FeLV
infection is still considered to account for most disease-related deaths in pet cats. Different treatment attempts with various drugs were performed in the past but none resulted in healing or complete virus elimination. Therefore, it caused a sensation when Horber and Mayr [Horber, D., Mayr, B., 1991.
Prax. 19, 311-314; Horber, D., Schnabl, W., Mayr, B., 1992. Tierarztl. Umschau 47, 556-560; Mayr, B., Horber, D., 1992. Kleintierprax. 37, 515-518] published that they were able to cure 80 to 100% FeLV-infected cats from
viremia by using an immunomodulating compound. Articles in cat breeder and cat owner journals appeared assuming that obviously there is a rescue for FeLV-infected cats suffering from this deadly
infection. The
immunomodulator [Buttner, M., 1993. Comp. Immun. Microbiol. Infect. Dis. 18, 1-10] used in those studies was the so-called '
paramunity inducer' PIND-ORF (
Baypamun, Bayer, Leverkusen, Germany) consisting of inactivated parapox ovis virus. Since that time,
Baypamun is the most commonly used
drug for treatment of FeLV
infection in Germany and other European countries. Four placebo-controlled double-blind trials were performed to determine the therapeutic efficacy of
Baypamun and other compounds in naturally FeLV-infected cats under controlled conditions.