Why retching changes everything for a 6 kg cat
Active retching means the oxalate crystals are aggressively irritating your cat's stomach lining and possibly his throat—this isn't mild nausea but acute distress. At 6 kg, three whole leaves deliver a concentrated dose of toxins already working to bind calcium and damage kidney tubules. The clock started ticking the moment he swallowed, making the first 4 hours critical for intervention.
Don't wait for more symptoms—kidney cells damaged by oxalates don't regenerate. Collect samples of his vomit if possible (use gloves), as the vet will check for undigested leaf fragments or characteristic crystal formations. Time matters more than distance right now—go to the nearest open vet, even if it's not your regular clinic.
The dangerous math of leaves versus body weight
Three medium rhubarb leaves can contain over 500 mg of oxalic acid—for a 6 kg cat, that's easily enough to overwhelm his kidneys' filtration capacity. Unlike dogs that might vomit once and recover, cats often hide pain until organs are severely affected. His retching suggests the stomach is desperately trying to expel the irritants before they reach the bloodstream.
Notice whether the retching produces anything—dry heaving is especially concerning because it means crystals may be moving deeper into his system. If he's pawing at his mouth, the leaves' sharp edges likely caused mechanical injuries too, compounding the chemical burns from oxalates. This dual trauma requires professional pain management.
What happens during the car ride to the vet
Transport him in a carrier with absorbent pads—oxalate poisoning can cause sudden diarrhea or vomiting from the intestinal irritation. Keep the car cool and quiet; stress worsens kidney strain. Don't offer water or food—this could accelerate toxin absorption or trigger aspiration if he vomits again during transit.
If he starts trembling or seems weak, note the time—these are signs of hypocalcemia (low blood calcium) as oxalates bind essential minerals. The vet team will want to know exactly when neurological symptoms appeared to guide their calcium supplementation protocol. Every minute detail helps them reverse the chemical cascade.
Why even post-treatment monitoring matters
After initial stabilization, your cat will need blood tests every 24 hours for several days—oxalate damage sometimes appears delayed as kidney cells succumb to the insult. The vet may prescribe a calcium-rich recovery diet temporarily and subcutaneous fluids to continue flushing his system at home.
Watch his litter box habits closely—straining or bloody urine could signal oxalate crystals forming in the bladder days later. Kittens often rebound faster than adult cats metabolically, but his small size means no aspect of this poisoning can be taken lightly. Future blood work will track his kidney values back to baseline.
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.