If your dog ate a mothball, the earliest and most reliable sign is vomiting, often within a few hours of ingestion. Mothballs are concentrated pesticide, and even a single one can be toxic to a small dog. A 22-pound dog can be poisoned by as little as one and a half naphthalene mothballs, so this is a situation where acting fast matters more than waiting to confirm symptoms.
Signs to Watch For
Mothball poisoning almost always starts with gastrointestinal symptoms. Vomiting, loss of appetite, abdominal pain, and diarrhea are typically the first things you’ll notice, appearing within hours of ingestion. Your dog may also seem unusually tired or disoriented.
If a larger amount was swallowed or treatment is delayed, more serious signs can develop. These include:
- Pale or white gums, a sign that red blood cells are being destroyed
- Labored or rapid breathing
- Trembling, loss of coordination, or stumbling
- Seizures (rare but possible with large exposures)
- Dark or discolored urine
- Yellowing of the eyes or skin, which signals liver involvement
Vomiting alone doesn’t confirm mothball poisoning, of course. But if your dog is vomiting and you’ve noticed a mothball is missing, or if your dog had access to a closet, storage bin, or garage where mothballs were stored, treat it as an emergency.
Why Mothballs Are So Dangerous
Mothballs contain one of two chemicals: naphthalene or paradichlorobenzene. Both are toxic, but naphthalene is roughly twice as dangerous. Unfortunately, most mothball packaging doesn’t make it obvious which chemical is inside, and they look and smell similar.
Naphthalene damages red blood cells, causing a condition called hemolytic anemia. Essentially, the chemical breaks red blood cells apart faster than the body can replace them, which starves tissues of oxygen. That’s why pale gums and breathing difficulty show up in more severe cases. The chemical also irritates the stomach lining, which is why vomiting happens so quickly and reliably.
Paradichlorobenzene causes similar gastrointestinal symptoms (vomiting, abdominal pain, tremors) and can also damage the liver and kidneys over time. It’s somewhat less acutely toxic, but still dangerous enough to require veterinary care.
Clues That Your Dog Got Into Mothballs
Sometimes you don’t see it happen. If you’re trying to figure out whether your dog ate a mothball after the fact, look for these clues beyond the symptoms listed above:
- A strong chemical smell on your dog’s breath or around their mouth. Mothballs have a very distinctive odor, and it lingers.
- Chewed packaging or scattered mothballs. Check wherever you store them. Dogs are often attracted to the waxy, ball-like shape.
- White or off-white crumbs or residue on the floor, in your dog’s bed, or around their mouth.
Even partial ingestion counts. A dog that chewed on a mothball and spit most of it out still absorbed some of the chemical through the mouth and stomach lining.
What to Do Right Away
Call your veterinarian or an animal poison control hotline immediately. Do not wait for symptoms to appear. Time matters because mothball chemicals are absorbed relatively quickly, and early intervention significantly reduces the risk of organ damage.
Do not try to induce vomiting at home unless a veterinarian specifically tells you to. Mothball chemicals can cause additional harm if vomited back up, and inducing vomiting in a dog that’s already disoriented or seizing is dangerous.
If you can, bring the mothball packaging with you to the vet. Knowing whether the product contains naphthalene or paradichlorobenzene helps the veterinary team choose the right treatment approach.
What Happens at the Vet
Your vet will likely run blood work to check for red blood cell damage, liver function, and kidney function. If ingestion was recent enough, they may induce vomiting in a controlled setting or use activated charcoal to reduce how much of the chemical gets absorbed. IV fluids are standard to support the kidneys and help flush the toxin.
If your dog is already showing neurological symptoms like tremors or seizures, treatment focuses on stabilizing those first. Dogs with significant red blood cell damage may need supportive care over several days.
Recovery and Long-Term Outlook
Dogs that get treatment early generally recover well. The key variable is how much was ingested relative to your dog’s size and how quickly treatment started. A large dog that ate part of one mothball and got to the vet within an hour has a very different prognosis than a small dog that ate multiple mothballs hours ago.
Some dogs do develop permanent liver or kidney damage, particularly when treatment was delayed or the dose was high. Death is uncommon but possible in severe cases. Your vet may recommend follow-up blood work in the weeks after the incident to make sure organ function has returned to normal.
Preventing Mothball Exposure
Store mothballs in sealed, hard-sided containers that your dog cannot open or chew through. Placing them in open closets, under furniture, or in cardboard boxes is an invitation for trouble. Dogs are curious about small, round objects that smell unusual.
If you use mothballs outdoors to deter animals from gardens or crawl spaces, be aware that this is actually an off-label use and puts pets at direct risk. Consider switching to pet-safe alternatives like cedar chips or sealed lavender sachets for moth prevention.