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'.

  • I am sorry for your loss...do you breed rabbits? What do you mean 'different floors'? Or as you say are they truly pets, do they have free roaming privileges, is hay all they eat? Are you feeding this hay to any other animal? I am very interested as I've never heard of botulism in hay. I've got horses and have never heard of this. Please talk about this a bit more and I'll be looking into this also. Great question...
    – stormy
    Jun 12 '14 at 17:40
  • @stormy These are pet rabbits, Ruby who is the surviving impacted rabbit, lives in my bed room. Prior to the event she would jump up on the bed and lay with me, reading, until I fell asleep. The hay in our house is shared by the (now) 4 pet rabbits living upstairs in our house, and with the visiting rabbits living downstairs (generally rescue rabbits looking for a home). For more about the hay and botulism look at the question biology.stackexchange.com/questions/19051 Jun 12 '14 at 17:52
  • @stormy you can learn more about pet rabbits at Pet.SE and/or rabbit.org Jun 12 '14 at 17:55
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    All the rabbits are spayed or neutered.... Jun 12 '14 at 17:58
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    Another thing to look into is mycotoxins from mold. Damped hay can be lethal to any animal that eats it and hazardous to humans that breath in the mold dust. Jun 13 '14 at 1:28

None that I can find or know about - ingestion of, or repeated exposure to organo phosphates (used as pesticide) may cause ascending paralysis, and some plants might cause ascending paralysis, but descending paralysis strongly suggests botulism, which was most likely present in the hay, unless you can think of another source.


In my former life growing up on a cow and a half dairy, having hay get damp is a major worry.

One of the issues is mycotoxins from mold. Damped hay can be lethal to any animal that eats it and hazardous to humans that breath in the mold dust.

  • +1 This is good answer, but still looking for plants that might have similar impacts. Jun 16 '14 at 19:20
  • Understood, there are plenty of nasties out there that you don't want your livestock eating. Jun 16 '14 at 19:27

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