Symptoms of Arsenic Poisoning in Dogs

Although quite rare, arsenic poisoning can pose a real threat to a dog’s health.

By: sherylspics
Arsenic can still be found in certain products such as rodent baits and herbicides. By: sherylspics

These days, arsenic poisonings is quite rare — but this wasn’t always the case.

A couple hundred years ago, arsenic was found in many household items, such as candles and wallpaper, and many people became ill from it without realizing the cause. We now know arsenic is toxic; its use is limited to certain wood preservatives, herbicides and rodent baits.

This means the risk of a dog accidentally coming into contact with arsenic is low, and cases of arsenic poisoning are rare, but it’s good to know what to look for in case your dog ingests arsenic.


The speed of symptom appearance, the severity and the rate of deterioration depend on the amount of arsenic ingested. A dog that has eaten, or drunk, a small amount of arsenic will typically become ill within a few hours.

The symptoms go through 2 phases: The first stage is gut-related, quickly followed by circulatory collapse and organ failure. Once ingested, arsenic irritates the gut lining and causes stomach cramps, vomiting and diarrhea.

The arsenic passes from the stomach into the bloodstream, where it binds to red blood cells and is circulated throughout the body. It then builds up in the liver and kidneys and causes organ failure.

Gastrointestinal signs:

Circulatory signs:

  • Blood loss from the bowel and in urine
  • Weakness from blood loss and anemia
  • A weak, racing pulse and signs of shock
  • Dehydration
  • Collapse

Arsenic is used in treating heartworms, but isn’t it toxic to dogs? In this video, Dr. Garner explains why it’s used:

YouTube player


In recent years, the use of arsenic as an active ingredient has reduced markedly. It is, however, still found in some herbicides, insecticides, ant baits, rodent baits, defoliants and wood preservatives.

With regard to treated timber, care should be taken even after it is burnt because wood ash still contains traces of arsenic that can be toxic to dogs who get it on their coat and then groom themselves.


A diagnosis can be tricky to pin down because routine blood tests give a picture of overall organ damage rather than the reason for it.

A specialist test that is run on gut contents, or urine, is available at certain commercial laboratories. However, even this test can be unreliable because the levels of arsenic in body fluids decay greatly within 2 to 3 days of ingestion, and so the damage is done, but the cause can’t be proved in the lab.


If you suspect your dog has eaten a poison (of whatever type), seek immediate veterinary attention.

If the dog ate arsenic less than 2 hours earlier, the vet will make your dog vomit to rid himself of any remaining poison in his stomach and then prescribe oral medicines to protect the gut lining and help mop up any poison yet to be absorbed into the bloodstream.


Depending on blood test results, your vet may start intravenous fluid therapy to flush the organs as free of the toxin as possible and to help them to function.

If the dog is already doing poorly, and arsenic poisoning is confirmed as the cause, an antidote can help bind to arsenic and decrease further toxic signs. If the patient is already extremely ill and experiencing anemia, then a blood transfusion may be necessary.


Key to prevention is stopping your dog from coming into contact with arsenic-laced products.

Though your dog is a lot safer than his ancestors were, the unforeseen may happen. If accidental exposure occurs, keep any packaging to show to your veterinarian and seek emergency treatment without delay.


  • Small Animal Toxicology and Poisonings. Gfeller & Messonnier. Publ: Mosby.
  • The Veterinary Formulary. Yolande Bishop. Publ: Pharmaceutical Press. 4th edition. 
  • Arsenic Century: How Victorian Britain Was Poisoned at Home, Work and Play. James Whorton. Publ: OUP Oxford.


This pet health content was written by a veterinarian, Dr. Pippa Elliott, BVMS, MRCVS. It was last reviewed Dec. 17, 2018.