Respiratory infections in reptiles are often associated with exposure to low environmental temperatures, either by consistently keeping the temperatures in the lows 70's°F or simply occasional drops to much lower temperatures.  A lot of times these drops are due to a power outages that disrupts the heat elements in the enclosures.  Sometimes the cold temperature is due to a failure of the heat source for the cage, either the light burns out, a fuse or circuit breaker fails, or the heat source is simply not warm enough for the size of the cage. If the power outage occurs at night, you may not even be aware of the suboptimal temperatures unless your reptile's enclosure has a maximum-minimum thermometer that is monitored daily.

A reptile is more susceptible to respiratory infections when it is stressed by poor diet, lack of ultraviolet-B light, overcrowding, and poor sanitation.  A reptile that has been mixed with other reptiles, particularly other kinds of reptiles, are being exposed to all sorts of germs they would never have encountered before. A reptile that was recently moved from one location to is under significant stress.

Signs vary depending on the severity of infection and the primary sites infected.  if the infection is confined to the nose, mouth, and windpipe, such as the classic mycoplasmosis of desert tortoises often presents with a clear to yellow watery to thick nasal discharge.  Bubbles or a crust may be detected on the nose or around the mouth.  Noises may be heard during breathing such as wheezes, clicks, coughs, or sneezes.  With infections of the lungs, a tortoise or turtle may be reluctant to withdraw into the shell. Snakes and lizards may move their bellies in their effort to breath.  Open-mouthed breathing is common.

If you see any of these signs in any reptile, a trip to the veterinarian is needed.