The deceptive 6-hour window
At the 6-hour mark, most of the mothball has dissolved in your dog's stomach, but the real damage happens as the chemicals enter the bloodstream. Naphthalene attacks red blood cells gradually—what looks like 'fine' now could be the calm before the storm. Dogs this size often show their first subtle signs between hours 8 and 12.
Watch for small behavior changes like drinking more water than usual or seeming slightly off-balance when turning quickly. These hint that oxygen delivery is already compromised, even before gums visibly pale. The 10 kg size buys some time compared to tiny dogs, but don't assume that means safety.
When to expect visible symptoms
If symptoms appear within the next 6 hours, they'll likely start with listlessness and loss of appetite, then progress to vomiting or diarrhea with an odd, metallic smell. Dark urine typically shows up between 12-24 hours post-ingestion—this is the body trying to flush out damaged blood cells.
Paradichlorobenzene mothballs (usually the newer, smoother ones) tend to cause more gastrointestinal upset first, while naphthalene (older, crumbly types) goes straight for the blood. Without knowing which type your dog ate, assume the worst-case timeline—the vet can adjust their approach if you find the packaging later.
Why weight isn't a full safety buffer
While a 10 kg dog has more blood volume to dilute the toxin than a chihuahua, mothball chemicals accumulate in fatty tissues before releasing back into the bloodstream. This means even a single mothball can cause waves of symptoms over 48 hours. Bigger dogs sometimes crash harder because owners delay treatment, assuming their size protected them.
Exercise speeds up circulation and symptom onset—keep your dog quiet and skip walks until the vet clears them. If they normally sleep through the night, check their gums with a flashlight before bed—color changes are easiest to miss in poor lighting. Press on a pink area—it should blanch then pinken up in under 2 seconds.
The critical 24-hour checkpoint
If 24 hours pass with no symptoms, the risk drops but isn't gone—late-onset liver issues can appear around day 3. The vet may want to run a blood smear to check for abnormal cell shapes even if your dog seems perfect. Some dogs show subtle anemia only on tests, not in obvious outward signs.
Save a fresh stool sample—chemical byproducts often exit this way, and testing it helps gauge how much was absorbed. Expect possible appetite swings for a week as the liver processes remnants. Never assume one clear night means all-clear; set phone reminders to check gums every 4 hours for 2 full days.
The step-by-step response, from the first minute to the vet visit, is in our Mothballs (Naphthalene, Paradichlorobenzene) emergency guide.