TB in deer - early stage indication?

[paulbshooting]

Hello all. Got the call last week as part of an investigation into TB found in raw venison used for cat food via a Hampshire game dealer. They are calling all stalkers that put carcasses into the dealer over a specific time period last year.
Whilst sad for the cats that died (maybe not!) on a serious note it is great to see the system works to protect those in the food chain.

I had a good chat with the investigation guy but one of his comments didn't make sense when I was considering it all later that day. He seemed to suggest that the deer could have TB without showing any symptoms that could be identified?

I have done my DSC and culled, inspected, sent to dealer or eaten plenty of carcasses in five species over the years. I do the best practice inspection every time and have had the usual non notifiable issues but never a notifiable disease.
I have looked at TB on SD and the web plus read the vet Peter Green's Disease deer book and it all shows the obvious internal and external TB symptoms.

Also spoke to a friend who had a confirmed case of TB in Scotland. From his comments and photos, especially the smell he recalls - his deer obviously had something majorly wrong and it did with the usual indicated visual issues.
I am not a vet but keen to learn and try to understand what the investigation guy means?

Maybe there can be no external TB lumps or obvious "issues" but surely one or more of the inspection gland(s) would be enlarged as a minimum?
Interested in any comments, thanks.

 

[SaOsborne]

Well you are not alone, had the same call 3-4 weeks ago, now again today another enquiry asking if I could help I.D a stalker who put a Fallow in, they had no name only 1825 in the name box and 13 November 2018, couldn't help. Really digging into the investigation. Wanted to know if we submitted any Ofal into the food chain too. They as far as I am aware they are not saying the T.B are from deer. I would have thought there are a lot of other sources for Cat 3 damaged meat from butchers, abitoirs etc, as I am sure cat food is made from a lot more than deer!

 

[Sharpie]

Deer can carry it with no obvious symptoms. By the time they have them, they are far gone. As with humans. All that we can do is our best when inspecting. Unlike domestic stock, there is no practical way of testing them in advance.

They linger off and die naturally. Not every one is culled by "deer management" in a managed plan.

Domestic stock that is condemned as being a "reactor" still gets sold into the food chain if there are no other symptoms on inspection. They are deemed safe for human consumption. TB is very fragile, fortunately it doesn't take much cooking to kill it.

FWIW I am a "reactor" too, as determined at school by the then compulsory BCG (Mantoux) test at age 12 or so, hence never vaccinated. Possibly I've been carrying it for most of my life, just hope it never catches up with me.

Not sure about making things like jerky, I think that could potentially go wrong.

Glad to hear that the raw cat (and dog) food outbreak is being taken seriously and that investigations are ongoing. Been discussed here on another thread.

Officially Scotland is TB-free, in some parts livestock does not even have to be tested. I presume that your friend's deer was taken seriously and that the confirmation was from responsibly taking it to be assessed. Rather than just burying or burning it, which would be the temptation.

Bovine TB: The enemy at Scotland's gates - Q&A

Despite having fewer than 100 herd breakdowns a year, bovine TB is seen as the enemy at the gates in Scotland.

www.fginsight.com

I have no doubt that TB is widespread in some of our wild deer population, even if they show no symptoms. And that they can carry several other nasties. Same as our "wild" boar. It's not just the badgers.

And that the posh expensive raw venison cat food may not have been entirely made of deer venison that supposedly passed cursory inspection.

PS: why sell it to a cat food manufacturer, unless they paid the same sort of prices as game dealers for human consumption, just curious ?

 

[Sharpie]

Well you are not alone, had the same call 3-4 weeks ago, now again today another enquiry asking if I could help I.D a stalker who put a Fallow in, they had no name only 1825 in the name box and 13 November 2018, couldn't help.

That might be a "trained hunter" number with the last digit missing. Or someone from the early days. DMQ might be able to ID it to within ten people, worth a try. Mine is 15xxx, issued by the BDS quite a few years ago.

 

[Buchan]

Deer (any animal in fact) can:

• Have TB, look ill (thin) and be full of abscesses
• Have TB without clinical signs, have advanced disease, but obvious on gralloch
• Have TB without clinical signs, at the early stages and harder to see at the gralloch (small abscesses you'd need to incise the lymph nodes to see)
• Have TB without clinical signs, at the earliest stage and nothng seen on the gralloch

The skin test used on cattle is very accurate (when the cow has TB) and if the skin is positive, there's a 99% certainty of it being TB. The test picks up INFECTED animals before they develop the abscesses that make them INFECTIOUS. There is no way to diagnose TB in a live wild deer (practically, before I get out-pedanted).
Disease in an animal can be caused by a single bacteria (Mycobacterium bovis and in cattle and badgers (probably fallow too) the bacteria is inhaled, sits in the lung, and can develop into a small abscess, which then spreads the infection around the body - or, critically, becomes a small walled-off abscess that the animal can live with quite happily.

The current TB outbreak in cats (and 3 of the owners) looks to relate to the inclusion of offal at the game handler. As offal was incuded, it should have been inspected (vet or meat inspector) but wasn't. The offal for the venison cat food would have been minced, so if there was a small abscess, say 1cm diameter, that would spread an awful lot of bacteria all over the mince. As no inspection too place, it's possible larger abscesses were missed.

 

[Sharpie]

Interesting Buchan. We are not supposed to incise the lymph nodes anymore, and I wouldn't have a clue how to tell much from that anyway.

I'm guessing that you are connected to Edinburgh University ?

Glad to hear that the investigations are exposing some of the goings-on, and dodgy practices.

So the cat food also included the un-inspected pluck. Ho hum.

Cynically, maybe "this deer looks a bit manky, but I'll still get good money from the cat food place, offal included. Wouldn't eat it myself though."

Interesting that TB reactors in domestic stock are 99% certain to actually have TB. I suppose since they are mostly slaughtered at 30 months or sooner, they won't have had time to develop overt symptoms of that, nor prion diseases. So they go into the food chain anyway.

 

[ileso]

isnt cat food cooked?
it doesnt take a lot to kill TB bacteria.

maybe they should look for the source of infection elsewhere... like stray cats.. infected mice.. contact with wild animals... access to unprocessed meat or carcass remains...
also it may not be apparent in the early stages. even upon internal inspection

 

[Sharpie]

isnt cat food cooked?
it doesnt take a lot to kill TB bacteria.

maybe they should look for the source of infection elsewhere... like stray cats.. infected mice.. contact with wild animals... access to unprocessed meat or carcass remains...
also it may not be apparent in the early stages. even upon internal inspection

No, this was the trendy raw version currently in fashion.

Just raw meat, and other bits, minced up and sold at rather a high price to owners of expensive pampered pedigree cats, never let out, who trusted that they were doing the right thing. As well as other pets, but that's not part of the investigation AFAIK.

It seems that you are allowed to make pet food out of almost anything, even rats, maggot farm leftovers and insects, I put a link on the other thread to the official information.

Fact is, dubious deer venison and offal got minced up and fed raw to cats, and the cats, and some owners caught TB from it (I presume the cat owners weren't eating it themselves but caught it from their cats, which mostly died, despite costly veterinary treatment). Isolated to one supplier, thanks to some very good investigation.

Which I think is also relevant to we humans who shoot deer ourselves, and either eat it, or sell it into the food chain.

Gentle cooking will kill TB, as said. 60C is enough.

 

[25 Sharps]

The skin test used on cattle is very accurate (when the cow has TB) and if the skin is positive, there's a 99% certainty of it being TB.

?? Not according to any cattle farmers I shoot for.

Taken from tbhub.co.uk

However, the main limitation of the tuberculin skin test is its sensitivity. Studies have shown that skin test sensitivity in Great Britain lies between 52% and 100% with an average of about 80% sensitivity at standard interpretation¹ and slightly higher at severe interpretation. In practical terms this means that on average 20-25% of TB-infected cattle can be missed by one round of skin testing using standard interpretation.

 

[ileso]

No, this was the trendy raw version currently in fashion.

Just raw meat, and other bits, minced up and sold at rather a high price to owners of expensive pampered pedigree cats, never let out, who trusted that they were doing the right thing. As well as other pets, but that's not part of the investigation AFAIK.

Ah.. I also feed my dogs raw food... didnt know there was a commercial version of raw diet. .. but as usual with any commercial product quality control is what it is .. giving raw diets for pets a bad name...

 

[CarlW]

?? Not according to any cattle farmers I shoot for.

Taken from tbhub.co.uk

However, the main limitation of the tuberculin skin test is its sensitivity. Studies have shown that skin test sensitivity in Great Britain lies between 52% and 100% with an average of about 80% sensitivity at standard interpretation¹ and slightly higher at severe interpretation. In practical terms this means that on average 20-25% of TB-infected cattle can be missed by one round of skin testing using standard interpretation.

I think you might have misunderstood @Buchan 's point. He didn't say that the skin test catches TB cases 95% of the time; he said, if the skin test delivers a positive reaction, then 95% of the time, it is TB. They are two different things.

 

[25 Sharps]

I think you might have misunderstood @Buchan 's point. He didn't say that the skin test catches TB cases 95% of the time; he said, if the skin test delivers a positive reaction, then 95% of the time, it is TB. They are two different things.

99% not 95%. He is saying it is accurate when a cow has TB.

“The skin test used on cattle is very accurate (when the cow has TB)”

My point is it is not an accurate test, because animals get missed and go through to infect others in the herd.

 

[CarlW]

99% not 95%. He is saying it is accurate when a cow has TB.

“The skin test used on cattle is very accurate (when the cow has TB)”

My point is it is not an accurate test, because animals get missed and go through to infect others in the herd.

You contradicted his point but the data you used to support your contradiction did not in fact support it. I therefore assumed you had misunderstood.

 

[25 Sharps]

You contradicted his point but the data you used to support your contradiction did not in fact support it. I therefore assumed you had misunderstood.

The data I posted shows that it is not necessarily an accurate test for cows that have TB, which was the point that is was contradicting. Granted I probably didn’t trim enough of the quote to show what point I was making

 

[Buchan]

Interesting Buchan. We are not supposed to incise the lymph nodes anymore, and I wouldn't have a clue how to tell much from that anyway.

I'm guessing that you are connected to Edinburgh University ?

Interesting that TB reactors in domestic stock are 99% certain to actually have TB. I suppose since they are mostly slaughtered at 30 months or sooner, they won't have had time to develop overt symptoms of that, nor prion diseases. So they go into the food chain anyway.

I should have been clearer, the incising of lymph nodes is only done in the lab when they are looking hard becasue the bacteria needs to be isolated and typed to trace the infection. We don't need to do that. I'm only loosely affiliated to Edinburgh, although my interest in this cases has come from my overall interest in One Health projects.
A cow can develop TB abscesses well within the usual 30-month slaughter, however, testing is done frequently enough to pick up the infection early. If all the cows that test positive have no absceses, then control is starting to work.

 

[paulbshooting]

Thanks for all the replies and discussion. I wanted to increase my understanding and be confident in how I operate in terms of the inspection, gralloch etc. which I now am.

 

[Buchan]

I realise this might not make sense to some folk:

"the incising of lymph nodes is only done in the lab when they are looking hard becasue the bacteria needs to be isolated and typed to trace the infection."

If there is a TB breakdown and there are reactor animals, then when slaughtered, the carcasses are examined for lesions and these are then cultured to grow the bacteria, taking up to 12 weeks. IF grown, the bacteria can be tested genetically and it can give a good indication where that particular strain of TB has come from. For instance, the recent breakdown around Shap in Cumbria is spologotype 17.z. This has previous only been found in Northern Ireland, so the disease was introduced by an imported animal and has spread to the badger population and then back to the cattle.

 

[foxdropper]

Badgers and deer have carried TB undetected for decades .Actual cases of it physically present in either species are few and far between .Both are vectors for it for sure .A few dairy farms I stalk on have a zero policy for deer due to vets casual chats about wild vectors .

 

[Buchan]

Badgers and deer have carried TB undetected for decades .Actual cases of it physically present in either species are few and far between .Both are vectors for it for sure .A few dairy farms I stalk on have a zero policy for deer due to vets casual chats about wild vectors .

Pedant alert! Sorry. Badgers, deer, cows, humans are not vectors, but hosts. Vectors usually transmit without being affected by the disease, so ticks are a vector for Lyme, midges for bluetongue and so on.

 

[foxdropper]

So if Tb is to be blamed on badgers and deer and us unfortunately at a high level in Britain ,why is it we don’t see large numbers of badgers and deer with full blown Tb ,answer -they are vectors carrying the disease unless their own immune system is down and they contract it .
Pedantic is me to a tee lol.