Theobroma cacao
Why is it risky?
Chocolate contains theobromine and caffeine, both methylxanthines that cats cannot metabolize efficiently. Theobromine is the primary concern: it inhibits phosphodiesterase and blocks adenosine receptors, causing cardiac stimulation and neurological effects. Dark and baking chocolate are most dangerous; milk chocolate is lower risk but still toxic. White chocolate contains negligible theobromine.
Affected Systems
Digestive · Nervous · Cardiovascular
Symptoms
Vomiting, diarrhea, restlessness, excessive thirst and urination, muscle tremors, seizures, cardiac arrhythmias. Severe cases: death.
What To Do
Contact vet or poison control immediately. If ingestion was within 2 hours and significant, vet may induce vomiting. No home treatment is appropriate.
Notes
Cats lack a functional sweet taste receptor (TAS1R2 is a pseudogene in felines) and are less attracted to chocolate than dogs. However, some chocolate products contain flavors cats find appealing. Cocoa powder and baking chocolate carry the highest theobromine concentration per gram.
Sources
→ ASPCA Animal Poison Control Center — https://www.aspcapro.org/sites/default/files/m-toxbrief_0201.pdf
→ Merck Veterinary Manual — https://www.merckvetmanual.com/toxicology/food-hazards/chocolate-toxicosis-in-animals?query=chocolate