What is “pyramiding”?

Pyramiding is the excessive upward growth of the scutes (the individual segments that make up the tortoise’s carapace or shell) that results in each segment taking on a pyramid-like shape.

What causes pyramiding?

Low humidity has been demonstrated to be a very significant factor in the development of pyramiding in sulcata tortoises (See reference at the end of this article.)  There are many other factors that contribute to the shape of a tortoise’s shell.  Some of the other things that may contribute to the development of pyramiding include:

• Overfeeding
• Excess protein in the diet
• Excess fat in the diet
• Imbalance of calcium and phosphorus (i.e., nutritional secondary hyperparathyroidism, also known as “metabolic bone disease”)
• Not enough exercise
• Genetics
• Environment influences such as being kept outside the preferred operating temperatures, inadequate water intake, lack of ultraviolet light, and lighting that is not bright enough

Tips to help prevent pyramiding in your tortoise

• Ensure proper humidity levels for your species of tortoise.  This has been scientifically proven to be the most significant factor in captive tortoises!
  • Even tortoises that naturally live in arid climates have exposure to increased humidity down in their burrows.
  • Young growing tortoises need at least 65% humidity for most of the day and need access to 90% humidity as desired in order to have normal shell growth.  In Arizona the air humidity is much lower than this even during the monsoon season.
  • Provide access to water with a large shallow pan that is cleaned and disinfected daily.
  • Spray-mist the enclosure daily or run a humidifier for a few hours a day.
  • Make a humidity chamber.  A simple chamber is a small plastic tub with a hole cut in its side.  Attach a sponge to the top of the container and soak it daily.  A different technique is to pack damp sphagnum moss into a corner of the cage.  Soaked cork hollows or half-section of logs soaked in water also help increase the humidity.
  • Soak the tortoise one or more times a week in a shallow bath of warm water for 30-60 minutes
• Provide a high fiber, low-calorie, low protein diet
  • Desert tortoises, leopard tortoises, and sulcata tortoises diet should be eating >75% fresh grasses and hays.  When this is not practical, Zoomed’s Grassland Tortoise Diet is a good part of a complete diet for younger tortoises.  Older sulcata tortoises should always have timothy hay available.
• Provide all day access to food vs. offering set meals
  • It’s important that you are offering the right foods so as not to promote overeating
• Feed plants and greens that have a high bioavailability of calcium or supplement with calcium carbonate or calcium citrate
• Encourage exercise and activity
  • This can be done by providing a large enclosure to roam or by instituting environmental enrichment to stimulate activity.  Placing new objects in the cage will cause many tortoises to come out and investigate them.
• Provide access to natural, unfiltered sunlight.
  • The sun is best, however there are several high quality lights available that provide adequate levels of UVB light
• Provide the correct temperature gradient for your particular tortoise
  • Too cool of an environment will affect how your tortoise absorbs and metabolizes what it eats

Why is pyramiding so bad for tortoises?

The problem can go deeper than a lumpy shell.  Shell deformities can interfere with normal lung function and cause female tortoises to have problems laying eggs.  It can also make the legs weak and move in abnormal positions resulting in overgrown toenails and arthritis.  Sometimes the pyramiding causes paralysis due to changes around the spinal cord.  Pyramiding can lead to an early death.  

Reference

Wiesner CS, Iben C. 2003. Influence of environmental humidity and dietary protein on pyramidal growth of carapaces in African spurred tortoises (Geochelone sulcata). Journal of Animal Physiology and Animal Nutrition 87:66-74.)