Some dog and cat health conditions are most effectively addressed using IV therapy which typically works faster than oral medicine. For example, dogs and cats suffering from recurring vomiting or diarrhea, or heatstroke need to replace fluids fast but often won't drink. IV therapy can help them rehydrate and recover fast. Some veterinarians recommend IV fluid treatment for cats with kidney disease, to help ease pain and possibly extend lifespan. Vitamin C IV treatment for pets may help prevent illness, boost wellness, and even help with cancer treatments.