How toxic are mothballs to dogs? What to do if your pet ingests napthalene?

How toxic are mothballs to dogs? What to do if your pet ingests napthalene?

Whilst the prevalence of mothball use has certainly changed over the last 10-20 years, they remain available in three common preparations. Unfortunately, dogs that get into mothballs can develop a range of toxic effects depending on the active ingredient and amount ingested.

What makes mothballs poisonous for dogs?

Perhaps the most toxic commonly found mothball ingredient is camphor. Camphor ingestion results in central nervous system poisoning where a dog can become agitated and develop seizures. The signs will occur quickly after ingestion and can be life-threatening. There is no antidote to camphor poisoning, however good supportive care by a veterinarian and provision of anticonvulsant medication as required can result in a good outcome.

Neurotoxic Effects of Napthalene on Dogs

Naphthalene is another ingredient which is commonly used in mothballs. Naphthalene can result in some early onset neurotoxic effects however the primary concern is the effects on the red blood cells. Exposure to naphthalene can cause damage to the red blood cells (known as haemolysis) and if the destruction is severe enough, the dog can develop anaemia. This red blood cell destruction can result in secondary kidney injury.

Another condition sometimes seen following naphthalene exposure is methemoglobinemia. This causes poor oxygen delivery throughout the body and can potentially be life-threatening without urgent treatment. Dogs with high levels of methemoglobin tend to have purple or dark gums and tongue, can be breathing rapidly and may be restless or look uncomfortable. The third common, and less toxic ingredient found in mothballs is paradichlorobenzene.

Paradichlorobenzene is also sometimes found in urinal cakes. This compound is considered less toxic than both camphor and naphthalene. It can result in gastrointestinal upset and in some cases drowsiness/lethargy and muscular weakness may also be seen. If you have no packaging to confirm which ingredient you are dealing with, there are several ways to differentiate between camphor, naphthalene and paradichlorobenzene. These processes take advantage of the different physiochemical properties of each chemical.

What to do if your dog has poisoning symptoms or has eaten mothballs?

If your dog has been exposed to a mothball, you can contact the Animal Poisons Centre for free advice on 1300 869 738 (from Australia) or 0800 869 738 (from New Zealand).