I have been involved in an event where the presumed diagnosis is botulism secondary to ingestion from hay from last year. In this case the hay is second cutting timothy hay (making it 6 plus months old).
Three pet house rabbits appear to have been effected. with 2 dead and one recovering from a case of descending paralysis. The three rabbits were widely separated with physical barriers and one being on a different floor. Each of the dead bunnies has a surviving partner who shared the same space and food with them. All occurrences started within a 36 hour window, with death occurring in 1 - 2 hours after symptom onset. The living bunny started to show recovery (head control) about 5 days after first symptom onset.
Several tests are underway, but my understanding is that it may be difficult to conclusively show either the botulism in the rabbits, or significant presence of 'botulinum toxin' or 'Clostridium botulinum' in the hay (samples from the mangers of affected animals are being tested). I have posted a question at Biology Can botulinum toxin be grown or kept from denaturing in an UNWRAPPED 50 pound hay bale?
While we are waiting for botulism to be ruled in, out, or unsure, it makes sense to look for other causes as well. I have searched the web for anything that can cause Descending Paralysis (Head, fore limbs and chest, followed by lower limbs, with recover in order of loss). Other than botulism and some shell fish toxins (which seem extremely unlikely) there is nothing else suggesting it could impact 3 rabbits as has happened here.
We live in the Pittsburgh, Pennsylvania area with our hay coming from a farm a few miles North East. We have been in contact with the vendor and multiple consumers of the hay and there are no other similar occurrences.
Looking for any plants or applications that could be in timothy hay from the region, that has the neurotoxin symptom 'Descending Paralysis'.