Arsenic poisoning is caused by many different types of arsenic compounds. Poisoning is relatively infrequent due to the decreased use of arsenic compounds as pesticides, ant baits, and wood preservatives. Arsenites are used in some dips for tick control. Drinking water containing more than 0.25% arsenic is considered potentially toxic, especially for large animals. Cats may be more sensitive than other animals to arsenic poisoning.

Arsenic compounds that dissolve in water are well absorbed after ingestion by mouth. After absorption, most of the arsenic is bound to red blood cells and distributed to body tissues, with the highest levels found in the liver, kidneys, heart, and lungs. In longterm exposures, arsenic accumulates in skin, nails, hooves, sweat glands, and hair. Generally, the gastrointestinal tract, liver, kidneys, lungs, blood vessels, and skin are considered more vulnerable to arsenic damage.

Signs of poisoning are usually sudden and severe, typically developing within a few hours (or up to 24 hours). Arsenic poisoning has major effects on the gastrointestinal tract and cardiovascular system. Loss of blood and shock may occur. Large amounts of watery diarrhea, sometimes tinged with blood, are characteristic, as are severe colic, dehydration, weakness, depression, weak pulse, and collapse of circulation. The course may run from hours to several weeks depending on the quantity of arsenic ingested. In very severe poisoning, animals may simply be found dead.

In animals that have been recently exposed and are not yet showing signs, vomiting may be induced (in species that can vomit), followed by activated charcoal and a medication that causes emptying of the bowels. In dogs and cats, this may be followed 1 to 2 hours later by a medicine that prevents damage to the gastrointestinal tract, such as kaolin-pectin. Fluids are given as needed.

In animals already showing signs of poisoning, fluid treatment, blood transfusion (if needed), and dimercaprol (an antidote to arsenic) are recommended. Severely affected animals need supportive treatment, including intravenous fluids to restore blood volume and correct dehydration. Kidney and liver function should be monitored during treatment.

Last full review/revision July 2011 by Barry R. Blakley, DVM, PhD; Cheryl L. Waldner, DVM, PhD; Rob Bildfell, DVM, MSc, DACVP; William D. Black, MSc, DVM, PhD; Herman J. Boermans, DVM, MSc, PhD; Cecil F. Brownie, DVM, PhD, DABVT, DABT, DABFE, DABFM, FACFEI; Raymond Cahill-Morasco, MS, DVM; Keith A. Clark, DVM, PhD; Gregory F. Grauer, DVM, MS, DACVIM; Sharon M. Gwaltney-Brant, DVM, PhD, DABVT, DABT; Larry G. Hansen, PhD; Safdar A. Khan, DVM, MS, PhD, DABVT; Garrick C. M. Latch, MASc, PhD; Gavin L. Meerdink, DVM, DABVT; Lisa A. Murphy, VMD; Frederick W. Oehme, DVM, PhD; Gary D. Osweiler, DVM, MS, PhD, DABVT; Mary M. Schell, DVM; David G. Schmitz, DVM, MS, DACVIM; Norman R. Schneider, DVM, MSc, DABVT