Why Rhubarb Is Dangerous for Dogs
Rhubarb leaves contain extremely high concentrations of oxalic acid (0.5-1.0% of leaf weight) and anthraquinone glycosides. The stalks contain lower but still significant levels of oxalic acid. Oxalic acid binds to calcium in the blood, forming calcium oxalate crystals that deposit in the kidneys, causing acute renal tubular necrosis and kidney failure. The calcium binding also causes acute hypocalcemia (dangerously low blood calcium), which can cause cardiac arrhythmias, muscle tremors, and seizures. Anthraquinone glycosides in the leaves act as irritant cathartics, causing severe GI inflammation and diarrhea. The combination of nephrotoxicity, hypocalcemia, and GI devastation makes rhubarb leaf ingestion a multi-system emergency.
Toxicity Profile of Rhubarb
Rhubarb leaves contain extremely high concentrations of oxalic acid (0.5-1.0% of leaf weight) and anthraquinone glycosides. The stalks contain lower but still significant levels of oxalic acid. Oxalic acid binds to calcium in the blood, forming calcium oxalate crystals that deposit in the kidneys, causing acute renal tubular necrosis and kidney failure. The calcium binding also causes acute hypocalcemia (dangerously low blood calcium), which can cause cardiac arrhythmias, muscle tremors, and sei
Safe Serving Size by Dog Weight
| Dog Size | Safe Amount | Frequency |
|---|---|---|
| Small (under 10 kg / 22 lbs) | NONE | Never |
| Medium (10-25 kg / 22-55 lbs) | NONE | Never |
| Large (25+ kg / 55+ lbs) | NONE | Never |
NONE — both leaves and stalks are toxic to dogs
How to Prepare Rhubarb for Dogs
Never give rhubarb to dogs in any form. While rhubarb stalks are consumed by humans (in pies, jams, and compotes), the oxalic acid content is still significant enough to cause kidney damage in dogs. Rhubarb leaves should be considered acutely poisonous. If you grow rhubarb in your garden, fence the plants off from dog access. Compost containing rhubarb leaves is also hazardous.
Warning Signs and Symptoms to Watch For
From leaf ingestion (most toxic): excessive drooling, vomiting, diarrhea (possibly bloody), abdominal pain, weakness, tremors, lethargy, decreased urination (kidney failure), seizures, cardiac arrhythmias (from hypocalcemia), and collapse. From stalk ingestion: similar but less severe symptoms, GI upset, potential kidney damage with large amounts.
What to Do If Your Dog Ate Rhubarb
Contact your vet immediately. Treatment includes IV fluids (avoiding calcium-containing fluids initially), calcium gluconate IV for hypocalcemia (administered slowly with cardiac monitoring), anti-nausea medication, kidney function monitoring, and supportive care. Blood chemistry should be monitored for calcium levels, BUN, and creatinine. ASPCA Poison Control: 888-426-4435.
Breed-Specific Note
Dogs with pre-existing kidney disease are at dramatically higher risk because their compromised kidneys cannot handle the additional oxalate crystal deposition.
Frequently Asked Questions
Are rhubarb stalks safer than the leaves?
Rhubarb stalks contain significantly less oxalic acid than the leaves, which is why humans can eat cooked rhubarb stalks safely. However, the oxalic acid content in stalks is still enough to cause kidney issues in dogs, especially small breeds. Leaves are acutely dangerous.
Can a small amount of rhubarb pie hurt my dog?
A small bite of baked rhubarb pie (made from stalks, not leaves) is unlikely to cause acute kidney failure in a large dog, but the sugar and butter in pie are also problematic. There is no reason to give rhubarb products to dogs when safer alternatives exist.
Does cooking rhubarb reduce the oxalic acid?
Cooking reduces but does not eliminate oxalic acid. Some oxalic acid leaches into the cooking water and is discarded. However, enough remains to be harmful to dogs. Adding sugar or dairy (as in rhubarb pie or crumble) does not neutralize the oxalic acid.
What other plants contain dangerous levels of oxalic acid?
Star fruit is extremely high in soluble oxalates and also causes acute kidney failure in dogs. Spinach, beet greens, and chard contain moderate oxalic acid levels — safe for dogs in small amounts but problematic in large quantities. Dieffenbachia and philodendron houseplants contain calcium oxalate crystals that cause oral irritation.
My dog ate rhubarb leaves from the garden — how urgent is this?
Very urgent. Rhubarb leaves are acutely toxic and can cause kidney failure. Do not wait for symptoms — contact your vet or ASPCA Poison Control immediately. Early IV fluid therapy can prevent or mitigate kidney damage.
Sources: American Kennel Club · ASPCA Animal Poison Control · PetMD · Merck Veterinary Manual.