Toxicity to pets

Pimobendan, a common veterinary heart medicine, is a benzimidazole-pyridazinone calcium sensitizer and phosphodiesterase III inhibitor. It works by increasing the contraction of the heart while providing some “vasodilatory” properties (which means it allows blood vessels to dilate). It is commonly used to treat dogs with congestive heart failure from either chronic valvular heart disease or dilated cardiomyopathy.
Pimobendan is available as a chewable tablet in 1.25, 2.5, and 5 mg sizes. As these are chewable tablets, pets may accidentally ingest large, toxic amounts. Poisoning can result in inappetance, lethargy, an elevated heart rate, collapse, low blood pressure, weakness, etc. Accidental ingestion should be treated immediately.