Why a 4 kg dog can't handle a cup of syrup
That much agave syrup is roughly equivalent to a human drinking an entire bottle of soda in one go. For a tiny dog like your Chihuahua, the sheer volume of sugar hitting their system at once is overwhelming. Their pancreas will work overtime trying to manage the blood sugar spike, which can lead to temporary digestive chaos.
Expect the first signs within 2-4 hours—look for restlessness, a distended belly, or excessive thirst. Diarrhea often follows as their body tries to expel the excess. Keep their water bowl full but don't offer food for at least 6 hours to let their stomach settle.
When small size makes sugar dangerous
Small breeds process sugars differently than larger dogs. What might give a Labrador mild gas could send a 4 kg dog into a sugar crash. Watch for trembling, weakness, or disorientation after the initial hyperactivity phase. These are signs their blood sugar is dropping too fast.
If your Chihuahua becomes lethargic instead of bouncing back after a nap, call your vet. Tiny dogs dehydrate quickly from diarrhea, and their small bodies struggle to regulate extreme blood sugar swings without help.
The next 12 hours matter most
Mark the time they ate the syrup—the first half-day is when problems typically appear. Sugar overload usually resolves within 24 hours if they're otherwise healthy, but the first 12 hours determine whether they'll need intervention. Set alarms to check on them every 2-3 hours tonight.
You're looking for progressive signs: first panting or pacing, then vomiting if their stomach rebels, finally diarrhea as it moves through. Any one symptom alone isn't alarming, but worsening combinations mean they need veterinary support to rebalance.
Why your other dogs weren't interested
Dogs vary in their sweet tooth—your Chihuahua likely went for the syrup because small breeds often crave quick energy. Larger dogs might ignore it unless very hungry. The real concern is that your little one consumed a massive dose relative to their size.
If your other dogs had lapped some too, their bigger bodies would dilute the impact. But for this 4 kg patient, you're basically waiting to see if their system can process what amounts to a sugar tsunami without medical help.
The full verdict, portion guidance and serving notes are collected on the Agave syrup food facts page.