Why two stems push this into emergency territory
A 4 kg cat chewing two entire rhubarb stems, especially with leaves attached, has crossed into dangerous exposure levels. The leaves hold the highest oxalate concentration, but the raw stems also contain these crystals in their skin and fibrous parts. For a small cat, this quantity likely delivers enough toxin to overwhelm their kidneys' ability to process it safely.
Oxalates bind calcium in the bloodstream, causing sudden drops that affect nerve and muscle function. They also form sharp crystals in the kidneys, damaging delicate tissues. Unlike dogs, cats lack certain liver enzymes to break down plant toxins efficiently, making them more vulnerable to smaller amounts.
The first signs you might see within hours
Initial symptoms often include excessive drooling and pawing at the mouth—oxalates irritate oral tissues on contact. Within 2-6 hours, vomiting may start as the stomach reacts to the toxin. The vomit might contain plant matter or appear foamy if the cat swallowed saliva repeatedly.
Neurological signs like unsteady walking or muscle twitching suggest calcium levels have dropped critically low. Less obvious but equally urgent are increased thirst and urination, indicating the kidneys are struggling. Any of these warrant immediate veterinary intervention—don't wait for 'all' symptoms to appear.
Why the leaves make this worse than stalk-only exposure
Rhubarb leaves contain roughly 3-5 times more soluble oxalates than the stalks. When chewed, they release these compounds rapidly into the system. Even if your cat spat out leaf fragments, enough toxin may have been absorbed through the gums during chewing to cause problems.
The stems' raw state matters too—cooking breaks down some oxalates, but raw plant material delivers the full dose. Cats often chew along the entire stem, ingesting more of the skin where oxalates concentrate. Two whole stems mean prolonged chewing time, increasing absorption through oral membranes before swallowing.
What the vet will prioritize for a 4 kg patient
For a cat this size, vets typically start intravenous calcium gluconate to counteract the oxalate's effects on blood calcium. They'll administer fluids aggressively to protect the kidneys and flush out toxins—a small cat's kidneys can be overwhelmed by relatively minor insults.
Blood work will monitor calcium, phosphorus, and kidney values closely. Hospitalization for 24-48 hours is common to watch for delayed kidney damage. Even if initial symptoms seem mild, kidney injury can progress silently over 12-24 hours, so early treatment dramatically improves outcomes.
The full verdict, portion guidance and serving notes are collected on the Rhubarb food facts page.