Mothball Poisoning in Dogs

By Renee Schmid, DVM, DABVT, DABT; Ahna Brutlag, DVM, MS, DABT, DABVT; Charlotte Flint, DVM

What are mothballs and how are they used?

Mothballs are solid pesticides that slowly release a vapor to kill and repel moths, their larvae, and other insects in stored clothing and fabric. Mothballs are sometimes used to repel snakes, mice, and other animals. Using mothballs in this way is not recommended and can be harmful to pets, children, and the environment.

Moth repellent products come in a variety of forms, including balls, cubes, spheres, cakes, scales, powder, and flakes. They may contain the insecticides naphthalene, paradichlorobenzene (PDB), or, rarely, camphor. Older mothballs usually contain naphthalene and the packaging often labels them as “old-fashioned mothballs.” Most modern mothballs contain PDB instead, because of concern about naphthalene’s flammability and toxicity. Camphor mothballs are more commonly found in Asia but are available in North America.

Mothballs are designed to be used in a sealed container to limit the spread of vapors. When used and stored properly, they are relatively safe to keep in a home with pets. Mothball ingestions make up a small percentage of calls to Pet Poison Helpline, a 24/7 animal poison control center. Approximately half of mothball-related calls are related to ingestion of naphthalene-type mothballs. The remaining calls regarding mothball exposures are divided between PDB and unknown types of mothballs.

Why are mothballs poisonous to dogs?

Mothballs contain a high concentration of insect repellent. Poisoning most commonly occurs when dogs ingest mothballs. Cats are more sensitive to their harmful effects, but dogs are more likely to ingest mothballs due to their curious nature. Long-term exposure to mothball fumes can harm pets and people.

“Old-fashioned” naphthalene mothballs are the most poisonous type of mothball. Ingestion of naphthalene mothballs can cause gastrointestinal upset and, less frequently, anemia, neurologic signs, and kidney or liver damage. Modern PDB mothballs are less toxic but can still cause illness, especially when ingested. Ingestion of PDB mothballs commonly results in gastrointestinal upset, neurologic signs, and rarely, kidney or liver damage. Mothballs containing camphor, an essential oil, have a low risk of poisoning, with stomach upset being the most common sign. Large ingestions, however, can result in stimulation of the nervous system and possible seizures.

How many mothballs could be harmful to a dog?

As little as one mothball could poison a dog. The toxic dose depends on the size of your pet, the size of mothball, the type of mothball, and whether the mothball was ingested, or if the pet was only exposed to the fumes.

What should I do if my dog eats a mothball?

If you think your dog has eaten a mothball, immediately contact your veterinarian or Pet Poison Helpline at 1-800-213-6680. The sooner you seek treatment, the better chance your dog has of fully recovering.

"Do not induce vomiting or give anything orally to your dog unless your veterinarian specifically directs you to do so."

Do not induce vomiting or give anything orally to your dog unless your veterinarian specifically directs you to do so. When possible, put the mothball package and remaining loose mothballs into a sealed plastic bag and take them with you to the veterinary clinic for identification.

What are the clinical signs of mothball poisoning?

Mothballs dissolve slowly when ingested by dogs and poisoning can be delayed for several days. Signs of poisoning may include:

  • Vomiting
  • Diarrhea
  • Abdominal pain
  • Mothball-scented breath
  • Pale or brown gums
  • Weakness or lethargy
  • Labored or rapid breathing
  • Walking off balance
  • Tremors
  • Seizures

In severe cases, the dog may develop damage to the liver or kidneys. Signs of kidney damage may include vomiting, lack of appetite, increased or decreased drinking, increased or decreased urination, and foul-smelling breath. Dogs with liver damage may have decreased appetite, lethargy, vomiting, diarrhea, discoloration of the stool, dark urine, yellow discoloration of the eyes or skin (icterus), and an increased chance of bleeding.

Is there an antidote for mothball poisoning?

There is no antidote for mothball poisoning. However, when early decontamination and supportive care are provided, most dogs survive this type of poisoning.

How is mothball poisoning treated?

Early decontamination and treatment decrease the risk of serious poisoning. If your dog has just eaten a mothball but has not yet developed any signs of poisoning, your veterinarian may induce vomiting to remove the mothball from the stomach.

The veterinarian may also administer medical-grade activated charcoal to decrease absorption of chemicals by the gastrointestinal tract. Activated charcoal should only be administered by a veterinarian. When given incorrectly, aspiration into the lungs and life-threatening changes in sodium levels may occur.

If clinical signs have developed, your veterinarian will treat your pet based on the signs. Treatment may include:

  • blood work,
  • fluid therapy,
  • X-rays (radiographs), and
  • medication to treat current signs.

What is the prognosis for recovery from mothball poisoning?

The outcome depends on many factors including the initial health of the pet, amount ingested, and time to treatment. With early treatment, pets are less likely to develop long term effects. Some pets may have permanent liver or kidney damage. Although uncommon, death may occur with high doses or when treatment is delayed.

How can I prevent mothball poisoning?

Always store mothballs out of reach of children and pets. Only store mothballs in closed, airtight containers to prevent accidental ingestion by pets. Make sure you follow label instructions and never use mothballs loose in your home, yard, or garden to repel pests. Do not mix different types of mothballs or mix mothballs with other chemicals or insecticides. There are many non-chemical alternatives to mothballs that can prevent insect damage to fabrics and are safer for pets.

If your dog consumes mothballs, contact your veterinarian or an emergency clinic immediately, and get your pet prompt treatment. As with any poisoning, your pet has the best chance of recovery when treated as quickly as possible.

Pet Poison Helpline, an animal poison control center based out of Minneapolis, MN, is available 24/7 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 per-incident fee includes follow-up consultations 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

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