Pennyroyal

Symptoms reported in cats

Most serious first.

1. 1
   Liver damage progressing to liver failure Unlike common garden mints (like spearmint or peppermint) that primarily irritate the digestive tract, Pennyroyal is explicitly noted for its severe systemic toxicity that attacks the cat's liver, which can ultimately lead to death.
2. 2
   Seizures, tremors, uncoordinated gait, weakness, and lethargy Seizures and profound neurological depression are hallmarks of severe mint/essential oil toxicity and are specifically associated with highly toxic mint plants like Pennyroyal.
3. 3
   Vomiting, diarrhea, excessive drooling, loss of appetite, and difficulty swallowing The essential oils in the mint family are highly irritating to a cat's gastrointestinal tract36. With Pennyroyal, these symptoms may occur alongside or precede more severe systemic organ failure.
4. 4
   Difficulty breathing, coughing, and sneezing In severe cases, the ingestion or inhalation of the essential oils found within toxic mint plants can cause significant respiratory distress45. Note: The provided sources do not specify the exact hourly onset times for these symptoms.

Important notes

Pennyroyal (Mentha pulegium) is a member of the mint family that is highly toxic to cats. It is much more dangerous than common peppermint. The plant contains a chemical called pulegone, which the cat's liver turns into a toxic substance that causes severe liver damage and can be fatal. In the past, pennyroyal oil was sometimes used as a natural flea treatment, but this is extremely unsafe for cats. Even a small amount of the concentrated oil absorbed through the skin or swallowed can cause the liver to fail. Symptoms include vomiting, diarrhea, yellowing of the eyes or skin (jaundice), tremors, and collapse. Eating the fresh plant is also a serious concern. If you suspect your cat has eaten pennyroyal or has come into contact with pennyroyal oil, this is an emergency. Please contact a veterinarian or an emergency animal hospital immediately.

• Toxic compounds: pulegone (primary); metabolised to menthofuran in the liver — the true hepatotoxic agent
• Mechanism: menthofuran causes direct hepatocellular necrosis (liver cell death); glutathione depletion amplifies the damage
• Symptoms: vomiting, diarrhea, lethargy; severe cases cause acute liver failure with jaundice, tremors, seizures, and collapse
• Pennyroyal essential oil is especially dangerous — do NOT use it as a flea treatment; even topical application can cause fatal liver failure
• Any exposure to pennyroyal oil is a veterinary emergency; plant ingestion also warrants prompt vet evaluation