Pennyroyal Oil Poisoning in Dogs

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Key takeaways

Pennyroyal oil is derived from the Hedeoma pulegioides and Mentha pulegium plants, commonly known as pennyroyal, and is extremely toxic to dogs.

  • Even a low dose can lead to life-threatening liver failure
  • Pennyroyal oil can be found in some flea prevention powders and sprays
  • Dogs are usually exposed through topical or oral routes
  • Symptoms include jaundice, vomiting, diarrhea, appetite loss, nervous system malfunctions, and symptoms of anemia
  • As liver failure progresses it can lead to seizures, coma, and death
  • The diagnostic process, including physical exam and blood work, is focused on establishing the extent of organ damage
  • Treatment focuses on life-saving symptomatic care, often including oxygen support and antiseizure medications
  • Decontamination is only effective if started shortly after exposure
  • Antidotes are available, but their efficacy is still being researched
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A closer look: Pennyroyal Oil Poisoning in Dogs


The active toxin contained in pennyroyal oil is known as pulegone and is particularly toxic to the liver. It can be found in some flea prevention powders and sprays. The risk of pennyroyal oil poisoning is one example of why it is important to always consult a veterinarian before choosing external parasite control. Many available products are toxic to pets.

Even a low dose can be life-threatening to dogs, and as such, intoxication must be considered a critical emergency.

Always consult a veterinarian before choosing external parasite control. Many available products are toxic to pets.

Risk factors


Pennyroyal oil intoxication is extremely rare and can be easily prevented by avoiding exposure.

This is a life-threatening emergency requiring immediate veterinary attention. The toxin in pennyroyal oil acts very rapidly, causing severe injury to the liver that can lead to death within hours of exposure.

Possible causes


Dogs usually come in contact with the poison through oral or topical routes (skin exposure, ingestion, or inhalation). For example, some flea-control products contain pulegone.

Always consult a veterinarian before choosing external parasite control. Many available products are toxic to pets.

Main symptoms


The main symptoms of pennyroyal oil poisoning in dogs usually appear 1 or 2 hours after exposure, and are direct consequences of liver damage.

As liver failure progresses, additional symptoms may arise, including abnormal bleeding and loss of consciousness.

Testing and diagnosis


A history of exposure to products containing pennyroyal oil is necessary to make a specific diagnosis, as many other toxins can produce similar symptoms. A physical examination alongside blood work helps in evaluating the extent of the toxicosis, but cannot identify the specific poison. A smell of mint can be a clue toward a diagnosis of pennyroyal oil poisoning.

Steps to Recovery


The priority in treating pennyroyal oil poisoning is immediate life-saving symptomatic care. Antiseizure medications, oxygen support, and intravenous fluid therapy are usually needed. Additional supportive care may include:

  • Antiemetics and gastroprotectants
  • Vitamin K for clotting disorders
  • Blood transfusions for anemia

Decontamination via induced vomiting, gastric lavage, and bathing may be an option, depending on the status of the patient and time elapsed since exposure.

Note: inducing vomiting or administration of activated charcoal should only be performed by a veterinarian. There is no safe way to induce vomiting or administer activated charcoal at home.

N-acetylcysteine and liver-support nutraceuticals are among the suggested medications, although data on their efficacy is lacking.

Very limited data exists on the prognosis for pennyroyal oil poisoning. Dosage level and time since exposure are factors. Pennyroyal oil poisoning is an extremely dangerous condition and can lead to death in a matter of hours.

Prevention


Pennyroyal oil poisoning can be easily prevented by avoiding exposure.

Always consult a veterinarian before choosing external parasite control. Many available products are toxic to pets.

Is Pennyroyal Oil Poisoning in Dogs common?


Pennyroyal oil poisoning is extremely rare in dogs.

Typical Treatment


  • Decontamination (depending on the patient’s status)

  • Antiseizure medications

  • Oxygen support

  • Intravenous fluid therapy

  • Antitoxicosis medications

  • Antiemetics and gastroprotectants

  • Vitamin K for clotting disorders

  • Blood transfusions for anemia

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