Mothball Poisoning in Dogs

Summary

Mothball poisoning is caused by close contact (ingestion, inhalation, or dermal exposure) with mothballs. 

Symptoms resulting from mothball exposure vary depending on the specific pesticide present in the mothball and the amount of exposure.  High levels of exposure, especially to more toxic types of mothballs, lead to nasal and eye irritation, gastrointestinal upset, liver and kidney damage, and central nervous symptoms like tremors and seizures. 

Gastrointestinal decontamination immediately after ingestion is the best chance for a good outcome. Once symptoms arise, supportive treatment is indicated. After symptoms arise, the outcome is dependent on the specific pesticide and the dose. Mothball ingestion may occur without witnesses but it can leave evidence, such as the smell of mothball on the dog.

Risk Factors

Mothball toxicosis is not a common poisoning in dogs. It is of no concern to pet parents who do not use or allow their pets around mothballs. Mothball exposures make up only a few percent of calls to pet poison hotlines each year. 

Even though it is not common and not all dogs are at risk, mothball poisoning is an emergency because small doses have the potential to be fatal. Starting treatment immediately after ingestion carries the best prognosis. Dogs who show severe symptoms like trouble breathing, seizures, or jaundice are less likely to have a good outcome.  Prognosis declines for dogs who develop liver or kidney damage as a result of exposure to mothballs. 

Consumption of as little as one mothball has the potential to be deadly, and there is no antidote for mothball poisoning. Smaller dogs are more at risk of toxicosis due to their lower body weight.

Possible Causes

Mothball poisoning is caused by ingestion, inhalation, or dermal exposure to a toxic dose of the pesticides naphthalene, paradichlorobenzene, or camphor as found in mothball products.

Main Symptoms

Symptoms of mothball poisoning vary slightly depending on which type of pesticide was ingested. Symptoms include: 

• Vomiting • Irritated eyes and nose from vapor exposure  • Burning sensation on the skin from dermal exposure

• Loss of appetite • Abnormal breathing, either labored (dyspnea) or fast and shallow (tachypnea)  • Seizures

Detailed Characterization

Mothballs come in many forms (crystals, flakes, cakes, or traditional mothballs), made up of one of three different active ingredients: 

• Paradichlorobenzene • Naphthalene • Camphor

The availability of these different pesticides varies globally, but all three are potentially deadly, especially to smaller dogs.

Symptoms of mothball poisoning can be categorized according to the pesticide present in the mothballs.   In addition to the general symptoms of mothball poisoning, specific symptoms of paradichlorobenzene toxicosis include:

Tremors  • Irritated eyes and nose • Weakness • Lethargy   Specific symptoms of naphthalene toxicosis include:

• Lethargy • Bloody urine (hemoglobinuria) • Abdominal pain • Diarrhea • Irritated eyes and nose • Red skin

• Excessive licking at the skin • Tremors • Seizures • Jaundice (icterus)   

Specific symptoms of camphor toxicosis include:

• Collapse • Seizures • Difficulty breathing (dyspnea) • Cessation of breathing (apnea)

Testing and Diagnosis

If ingestion of the mothball was witnessed, this information will guide diagnosis. After a thorough history and physical exam, a dog showing the types of symptoms that arise after mothball exposure typically undergoes the following diagnostics:

• Routine blood tests • Advanced blood testing, like blood gasses • Urinalysis • Diagnostic imaging

Steps to Recovery

There is no antidote for mothball poisoning. The goal of treatment initiated shortly after mothball ingestion is the removal of as many mothballs from the digestive system as possible via induction of emesis (vomiting) or gastric lavage. These procedures are more risky and may not  be recommended once the dog shows clinical signs of poisoning. Note: there is no safe method to induce vomiting in a dog at home. This should only be performed by a veterinarian. 

Once clinical signs develop, treatment is largely supportive and symptomatic, including:

• Fluid therapy • Antiemetics and GI protectants • Anti-seizure medications • Oxygen and ventilatory support

• Blood transfusions

If quickly and properly treated soon after ingestion, prognosis of mothball poisoning is favorable. 

Once symptoms develop, the prognosis is guarded and depends on the type of pesticide in the mothballs and how much was consumed relative to the dog’s body weight. With camphor or naphthalene, consumption of only one mothball has the potential to be lethal to a healthy, medium-sized dog. A one-time ingestion of a single paradichlorobenzene mothball is expected to be well-tolerated by most dogs.

Prevention

Mothball poisoning is prevented completely by removing the possibility of exposure to mothballs. Strategies include:

• Avoiding mothballs altogether • Diligent storage of mothballs (out of reach from both pets and children) 

• Proper disposal of mothballs 

When used as directed, mothballs pose less risk to children or pets because they are sealed in metal containers. It is dangerous (and illegal in the US and Canada) to use mothballs in any other fashion. Traditional practices like using them in gardens or around baseboards in an effort to repel snakes or rodents are banned in an effort to protect children, pets, and the environment.

Is Mothball Poisoning Common in Dogs?

Mothball toxicosis is not a common poisoning in dogs.

Typical Treatment

Typical treatment of mothball toxicosis includes:

• Decontamination • Fluid therapy • Anti-vomiting medication • Anti-seizure medications

• Oxygen and ventilatory support • Blood transfusion

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