chicken (or any) necks, and hyperthyroid risk

Wondering -- is anyone concerned with feeding chicken necks for bone-in meals? I've fed these to my cats, and find them quite convenient as far as the ratio of meat to bone. However, my vet alerted me to thyroid problems developing as a result of raw food diets. I don't know if, say, 2-3 chicken necks/week constitutes over-consumption of thyroid (I've read that even if the thyroid gland itself isn't present, the nearby tissue likely contains thyroid hormones), or if most of the problems that vets are seeing result from an abundance of necks in commercial raw products. Has anyone explored this / does anyone know what constitutes safe amounts / upper limits of necks in a prey model diet? 

Thanks for alerting us to this!  I did a bit of reading, and it seems that the problem is linked to beef gullets (necks), but not poultry.  However I could not find a definite source on that.  Here is the study that triggered the concern:

http://www.ncbi.nlm.nih.gov/pubmed/22931400

It sounds like Hare Today's beef organ grind should be used sparingly, if at all.  It may be prudent to use chicken necks only in rotation with other bone-in sources, like wings and ribs, also.

The full article:

http://onlinelibrary.wiley.com/doi/10.1111/j.1748-5827.2011.01189.x/full

Here is the descrition of what the of owners fed:

 Dietary history showed that eight owners fed a diet of exclusively bones and raw food (BARF) while four owners fed a commercial diet but added dried gullet on an almost daily basis.

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This part is really interesting (my added bold):

 It is of interest, why non-domestic animals, such as wolves or coyotes, do not suffer from thyrotoxicosis factitia. By the end of the 19th century, Cunningham performed several experiments feeding thyroid glands to animals and humans (Cunningham 1898). One of his observations was that feeding absolutely fresh and raw thyroidal material (<30 minute after slaughtering) did not lead to any signs in chicken, rabbits, cats, dogs, monkeys or humans. However, when keeping the tissue on ice for a minimum of 24 hours, toxicity did develop. It is likely that the meat and gullets obtained by owners from the slaughterhouse has been cooled for a prolonged period of time, either at home or in the abattoir and thus thyrotoxicosis could have occurred.

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Maybe it isn't a good idea to feed any organ mix or meat + organ mix that contains thyroid??????

Thanks you @cat7bird  and @sophie1  for bringing this to our attention

sophie1 said:

It sounds like Hare Today's beef organ grind should be used sparingly, if at all.  It may be prudent to use chicken necks only in rotation with other bone-in sources, like wings and ribs, also.

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 Although I doubt there could be enough thyroid gland clinging to a chicken neck to be of  concern, but... 

Well, this is kind of scary as I do feed whole animal grinds, supposedly with the thyroid gland included.

So my understanding was that consuming thyroid isn't inherently unhealthy (it's in fact necessary, or at least an iodine source is). I was concerned about the amount / possibility of cats consuming more thyroid with frankenprey / commercial raw than they would in the wild -- I thought that was the issue. That study about the toxicity due to freezing brings it to another level. Hmmm...

oh @mschauer  I did read (I will look for the source) that thyroid hormones are present in surrounding tissue (around the trachea, and even potentially in the chest), even if the gland isn't included, though in much smaller concentrations. so little information seems to be available about this.

cat7bird said:

 
oh @mschauer  I did read (I will look for the source) that thyroid hormones are present in surrounding tissue (around the trachea, and even potentially in the chest), even if the gland isn't included, though in much smaller concentrations. so little information seems to be available about this.

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Nutrients are frequently found throughout the tissues of an animal with some being concentrated in specific locations. It's overfeeding of organs that contain potentially toxic substances in high concentrations that we usually are concerned about.

mschauer said:

 
Nutrients are frequently found throughout the tissues of an animal with some being concentrated in specific locations. It's overfeeding of organs that contain potentially toxic substances in high concentrations that we usually are concerned about.

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That makes sense -- so it's specifically the presence of all or part of the thyroid gland that is of concern. Thanks for reading up on this!