Yes, Aloe Vera plants are considered toxic to both cats and dogs. While the plant has numerous beneficial uses for humans, its internal composition contains specific compounds that can cause adverse reactions in our pets. Understanding this from a botanical perspective clarifies why a plant so helpful to people can be problematic for animals.
Aloe Vera (*Aloe barbadensis miller*) is a succulent plant species from the genus *Aloe*. It is characterized by its thick, fleshy, greenish-grey leaves that grow in a rosette pattern. The leaf itself is composed of three major layers: the outer green rind, a middle layer of latex, and the inner clear gel. Each of these layers has a distinct chemical makeup and purpose for the plant. The gel, which is mostly water, is used by the plant for water storage to survive arid conditions. The latex and rind contain defensive compounds that protect the plant from herbivores and pests.
The toxicity of Aloe Vera to cats and dogs is primarily attributed to a group of chemical compounds known as anthraquinone glycosides, which are concentrated in the latex layer of the leaf—the yellow sap found just beneath the plant's skin. The most prominent of these compounds is aloin (also known as barbaloin). For the Aloe Vera plant, aloin acts as a powerful bitter-tasting laxative and deterrent. When an animal bites into the leaf, the release of these bitter compounds is a defensive mechanism designed to discourage further consumption.
When ingested by a cat or dog, these anthraquinone glycosides are metabolized by the bacteria in the animal's intestines. The resulting compounds aggressively irritate the mucous membranes of the digestive system. This irritation leads to a rapid purgative effect, essentially causing severe cramping and diarrhea. The body's attempt to rapidly expel the irritant can lead to dehydration and a significant loss of electrolytes. While the inner gel does not contain these compounds in high concentrations and is sometimes used in pet products in a purified form, the raw plant always presents a risk due to the proximity of the latex to the gel.
The symptoms a pet may display after chewing on or ingesting part of an Aloe Vera plant are direct results of the plant's defensive chemistry. The most common signs of toxicity include vomiting, diarrhea (which may contain blood), lethargy, depression, and tremors. Changes in urine color (noted as reddish) can also occur due to the compounds being processed by the kidneys. The severity of these symptoms depends on the amount of plant material consumed relative to the size of the animal.
