 11 kg
dog to eat 765 grams of milk chocolate and for an 11 kg dog to eat 85 g
of baking chocolate.
These are rough guidelines however, and all dogs will respond
differently.
There is no specific antidote for chocolate toxicity. The treatment is
supportive and symptomatic.
For recent exposures, the dog may be made to vomit. The problem is
that chocolate tends to sit as a gooey mass in the stomach and it is
unlikely the dog would vomit up all of its stomach contents. There is
also a risk that the vomit might be breathed into the lungs if the dog
is having seizures or isn’t mentally alert.
Activated charcoal is given several times each day by mouth in an
attempt to decrease further absorption. Intravenous fluids would likely
be administered and drugs would be given if the dog was having seizures
or significant cardiac problems.
Other treatments would be given on an as-needed basis, such as cool
baths to decrease the body temperature and possibly a urinary catheter
to help get rid of the theobromine. The dog would likely stay in the
clinic for a few days for treatment and monitoring.
