Arsenic Poisoning in Dogs
Dr. Dawn Ruben
Arsenic may be a common poison used in murder mysteries, but it is not common as a poisonous danger to animals. Years ago, however, accidental arsenic poisoning was more common because it was often used in ant and roach bait. Children and animals sometimes ingested the bait. Vomiting
To reduce the danger, the federal government mandated the gradual reduction of arsenic in roach and ant bait. Since 1989, arsenic products have become less available. This has reduced the frequency of poisoning in children as well as our pets.
For those pets that ingest arsenic, the lethal dose is 1 to 12 mg of arsenic per pound of body weight. Most often, arsenic ingestion today is associated with ingestion of old ant and roach baits produced prior to 1989. Another potential source of arsenic is in medication. Arsenic compounds are used in the treatment of heartworm infections in dogs. This is not the same as heartworm preventatives. Small amounts of arsenic will kill the heartworms but not affect the dog. Overdoses of heartworm treatment can result in arsenic poisoning.
Arsenic is toxic to the gastrointestinal tract, liver and kidneys. After ingestion, the animal's initial reaction is to begin vomiting. This reduces the amount of poison in the gastrointestinal tract. If not treated, the liver and kidneys become damaged, resulting in the animal's demise.
If a small amount of arsenic is ingested, most animals do well with treatment. If a high dose is ingested, signs of illness develop within minutes and death may occur within hours. Animals that ingest any amount of arsenic should be examined and treated by your veterinarian immediately.
Prognosis of animals that ingest large amounts is poor to grave. If aggressive treatment is begun soon after ingestion and before the signs of illness are severe, the animal has a guarded to fair chance of surviving.
What to Watch For
Diagnosing arsenic poisoning can be difficult. Most people are aware that arsenic is deposited in the hair and fingernails and can be detected long after ingestion. For a poisoned animal, this is not an effective way to diagnose acute arsenic poisoning. Testing hair and nails is usually done to confirm chronic exposure and is rarely done in animals. If arsenic is suspected, the diagnosis can be confirmed by testing the urine, and sometimes the stomach contents. The results of the test are usually not available right away and the animal is treated before the diagnosis is confirmed.
Often, diagnosis of arsenic poisoning is made based on the signs of illness and knowledge that the animal ingested an arsenic compound or received an overdose of heartworm treatment (not preventative). Recommended tests include:
Complete blood count – usually normal.
Biochemical profile – may indicate dehydration and reveal mild elevations in liver enzymes. In severe cases, kidney failure and severe liver damage may be detected.
Urinalysis – often reveals dehydration.
Urine should be submitted to confirm the diagnosis.
The goals of treatment are to remove any residual poison, reduce the amount of poison absorbed and enhance elimination of the poison from the body.
Removing poison. This is done by either inducing vomiting or pumping the stomach. If ingestion is witnessed, vomiting can be induced at home. Often, animals will vomit on their own immediately after ingestion since arsenic can be irritating to the stomach. If treatment is delayed, vomiting is not induced. The arsenic can weaken the stomach walls. Therefore, the stomach is pumped instead of forcing the animal to vomit.
Reducing the amount absorbed. Those animals that have ingested large amounts of arsenic and are profoundly ill may benefit from chelation therapy. Chelation is the use of a medication that binds to the arsenic, preventing its absorption into the bloodstream. The arsenic then passes through the body without causing damage. Unfortunately, the medication used to chelate the arsenic can have significant side effects and can be very hard on the body. It should only be used in confirmed cases of high dose arsenic poisoning.
In the treatment of arsenic, dimercaprol is the chelation drug of choice. Activated charcoal, which is often used in other types of poisonings, is not very effective in heavy metal poisonings, such as arsenic.
Enhancing excretion. Arsenic that has been absorbed into the blood needs to be removed as fast as possible. To do this, intravenous fluids are used. This will help treat dehydration and speeds elimination of the arsenic in the urine.
Additional treatment. In addition to intravenous fluids and chelation therapy, anti-vomiting medication may be necessary. Vitamin B and antibiotics may also be used.
Since some animals may vomit blood or have bloody diarrhea, blood loss is a concern. Some animals may need a blood transfusion if blood loss is significant.
Arsenic is excreted by the kidneys. Usually, most of the arsenic is removed from the body within 48 hours. Animals are often hospitalized and treated for 2 days until the majority of the arsenic is gone.
Home Care and Prevention
After release from the hospital, there is little special care at home. Initially, animals are fed a bland diet and gradually returned to their normal food. Antibiotics and stomach protectants may be continued if significant gastrointestinal irritation has occurred.
Prevent ingestion of arsenic by discarding old ant and roach baits and keeping all poisons away from your pet.