Why overnight fermentation changes the risk for a 7 kg dog
When lychees sit out overnight, two things happen: sugars break down into alcohol through fermentation, and mould spores take hold. For a small dog, even trace amounts of alcohol from two fruits could cause mild disorientation or stomach irritation. The real concern is whether those lychees grew visible mould — grey fuzz or greenish patches mean mycotoxins are present, which attack the nervous system faster than plain fruit sugars would.
Check where your dog found them. If the counter had juice stains where the lychees sat, your dog likely ingested more fermented liquid than solid fruit. This means quicker absorption of any alcohol content, which could lead to stumbling or excessive thirst within an hour. Mould toxins work slower but last longer — watch for muscle twitches or unusual fatigue over the next 6 hours.
The difference between pits and mould in this case
Normally, lychee pits are the main hazard because they can block a small dog’s intestines. Here though, the softness of overripe fruit means your dog probably didn’t encounter hard pit fragments — fermented flesh turns mushy and separates easily. That’s one less worry, but mould introduces new dangers that fresh lychees don’t carry.
If you can still see the remains of the eaten lychees, inspect them closely. Black spots or a musty smell indicate advanced mould growth, which warrants an immediate vet visit. Without those signs, focus on hydration — offer water every 30 minutes to help flush any mild toxins. Skip food for 4-6 hours to let the stomach settle.
Timing of symptoms after eating spoiled fruit
Fermentation effects show up fastest. If your dog ate these within the last 30 minutes, you might notice burping or lip-licking as the alcohol hits their system. Small dogs process alcohol poorly, so even this tiny amount could make them unsteady on their feet for a short while. These signs should fade within 2 hours if no mould was involved.
Mould toxins take 3-6 hours to cause vomiting or tremors, which would persist longer than alcohol-related wobbliness. Write down exactly when your dog ate the lychees — this helps the vet timeline potential reactions. If it’s been over 4 hours without symptoms, the risk drops significantly, but monitor for diarrhoea tomorrow from the high sugar content.
When to bypass home care for vet help
Any neurological sign — head tilting, inability to stand, or repetitive paw motions — means the mould toxins are affecting the brain and require IV fluids to flush out. Don’t wait these out at home. Similarly, if your dog vomits more than twice in an hour or can’t keep water down, dehydration becomes a real threat for small breeds.
For mild cases where you’re unsure about mould exposure, collect a stool sample later. Mould toxins often leave visible traces in waste, which your vet can test. Until then, restrict activity to avoid falls if your dog seems dizzy, and keep them in a cool area — fermented fruit can temporarily raise body temperature.
The full verdict, portion guidance and serving notes are collected on the Lychee food facts page.