Vaccinal adverse reactions are becoming more recognized and acknowledged in the veterinary community -- in an August 1, 2008 article in DVM360
entitled Vaccination: An Overview
Dr. Melissa Kennedy states that of the two types of vaccinal adverse reactions:
Adverse reactions have also become a major concern in small animal medicine. .... These fall into two general categories. The first is immediate hypersensitivity. This may be a local or systemic response, and is due to pre-existing antibody to the agent. This is the classic "allergic reaction" to the vaccine and can be life-threatening. The second is a delayed response, requiring days of longer to develop. The vaccine, seen as foreign, elicits a significant inflammatory response and is especially true for adjuvanted vaccines. This response can manifest as a granuloma, or more seriously, a fibrosarcoma .
Further, she reports that The likelihood of adverse reactions in dogs has been found to correlate with the size of the dog and the number of inoculations given, with higher risk associated with small size and multiple inoculations.