Every time I take my three-year-old Cavalier King Charles Spaniel, Rhett Butler, for a walk in our neighborhood I consistently find myself thinking “What is he sniffing and what could he be ingesting?”. As a spaniel, his nose is constantly glued to the ground – he often eats grass too! But what chemicals are on that grass? Are they getting ingested? Furthermore, spotting little yellow signs that say “Caution: Pesticide application – KEEP OFF”, make me wonder if there are any consequences of walking my dog through these urban areas (Fig. 1).
Figure 1. A common sight for many dogwalkers in neighborhoods across the United States. But what do they really mean for your pet? (Source: © 2009 John Nordell)
Upon combing the scientific literature, what I found regarding pets and pesticides was shocking. Pesticides are any substance used to kill, repel, or control pests and can include insecticides, herbicides, and fungicides [1]. One study showed that exposure to common herbicide- and insecticide-treated lawns, particularly with the chemical 2,4-dichlorophenoxyacetic acid (2,4-D), significantly increased (a 7.2-fold increase!) the risk of developing urinary bladder cancer in Scottish Terriers. Exposure data (i.e. how much, how often, main ingredients of chemicals) was collected within the year prior to the dogs diagnosis with urinary bladder cancer. In addition, common lawn chemicals such as 2,4-D, 4-chloro-2-methylphenoxypropionic acid (MCPP), and dicamba were commonly detected on untreated lawns in another study suggesting that chemical drift can occurr [3]. In urban areas, even “untreated” lawns might be unsafe. Due to the movement of pesticides, dogs could become exposed to chemicals moving through any grassy area [3]. One study found that 56% (14 out of 25 households) of dogs living on previously treated lawns had detectable levels of these chemicals in their urine. This number rose to 76% following pesticide application to all 25 lawns within two days [3]. The control group consisted of 8 households, with lawns never chemically treated, yet 50% of dogs had detectable levels of 2,4-D, MCPP, and dicamba in their urine. More research is needed to determine how long we should restrict a dog’s access to treated lawns following pesticide application [3].
Although I am only highlighting a few studies here, there are more out there suggesting pesticides are increasingly prevalent in the life of your pet. Findings are raising concern about widespread use of chemicals, their persistence in the environment, and the consequences to humans and canines alike. If, like me, you are still concerned about the exposure of your pet to common pesticides, I would suggest checking out the following resources [4,5,6,7] or learning more about the regulations your own communities may have regarding pesticide use.
References
[1] Correa, Julio E. “Dogs and Pesticide Use.” Alabama Cooperative Extension System (2016): UNP-0050.
[2] Glickman, L.T., M. Raghavan, D.W. Knapp, P.L. Bonney, and M.H. Dawson. “Herbicide exposure and the risk of transitional cell carcinoma of the urinary bladder in Scottish Terriers.” Journal of the American Veterinary Medical Association 224 (2004): 1290-1297.
[3] Knapp, Deborah W., et al. “Detection of herbicides in the urine of pet dogs following home lawn chemical application.” Science of the Total Environment 456-457 (2013): 34-41.
[4] Plechner, Alfred J. “Adrenal toxicity in dogs and cats as a contributing cause of hormonal and immune destabilization.” Journal of Applied Toxicology 24 (2004): 53-58.
[5] Hoar Zahm, Shelia, and Aaron Blair. “Pesticides and Non-Hodgkin’s Lymphoma.” Cancer Research 52 (1992): 5485s-5488s.
[6] Maddy, K.T., S. Edmiston, and J. Wellings. “Poisoning of animals in the Los Angeles area with pesticides (1981).” In: Ruckebusch Y., PL. Toutain, and G.D. Koritz (eds) Veterinary Pharmacology and Toxicology 1983: 725-731.
[7] “Pesticide Use Around Pets.” National Pesticide Information Center. Accessed: November 18, 2018.