Parsley (Petroselinum crispum) is a familiar herb cultivated and consumed worldwide, prized for its fresh flavor and nutritional content. Belonging to the carrot family (Apiaceae), this biennial plant is common in gardens and kitchens. Understanding who consumes this herb, from the wild to the domestic setting, reveals important considerations for animal safety.
Garden Pests and Wild Consumers
The larva of the Black Swallowtail Butterfly (Papilio polyxenes) is a specific consumer of parsley. These caterpillars rely on parsley and other members of the carrot family as exclusive host plants for development. The female butterfly deposits eggs on the leaves, and the resulting larvae feed voraciously, often consuming entire stems before forming a chrysalis. Beyond specialized insects, mammalian herbivores view parsley as a favored food source. White-tailed deer and rabbits readily browse the tender leaves, sometimes causing significant damage to garden beds overnight. Groundhogs and smaller invertebrates like slugs and snails also feed on the foliage, drawn to the plant’s texture and moisture content despite its strong aromatic compounds.
Domestic Animals and Feeding Safety
Parsley consumption by domestic animals requires careful consideration due to the risk of toxicity. For small herbivores, such as pet rabbits and guinea pigs, parsley is safe and beneficial when fed in moderation. Guinea pigs benefit from its high Vitamin C content, which they cannot produce. However, the herb must be rotated with other greens to manage calcium and oxalate levels, as excessive consumption can contribute to urinary stones.
For companion animals, safety depends on the amount and variety. Small quantities of common curly parsley are usually safe for dogs and cats and are sometimes added as a breath freshener. However, large doses, or consumption of certain varieties like Italian flat-leaf parsley or the highly toxic Spring Parsley (Aethusa cynapium), pose a serious risk. These varieties contain higher concentrations of toxic essential oils, and the roots and seeds are particularly dangerous.
Parsley is generally tolerated by chickens and horses in small amounts, though high quantities are listed as toxic to horses. Additionally, parsley contains compounds that can stimulate uterine contractions, meaning it must be avoided by pregnant or lactating pets and livestock.
The Nutritional Value and Potential Toxicity of Parsley
Parsley’s appeal stems from its dense nutritional profile, being an excellent source of beneficial compounds. The herb contains high levels of Vitamin K, which supports blood clotting, along with Vitamin C and Vitamin A. Parsley also provides antioxidants and iron, making it a nutritious addition when portioned correctly.
The risks associated with the plant are concentrated in its natural chemical defenses, specifically two types of compounds. Furanocoumarins are present and can cause phytophotodermatitis, a skin reaction that makes animals sensitive to sunlight. This effect is a concern for livestock and pets with light-colored skin exposed to the sun after consuming large amounts.
The essential oils, namely apiol and myristicin, pose the other major risk. These oils are found in the leaves, roots, and seeds. When concentrated, they can act as neurotoxins and diuretics, potentially causing central nervous system effects, liver, and kidney damage in small animals. The concentration of these oils varies significantly between cultivars, with some varieties having up to 80% apiol content.