[Hamoth]

http://www.fourpawsonly.ca/canadian_...h_trachea.html

http://azlink.com/~mkk/trachea.html

http://www.hillary.net/school/spring...g.lec.03.19.98

http://yorkshire-terrier.com/lacy/medical.htm

http://www.veterinarypartner.com/Con...=1&SourceID=42

http://www.fourpawsonly.ca/canadian_...h_trachea.html

http://www.vetsurgerycentral.com/tracheal_collapse.htm

http://www.petfinder.org/journalinde...th/1.34.13.txt

http://www.rievaulx.org/health_prob.html

http://www.vetnetwork.com/petcare_ar..._articleID=189

http://www.vetsurgerycentral.com/tracheal_collapse.htm

http://www.marvistavet.com/html/body..._collapse.html

The information out there is highly varied. Read with cautioun and a discriminating eye. Some articles are older than others, some are more medical than others. Most focus on the issue of an actual collapse, rather than the cause which is the weakened trachea. There is little official interest in the weakened trachea at this point, however studies are being done. I have contacted the president of the YTCA and Mary Elizabeth Dogmure of YTNR in order to refine my understanding. Given that research on this problem if funded by clubs like the AKC and YTCA, I thought these groups would know more about what has been done. The answer is that they are only now beginning to research this in earnest.

Question:
Can a dog with this disease pass it on to litters – Is this genetic.

Answer:
At this point they don't know yet. There hasn't been enough research done yet to make that determination.

http://www.collapsingtrachea.com/

Note that I believe the above to be innapropriate for public understanding. What the author means (and I have spoken with the author) is that the genes have yet to be determined. There is ample reason to believe this is a genetic defect, but the genes involved are many and complex.

Article on ct written by a vet that is more in line with modern thinking.

We also know that it occurs in certain breeds of dogs, notably Chihuahuas, Pomeranians, Shih Tzus, Lhasa Apsos, Toy Poodles, and Yorkshire Terriers. Because of that, we suspect that there is a genetic factor involved.

http://www.fourpawsonly.ca/canadian_...h_trachea.html

Medical source with similar opinion:

Inheritance: Unknown but assumed complex

http://www.rievaulx.org/health_prob.html

And another:

The cartilage defect that leads to the flattened “C” rings seems to be hereditary.

http://www.marvistavet.com/html/body..._collapse.html

In other cases I have read that it's sepcifically assumed to be polygenic. I hope I included that source in the above somewhere.