The park's Frequently Asked Questions page includes:
11) What other items are not permitted in the cave?
Walking sticks, baby strollers and pets (except for service dogs) are not permitted in the cave. Backpacks for carrying babies are available for purchase in the visitor center gift shop. Also, for a small fee, pets are sheltered in a kennel in the visitor center while you visit the park. Pets must not be left in your car if the outside temperature is more than 70°F (21°C), as heat may cause serious injury or death.
The 2009 Superintendent’s Compendium
Unattended Pets in Parking Areas
• Pets shall not be left unattended in vehicles when the ambient air temperature, as recorded by the weather station at Bat Cave Draw, is at or above 70 degrees Fahrenheit. These unattended pets will be removed from the vehicles and impounded at the owner’s expense.
Closure/Determination Justification: On warm days temperatures in closed motor vehicles can rise quickly to levels dangerous to the life and health of animals. These unattended animals can cause public nuisance and alarm when noticed by concerned passersby.
Pet Excrement Disposal
• All solid waste must be picked up and disposed of in outdoor trash receptacles with the exception of residential yards.
Areas closed to pets:
All surface and cave areas within Carlsbad Caverns National Park are closed to pets with the exception of the following:
• On and within 30 feet of paved pullouts and paved parking areas on the surface.
• Along the non-paved Walnut Canyon Desert Drive (Loop Road).
• The NPS employee housing area.
• Permian Drive and Reef Top Drive.
• The paved nature trails excluding the Natural Entrance Trail.
• Bat Draw road and parking area.
• Rattlesnake Springs picnic area and roadways.