Is Deadly Webcap Mushroom (cortinarius Rubellus) safe for Dogs?
⏳ Pending source check by the Eaoae Safety Review · Drafted 2026-10-06
⚠️ AI-generated answer \u2014 not yet verified. This check was generated by AI and has not been source-checked by the Eaoae Safety Review, so it is not part of Eaoae’s verified database. Use it as a starting point only: confirm with an authoritative source such as ASPCA Animal Poison Control or Pet Poison Helpline, or ask your veterinarian. If your pet may have eaten something dangerous, contact your vet or a poison helpline now \u2014 don’t wait on a website.
No, deadly webcap mushrooms are unsafe for dogs. They contain orellanine, which destroys kidney tissue with symptoms delayed 2-21 days -- by the time the dog shows increased thirst and decreased urination, the kidney damage is often irreversible.
🚨 Emergency: Yes — contact your veterinarian immediately.
💡 Why
Deadly webcap (Cortinarius rubellus) is one of the most insidious mushroom poisons. Orellanine attacks the kidneys silently: the dog may seem fine for days or even weeks after eating it, then develop excessive thirst, nausea, back pain, and fading urination as renal failure sets in. Cooking, drying, and freezing do not neutralize orellanine. Even small amounts can cause fatal kidney damage. The extreme delay makes this poisoning particularly cruel -- owners rarely connect the illness to a mushroom eaten weeks earlier.
🩺 What to do
- Remove all Cortinarius-type mushrooms from areas dogs access; they are rusty-brown with a cobweb-like veil when young.
- Any suspected ingestion needs immediate vet evaluation -- do not wait for the delayed symptoms.
- Tell your vet about the delay so kidney values are monitored over the following weeks.
❓ Common questions
How long before symptoms appear?
2 to 21 days -- the longest delay of any common mushroom toxin. This is what makes it so dangerous.
What are the warning signs?
Increased thirst, nausea, loss of appetite, back/flank pain, and progressively reduced urination.
Is kidney damage reversible?
Rarely, once established. Early aggressive IV fluid therapy offers the only chance, which is why any suspected ingestion needs immediate vet assessment.
📚 Sources
- Pet Poison Helpline: Mushrooms Toxicity
- Zoetis PetCare: Are Yard Mushrooms Bad for Dogs
- FungiAtlas: Cortinarius rubellus
- First Nature: Cortinarius rubellus
🔎 How the sources compare
What each authority says about Deadly webcap mushroom (Cortinarius rubellus) \u2014 compiled 2026-10-28. Eaoae’s verdict summarizes these sources; it is not our own diagnosis.
| Source | Dogs | Cats | Dose info |
|---|---|---|---|
| ASPCA Animal Poison Control | Not named — ASPCA's mushroom-safety article for pet owners is a general overview and does not name the deadly webcap or Cortinarius; it names Amanita phalloides (death caps, liver toxicity), Scleroderma species and Inocybe species, and advises that it is best to avoid giving pets mushrooms of any type | Not named — ASPCA's mushroom-safety article for pet owners is a general overview and does not name the deadly webcap or Cortinarius; it names Amanita phalloides (death caps, liver toxicity), Scleroderma species and Inocybe species, and advises that it is best to avoid giving pets mushrooms of any type | — |
| Pet Poison Helpline | Not named — the page does not name Cortinarius or webcap mushrooms anywhere; its general advice is that all mushroom ingestions by pets should be considered toxic unless a specialist can accurately and quickly identify the mushroom as non-toxic, and that mushroom toxins can affect the gastrointestinal tract, central nervous system, liver and kidneys | Not named — the page does not name Cortinarius or webcap mushrooms anywhere; its general advice is that all mushroom ingestions by pets should be considered toxic unless a specialist can accurately and quickly identify the mushroom as non-toxic, and that mushroom toxins can affect the gastrointestinal tract, central nervous system, liver and kidneys | — |
| Merck Veterinary Manual | Species not named — Merck's mushroom overview does not name the deadly webcap or Cortinarius; it lists orellanine among its mushroom toxin classes (cyclopeptides, gyromitrin, orellanine, muscarine, ibotenic acid and muscimol, psilocybin) - orellanine is the webcap toxin, which targets the kidneys - and names only Amanita phalloides as a species; the overview notes dogs are particularly susceptible because of their indiscriminate eating habits | Not covered | — |
| VCA Hospitals | Not named — VCA's mushroom overview does not name Cortinarius or webcap mushrooms; its nephrotoxic category describes mushrooms that affect the kidneys, with nausea, vomiting, inappetence, increased drinking and urination and dehydration, and signs that can be delayed for 12 hours up to a week or longer; the page notes these mushrooms are not plentiful in North America, so cases in pets are rare | Not named — VCA's mushroom overview does not name Cortinarius or webcap mushrooms; its nephrotoxic category describes mushrooms that affect the kidneys, with nausea, vomiting, inappetence, increased drinking and urination and dehydration, and signs that can be delayed for 12 hours up to a week or longer; the page notes these mushrooms are not plentiful in North America, so cases in pets are rare (the page addresses dogs and cats together) | — |
| Eaoae summary (dogs) | ⛔ Unsafe \u2014 Known to be harmful or toxic. Keep it away from your pet. | ||
🔗 Related checks for dogs
- onion ⛔ Unsafe
- Pumpkin Puree ✅ Safe
- Kalanchoe ⛔ Unsafe
- peach pits ⛔ Unsafe
- Onions and Garlic ⛔ Unsafe
- corn cob ⛔ Unsafe
Checked with Eaoae’s safety lookup. Answers are generated for reference and may be incomplete — always confirm with your vet for your individual pet. Spotted an error? Let us know.
