Untrue PenMarMom.
The wood, bark, leaves and seeds of the elderberry contain cyanide, but the(blue elderberry) themselves are edible and Sweet/Tasty raw; (Red berry)Is edible and strong mealy and zingy flavors once cooked.
To use for a human or cat, it must first either be dried or cooked/boiled(tea).
The berry itself contains no cyanide if the pit has dried, or cooked.
The blue/purple Berry veriety, the berries can be eaten raw in humans, but too much can upset your stomach, so one shouldnt eat more than a handful or so raw.
I would not see the consumption of the blue elderberries to be any more than a stomach ache at worst. And medical at best.
However, the rubbing on the leaves, stem and wood could put a brief lasting cyanide toxin on the fur.
If licked off fur soon after rolling/rubbing said items, it could irritate the cats Kidney's/liver, and if constant enough, theoretically it could damage the kidney's and liver a little.
Dried flowers and berries, make a potent cold minimizer, and is recommended in conjunction with HIV/AIDS medication to lessen effects.. either that, or it is in the medication, I cannot remember which.
It is also Used to help fight cancer, and shrink some cancers, like Cbd and THC, but probably not as effective I would imagine.
I do not know for sure if the Elderberry/Flowers are safe for cats to consume, but I honestly think once cooked it could be mixed in after cooked/dried with wet cat food to help with allergies, runny nose/goopy eye/cough/sneeze; Cold/Flue viruses.
I hope this is satisfying information for you JB920,
Sincerely, Gabriel Lee Millikan
I had a similar experience today with my cat--I brought home the leaves of an elderberry tree (to identify them) and my cat immediately tried to bite and scratch his way into my pocket to try to get at them, and started scratching me when I took them away. Google gives results for a handful of similar anecdotes but I found very little authoritative information. I thought this article was interesting, though: http://www.messybeast.com/catnip-valerian.htm It has a list of chemicals cats are known to react to (similar to the classic catnip reaction). So the takeaway that I got is that there's probably a chemical that at least some cats react to in the elderberry plant, but elderberries also contain cyanide-inducing glycoside--as in, can cause cyanide buildup when it's metabolized, which can lead to cyanide poisoning--so keep cats away from it and stick to other plants (catnip, valerian) which aren't poisonous.