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View Full Version : Post hoc ergo propter hoc?


Rolfe
8th June 2004, 03:49 PM
On Thursday a distraught pet owner turned up at the lab, cradling the dead body of his three-month-old labrador puppy. The puppy's head was showing out of the top of the bag, and the owner came to the front door, not the back where post-mortems usually arrive, and everyone who saw the case being booked in was very upset.

The post-mortem was being paid for by a vaccine manufacturer, because the puppy had had the second injection of his primary vaccination course only two days before his sudden death, and the finger was being pointed.

My colleague did the post-mortem. The puppy had a congenital malformation of the omentum, with a couple of gaps in what should be a complete fan of tissue carrying the blood and other vessels to the gut. A loop of intestine had happened to twist through one of the defects, and become trapped. The puppy had died of a twisted gut.

It was a tragedy for sure, because if only the defect had been known about in advance it would have been easy to correct - even if the puppy's illness had been discovered earlier, surgery might have saved him. But there was no way to know, and circumstances were such that the illness wasn't discovered until too late. But it didn't have anything to do with the vaccine.

Now, if the post-mortem had never been done, and instead the original assumption had been allowed to stand, it would have been one more brick in the wall of lies being built to discredit vaccination. I suppose it was worth the vaccine company paying for the post-mortem for that alone.

Today an eldery dog was brought in for post-mortem, by more conventional means. He had become ill and died within 48 hours of being treated by a widely-used anti-flea preparation. Again the drug company was paying for the post-mortem.

This dog had widespread cancer, of a type we won't know until we get the histopathology report back. Might have been a malignant melanoma, but I've never seen anything quite like it before. It's a bit surprising that nothing showed up either clinically or on a general blood profile done at the time the flea treatment was prescribed, but having said that, I've seen that happen before.

This happens all the time. I recall an incident involving two very sick dogs, one of which died, soon after being given another flea treatment, which was new on the market at the time. Although the owner was hell-bent on getting compensation from the drug company, to the point where she accused us of a cover-up, it transpired that the dogs had been let loose on the common after being treated, and they had found some illegal slug bait that had been dumped behind a bush.

Just a few examples to illustrate where first assumptions might not necessarily be confirmed when proper investigations are done.

Rolfe.

cbish
8th June 2004, 05:36 PM
More importantly though, how did the owners respond when informed of the actual findings?

sorgoth
8th June 2004, 07:36 PM
Sorry to be a bit off topic, but is there somewhere that explains what all those things mean? Ergo propter hocaaowifuer!
I don't know what you're talking about!

espritch
8th June 2004, 10:09 PM
Sorry to be a bit off topic, but is there somewhere that explains what all those things mean? Ergo propter hocaaowifuer!
I don't know what you're talking about!

I believe that translates as "after this, therefore because of this." (or something like that). It's the proper name for the logical fallacy of assuming that because one event follows another, that the second event must have been a result of the first.

Benguin
8th June 2004, 11:18 PM
Originally posted by sorgoth
Sorry to be a bit off topic, but is there somewhere that explains what all those things mean? Ergo propter hocaaowifuer!
I don't know what you're talking about!

There's an explanatory site here (http://datanation.com/fallacies/index.htm)

Espritch was right, this one is used to say that just because one thing happens after another does not necessarily mean there is any causal relationship.

We find it applicable in IT a lot as well, where people construct these odd theories about how their computer came to be screwed up (or unscrewed) based on any old sequence of events.

Loon
9th June 2004, 12:38 AM
I think it's a good idea for the drug companies to do this. It is possible that a drug or treatment has an unknown side effect, and the sooner such a thing can be caught, the better. It also eliminates (reasonable) doubt when the post-mortem comes back with a different cause of death.

Rolfe
9th June 2004, 02:25 AM
Originally posted by cbish
More importantly though, how did the owners respond when informed of the actual findings? I don't know about the labrador puppy owner (the vet was just glad to get a diagnosis), and of course the elderly dog with the cancer hasn't been reported yet.

The owner of the poisoned Alsatians was an odd one though. She was a veterinary nurse, and she'd used a brand-new flea control product which had just been bought in by the practice. At first she told us she'd treated two dogs and they'd never been out the house after that before they collapsed. Well, that did sound suspicious. But then came the admission that they had been taken for a walk "but had never been off a short lead". Finally, the whole story emerged. THREE dogs had been treated, but only two taken for the walk. The third dog, which had stayed home, was fine. The two that had gone out had been allowed to roam free on the common. Then we got the analysis of the stomach contents - brown metaldehyde, nasty slug-bait poison prepared by an amateur, without the usual blue dye that marks the commercial product, illegally dumped on the common behind a bush.

The drug company had been baffled because the product had been on sale in America for a year or two, without any problem. And of course it had passed all the safety trials to be licensed in this country. Then practically the first two dogs treated with it in this country fell over sick! So they were relieved to find out about the metaldehyde.

The owner, however, had convinced herself that the flea treatment was to blame and got very angry when we said it wasn't. Cover-up and all that. But I have to say I used the same product on my kitten some years later without any qualms. And it was suspicious the way we weren't given the full story about the third dog and the walk on the common in the first place. I wonder if she scented compensation payments. People can be funny.

Rolfe.