Personally, I like pointing out how the declare by antivaxxers that the MMR was by no means tested towards a saline placebo is utter hogwash. In very uncommon circumstances (1-10 of each 10,000 vaccines administered), cats can have allergic reactions to vaccines. In mild instances, which represent the majority of allergic reactions to vaccines, cats might develop hives, itchiness, redness and swelling of the eyes, lips, and neck, and mild fever. Severe allergic reactions may cause respiratory difficulties, weak spot, vomiting, diarrhea, pale gums, and collapse. If a cat exhibits any signs of allergic reaction after vaccination, contact a veterinarian instantly.