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Antifreeze: A Deadly Poison to
Our Pets
By Greg Pietsch, DVM
 Fall
is a busy time of year for everyone.
You’re getting kids back to school,
trying to finish those summer
projects, and getting the car ready
for winter. This time of year we get
concerned about one of the most
serious poisonings that we see in
dogs and cats….ANTIFREEZE.
Antifreeze is essential to keeping
your car running during the winter.
Many people have an old jug of it
lying around in the garage or
basement. Many people’s cars may
also develop a leak in the radiator
over the course of the winter and
there may actually be antifreeze on
the driveway or garage floor.
The active ingredient in most
antifreezes is called ethylene
glycol. This works as antifreeze
because it lowers the temperature at
which water freezes. Unfortunately,
ethylene glycol has a sweet flavor
and is often consumed by cats and
dogs (and even children).
Ethylene glycol is extremely toxic.
Initially ethylene glycol causes
similar symptoms to alcohol
ingestion such as depression,
weakness, and difficulty walking. In
short they may act drunk for several
hours. This generally resolves
within several hours and the pet may
appear fine. However, ethylene
glycol causes massive and severe
damage to the kidneys and within 1-3
days kidney failure occurs.
Kidney failure caused by ethylene
glycol toxicity is severe and
progresses rapidly. Symptoms seen
often include lethargy, loss of
appetite, vomiting, increased thirst
and urination. These symptoms
develop rapidly because the ethylene
glycol and its breakdown products
essentially kill the kidneys. By the
time these symptoms are present
treatment becomes much more
difficult and many animals will die
despite treatment.
Because ethylene glycol toxicity is
so severe and often fatal the best
treatment is prevention. Do not
store antifreeze in your house or
garage where pets or children may
have access. Make sure that there is
no antifreeze leaking from your car.
If there are any spills of
antifreeze clean them up
IMMEDIATELY.
My Pet May Have Consumed
Antifreeze….What should I do?
If you think that your pet may have
consumed or had exposure to
antifreeze contact your veterinarian
IMMEDIATELY. If this occurs when
your veterinarian is closed you
should contact a 24 hour emergency
facility (these have become common
all over the country and usually
there is at least one just a short
drive away).
Some antifreezes are so-called
“Safe” antifreezes. These generally
contain propylene glycol instead of
ethylene glycol. While these are
less toxic than the ethylene glycol
antifreezes they can still cause
significant harm and you should
contact a veterinarian immediately
if your pet ingests them.
Rapid treatment of antifreeze
poisoning is essential. If the
poisoning is treated before the
ethylene glycol has a chance to
damage the kidneys, most pets will
do well and have no long term
effects.
However, once kidney damage begins
occurring it may be too late.
Treatment of ethylene glycol
toxicity involves inhibiting the
alcohol dehydrogenase enzyme (the
enzyme that breaks down alcohol).
Alcohol dehydrogenase breaks
ethylene glycol down into more toxic
components which attack the kidneys.
By blocking the breakdown of
ethylene glycol into its more toxic
byproducts it is less likely to
cause damage to the kidneys and it
is slowly excrete from the body.
There are 2 medications available
for the treatment of ethylene
glycol.
1. The original treatment is the
intravenous administration of
alcohol (ethanol). Essentially, the
patient is made drunk. The alcohol
fills up all of the alcohol
dehydrogenase enzyme sites and the
ethylene glycol cannot be converted
to its toxic components and is
excreted. While this treatment can
be effective it is not ideal. As
most people are aware alcohol has a
number of serious side effects, in
most cases it must be administered
for at least 24 hours. Do not
attempt this treatment at home.
2. A newer medication is called
Fomepizole (also known as 4-MP or
Antizol). This is the preferred
treatment of ethylene glycol
toxicity. It blocks the alcohol
dehydrogenase enzyme without
producing the serious side effects
of ethanol.
Most pets will also receive IV fluid
therapy as part of their treatment.
Hemodialysis is also an effective
treatment but this treatment is
limited to universities and is
expensive.
Remember, antifreeze can be deadly.
Use care if you are using it. Make
sure you immediately clean any
spills and discard any unused
antifreeze (contact your town for
proper disposal practices). If you
have any concerns that your pet has
been exposed to antifreeze call your
veterinarian immediately. If
treatment occurs within 8 hours of
ingestion the prognosis is usually
good. After 8 hours the prognosis
rapidly declines and many pets will
die or have permanent kidney damage.
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