Lemon and Lime Poisoning in Dogs

Symptoms of poisoning from citrus fruits like lemons and limes are caused by a combination of the phototoxic compounds known as psoralens and the essential oils limonene and linalool.

• Cold limbs
• Collapse
• Depression
• Diarrhea
• Excessive drooling
• Lethargy
• Liver failure
• Loss of coordination
• Low blood pressure
• Photosensitivity 
• Rash or skin irritation
• Sudden death
• Tremors
• Vomiting
• Weakness

Types

Both psoralens and linalool are found in other plants as well. However the essential oil limonene is generally restricted to citrus plants. Other plants that produce linalool:

• Beech trees 
• Cinnamon
• Laurels
• Mint plants
• Rosewood

Other plants with high concentrations of psoralens:

• Anise seeds
• Caraway seeds
• Carrots
• Celeriac
• Celery
• Chervil
• Cilantro
• Coriander seeds
• Cumin seeds
• Dill
• Fennel seeds
• Figs
• Grapefruit
• Lovage
• Mustard seeds
• Oranges
• Parsley
• Parsnips
• Root parsley

The toxicity of citrus plants lies in the essential oils limonene and linalool, as well as in the phototoxic compound psoralen.

Limonene

A terpene produced in all citrus fruits which is the main component in the aroma of the different citrus fruits. It is often used in cosmetic products, flavoring compounds, and cleaning products. d-limonene is often employed in fragrances and shampoos for dogs. It is important to note that although the amount of d-limonene in these shampoos is safe for most canines, can be lethal to use on cats. 

Linalool

A terpene that contributes a floral scent to the citrus aroma, linalool is often utilized as an insecticide in soaps and lotions as a fragrance as well as being employed as an insecticide.

Psoralen

A compound found in many plants, including citrus plants like lemons and limes, it is used as a treatment for skin disorders but can also induce phototoxicity.

If you catch your pet consuming any type of citrus plant, signs and symptoms combined with the identification of the plant may be sufficient to make an initial diagnosis. Your veterinarian will question you regarding factors that will help to choose the most effective treatment plan, such as the amount of plant material ingested, how long ago it was ingested, and what part of the plant was eaten. If the toxin is unknown because the ingestion was unwitnessed, a urinalysis, blood chemistry profile, and complete blood count will be needed in order to determine which toxin is causing the distress. 

Any skin interaction will be noted, and any vomit or stools will be analyzed for toxins as well. Neurological testing to measure your pet’s reflexes and coordination may also occur during the diagnostic appointment. These evaluations are done in an attempt to pinpoint the specific areas of the nervous system that have been affected.

Any parts of the skin that have been exposed to the oil of the citrus plant should be washed immediately removed using a mild soap and clean water. Limonene and linalool are included in several dog shampoos as a fragrance and therefore, should be avoided when removing citrus oil. It is not advised to induce vomiting as breathing the oil into the lungs can be harmful. Gastric irrigation will be performed on the patient to physically remove as much of the toxin from the digestive system as possible. Activated charcoal will then be administered to prevent any further absorption of the toxic compound into the bloodstream. 

There is no antidote for either the psoralens or the essential oils, so treatment is generally supportive beyond decontamination. This can include IV fluids for dehydration as well as mixtures of electrolytes and sugars to adjust for any imbalances that might develop. If your dog is having difficulty breathing, oxygen will be provided, and antiseizure medications may be administered if tremors become acute.