Mothball Poisoning in Dogs

One may not commonly think of mothballs as a pesticide product; in fact, mothballs are often used in ways that are not suitable or effective. Placing mothballs in a garden, attic space or garbage can in an attempt to discourage creatures like raccoons, snakes, birds, and squirrels is entirely erroneous and presents a danger to wildlife and in turn, to domesticated pets like cats and dogs. The ingestion of mothballs, which come as flakes, tablets, crystals, bars, and balls, can be appealing to dogs due to the odor that they emit and the curious nature of our pets. Toxicity from naphthalene and paradichlorobenzene is most dangerous with ingestion, but documentation shows that inhalation of vapors and dermal exposure can cause serious effects and irritation to dogs as well.

Naphthalene and paradichlorobenzene are two ingredients used in mothballs. Paradichlorobenzene is considered to be about half as toxic as naphthalene, though both can cause toxicity and symptoms such as vomiting, lethargy, and tremors. In a case of mothball poisoning, immediate and aggressive treatment is needed in order to prevent serious complications, including kidney damage.

The poisoning effects of the mothballs consisting of paradichlorobenzene are somewhat less than the very toxic naphthalene mothballs. Despite this, the amount of toxicity that your pet will experience is contingent on the amount of ingredients consumed. In addition, your pet may experience serious complications with the liver or kidneys if there is an ongoing or underlying problem with these organs already in place.

Paradichlorobenzene exposure can generally be tolerated in a very small dose, but the ingestion of this compound will most likely produce toxic effects. Of course, a very small dog will become sick faster than a larger canine who has consumed the same amount. Dogs can experience discomfort as follows.

• Nausea
• Vomiting
• Shaking
• Irritation of the eyes and nose from vapors
• Burning sensation on skin from dermal exposure

Naphthalene is the ingredient that is found in mothballs that are considered “older”, as the newer mothball concentrations on the shelves are produced with the less toxic paradichlorobenzene. The vapors from this component of fossil fuels are highly odorous and will allow for toxicity in a much smaller amount than paradichlorobenzene. Your dog may exhibit the following signs of poison.

• Nausea
• Vomiting
• Loss of appetite
• Lethargy
• Tremors
• Seizures
• Irritation of eyes and nose from vapors
• Burning sensation on skin from dermal exposure
• Severe cases will see anemia and possible vomiting of blood
• Dogs with extensive poisoning may have brown mucus membranes

Types

Paradichlorobenzene is an organochlorine insecticide which is considered to be half as toxic as the “older” bicyclic aromatic hydrocarbon naphthalene. During metabolism, excretion is primarily through the urine but sometimes the bile is involved. It should be noted that prolonged exposure can be an occurrence because these toxins are slowly absorbed no matter how they were exposed to your pet (orally, dermally or through inhalation).

• Pets can inhale poisonous vapors
• Mothballs are very odorous and inhalation of the fumes is toxic
• Ingestion of mothballs can occur when a pet finds them in a garden or in an area where they have been left exposed
• Mothballs are designed to be used in closed containers or bags containing clothing in order to repel moths, and are not meant as a rodent, snake or wildlife repellent
• Both paradichlorobenzene and naphthalene vaporize at room temperature which can cause toxicity due to the fumes
• Naphthalene in particular can damage red blood cells
• The red blood cells can no longer transport oxygen to the heart and other organs

If there is a suspicion that your pet has encountered mothballs, a visit to the clinic is imperative. You may smell a slight odor of mothballs on your dog which is indicative of the poisoning. If you have the packaging on hand, be sure to bring it along to the clinic. The veterinarian will want to determine which type of mothball your dog has consumed (“old” being naphthalene and the new type being paradichlorobenzene). There is a test that can be performed by the veterinary team (dropping the mothballs into a solution of water and salt) but to save time, or if there are no mothballs available, having the packaging is most beneficial. Knowing whether your dog has ingested the most toxic ingredient or the milder chemical is beneficial.

The diagnosis will be made based on clinical signs and the information that you are able to provide. Your veterinarian may decide to do blood tests like serum chemistry and complete blood count so that the functioning of the organs can be assessed. Blood markers taken at time of admission will be compared to tests taken during treatment to ascertain how well your dog is recovering. X-rays of the abdomen may show the presence of mothballs in the stomach which can help to determine the treatment steps.

First and foremost, the veterinary team will want to stabilize your furry family member so the severity of the poisoning can be evaluated. Mothballs do not dissolve quickly in the stomach; therefore, if the ingestion was less than 2 hours prior, vomiting may be induced but only if your dog is asymptomatic. Pets who have visible signs of toxicity will be started on decontamination and supportive measures which can be as follows.

Medication

Medication will be given to alleviate gastric irritation and to lessen the production of acids. If there are heavy tremors and seizures your pet will receive drugs to counteract these symptoms as well.

Intravenous

Fluid therapy is crucial as it can flush out the system and protect organs such as the kidney, which is known to be affected by mothball poisoning.

Oxygen

Because naphthalene in particular causes red blood cell damage that can lead to oxygen deficiency in the blood, your pet will be monitored carefully and given oxygen as an additional supportive measure.

Activated Charcoal

This is used to bind poisons together and will be used at the discretion of your veterinarian, depending on the circumstances of your pet.

Blood Transfusion

In severe cases, the need for a blood transfusion could be evident by brown blood samples and brown mucus membranes. This is called methemoglobinemia and will be addressed by medication such as ascorbic acid, methylene blue, or N-Acetylcysteine, and blood transfusion if needed.

Mothball poisoning can have a good prognosis if dealt with quickly and aggressively. If your dog has underlying anemia or organ problems to begin with, or if the poisoning was so severe that the kidneys or liver were damaged, the outlook is more grave. Your pet will need to be in the hospital until all symptoms are resolved and blood markers are within the normal ranges.