According to manufacturer's label directions, it is unwise to administer rabies or other vaccines when a dog or cat is ill, pregnant or stressed. Safety and efficacy are deciding factors. Adverse reactions are more likely and the potential for vaccine failure increases. Even a slight elevation in temperature can thwart a vaccine.
Most vets agree that certain animals should NOT be vaccinated (absent proven, urgent need such as inevitable exposure to a life-threatening disease). These include, but aren’t limited to, pets with autoimmune disease … pets undergoing chemo, radiation or surgery (even dental cleaning or neutering) … pets with autoimmune disease, cancer, severe allergies and skin diseases … pets fighting an illness or parasites … pets stressed from shipment or a move to a new home … malnourished pets … and dying housebound pets. Assaulting the immune systems of these animals with vaccination has been likened to throwing gas on a raging fire.
Author Jan Rasmusen, national award-winning author of Scared Poopless: The Straight Scoop on Dog Care and a host of veterinarians offer more insight.
Vaccinating Unhealthy Pets: Beware Reactions & Vaccine Failure