Key points

  1. Antiviral therapy almost always "lessens disease severity" it almost never "cures" or eliminates viral infection.
  2. Antiviral therapy that works in people possibly works in animals but often does not.
  3. Public health concerns about using antivirals in animals exist. FDA has banned use of oseltamivir (Tamiflu® in food animals.
  4. to date, antiviral drugs NEVER work as well as vaccination.
AntiviralspectrumroutesClinial use and comments
herpesvirus, poxvirus Topical only Yes - herpes keratitis in affected species.
DNA viruses Topical, IV Cat - herpes keratitis (topical)
Ribavarin Most active Influenza A and B
some activity against many others
Oral, intravenous and aerosol routes Unsuccessful trials against FIP and feline calicivirus
Acyclovir (others) Herpes viruses (only) topical, poor oral absorption improved by prodrugs. In vitro against EHV-1, clinical efficacy uncertain
famciclovir has been used successfully in cats FHV (one trial)
successful use in psittacine herpes virus infections (prevention during outbreaks - not treatement of sick birds)
Zidovudine (AZT) Retroviridae Oral and IV Shown to prevent FeLV infection in challenged cats.
Foscarnet DNA and RNA viruses Topical, extremely low oral bioavailability No activity against FHV-1
Use for preventing transmission of FeLV has been SUGGESTED but not proven
myxoviruses, paramyxoviruses, togaviruses, most influenza A strains Good oral absorption ESfficacy has been demonstrated in equine influenza but toxicity proved unacceptable. Rimantadine seems more promising (less toxicity anticipated).
Osteltamivir Influenza A and B (only) - limited efficacy, Good oral bioavailability Use for Influenza A in Dogs has been suggested, has not been proven.

Idoxuridine (Heplex®, Stoxil®) and Trifulridine(Viroptic®)

Cytarabine (Ara-C®) and Vidarabine (Ara-A®)

Ribavarin (Virazole®)

Acyclovir (Zovirax®), Penciclovir (Denavir®) and related prodrugs Valacyclovir (Valtrex®) and Famciclovir®

Zidovudine (AZT®, Retrovir ®) and related compounds

Foscarnet (trisodium phophonoformate hexahydrate or PFA)

Amantadine (Symmetrel®) and Rimantadine (Flumadine®)

Osteltamivir (Tamiflu®)