Primary Von Willebrand’s Disease a blood clotting disorder similar to hemophilia, is extremely rare in Aussies. The disease can also be secondary to thyroid disease, which is very common. VWD symptoms can vary from periodically problematic to life-threatening. There are three forms of primary VWD, Types I, II, and III, with Type I being the least severe and Type III being the worst.
There are DNA tests available for VWD which can be used to confirm diagnosis. Your veterinarian may first use a blood test. Tests of this kind are not as black-and-white as DNA tests; the results won’t tell you a dog’s genotype for certain. However, if the result is well into the normal range the dog is almost certainly clear. If it is borderline the dog being tested may or may not be a carrier. Given the rarity of dogs with this disease in this breed, I would be inclined to “not” unless there is a relative which has been diagnosed with primary VWD. The DNA test will confirm the diagnosis.
If your Australian Shepherd is diagnosed with VWD we strongly recommend that its thyroid function be tested if that has not already been done. If there is underlying thyroid disease, the VWD likely arose from that and treating the primary disease may alleviate VWD symptoms. If the dog has primary VWD, its near relatives who are used for breeding should be tested so their status is known.