🚨 If symptoms are present — go to emergency vet NOW. ASPCA Poison Control: (888) 426-4435 (24/7)
Mothball Toxicity in Dogs
Mothballs are deceptively dangerous — they look like small candy, smell strongly which attracts dogs' noses, and are often stored in accessible areas. Two types exist: naphthalene-based (most toxic) and paradichlorobenzene-based (moderately toxic). Both are serious veterinary emergencies if ingested. Even skin contact or inhalation of vapors in an enclosed space can cause toxicity.
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⚡ Immediate Actions
- 1Call ASPCA Poison Control (888) 426-4435 or your vet immediately
- 2Note the type of mothball if possible — naphthalene vs. paradichlorobenzene (check the label)
- 3If skin or fur contact: wash with dish soap and warm water — wear gloves
- 4Do not induce vomiting without vet guidance — mothball compounds can be caustic on return
- 5Take the mothball packaging to the vet to identify the active ingredient
Symptoms & Timeline
Inhalation / minor exposure
Naphthalene has a high vapor pressure, releasing volatile molecules that irritate mucous membranes of the eyes and upper respiratory tract on contact. Even brief exposure in an enclosed space can deliver sufficient vapor to trigger sympathetic arousal and GI nausea without systemic absorption.
- Eye and nose irritation
- Nausea
- Headache-equivalent behavior (restlessness, pawing at head)
- Mild lethargy
Ingestion — naphthalene
Absorbed naphthalene is oxidized in the liver to naphthol metabolites that attack hemoglobin and red blood cell membranes. Heinz body formation causes the spleen to remove damaged red cells at an accelerated rate, producing hemolytic anemia visible as pale gums. Hemoglobin released from lysed cells is excreted in urine, producing the characteristic reddish-brown color.
- Vomiting
- Lethargy
- Pale gums (hemolytic anemia)
- Loss of appetite
- Liver pain and abdominal discomfort
- Reddish-brown urine (hemoglobin in urine)
Severe toxicity
Naphthol metabolites also convert hemoglobin to methemoglobin — an oxidized form that cannot carry oxygen — superimposing oxygen deprivation on the anemia. The liver, simultaneously under direct toxic attack from naphthol, develops hepatocyte necrosis that progresses to jaundice and coagulopathy.
- Methemoglobinemia — brown/muddy gums, breathing difficulty
- Seizures
- Liver failure signs: jaundice, black stools
- Coma
How Mothballs / Naphthalene / Paradichlorobenzene Affects Dogs
Naphthalene is oxidized in the liver to alpha-naphthol and naphthol epoxide, which react with hemoglobin to form methemoglobin (unable to carry oxygen) and cause Heinz body formation in red blood cells, leading to hemolytic anemia. Simultaneously, naphthalene metabolites are directly hepatotoxic, causing liver cell necrosis. Paradichlorobenzene is less acutely toxic but causes liver and kidney damage with large exposures. Both compounds cause CNS depression at high doses. The strong vapor pressure of naphthalene means even inhalation in a closet or confined space can cause toxicity.
What Your Vet Will Do at the Clinic
Mothball ingestion treatment focuses on interrupting toxin absorption and supporting the organs under attack. Vomiting is not induced because naphthalene can trigger seizures during the emetic response. Activated charcoal is given to bind remaining naphthalene or paradichlorobenzene in the gut. IV fluids support both liver and kidney function as they filter and metabolize the toxin. A complete blood count with Heinz body smear detects early hemolytic anemia before it becomes severe enough to cause cardiovascular compromise. Ascorbic acid (Vitamin C) may be used to reduce methemoglobin back to functional hemoglobin. Dogs with severe anemia may require blood transfusion. Liver enzyme panels and kidney values are repeated every 24 hours throughout treatment, with hospitalization for a minimum of 72 hours in significant exposures.
Step-by-step protocol:
- 1Do NOT induce vomiting — mothball compounds may trigger seizures during emesis
- 2Activated charcoal to reduce absorption of naphthalene or paradichlorobenzene
- 3IV fluids to support kidney and liver function
- 4Liver and kidney function panels (ALT, AST, BUN, creatinine)
- 5Blood monitoring for hemolytic anemia (CBC, Heinz body smear) with naphthalene
- 6Anti-seizure medication if tremors or seizures develop; observation for 72 hours
Frequently Asked Questions
My dog found and licked a mothball. How serious is this?
Any mothball ingestion warrants an immediate call to your vet or ASPCA Poison Control. Even a lick of a naphthalene mothball can deliver a significant dose. The severity depends on the dog's size and the type of mothball. Do not wait for symptoms to appear.
Are cedar mothball alternatives safer for dogs?
Cedar chips and cedar blocks are generally considered non-toxic to dogs — they repel moths through cedar oil which, while it should not be ingested in large amounts, is far safer than naphthalene. Lavender sachets are another non-toxic alternative. If using essential-oil-based repellents, ensure they are kept out of reach.
How long do mothball symptoms last?
With treatment, mild to moderate cases can resolve over several days. Hemolytic anemia may take 1–2 weeks to fully recover. Liver damage can take longer and requires follow-up bloodwork. Dogs with pre-existing liver conditions are at higher risk of serious complications.
🛡️ Emergency vet bills average $1,500–$5,000
Most US dog owners pay out of pocket. Pet insurance can cover 70–90% of unexpected emergency costs.
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