All dogs' livers are shunted extrahepatically before birth. It is a problem when the shunt doesn't close as it should shortly after birth.
The research that's been done is inconclusive and confusing....shunt dogs having shunt-free pups and vice-versa.
My own personal opinion is that the cumulative effects of yearly vaccinations and monthly flea and heartworm treatments contribute to a toxic state that is more pronounced in small dogs. Research shows a clear link with small dogs having more reactions to vaccines than larger breeds. Also remember, heartworm and flea preventatives are NOT medicines, but pesticides.
We have seen birth defects before in children of parents (both human and animal) that bears out the disastrous effects toxins can have. Think of DDT in birds and the effects of Agent Orange on children of Vietnam vets and on the Vietnamese themselves. In the case of dogs, my thinking is that a female dog has all her eggs at birth and those eggs can be affected by the cumulative effects of toxins before they are fertilized.
The most direct genetic link I've seen with LS in dogs is with the Irish Wolfhound. By identifying and removing affected dogs from breeding, the incidence was reduced by about 50% in a relatively short time. I believe these were cases of intrahepatic shunts rather than extrahepatic shunts though and Yorkies are prone to extrahepatic shunts.
We all are looking for research to give us better guideposts but I have to wonder if environmental factors are being looked at enough.
LS is characterized as a congenital (present at birth) defect. There is no more certainty than this so far. |