Grass sickness

Re: Grass sickness

nikki — Mon, 15 Nov 2010 21:53:10 GMT

The stuff in H&H was done by the School of Pharmacy at the University of London. Affected grazing areas has higher levels of soil nitrogen and higher levels of iron, lead, arsenic and chromium. They also found buttercups in abundance on affected sites. Be interesting to read the actual study though as they also quote an AHT vet saying there are potential issues with the study so not sure how reliable the findings are.

Re: Grass sickness

Wren — Mon, 15 Nov 2010 14:28:49 GMT

There was an article in Horse and Hound this week proposing heavy metals but my copy is at home and I'm not sure whose research they were quoting as I haven't read it yet. I'll update this once I have done so.

Re: Grass sickness

Nigel Haizelden — Sun, 14 Nov 2010 20:24:10 GMT

The "recent" idea you mention is that grass sickness is caused by C.Bot type C toxin and may be transmitted by migrating birds. This would explain why GS is reported on the same farms and even the same fields repeatedly over a number of years as the birds always use the same route of migration. There must probably be some weather/enviromental factors involved also to explain the peaks and troughs of incidence throughout the year although this might also be due to bird movement.

As for "recent" I believe this was first proposed around 1929! There was even a vaccine trial done with some success, but the whole idea was seriously rubbished by a (Bristol uni???) prof of infectious diseases who had his own bacterial pet theory and this caused the idea to be shelved for a further 60-70 years!

Hopefully funding will be found for another vaccine trial and lay this awful disease to rest for many horses and thier owners.

Re: Grass sickness

Richard Fox — Wed, 27 Oct 2010 14:28:29 GMT

Hi marie. Hmm over-informed clients ;)

Histopath on terminal ileal biopsies in horses and post-mortem samples of the coeliacomesenteric autonomic ganglia display in early? stages chromatolysis of nissl substance (enhanced by luxol-fast blue / cresyl violet staining), pkynosis (shrinking) of neuronal nuclei and in end stages? complete loss of neuronal cell bodies. We most often had cases where we had ileal biopsies with a complete lack of neuronal cell bodies in the 2 plexi (mucosal and intramyenteric). A recent (but oldish) paper demonstrated performing immunohistochemistry on biopsies which were equivocal for synaptophysin (not normally expressed in non-degeneratin neurons). ED is non-inflammatory (well no inflammation is seen in associated with the degenerating neurons).

Have a read of this?

Hahn CN, Whitwell KE, Mayhew IG. Neuropathological lesions resembling equine grass sickness in rabbits. Vet Rec. 2005 Jun 11;156(24):778-9.

Is this applicable? If you can't get it mail me and I can send it to you? Happy to do Histopath if you do a systematic PM if you do go down this route :)

Re: Grass sickness

Marie Kubiak — Wed, 27 Oct 2010 12:41:22 GMT

Great, thanks all, the Grass Sickness Fund website is really interesting. It's been a while since equine lectures and I'm out of touch with the equine world.

Richard, the neuropathies I see are proventricular dilation syndrome in parrots for which there is strong evidence of virally induced immune-mediated destruction of gangliosides, and megacolon and caecal paralysis in rabbits (strong genetic links are seen in one breed, otherwise all so far are E.cuniculi seropositive so there is a suspicion of parasitic neurological damage but all very vague). I have some very clued up clients (read this as neurotic for some owners), especially on the rabbit side, that research wildly and present me with a dozen theories at each recheck appointment and similarities with grass sickness keep cropping up and I keep either shrugging or quickly changing the subject! What is the histopathological picture on grass sickness biopsies? I have one terminal rabbit that the owner is willing for me to do histopath on when his time comes (most decline p-m so this is a real benefit to me in understanding this process) and I am intrigued to see what it shows.

Marie

Re: Grass sickness

Richard Fox — Wed, 27 Oct 2010 11:50:50 GMT

Nothing has been confirmed yet and biopsy specimens are the only way of confirming the diagnosis at present. Research is leaning more and more to clostridial toxin involvement but the aetiology still remains unclear. What neuropathies are we taking about in exotics as this specific topic maybe irrelevant to your clients?

by the way - The AHT and Liverpool University also have very strong research groups in Equine dysautonomia. I used to do a lot of ileal biopsy ED diagnosis when I was there.

Newton JR, Wylie CE, Proudman CJ, McGorum BC, Poxton IR. Equine grass sickness: are we any nearer to answers on cause and prevention after a century of research? Equine Vet J. 2010 Sep;42(6):477-81.

Re: Grass sickness

Hannah Wynne Richards — Wed, 27 Oct 2010 11:24:42 GMT

I agree awful disease, and that the current thought is reaction to Clostridial toxins, but there have been some successes with nursing the chronic cases through it. I believe Edinburgh veterinary school are the experts, so you should offer your clients the choice of referral before shooting if it is a chronic case-obviously not if acute

Wynne

Re: Grass sickness

Michael Woodhouse — Tue, 26 Oct 2010 22:39:22 GMT

[quote user="nikki"]

i believe current research is geared towards Clostridium botulinum. Not sure how far they're getting with it though as haven't heard any ground breaking news on it recently.

[/quote]

I've heard the same as Nikki, but not too surprising. As far as I know it's not proven.

Not seen much around here but from my experience [of one] this is a useful website for the owners to read before you inevitably go and shoot the horse. Awful disease.

Re: Grass sickness

nikki — Tue, 26 Oct 2010 22:32:33 GMT

i believe current research is geared towards Clostridium botulinum. Not sure how far they're getting with it though as haven't heard any ground breaking news on it recently.