Why drooling is the first red flag
The heavy drooling you're seeing means calcium oxalate crystals are already irritating your dog's mouth, throat, and possibly her stomach lining. These needle-like compounds cause immediate pain on contact, which explains the excess saliva as her body tries to flush them out. Since she ate the leaves 30 minutes ago, the crystals have likely reached her stomach acid, where they may start causing deeper tissue irritation.
Watch for her to paw at her mouth or repeatedly swallow, as these are signs the oral irritation is worsening. The drooling may temporarily lessen if she drinks water, but don't assume this means she's improving — stomach cramping and nausea often follow within the next hour. Keep a bowl of fresh water available but don't force her to drink, as swallowing may remain painful.
What the next 3–6 hours could bring
With a 10 kg dog, the next visible signs will likely be vomiting or retching, possibly with frothy saliva or bits of leaf material. The vomit may contain blood if the crystals have scratched her esophagus. Diarrhea can develop separately as the toxins reach her intestines, sometimes appearing watery or containing mucus. These gastrointestinal signs are her body's attempt to expel the irritants.
Less obvious but equally concerning is kidney stress, which won't show immediate outward signs. The oxalates bind calcium in her bloodstream and can crystallize in the kidneys over the next 12–24 hours. Note whether she urinates normally tonight — straining, decreased output, or unusually strong-smelling urine all warrant an emergency vet visit, even if she seems otherwise stable.
When to escalate beyond monitoring
If her drooling hasn't subsided within two hours or she refuses all water, she needs veterinary pain relief and possibly intravenous fluids to protect her kidneys. Small dogs process toxins faster than large breeds, so waiting overnight isn't safe with this exposure level. Similarly, any twitching muscles, lethargy, or collapse suggests her blood calcium has dropped dangerously low — this is an immediate emergency.
Collect a sample if she vomits or has diarrhea, as the vet may want to check for leaf fragments. Note the times of any symptoms, as the sequence helps determine how far the toxins have progressed. Even if she seems to recover after vomiting, schedule a daytime vet visit to check her kidney values, as damage can be delayed.
Why hydration matters more than food right now
Don't offer food for at least six hours — her stomach needs rest, and eating could trigger more vomiting. Focus instead on encouraging small licks of water or ice cubes to rinse residual crystals from her mouth. If she won't drink voluntarily, wet her gums with a soaked cloth every 15 minutes to prevent dehydration.
Watch her water bowl closely over the next day. Drinking excessively or not drinking at all are both red flags post-rhubarb exposure. Increased thirst can indicate kidney strain trying to flush toxins, while avoiding water may mean mouth pain or nausea. Either extreme means she needs veterinary assessment, even if other signs seem mild.
The step-by-step response, from the first minute to the vet visit, is in our Rhubarb Leaves Poisoning in Dogs and Cats emergency guide.