Treatment is primarily symptomatic. Generally some TLC and good nursing care is all that is required. Cats can be fed warmed canned food to stimulate their appetite and offered chicken broth to encourage water intake.
Gently cleaning around the eyes and nose to remove dried mucus and crust will help with breathing and comfort.
Severely effected cats who are not eating, have painful ulcers or concurrent bacterial infections should be seen by a veterinarian. These cats may need fluids, pain medication, appetite stimulants and antibiotics.
Keep in mind antibiotics are not effective against viral infections. They are reserved for treatment of concurrent bacterial infections.
Antivirals are available to treat feline herpesvirus. Unfortunately the primary antiviral (famciclovir) used for feline herpesvirus is not effective for feline calicivirus.
You can help prevent the spread of disease by using the same common sense guidelines we all follow for avoiding colds ourselves.
Keep sick cats isolated. Wash your hands after interacting with a sick cat. Be aware you can transmit virus on fomites such as your clothing, shoes and grooming tools. Wash bedding, food dishes and litter boxes regularly.
While all this information can sound daunting, keep in mind most cats will recover within a week or two and be entertaining you with their antics once again.