(Drug class: Methylxanthines)
Dogs are particularly sensitive to a class
of chemicals called methylxanthines, and caffeine and theobromine are members
of that family. Dogs simply cannot metabolize and excrete methylxanthines
as efficiently as humans can. The half-life of those compounds in the human
body is on the order of two to three hours; the half-life in a dog is more
like18 hours. What happens in a dog is that the compounds are taken up
by the liver, transmitted via the bile into the intestine, and then converted
back into the original methylxanthines for an-other circuit through the
animal. This repeats itself a number of times. Instead of getting rid of
the substance, the dog keeps re-poisoning himself.
There are many different formulations of
chocolate, with varying amounts of caffeine and theobromine. The mildest
form is sweet milk chocolate, and the strongest form is the dark bitter
product called baker's chocolate. The lethal dose of sweet milk chocolate
for a dog is two ounces per kilogram of body weighs. For an 11-pound dog,
this would be about 10 ounces. A lethal dose of milk chocolate for a 55-pound
dog would be about 50 ounces, or just little over three pounds.
The darker baker's chocolate is at least
ten times as lethal. A 55-pounddog could die from the methylxanthines in
5 ounces of baker's chocolate.
A typical poisoning incident happens around
Easter or Christmas, when there are a lot of chocolates around the house.
Symptoms of methylxanthine poisoning include
vomiting, hyperactivity, restlessness, hypersensitivity to touch (the dog
will jump when touched), very rapid heartbeat and breathing rate, a loss
of control of leg muscles, muscle tremors, then seizures, general weakness,
coma and while rare, death can occur, usually due to the adverse action
of methylxanthines on the heart.
The vet works to clear the chocolate from the dog's stomach,
administers activated charcoal and other substances to absorb the poisons,
keeps the dog's fluids under control and applies other supportive measures
Keep These Numbers Handy
The National Animal Poison Control Center
can be reached at 1-800 548-2423. If you call this number, have
your credit card ready. The flat fee for following your case is $30,
which can be reimbursed.
Another way to reach the NAPCC is to call
1-900-680-0000 This really is the number!). The first five minutes
is $20, with a charge of $2.95 per minute there
after. These charges are not reimbursable.
The NAPCC asks that you always call the
800 number first. They will direct you to the 900 number if need be, but
they say this is generally not necessary.
Both numbers get to the same place. When
you call either one of them, you will be put into immediate contact with
a veterinary toxicologist, and you will be asked to provide the following
a personal note, even though the darker, baking chocolate contains more
theobromine, my mini long, who is a "chocoholic" and seeks it however she
can find it, did manage to get a jumbo sized Hershey Kiss off the counter.
(How? we figure one of the dogs levitated her somehow or assisted in the
plan since there was no conceivable way she could have gotten it herself)
But, even though it was a milk chocolate, she ingested enough so that when
we came home we witnessed a mini running tracks around the house, up walls,
up furniture, bouncing higher than a pogo stick. The only clues were some
red foil in a little tiny ball, chocolate colored and smelling vomit everywhere,
and the most powerful "chocolate breath" exhuding from her little hyperactive
body. We found no remains of the jumbo kiss, and with the clue that
she had to have eaten it, and her amazing strength she had trying to wiggle
out of my arms, I called the emergency clinic (yes, it was 11:00PM) and
told them I was on my way. Have you ever seen a dog run circles in
a carry crate? Chocolate will do it!
The Vet, having listened to her vitals, said her heart
was racing, she was having a caffeine overdose, was so hyperactive she
was impossible to even hang on to, her eyes were showing nastagma (rapid
movement back and forth), but, he felt she just needed to get it out of
her system because she was actually coming "down" from her chocolate binge
and therefore didn't feel we needed to pump her stomach or administer the
charcoal treatment. (she had vomited quite a bit) My duty was to
watch her and make sure she continued to return to normal, but if there
was a change to a negative effect, then to get her right back in there.
Fortunately, he was right and she was beginning to calm down, and by morning
she had become her normal, silly, self. In hindsight I probably would
have been smart to have strapped pledge and a dust rag to her so she could
have done a little cleaning while she was in her "up on everything, around
the walls" mode.