BVD (Bovine Viral Diarrhea) is a simple diarrhea that affects ruminants. Like with humans, some animals will defend themselves easily against the virus, showing only mild symptoms, while more fragile animals (younger, older or sick animals) might show very strong symptoms, sometimes leading to death. BVD will, most of the time, cause abortions.
The alpaca can catch the BVD by a contact with a permanently infected (PI) alpaca or by the contact with cattle. During certain weeks of a pregnancy, if a female alpaca catches the virus, the cria will survive but will not recognize the virus as being "unwanted" and thus, will not defend itself against it. That's what we call a PI cria. Since the cria will not produce the antibodies, the virus will grow in numbers dramatically and the cria will be highly contagious.
Some crias will show some signs a sickness or weakness and will die, but others will show absolutely no sign of the virus and will grow at the same rate a healthy cria would. A PI cria cannot be treated and has to be put down. If a PI cria is left in contact with other alpacas, it will cause abortions, diarrhea and births of other PI crias. If a female PI cria was well enough to grow and reproduce herself, she would automatically give birth to PI crias.
That's why we can follow these rules when testing for BVD PI animals :
- A negative BVD test is valid for the life of the animal, even if it was performed very early in it's life.
- A negative BVD test for a cria certifies that both the cria and the dam are not PI.
- A female needs to get only 1 negative test for any of her crias to certify she is not PI (a test performed on her first cria can be presented as proof for herself for all her life).
A healthy alpaca will eliminate the BVD within a 2 to 3 weeks period of time. If a BVD test is performed during that period, it will come out positive. This does not mean the alpaca is PI. Your vet will perfom another test 3 weeks later. If that second test is positive, it will mean that your animal doesn't defend itself against the virus: it is a PI alpaca. An alpaca will be declared PI only after 2 positive BVD tests performed 3 weeks appart.
