Garden Toxins … Beyond Plants

By Amanda Poldoski, DVM, Senior Consulting Veterinarian, Clinical Toxicology | Pet Poison Helpline
While the warmer weather of spring and summer can bring much joy (especially to those of us residing in Northern states) it also ushers in an increase in outdoor toxin exposure calls to Pet Poison Helpline. Aside from plants and flowers, gardening items like fertilizers and insecticides can pose their own toxicity risks to curious pets.
Most general fertilizers and plant foods are quite safe around pets, especially when small amounts of ready-to-use (RTU) or properly diluted products are ingested. The toxicity risk increases if the product contains bone meal, blood meal, iron, and/or pesticides. Ingestion of large quantities of bone meal (especially 100% products) can lead to foreign body obstruction of the gastrointestinal tract due to formation of a concretion of product in the stomach. Gastroenteritis and
pancreatitis are also possible.1 Blood meal may also form a gelatinous foreign body following large ingestion but is a rare occurrence. Vomiting, foul-smelling diarrhea, and melena (due to the presence of digested blood) are more common.1  The smell of these meal-based fertilizers may attract dogs to areas where they were applied or to stored bags of product.  Some fertilizers are fortified with iron and may pose risk for iron toxicity if enough product is ingested. Severe iron poisoning may occur at dosages greater than 60 mg/kg elemental iron.2 Determining the type of iron in the product, along with concentration and the approximate amount ingested, are imperative in evaluating toxicity risk following exposure. Signs of iron poisoning may include vomiting, diarrhea, GI bleeding, tachycardia, hypotension, metabolic acidosis, and hepatic necrosis. Obtaining a serum iron level may be useful in determining if chelation therapy is warranted in cases involving large ingestion and significant clinical signs.
A wide variety of environmental insecticides are available for use by consumers and pest control companies and may be sold as sprays, dusts, or granules. Three common classes of insecticides are pyrethroids, neonicotinoids, and organophosphates/carbamates. Pyrethroids are synthetic derivatives of pyrethrins which are derived from Chrysanthemum flowers. Examples include allethrin, cyphenothrin, esfenvalerate, and permethrin. They are still used widely in insecticidal sprays and shampoos for dogs and cats and topical spot-on products for dogs. Often found in low-concentration sprays for indoor or outdoor use, pyrethroids
often target ants, flies, roaches, spiders and many other pests. In general, products containing < 1% pyrethroid are of low toxicity risk to mammals, including cats.3 One notable exception appears to be bifenthrin. Despite typically being present in granular products at 0.2% or less, ingestion by dogs has resulted in cases of mild to severe muscle tremors.  Treatment with IV fluids and methocarbamol, similar to cats exposed to concentrated pyrethroids, is generally effective.  Introduced in the 1990s, neonicotinoids are a relatively new class of insecticides that have a wide margin of safety in mammals. Examples include dinotefuran, imidacloprid,
nitenpyram, and thiamethoxam. Utilized in many veterinary products, these active ingredients are also found in sprays and granules for gardens, yards, and crops. Ingestion by dogs or cats may cause mild hypersalivation, vomiting, and diarrhea but systemic toxicity is not expected. This class of products have recently been implicated as a cause of colony collapse disorder in bees.  Organophosphates (OPs) and carbamates are older classes of insecticides that, while still available, have decreased in popularity likely due to the withdrawal of some products from the marketplace and the introduction of newer, less toxic products. The toxicity of OPs and carbamates varies greatly from low (e.g. chlorpyrifos in dogs) to intermediate (e.g., carbaryl, malathion) to highly toxic (e.g., disulfoton, methomyl).4 Signs may range from minor local irritation to severe muscarinic (SLUDGE – salivation, lacrimation, urination, diarrhea/defecation, gastroenteritis) and nicotinic signs (twitching, tremors, ataxia, weakness, etc.).  Formulation changes to pesticide products from more toxic ingredients to less toxic versions are common. However,
since owners may have older versions in their possession for years and the product name may remain the same, care should be taken to accurately identify the product to which a pet was exposed. For example, potent OPs (like disulfoton) have been used in some rose and flower care products previously only to be replaced by neonicotinoids. Identifying a product simply by name only and not verifying the active ingredient(s) and/or EPA registration number directly from the product packaging could lead to case mismanagement and inappropriate or delayed care.
The toxicity of yard and garden products like fertilizers and insecticides is variable and depends upon the specific product ingredients, concentration, and exposed species.  Accurate product identification is essential to properly assess the risk of toxicity in a given case. If you believe your patient has been exposed to something harmful, take immediate action and contact Pet Poison Helpline at 1-800-213-6680 for assistance.
About Pet Poison Helpline:
Pet Poison Helpline, an animal poison control center based out of Minneapolis, is available 24 hours, seven days a week for pet owners and veterinary professionals that require assistance treating a potentially poisoned pet. The staff provides treatment advice for poisoning cases of all species, including dogs, cats, birds, small mammals, large animals and exotic species. As the most cost-effective option for animal poison control care, Pet Poison Helpline’s fee of $59 per incident includes follow-up consultation for the duration of the poison case. Pet Poison Helpline is available in North America by calling 800-213-6680. Additional information can
be found online at www.petpoisonhelpline.com.
1. Flint C. Bone and Blood Meal. In Hovda LR, Brutlag AG, Poppenga RH, Peterson KL, eds.  Blackwell’s Five-Minute Veterinary Consult Clinical Companion: Small Animal Toxicology. 2nd ed. Ames, IA: Wiley-Blackwell, 2016.; pp. 547-551.
2. Flint C. Fertilizers. In Hovda LR, Brutlag AG, Poppenga RH, Peterson KL, eds. Blackwell’s Five-Minute Veterinary Consult Clinical Companion: Small Animal Toxicology. 2nd ed. Ames, IA: Wiley-Blackwell, 2016; pp. 560-564.
3. Gwaltney-Brant S. Pyrethrins and Pyrethroids. In Hovda LR, Brutlag AG, Poppenga RH, Peterson KL, eds. Blackwell’s Five-Minute Veterinary Consult Clinical Companion: Small Animal Toxicology. 2nd ed. Ames, IA: Wiley-Blackwell, 2016; pp. 697-704.
4. Talcott PA. Organophosphorus and Carbamate Insecticides. In Hovda LR, Brutlag AG, Poppenga RH, Peterson KL, eds. Blackwell’s Five-Minute Veterinary Consult Clinical Companion: Small Animal Toxicology. 2nd ed. Ames, IA: Wiley-Blackwell, 2016; pp. 689-696.