Oregano Poisoning in Cats

Oregano contains an essential oil that is capable of causing gastrointestinal upset in cats. This reaction is generally mild, and only occurs if a lot of plant material has been consumed. The real danger exists from owners believing the plant to be safe for cats, and in turn thinking that oregano essential oil would also be safe, as it is used medicinally in a lot of home remedies. Oregano essential oil, or OEO, is far too concentrated to be used on cats. It is high in both phenols and terpenoids, which cats can not properly digest due to a lack of glucuronyl transferase digestive enzymes in the liver. This can result in a toxic reaction and permanent liver damage to the cat.

Oregano is a widely used culinary herb that can grow successfully in many climates. Its scientific name is “Origanum vulgare hirtum” of the Lamiaceae plant family, and it is sometimes called Greek oregano. The herb is often kept in a pot but can also be used as a ground covering for its rapid growth. Oregano grows long stems covered with rounded, green leaves. It is very aromatic, especially when the leaves are crushed. Small white flowers bloom from the plant during the late summer months. 

Plant consumption usually only results in mild digestive upset, if any illness even develops. Severe reactions can occur from administering oregano essential oil internally or topically to a cat. Symptoms may develop over time if use is continuous. All signs to watch for include:

• Nausea
• Vomiting
• Diarrhea
• Shallow breathing
• Oral irritation
• Anorexia
• Liver-related issues
• Collapse

The oregano plant is likely to be found around the home as it is a very common cooking herb that is easy to grow. Some people keep oregano growing in their kitchen for easy access while cooking. A cat will likely only come into contact with oregano essential oil if someone in the household is purposely applying it to the animal. Many mistakenly believe that OEO may be used in place of antibiotics, which can lead to a very dangerous situation for the affected cat. 

If your cat begins to exhibit any of the symptoms listed above, take it in to be professionally assessed by a veterinarian. It is of the utmost importance that you disclose any at home treatments you have been giving to your cat in full detail. This can help quicken the diagnostic process immensely and get your cat the medical attention it needs. The veterinarian will likely ask what ailment was being treated with oregano essential oil so that it also may be addressed after the cat has been stabilized. You may also be asked to provide your cat's full medical history to help identify any health issues that may pose further complications.

The vet will then perform a complete physical examination of the cat including an oral or dermal examination if burns from OEO application have occurred. All vital signs and functions will be measured, including temperature, blood pressure and heart rate. A sample of the cat's blood will be taken so that standard tests can be run to measure levels of cells and minerals in the bloodstream. These tests generally include a complete blood count and a biochemical profile. Urinalysis may be used to determine how the liver is functioning. In extreme cases, a biopsy of the liver may be taken and sent for microscopic examination.

In cases which a cat has eaten oregano plant material, it is likely that the only course of action will be to monitor the animal until symptoms subside. If a cat has been poisoned by oregano essential oil more severe reactions may develop.

Supportive Care 

Depending on the symptoms that have manifested in the cat, extra care and hospitalization may be required. Intravenous fluids may need to be administered to counteract dehydration from extended periods of gastrointestinal distress. The cat's breathing may need to be regulated throughout the episode. The cat will be kept as comfortable as possible during hospitalization. 

Wash Oral Cavity 

If the cat has experienced burns or irritation from OEO exposure, its mouth will need to be flushed with water. Any other body parts that have contacted the oil may also need to be thoroughly washed to soothe the inflammation.

If the oregano plant has been ingested by a cat, a full and quick recovery is to be expected with no lasting health effects. Consuming oregano essential oil has the potential to cause permanent damage to the liver which may require ongoing treatment to manage. Skin and oral burns should heal as soon as OEO administration has been stopped.

Do not use oregano essential oil on cats under any circumstances. Even topical use can result in irritation and pain for the cat. Consult with your veterinarian before using any other type of essential oil on your cat to confirm that it will not cause injury to the animal. Keep all potted herbs out of your cat's reach to prevent them from being eaten. Keeping your cat indoors can protect it from contacting toxic plants in surrounding areas and gardens.