Rodenticides (like d-Con) are toxic to all animals, especially dogs. Ingredients of concern include brodifacoum, bromadiolone, chlorphacinone, difethialone, diphacinone, and warfarin. Rodenticides containing bromethalin also have a risk of toxicity.

Signs and symptoms of toxicity: Clinical signs usually develop approximately 3 days after ingestion and it is, therefore, important to continue to monitor your animal. Signs of toxicity include difficulty breathing, coughing (especially coughing up blood), fatigue, inability to exercise, and blood-containing vomit or urine.

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

References:
Osweiler, G, et al. (2011). Blackwell’s five-minute veterinary consult clinical companion. Small Animal Toxicology. [Kindle version]. Retrieved from Amazon.com