Toxicology Brief: Moth repellent toxicosis - Veterinary Medicine
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Toxicology Brief: Moth repellent toxicosis


In people, oral exposure to naphthalene can cause gastrointestinal signs, including vomiting, nausea, abdominal pain, and diarrhea. Hemolytic anemia and cataract formation have also been reported.1 An association exists between glucose-6-phosphate dehydrogenase deficiency and the hematologic effects of naphthalene. Inhaling naphthalene can also cause hemolysis and gastrointestinal effects in people.1


In the ASPCA APCC database, the clinical signs reported after ingestion of paradichlorobenzene-containing moth repellent products were vomiting and trembling (ASPCA APCC Database: Unpublished data, 2004). A bird that had inhaled paradichlorobenzene showed depression, head bobbing, weakness, and anorexia. The bird recovered with symptomatic treatment including force-feeding, thermoregulation, and confinement. Long-term oral exposure studies in laboratory animals showed no hematologic or ocular effects with paradichlorobenzene, but liver and renal changes were noted. Additionally, neurologic signs including weakness, ataxia, and tremors were noted in rats receiving doses between 770 and 1,200 mg/kg/day for at least five days.5

In people, paradichlorobenzene ingestion can cause nausea and vomiting. Hepatotoxicity is also possible but uncommon after large oral exposures. Paradichlorobenzene vapors are irritating to the nose and eyes, and central nervous system depression may occur at concentrations that are extremely objectionable. With dermal contact, the solid material produces a burning sensation but causes only slight skin irritation. Paradichlorobenzene has less potential for hematologic damage than naphthalene, but methemoglobinemia was seen in one pediatric patient, and anemia has been seen with long-term exposures. Paradichlorobenzene may cause cataract formation.4


When treating moth repellent exposure, assess and stabilize the patient. If the patient is dyspneic, provide supplemental oxygen and place an intravenous catheter. Initiate decontamination procedures if the patient is stabilized and provide supportive care. Fluid therapy is recommended in symptomatic animals. Induce emesis only in asymptomatic patients and only if ingestion occurred less than two hours before presentation and no contraindications to inducing emesis exist. Dogs, cats, ferrets, and potbellied pigs can vomit, but rodents, rabbits, birds, horses, and ruminants cannot. After the vomiting has subsided, administer activated charcoal (1 to 2 g/kg orally) and a saline cathartic (250 mg/kg magnesium sulfate or sodium sulfate orally).9 Administering activated charcoal with a cathartic may be beneficial up to 24 hours after mothball ingestion because mothballs dissolve slowly in the gastrointestinal tract.2

In general, naphthalene ingestion requires more aggressive treatment than paradichlorobenzene. If the type of mothball ingested is unknown and the owner has brought in a sample, perform the following test. Add three heaping tablespoons of table salt to tepid water, and mix vigorously until the salt will no longer dissolve. Place the mothball in the saturated salt water. Naphthalene mothballs float, and paradichlorobenzene mothballs sink.10

Obtain a baseline complete blood count and serum chemistry profile. Address any gastrointestinal signs. Vomiting may be controlled by administering metoclopramide hydrochloride (dogs and cats 0.2 to 0.5 mg/kg orally, intramuscularly, or subcutaneously t.i.d.11) or another standard antiemetic. Sucralfate (1 g for large dogs, 0.5 g for small dogs orally t.i.d.; 0.25 g orally b.i.d. to t.i.d. for cats11) can be used to relieve gastrointestinal irritation. Additionally, consider adding a medication to decrease gastric acid production, such as the H2 antagonist famotidine (dogs and cats 0.5 to 1 mg/kg orally, subcutaneously, or intramuscularly once or twice a day11) or proton-pump inhibitor omeprazole (dogs 0.5 to 1 mg/kg orally once a day; cats 0.7 mg/kg orally once a day11). Seizures may be controlled with diazepam (dogs and cats 0.5 to 1 mg/kg intravenously to effect11). Blood transfusions or polymerized bovine hemoglobin glutamer-200 (Oxyglobin—Biopure) (dogs single dose of 30 ml/kg intravenously at a rate of up to 10 ml/kg/hr; not labeled for use in cats11) may be needed in patients with severe methemoglobinemia.


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