Poison Guide

A Pet Owner’s Guide to Common Small Animal Poisons 

Table of Contents


Household Products



XXX – Emergency!

  XX – Highly Dangerous

    X – Dangerous


It is difficult to give concise information about plant
toxicities as there are hundreds of plants that are potentially
poisonous to animals(1).
However, actual reports of animals getting seriously ill from
eating plants are relatively infrequent compared to reports of
poisonings from household products or drugs. The plants
discussed below can be found in Minnesota and represent among
the most dangerous of poisonous plants. You may notice the
conspicuous lack of “holiday plants” among the list.
While many people seem to think poinsettias, ivy and mistletoe
are dangerous plants, and while these plants have toxic
potential, they seldom cause serious clinical signs if eaten.

It is worth noting here that dogs and cats often vomit after
chewing on plants; this probably does not represent
“poisoning” or any dangerous exposure. Only severe or
persistent vomiting is a danger sign in small animals. Sporadic
vomiting without accompanying signs of illness (for instance,
diarrhea, depression, loss of appetite) is rarely a cause for
worry, whether associated with plant ingestion or not. The best
advice, however, is to contact your veterinarian if you have
specific concerns.


Scientific Name — Taxus cuspidus

Common names — Yew, Spreading English Yew, Canada Yew

Plant with similar toxicity: Zygadenus nuttzii, common
name Deathcamas.

The Yew plant is an ornamental yard plant, most often used in
landscaping around the foundation of a house. It is an extremely
poisonous plant and the animal needs to eat only one-tenth of
one percent of its body weight to get a toxic dose. (For
example, a 50 pound dog would need only 0.05 pounds or less than
2 ounces of the plant to get a potentially fatal dose!)

The toxin in the Yew is an alkaloid and works by depressing
electrical activity in the heart. Signs may include sudden death
from heart failure. If the animal shows clinical signs of
toxicosis other than sudden death those could include:
trembling, incoordination, diarrhea, and collapse.

We rarely recognize clinical cases of JapaneseYew poisoning
in animals at the University, although that may be partly
because of the difficulty in proving the presence of the toxin
as well as the great toxicity. In cases where animals are found
dead it is very difficult to prove the Yew caused the death
unless the animal is necropsied (a veterinary term for an
autopsy) and evidence of ingestion – evidence that the animal
actually ate the plant — is found. There are no specific blood
or chemical tests to determine if Yew toxicity is present. While
Yew poisoning does not seem to be very common, the best advice
is to know what ornamental plants are present around your house
and other buildings and to make sure the Yew is not one of them!


Scientific name — Many, including: Schefflera
, Dieffenbachia maculata, Begonia
, Philodendron

Common names — Starleaf, Tuftroot, tuberous begonia, wax
begonia, water plant, yellow calla, peace lily, etc.

This family of house plants and ornamentals contains oxalates
and causes toxicity by the formation of calcium oxalate crystals
in the animals organs and by causing the release of chemicals in
the body which can cause an acute allergic reaction. Signs may
include excessive salivation, head shaking, pawing at the mouth,
difficult breathing, vomiting, and diarrhea.

Fortunately, the plant causes pain and irritation on chewing
and therefore animals rarely eat it in sufficient quantities to
cause severe damage. Much of the motivation for chewing on such
a plant involves boredom and other psychological factors (recent
changes in the household, etc.) so it may be worth noting if an
animal begins suddenly eating house plants they used to ignore
and discussing the subject in a phone call or visit to your
veterinarian. If your household plants include any of those in
the Araceae family, be aware of the potential for toxicity and
preferably keep the plants away from the pet or switch to safer
house plants.

(and other cardiac glycoside containing plants)

Scientific name — Many, including: Rhododendron, Nerium
, Digitalis purpura.

Common names — Rhododendrons, milkweeds, lily-of-the-valley,
laurel, oleander, azalea, foxglove, etc.

This group of common plants all contain cardiac glycosides.
Cardiac glycoside drugs derived from one of these plants,
digitalis (foxglove), have been used for many years in the
treatment of heart disease in people and animals. Due to their
actions on the heart, however, ingestion of plants containing
glycosides can be fatal. Signs may include vomiting, diarrhea,
collapse, or death from heart failure. Fortunately, the plant
has a bitter and very unpleasant taste! Nonetheless, the
American Association of Poison Control Centers (AAPCC) report
covering 425 fatal animal poisonings in 1990 includes 4
resulting from cardiac glycoside-containing plants.


Scientific name — Many, including: Solanum dulcamara,
Solanum nigrum, Physalis.

Common names — Nightshades, Chinese lantern, Christmas cherry,
Ornamental pepper

These primarily ornamental plants contain toxins called
solanines that affect either the stomach or the brain, depending
on the type of poison contained in the plant. It should be noted
that some plants contain no poison whatsoever and it is
impossible to be certain whether a given plant contains the
poisonous substances. Clinical signs of toxicity for the plants
containing the stomach poison include severe gastrointestinal
upset, such as vomiting, diarrhea (possibly bloody), abdominal
pain. If the toxin affecting the brain is present in the plant
eaten, signs may include drowsiness, salivation, difficult
breathing, trembling, weakness and collapse. The AAPCC report
indicated 2 of 425 fatal poisonings occurred as a result of
poisoning by solanines.


Animal poisoning by drugs is by far the most common type of
small animal poison exposure, accounting for 75% of 1990 toxin
exposures as reported by the AAPCC and 82 of 425 fatalities.
Dogs and, less frequently, cats, can be poisoned by human or
veterinary drugs as a result of accidental ingestion or overdose
just like children can; it is worth emphasizing that all
medications should be placed out of reach of inquisitive noses
which are too often attached to undiscriminating mouths!

This section focuses on those medications which are too
frequently given by well-intentioned owners for the purpose of
relieving discomfort experienced by the animal and which instead
can cause a much more serious problem for the pet. Human
over-the-counter pain relievers are occasionally used in
veterinary medicine for pain relief but they should only
be given upon specific advice and direction of a veterinarian
Pain relievers, or analgesics, are not designed for use by cats
and dogs and a minimal human dose can poison a pet. Cats and
dogs do not utilize and tolerate drugs in the same way people do
and human drugs should NEVER be assumed to be safe for animals.


Tylenol is, of course, the human over-the-counter analgesic
medicine used to relieve pain. In people, after the pills are
taken, the ingredients are broken down in the body by enzymes in
the liver. In people, Tylenol is generally a safe and useful
painkiller. Cats, however, have less of the enzyme required to
detoxify the drug following ingestion. As a result, there are
many dangerous metabolites, or break-down products of
acetaminophen that bind to red blood cells and other tissue
cells, resulting in the destruction of these cells. There may
also be direct damage to tissue cells from the painkiller. As
little as one regular strength tablet (325 mg) can poison a cat
to the degree that it can develop noticeable clinical signs of
illness. Two extra-strength tablets are likely to kill a cat.
Dogs (particularly small dogs) are also susceptible to
significant tissue damage from as little as two regular strength
Tylenol and repeated doses increase the risk significantly.
Signs develop quickly and can include salivation, vomiting,
weakness and abdominal pain.

Due to the significant toxicity to pets in relatively minimal
dosages, the recommendation is clear — Tylenol should
not be given to dogs or cats
. Other, safer, drugs are
available for pain relief; talk to your veterinarian about your
own pet’s specific needs.


The pain relievers discussed here are known as NSAID’s
(non-steroidal anti-inflammatory drugs) and are widely
prescribed with caution by veterinarians to relieve pain from
arthritis and other conditions. Animal dosages, however, are
much lower than human dosages. Use of NSAID’s can significantly
increase the risk for development of stomach or intestinal
ulcers, particularly in a sick patient, or one receiving other
medications. These pain relievers cause signs of poisoning by
decreasing the mucous production in the stomach. Mucous serves
to protect the stomach from the acids it secretes and reduction
in mucous production decreases the protection the stomach has
from acid secretion and increases the likelihood of ulcer
formation. In addition these drugs indirectly decrease the blood
flow to vital organs, particularly the kidney, and can result in
significant kidney damage. Two regular strength aspirin in a
small dog can cause clinical signs of poisoning. As with
Tylenol, cats are more sensitive to these drugs
and should never be given these medications unless under the
specific direction of a veterinarian.

Again, these drugs can be safely used and, in fact, are
employed in veterinary practice every day in appropriate doses
and after careful medical evaluation of the patient. The
important point is to recognize that dogs and cats do not
respond in the same way to human medications that people do. Any
medications need to be discussed with and prescribed by a
veterinarian prior to giving them to your pet
to avoid
an inadvertent and tragic poisoning.


The category of “household products” probably
contains most of the non-drug substances that poison animals
throughout the country each year. This would include
insecticides designed to kill ants, fleas, termites, wasps,
etc., pesticides against rats, mice, gophers and other unwanted
pests, herbicides to kill weeds in our yards and gardens,
cleaners for our homes and businesses, and ethylene glycol and
fuel and other petroleum products used in cars, heaters, and
even lighters. These are products which are both widespread in
use and frequently highly toxic. The combination of being common
and deadly frequently results in a very dangerous situation for
household pets who share our homes, cabins, yards and cars.

For ease of reading and organizational purposes, I have split
this category into five narrower groupings. Remember, however,
it is the toxic active ingredient in the substance the pet is
exposed to which will determine how much danger is present.
Therefore, it is critical in any case of potential
poisoning to find the container of the toxic substance and know
the ingredients when seeking advice or veterinary services
All rat poisons are not alike and the same is true of ant
poisons, herbicides, flea products, etc. Different poisons may
require very different treatments and it is necessary to know
the active ingredient in a potential poison to know how to treat
an exposed animal and to give a reasonably accurate prognosis.
Ideally, the veterinarian should have the intact container with
the label when evaluating the toxic potential of the product.


There are dozens of insecticides available in hardware and
home repair stores designed to kill ants, termites, wasps,
garden pests and many other nuisance insects. Unfortunately,
these products present a risk to our household pets when a dog
or cat is accidentally exposed to the poison, usually by eating
the bait or poison. Although there are a host of different
active ingredients found in these preparations, many of them can
be grouped into two categories: Organophosphates and carbamates.

Both organophosphates (known as OP’s) and carbamates have
similar toxic effects which involve disruption of the normal
nervous system function by causing an excess of the
neurotransmitter, acetylcholine, to accumulate in the body.
Although acetylcholine is a necessary body chemical for normal
nervous and muscular function, this excess or overdose, causes
severe clinical signs that can result in the death of the
animal. If an animal is exposed by eating a poison containing
OP’s or carbamates (or, less frequently, absorbing the substance
through the skin in a dip product) it can experience a number of
clinical signs. These include excess saliva production,
lacrimation or tearing of the eyes, excessive urination,
diarrhea, muscle twitching, weakness, difficult breathing and
collapse. It is critical than an animal potentially exposed to
these insecticides be evaluated by veterinary personnel as
quickly as possible in order to provide treatment if necessary
before signs become severe, at which point treatment is often

There are many other types of insecticides besides OP’s and
carbamates, including: Chlorinated hydrocarbon compounds,
pyrethrins, arsenic and others which have different poisonous
properties and which may require different treatments for
accidental exposure. As mentioned earlier, in the case of an
accident, it is important to get the container with the label
including the insecticide’s active ingredient(s) and bring that
information to the attention of the veterinary staff. They can
then determine the type of toxicity and any possible treatments
as quickly as possible, preferably before the pet is very sick.
Many of these products are extremely toxic and any delay in
evaluation of the cat or dog can be life-threatening.


Poisoning by antifreeze, or ethylene glycol, is one of the
most common small animal toxicities, particularly up here in the
cold north. Every year do-it-yourself motorists get out the gear
needed to winterize their vehicles, including antifreeze.
Unfortunately, this poison has a sweet taste and spilled or
leaked antifreeze is lapped up by many dogs and cats in
quantities sufficient to cause severe sickness and even death.

It takes only about 1/2 teaspoon per pound for a dog to get a
toxic dose of ethylene glycol, the active ingredient in
antifreeze, and less for a cat. Although the poison affects both
the animal’s neurological and kidney function, the most severe
damage usually involves the kidneys. Clinical signs in affected
animals include depression, incoordination, vomiting, and
seizures. The best way to combat antifreeze poisoning is by
preventing the animal from having the opportunity to drink the
poison. Keep all containers tightly closed when not in
use and clean up spills immediately
. It should be noted
that this toxin affects people as well as pets and that small
children are also at risk for ethylene glycol poisoning.

There is currently a new product on the market (one trade
name is Sierra) which claims to be safer than
other brands of antifreeze. This product contains propylene
glycol as its active ingredient. If ingested, it can still cause
the nervous system injury resulting in incoordination and
possibly seizures but does not cause the more frequently fatal
kidney damage. It is clear using such a product would pose less
of a health hazard. The best advice remains, however, to always
use any potentially toxic product carefully to prevent
accidental poisoning in the first place.


Again, this category contains dozens of products used around
the home including toilet bowl cleaners, bleach, detergents,
caustics (e.g., Drano, Ajax), pine
oils and others. Although intended to keep our lives safe and
healthy by maintaining a clean environment, these products are
often highly poisonous to living tissue if a dog or cat eats or
becomes otherwise exposed to the chemicals in the cleaner.

These cleaners can destroy tissue on contact by acid or
alkaline burns, by dissolving through tissue membranes, by
absorbing through to the animal’s bloodstream and causing
generalized illness and a variety of other mechanisms. Pine oils
and electric dishwashing detergents particularly tend to be
quite toxic although the range of chemicals included in cleaning
products can cause signs varying widely from mild local
irritation (many detergent soaps) to deep penetrating tissue
damage (alkaline products) to severe systemic disease (pine oils
and others). Once again the best remedy is prevention.
Keep all cleaners tightly closed when not in use to prevent
accidental spills and ingestion
. Also, be sure to keep
pets out of newly cleaned areas to avoid paw injuries from
walking in the newly applied cleaning solution and mouth burns
from the animal then grooming itself. Also be aware of the
possible dangers of toilet bowl cleaners from dogs and cats who
consider the toilet just another water bowl! In case of
accidental exposure to cleaning products, it is generally
recommended to flush the skin (or mouth) with plain water to
wash away remaining chemicals, then call in to your veterinary
clinic for further instructions. In the AAPCC 1990 report, 5.9%
(2,217 animals) of all non-drug poison exposures were inquiries
following exposure to cleaning products, with 80 of those
animals being moderately to severely affected.


Millions of dollars are spent every year on products designed
to rid our non-human companions (and our homes!) of these
unwanted pests. Fleas are highly irritating to dogs and cats and
can sometimes result in severe flea bite allergies for those
animals who develop a sensitivity to proteins in the flea’s
saliva. Most of the products on the market to combat these
insects (the most common of which is Ctenocephalides felis,
the cat flea) create few problems when used as directed.
Unfortunately, some dog flea preparations can be toxic to cats
and almost all topical flea preparations (dips, sprays, etc.)
can be poisonous if not used in accordance with label
instructions. If label instructions are for once weekly use, and
the product is used daily or more often, poisoning can result.
If premise sprays, specifically not for use directly on pets,
are used on or near pets, poisoning may result. The message is
clear — use brand names you are familiar with (ask your vet
for recommendations if you’re not familiar with any specific
products), and use according to label instructions.
STOP use if your animal shows any abnormal signs (possibly poor
appetite, depression, vomiting, diarrhea, excessive salivation).
Excessive drooling may be caused only by the taste of the
product, or may truly be of concern. Contact your veterinary
clinic. Consider bathing your pet in warm water with diluted
liquid dish detergent to remove flea products from the hair and
skin oils, thereby limiting your pet’s exposure.

Every year hundreds of animals are poisoned by these
products, some fatally, by accidental misuse resulting from
misreading, or failing to read, the label instructions. Do
not use products intended for dogs on cats
as these may
contain compounds that are appropriate for dogs but poisonous to
cats. Do not use premise sprays intended for the house and/or
yard on or near pets and always carefully read
instructions prior to use
. Call your veterinary clinic
with any questions or if your animal shows any clinical signs
during or following flea treatment.


Lead poisoning is seen occasionally in small animals,
notably in birds, frequently as a result of ingestion of a
foreign object containing lead, for instance, a toy, drapery
weight, fishing weight, lead shot or battery. However, it can
also be seen with ingestion of lead-containing paint, caulking,
motor oil and other lead sources. Clinical signs for animal
suffering lead poisoning usually include a combination of signs
involving the gastrointestinal system (vomiting, constipation
diarrhea, painful abdomen) and the neurological system
(depression, blindness, circling, muscle tremors, incoordination).
Onset of signs is usually relatively quick but signs can
progress more slowly if the animal is slowly being exposed to
the poison, i.e., repeated ingestion of lead based paint.

Zinc poisoning occurs most frequently when dogs ingest
zinc in the form of pennies. The metal interacts with components
of the animal’s red blood cells and can cause, weakness,
trembling, loss of appetite. Although not seen frequently, it is
interesting to note how such a mundane object can be toxic when


Poisons intended to kill rats, mice, gophers, moles and other
mammalian pests are among the most common and deadly of small
animal toxins. Since rodent and other pests and our companion
animal dogs and cats are all mammals, it follows that substances
highly poisonous to the pests would be just as lethal to our
pets, and indeed that is the case. In the 1990 AAPCC report, 8%
of all non-drug toxin exposures resulted from rodenticides and
of 425 fatalities, 60 (14%) of deaths were subsequent to these
poisons. Commonly, owners have all but forgotten the old rat
poison in the garage cabinet until it gets knocked onto the
ground and the dog has eaten it. Or on farms or stables, rat
poison is left in what seems like a safe place to attract only
the rats and then the empty chewed container is seen outside the
doghouse. It cannot be too highly stressed that rodenticides
are highly toxic and any such poisons designed to kill small
mammals need to be carefully contained in closed metal cabinets
or high on stable shelving
. The poisons usually come in
flimsy cardboard containers and any dog, puppy or cat can chew
through the container to get at the bait. Unfortunately, every
year far too many do just that.

Rodenticides are classified according to both their basic
ingredient compounds and by how they act on their target. These
categories include: Anti-coagulant rodenticides, cholecalciferol,
strychnine, zinc phosphide, bromethalin, compound 1080 and more.
The most common rodenticide poisoning seen in veterinary
practice is that of the anti-coagulant rodenticides. These
poisons — with ingredient names like warfarin, fumarin,
diphacinone, bromadiolone — act by interfering with the
animal’s ability to utilize Vitamin K. One of they key roles of
Vitamin K is in the production of coagulation factors in the
body which cause blood to clot when necessary. Although we are
not aware of it, normal physiological processes require blood to
clot many times a day in our bodies and that of our pets.
Without the necessary coagulation factors, normal minor bleeding
in the body goes unchecked which, without treatment, becomes
major bleeding, with blood loss anemia, hemorrhage and death
resulting. With most anti-coagulant rodenticides, signs are not
seen until 3-5 days after the pet has ingested the poison.
Clinical signs include weakness, difficult breathing, pale
mucous membranes, and bleeding from the nose.

Other types of rodenticides have different mechanisms of
action with some (i.e., strychnine and bromethalin) causing
neurological signs such as incoordination, seizures and others
cardiac failure (i.e., cholecalciferol). If accidental ingestion
of rat poison is suspected, contact your veterinary clinic
immediately, even if your dog or cat is showing no obvious signs
of being ill. Be sure, if possible, to bring the poison
container in to the clinic in order to determine the specific
toxin and provide the best treatment. Early recognition is
critical as some poisons, particularly the anti-coagulant
rodenticides, can be successfully treated if the poisoning is
caught early and treated appropriately.


Spring and fall are times for seeding and fertilizing — and
accidental animal poisoning. Cats and dogs often lick their
paws, especially after walking outdoors, perhaps over newly
fertilized lawns. Confine your pet for a while after you



This is primarily a problem of dogs and cats that roam freely
around the farm or neighborhood with easy access to “road
kill,” garbage cans, etc. However, any animal that eats
decaying, rotten carcasses or other food material (i.e.,
left-over hamburger) that has been contaminated by bacteria and
bacteria-produced toxins is susceptible to this poisoning. The
toxicity of the rotten food lies largely in toxins produced by
bacteria in the food material which are then delivered in the
meal to the dog or cat and cause severe gastrointestinal upset.
Clinical signs can include vomiting, diarrhea (which may be
bloody), fever, abdominal pain, and weakness. Severely affected
animals can go into shock and even die as a result of the
absorbed bacterial toxins.

For those animals who are not restricted in their activity it
is impossible to prevent possible garbage poisoning (as well as
the all too common “hit-by-car” injuries which are a
much more common and deadly risk for free-roaming animals).
However, if your animal has “escaped” and you suspect
he or she has gotten into something very unappetizing
(frequently the odor of the meal is obvious even before the pet
throws it up!) be aware that this type of poisoning can be quite
serious and follow up with your veterinarian if you see any
signs of illness (repeated vomiting, lethargy, depression).


Teflon toxicity occurs most often in pet birds and in the
1990 AAPCC report on small animal poisoning, resulted in 5 of
425 fatalities. The problem arises when pots or pans containing
either Teflon or Silverstone are
left on a hot stove until heated to >280
degrees Celsius (generally when a pan is forgotten on a hot
stove for some time until it is “white hot”). The
result is the release of toxic particles into the air that cause
severe damage to the bird’s lungs when inhaled. Birds are unable
to clear the toxic particles by exhaling, coughing, etc. and are
therefore more susceptible to this type of poisoning. Although
hard to avoid as it results from an accident, it might be a good
idea to house pet birds a distance from the kitchen (especially
if you tend to be an absent-minded cook!)

CHOCOLATE (Drug class: Methylxanthines)X

It often surprises pet owners to discover that for animals,
chocolate is poisonous in sufficient dosages. Specifically it is
the drugs in chocolate, theobromine and caffeine (of the drug
class methylxanthines), that are toxic to pets. Only a moderate
amount needs to be eaten by an animal, typically a dog, in order
to be poisonous (approx. 1/2 oz. of baking chocolate per pound
of body weight and less in some animals). With the poison in
this case being so appealing, overdose is not a rare occurrence.
Poisonings of this type typically occur during the holiday
seasons of Easter, Christmas and Halloween. Depending on their
appetite and the specific ingredients contained in the recipe,
some dogs have ingested a toxic dose of chocolate by eating an
entire pan of brownies or another chocolate dessert,
particularly one containing baking chocolate. Fortunately, the
animal frequently vomits soon after which reduces the amount of
poison in the stomach available to act on the body and decreases
the toxicity somewhat. If clinical signs are seen, these can
include vomiting, excessive urination, hyperactivity, fast
breathing, weakness and seizures. While rare, death can occur,
usually due to the adverse action of methylxanthines on the

Many people unknowingly feed their dogs chocolate treats
(candy bars, cookies, etc.) without obvious illness resulting;
the lack of clinical signs is due only to the relatively low
dose of methylxanthines in small amounts of milk chocolate. It
is certainly better for your pet to stick to treats he or she
will like just as much (freeze-dried liver pieces come to mind
yummy!) and avoid chocolate-containing treats where
the dog is concerned. Also be aware that an accidental overdose
of cake, bars, etc. containing chocolate can pose a significant
risk to a dog. If this should happen to your pet, make note of
the amount of chocolate used in the recipe, the approximate
amount eaten by your pet and give your veterinarian a call to
determine if the dose was sufficient to cause any problems.


Hopefully you have found this guide interesting and useful.
The underlying message in any discussion of poisons is to avoid
poisoning wherever possible by careful packaging, storing and
appropriate use of potentially toxic items. A second important
concept is to recognize potential poisoning as soon as possible,
ascertain what it was the animal was exposed to and get help.
Whereas poisoning is not the most common of problems that most
pet owners face with their companion animals (thankfully!), if
such a situation should arise it is worth having considered the
possibility beforehand. Having some guidelines on how to proceed
can provide the pet the best chance to be treated and recover
from the crisis. Even more importantly, it is worth having
considered the risks and eliminated them before those risks
become reality.


This guide was generously prepared by Julie Dahlke, DVM, a graduate
of the University of Minnesota, College of Veterinary Medicine.
She compiled information on poisons which are commonly
accessible to pets and which cause their owners great concern.
This is not an exhaustive guide to companion animal poisons but
instead a useful, readable reference designed for the pet owner.
Dr. Dahlke thanks Dr. Mike Murphy, a veterinary toxicologist and
Ms. Lynn Lawrence, both of the University of Minnesota for their
assistance in the development of this guide.

For more information on poisonous plants, read, Poisonous
Plants of the United States and Canada
. John M.
Kingsbury, Prentice-Hall or any of a variety of books on
regional plants at your local book store