Muramyl-dipeptide-induced fever in cats.

The characteristics of fever induced by intravenous injection of muramyl dipeptide (MDP; 25 micrograms/kg) were studied in cats implanted with electrodes for chronic recording of electromyograms, brain temperature (Tb) and subcutaneous temperature. Intravenous injection of MDP was followed by a bimodal fever response after a latent period of 19.4 +/- 1.3 min. Maximum Tb was reached 62.0 +/- 20.7 min after injection, with a second minor peak at about 4 h following injection. Tb returned to baseline after 6-8 h. A single intravenous injection of MDP induced a stable reproducible thermal response which allowed to study the properties of body temperature and effector mechanisms during fever in cats.