The snake vaccine IS NOT A YEARLY BOOSTER If it isn't kept up it is not going to be effective at all Here is the proper information copied from Red Rock Biologics the makers of the Snake vaccine and how to properly keep your dogs titer counts up www.redrockbiologics.com/FAQ.html How long does protection last? How often should my dog be vaccinated? The maximum protection generated by vaccination typically becomes available about four to six weeks after the most recent vaccine booster dose. That protection then declines slowly over time. Vaccinated dogs typically receive good protection for about six months after boostering. Depending on the dog, some protection may continue out to a year, or longer. The first time your dog is vaccinated, we recommend an initial vaccine injection followed by a booster dose about one month later. The recommended subsequent boostering schedule of one, two or three vaccine doses per year depends upon your dog's anticipated exposure to rattlesnakes and the size of your dog. Most dogs that are exposed to rattlesnakes for less than six months per year will only require a single booster dose for that year. The best time to give that dose is approximately one month before the start of the rattlesnake "season." This category includes dogs who live in roughly the northern half of the United States, or dogs who briefly visit locations where rattlesnakes may be active -- such as during a camping or hunting trip. If your dog will be in an area where rattlesnakes are active for more than six months per year (roughly the southern half of the United States) we recommend two annual booster doses given four to six months apart. Again, the first booster dose should be given one month before the rattlesnake season begins. The second dose is given approximately half-way through the season. If your dog is at particular risk of being bitten by a rattlesnake (for example, a search and rescue dog, some hunting dogs or dogs living in a high density rattlesnake area), you should consider using three booster doses per year at four month intervals. Since resistance to venom depends upon the amount of venom neutralizing antibody available, small dogs (under 25 pounds) are at increased risk of envenomation injury. Because of this, a third dose in the initial sequence, and in subsequent years more frequent boosters (e.g. every four to six months), may be advisable in small dogs to maximize their antibody production for more protection. Large dogs (over 100 pounds) do not develop as high an antibody level as intermediate-sized dogs in response to the two dose initial sequence. For this reason, large dogs may also benefit from a third dose in the initial sequence, although they do not necessarily require additional annual booster doses to maintain that antibody level.