Phenazopyridine, found in products such as Pyridium, is an OTC medication used to urinary tract infections and other urinary problems. This medication may be toxic to pets and should never be administered to animals.

Signs and symptoms of toxicity: Clinical signs and symptoms of toxicity include blue or purple gums or skin, shortness of breath, changes in mental status, fatigue and liver damage.

Toxic consumption: There is no established threshold for toxicity. All incidents of exposure should be reported immediately.

References:
Holahan, M.L., et al. (2010). Presumptive hepatotoxicity and rhabdomyolysis secondary to phenazopyridine toxicity in a dog. J. Vet. Emerg. Crit. Care. 20(3):352-8.