Aspirin Toxicity By: Dr. Anne Marie Manning Edited by: Dr. Nishi Dhupa

Aspirin toxicity (salicylate toxicity) is poisoning that
occurs following the ingestion of aspirin or aspirin-containing
products. Aspirin toxicity usually occurs because of the ingestion
of improperly stored drugs or the administration of the incorrect
dose of aspirin for dogs.

Cats are more susceptible to the effects of aspirin than are
dogs because they are unable to metabolize the drug as quickly.
Young animals are more susceptible to the toxic effects than are
adult animals.

Aspirin toxicity may cause gastrointestinal problems, respiratory
difficulties, neurological problems, bleeding disorders, and
kidney failure. Gastrointestinal problems are common in dogs
whereas central nervous system depression is most common in cats.

What to Watch For

The most common symptoms of aspirin toxicity are the gastrointestinal
effects such as loss of appetite, abdominal pain, nausea, vomiting,
black stools and lethargy. Aspirin toxicity can lead to ulceration
of the stomach or intestine and, in extreme cases, stomach or bowel
perforation that causes a severe, life threatening, bacterial infection
of the abdomen. Gastric (stomach) and intestinal bleeding may cause
bloody vomit and melena (black, tarry stools).

Aspirin for dogs stimulates the brain’s respiratory center
so most dogs will pant excessively, although the dog may also
experience extreme mental depression with decreased respirations.

Neurological symptoms may include restlessness, anxiety, depression,
incoordination and (rarely) seizures.

Aspirin toxicity can cause acute kidney failure with symptoms such
as vomiting, diarrhea, loss of appetite, lethargy, extreme thirst,
and dilute urine. Owners may also notice that the urine is dilute
(lighter in color) when the dog urinates. The symptoms of acute
kidney failure are almost identical to the gastrointestinal symptoms
of aspirin toxicity.

Aspirin interferes with platelets, which are responsible for helping
the blood to clot. Disruption of platelet function increases the amount
of time it takes the blood to clot after being cut. Spontaneous
bleeding may also occur causing pinpoint bruises to appear in the
skin and on the gums (petechiae).

Related Conditions

Other diseases can have symptoms that appear similar to aspirin
toxicity. These include:

Administration of other non-steroidal anti-inflammatory medications
such as Rimadyl®, Etogesic®, phenylbutazone, flurbiprofen, and
ibuprofen may cause identical symptoms as those caused by aspirin
toxicity.

Administration of steroids can cause vomiting and stomach ulceration
as well as increased thirst, urinations and urine dilution. These
symptoms can mimic those of acute kidney failure.

Gastroenteritis (inflammation of the stomach and intestines) of any
cause can mimic the gastrointestinal symptoms of aspirin toxicity.
History of aspirin administration or intoxication is the best way
to distinguish aspirin toxicity from other causes of gastroenteritis.

Pancreatitis (inflammation of the pancreas) can cause all of the
symptoms associated with aspirin toxicity. Pancreatitis can be
diagnosed and distinguished from aspirin toxicity on the basis of
elevated pancreatic enzymes on the biochemistry profile and
visualization of an inflamed pancreas on ultrasound of the abdomen.

Ethylene glycol (antifreeze) poisoning can cause symptoms similar
to those of aspirin toxicity. A specific test can be performed
to diagnose ethylene glycol poisoning if this is suspected.

Diagnosis

A history of administration or accidental ingestion of aspirin
is helpful to your veterinarian in determining the cause of your
dog’s illness. In addition to obtaining a history and performing
a thorough physical examination, your veterinarian will likely
perform the following tests.

A complete blood count (CBC) is used to assess the dog’s white
blood cell count and red blood cell count. If the dog has intestinal
bleeding secondary to ulceration of the stomach, the red blood cell
count may be decreased.

A biochemistry profile is a blood test used to assess internal
organs such as the kidneys. Elevations in the kidney values indicate
that the kidneys have been damaged. This blood test also indicates
evaluation of the liver and pancreas values, which is important
because diseases of the liver or pancreas could produce symptoms
similar to those of aspirin toxicity.

A urinalysis is performed to assess the kidney’s ability to
concentrate urine. In cases of kidney damage, the urine becomes
more dilute and appears lighter in color.

A blood gas is done to assess the pH of the blood. Animals that
have aspirin toxicity often have a low blood pH (acidosis).

An activated clotting time (ACT) is a blood test done to measure
a dog’s ability to form a clot and to stop bleeding when cut.
Because aspirin may interfere with the ability to form a clot,
clotting tests such as the ACT may be prolonged.

Treatment

Hospitalization is often required for definitive care and may
require two to five days.

Induction of vomiting followed by gastric lavage (pumping the stomach)
to remove undigested pills if the dog is examined within four
hours of ingestion.

Administration of activated charcoal to prevent absorption of
aspirin for dogs from the stomach.

Placement of an intravenous (IV) catheter to administer IV fluids
to re-hydrate and to treat or prevent kidney failure.

Administration of antacids such as misoprostol (Cytotec®),
cimetidine (Tagamet®), famotidine (Pepcid AC®), or sucralfate
(Carafate®) to prevent or treat ulceration of the stomach.

Administration of antiemetic (anti-vomiting) drugs such as
metoclopramide (Reglan®), prochlorperazine (Compazine®) or
chlorpromazine (Thorazine®).

Home Care

If accidental ingestion has occurred, remove any remaining
pills from the environment. Take your dog to a veterinarian
as soon as possible for treatment. If you live more than 30
minutes from the veterinary hospital, call ahead for advice
on whether or not to induce vomiting at home prior to
transportation.

If you have been administering aspirin and you note vomiting,
black colored stools, pale gums, or loss of appetite, stop
giving the aspirin and seek veterinary care as soon as possible.

Preventative Care

Do not administer aspirin for dogs unless instructed to do
so by a veterinarian. Keep bottles of aspirin out of your pet’s
reach, including bottles kept in purses or pocketbooks.

If your dog’s regular care involves administration of aspirin,
give enteric-coated aspirin. Administer aspirin with food to
limit stomach upset and never exceed the dose prescribed by
your veterinarian. Remember: more is not necessarily better.