Slugs are a common sight in gardens, often leaving behind tell-tale slime trails. While these mollusks play a role in the ecosystem by breaking down decaying plant matter, their presence can raise concerns about risks to human and pet health. Slugs themselves are not directly harmful through contact. However, they can act as intermediate hosts for various parasites, posing indirect threats if accidentally ingested.
Health Risks to Humans
Slugs can pose a health risk to humans by carrying parasitic nematodes, most notably the rat lungworm, Angiostrongylus cantonensis. This parasite’s larvae are shed in rat feces, which slugs and snails ingest, becoming infected intermediate hosts. Humans can become infected by accidentally ingesting these infected slugs or their slime, for instance, when consuming unwashed raw produce like lettuce that a slug has crawled across.
Once ingested, the rat lungworm larvae cannot complete their life cycle in humans but can migrate through the body, sometimes reaching the brain and spinal cord. This can lead to eosinophilic meningitis, with symptoms including severe headaches, a stiff neck, nausea, vomiting, and tingling sensations. While most people recover, severe cases can result in neurological issues or be fatal. Symptoms often appear 1-3 weeks after exposure, with an incubation period ranging from a few days to several weeks.
Health Risks to Pets
Slugs present health risks to pets, particularly dogs, due to their ability to carry lungworm parasites. The main concern is Angiostrongylus vasorum, known as French heartworm. Dogs can become infected by eating slugs or snails, ingesting slug slime from contaminated surfaces like toys or water bowls, or by eating grass where slugs have been present.
Once inside a dog, lungworm larvae migrate through intestinal walls and develop into adult worms that reside in the heart and major blood vessels connected to the lungs. Symptoms of lungworm infection in dogs include coughing, breathing difficulties, lethargy, weight loss, and in severe cases, bleeding disorders, seizures, or heart failure. The disease can be fatal if left untreated. Beyond parasites, slug baits containing metaldehyde are highly toxic to pets, causing severe neurological symptoms and potentially death if ingested.
Minimizing Encounters and Risks
Reducing the risk of exposure to slugs and their parasites involves several practical measures for both humans and pets. Thoroughly washing all produce, especially leafy greens from gardens, can remove any hidden slugs, snails, or their contaminated slime. For pets, discourage them from eating slugs or snails and supervise them outdoors. Regularly cleaning outdoor water bowls and bringing pet toys inside overnight can prevent contamination by slug slime.
Maintaining good garden hygiene helps reduce slug populations. Remove debris, fallen leaves, and excess mulch that provide moist hiding places for slugs. Watering plants in the morning allows the soil to dry out by evening, making the environment less appealing to slugs. If slug control products are necessary, choose pet-safe alternatives like iron phosphate-based baits instead of those containing highly toxic metaldehyde. Should exposure be suspected or symptoms appear in humans or pets, seeking prompt medical or veterinary attention is advised.