As an update to a previous post on this topic, I’d like to share a little extra information I have been able to find. Enquiries with a number of organisations seem to suggest that orchids are not toxic to cats and dogs.
The International Cat Care (ICC) website does have a list similar to the American RSPCA, where they list houseplants and outdoor plants that are potentially harmful to cats (orchids do not appear on this list). They do suggest removing orchids from your pets’ environment to help minimise the risk of them being ingested, but do not warn that they are toxic. They also suggest that providing your pet with enough stimulation (particularly if you have a housecat) may help limit the likelihood of them eating a houseplant out of boredom.
Additionally, ICC signposted me to the Horticultural Trades Association (HTA). This organisation has also done a little bit of digging and can find very little to suggest orchids are toxic to pets. They do point out that some pets may be sensitive to plant material than others, even though an orchid is not considered toxic.
So, as a rule it seems orchids are not likely to cause your cat or dog any problems. This being said, there are always exceptions to rules, and some pets may be more sensitive than others. If you think your pet may have a reaction after ingesting a part of an orchid, or any other plant, seek advice from your vets.
Hope this is useful.