Dyskinetic Syndrome

[Grant Brown]

DKS is the first port of call for people who see unusual issues with their tarantula. Its attributed to so many other issues that it discredits the term DKS to the point some people argue against it so much the actual issue is completely ignored!
My experience of DKS has been directly linked to using locusts to feed my Ts, since Ive stopped using them Ive not had a single instance.

However, subsequent studies (which? Genuinely curious here I'd like to read them) have mentioned the feeding regime we give to our feeders and the plausible knock-on effect it has on our tarantula. Its not surprising considering its perfectly acceptable to gut-load our feeders for reptiles and other exotics!

You can't correlate a few cases of say, locusts and DKS specimens (especially in a single collection) and suggest they are the causative agent.

1. You are pseudo-replicating because if they come from one collection they will all be influenced by each other - e.g. temps, day light etc in the room or house. So multiple instances from your collection is not "more proof" in the traditional sense of replication where the different samples would be independent.

2. You make a prior assumption that locusts are the causative agent and do not consider the null - e.g. Locusts have no effect on frequency of DKS.

I'm sure if you looked at a more complete set of data and did the same correlations you'd find more examples where people fed locusts and did not develop DKS in their specimens.

Correlation does not imply causation - here's a famous example which illustrates the same idea taken to extremes:



You could spend a lot of effort looking for ways that pirates would influence the climate if you assumed your first correlation was the correct correlation. Or indeed the only one.


This is the same with ICU treatments - there is a correlation possible that specimens in ICU recover. But do they recover more often than you'd expect by chance alone?

I've said before, this doesn't actually make a lot of sense when you consider the physiology of tarantulas and how they normally behave. No arthropod is particularly fond of having rapid changes in conditions external to it (although there are exceptions I'm sure)- yet we have people who take arid specialists and plonk them into 100% RH boxes of a different temperature, with no acclimatisation. Tarantulas are often quite tolerant of changing conditions when healthy, but unhealthy individuals will obviously be less robust to rapid changes or stress. Handling a specimen, changing a container, raising the RH, altering the temperature - I'm not sure what else you could do to make such an event more drastic.

That's ignoring other questions like - what if the real cause of illness is RH that is too high? Surely the ICU will then hinder recovery? You could pose several such situations where it would be difficult to see what the benefit of ICU is.

That a few specimens have recovered in ICU doesn't mean the that cause of the recovery is the ICU. You have no "control" to contrast, and since most of the time the cause of the issue is unknown, you cannot be certain that the ICU didn't actually hinder recovery but the surviving individual was simply strong enough to recover despite the ICU.

I've also highlighted in the past that there may be several causative agents at work and perhaps ICU only helps a single one of these but could exasperate the others (it also may benefit or be neutral - the key point is we don't know and in the absence of fact we can only infer from other biological knowledge).

What of the specimens that do not recover when placed in an ICU? Under this framework, would they not also by necessity have to provide evidence of equal value against your hypothesis? (i.e that the ICU helps).

You are only using one side of the coin in highlighting where ICU "works" and assuming it is capable of causative explanation, discarding the "non-significant" results (i.e. the spider still dies). If you took a balanced approach you'd surely be swamped by instances where the ICU "caused" the death of the spider. It's only because of prior assumption that the ICU has to work that these positives could be taken as any sort of evidence for cause and effect.

I'm not trying to dismiss DKS as a thing - there is definitely something influencing some tarantulas.

I just wish people would appreciate that these sorts of conversation are not providing strong (or any, really) evidence. They are good at generating hypotheses, when adjusted, but to be honest we don't need more questions we need some actual answers and they will not come from re-hashing the same material on threads and pushing easily dismissed correlations (at least think they would not stand up if you tried to analyse these formally). For all we know, locusts could be toxic in some conditions - we should know those conditions. Perhaps they do cause an illness, but it might be different from the issue caused by say, toxic metals in water, which produces similar symptoms to the untrained eye.

[Grant Brown]

I meant to add - in case you might suggest that caution is worthwhile.

It canbe. To take an extreme example, however, of how misdirection can damaging you only need to look at the Autism/MMR vaccine fiasco. Weak data, flimsy correlation and outright lies (not saying anyone is lying here, why would they?) led to large scale changes that actively damaged health.

OK, so it's hyperbole to compare the two situations, but hopefully it gets my gist across - we could be taking a cautious route and actually directing people to a more damaging alternative. What if locusts actually delay the onset of DKS? What if DKS is like Tarantula Alzheimers?

[Peter Lacey]

When these questions come up, we have 1 hobbyist, with 1 tarantula, with an ailment seeking advice that may help.
We don't have numerous specimens in a controlled environment seeking a scientific conclusion. Nor are we likely to.

Just as our conclusions may be wrong, by your argument they could equally be right. So, we're left, as we are with many issues concerning tarantula, with hobbyist experience.

Ive provided references before, forgive my inexact reference but from memory the issue of locust gut bacteria was raised by Dillon for the University of Liverpool. And the diet of inverts and links to DKS was raised by Huber and Lautensacker.

[Grant Brown]

When these questions come up, we have 1 hobbyist, with 1 tarantula, with an ailment seeking advice that may help.
We don't have numerous specimens in a controlled environment seeking a scientific conclusion. Nor are we likely to.

Just as our conclusions may be wrong, by your argument they could equally be right. So, we're left, as we are with many issues concerning tarantula, with hobbyist experience.

Ive provided references before, forgive my inexact reference but from memory the issue of locust gut bacteria was raised by Dillon for the University of Liverpool. And the diet of inverts and links to DKS was raised by Huber and Lautensacker.

Well, we have a captive audience of hobbyists who have interest in solving this - and there's a fair few scientists on this board. It would not be too hard to come up with some "citizen science" type project that we passively collect data on over the next few years. It doesn't even need funding if people just chip in a little time now and again - and the hobbyists would be doing the main data collection.

I'm sure we could probably come up with some BTS membership based study that the data could be provided by hobbyists and then analysed later. All we'd need were each hobbyist to record their own stock - or some of it - over a period of time and then submit that data to a central place in a consistent manner. Prey items could form part of it - it would be interesting to see if Locusts did actually correlate positively with instances of DKS. We could even plot cases of geographically and see if there was any spatial clustering - which might suggest other sources worth looking at.

It could even happen on the BTS website. All we'd need is a standard form with data fields we specify, get people to fill them in. Yes it's still basically correlation but with enough data you can look for subtle effects and interactions. A bit of thought on what data to collect and some part time collating of the data and we could actually progress beyond what we have now. Even if all we could say was "these things are not looking strongly related to cases of DKS, but these might be" at least it is progressing.

My point re: hobbyist experience is that we have to collectively be aware that our experience might be biased by prior experience. When we expect certain things we will sometimes unintentionally shoehorn data to fit our expectations.