Larry’s touching email & our post about his dog Toto has caused quite a few email inquiries about Canine von Willebrand’s Disease & how it affects Shelties. We have put together a basic overview of the disease & how it is passed on.
Von Willebrand’s Disease (vWd) is an inherited bleeding disorder, similar to hemophilia. It is a complex and difficult disorder to deal with, because genetics, diagnostic abnormalities, pathogenic mechanisms, and sometimes conflicting clinical signs are all involved.
There are 3 status levels of the disease:
1. Clear – does not have the disease and can not pass on the defective gene for the disease.
2. Carrier – does not have the disease but can pass on the defective gene for the disease.
3. Affected -has the disease and passes on the defective gene for the disease.
It comes in 3 major types, but only two affect Shelties, Type I and Type III.
Type I is a mild bleeding disorder with the risk coming mostly from trauma or surgery. (This form of the disease is rarely found in Shelties.)
Type III is a severe bleeding disorder that results in a high risk of bleeding from something as simple as a nail cut too short to the risk of serious bleeding due to trauma or surgery. Sadly, Type III is the most common type found in Shelties.
The commonality between all vWD is a reduction in the amount or function of von Willebrand factor (vWF), which is manifested through abnormal platelet function and prolonged bleeding. The vWF factor is a blood protein which binds platelets to blood vessels when they are injured. Absence or deficiency of the factor can, therefore, lead to uncontrolled bleeding episodes.
Diagnosis can be performed by measurement of plasma concentrations of vWF. Testing should be done at an early age since the disorder often diminishes with age, causing false-negative test results in older animals.
In dogs, the most common clinical signs are spontaneous bleeding from the gums or nose, blood in the urine or gastrointestinal tract, or excessive bleeding at the time of surgery. Clinical signs also include a bloody nose, prolonged estrus or postpartum bleeding, bloody urine, bloody stool, excessive bleeding after toe-nail cutting and sometimes hemorrhaging into body cavities and organs.
The good news?
A February 3, 2004 report showed that 92% of the Shelties tested are DNA clear of the disease, 7% are determined to be carriers of the disease, and 1% are affected by the disease. But, the results only represent those responsible breeders who test for & eliminate breeding stock based on the results. This is another example of why you should obtain your new Sheltie puppy from a responsible breeder, and not from a pet store or newspaper “back yard” breeder ad.
The results of various breeding combinations are as follows:
Clear x Clear = 100% Clear
Clear x Carrier = 50% Carrier, 50% Clear
Clear x Affected = 100% Carrier
Carrier x Carrier = 25% Clear, 50% Carrier, 25% Affected
Carrier x Affected = 50% Carrier, 50% Affected
Affected x Affected = 100% Affected
Because this disease can be eradicated before breeding (by having a dog tested) it can be eliminated from the breed all together. Unfortunately, experience and hearsay indicate that the AKC is not active in the enforcement of these preventive measures. Testing prior to breeding is a must if it is ever going to be completely eliminated.
As we have stated before in previous posts – always obtain your new puppy from a reputable breeder. A breeder that genuinely cares for the Sheltie breed will not knowingly pass along the genes of an affected dog. When interviewing breeders, be sure to ask if they have tested their breeding stock for von Willebrand disease.
For those who wish additional
information, an excellent source concerning the disease is Ettinger’s Textbook of Veterinary Internal Medicine: 2-Volume Set