One of the most common captive-reptile diseases, Metabolic
Bone Disease in turtles is a condition that results in
warped shells, frozen hinges in hinged shells, pyramiding or
upward curving shells, overgrown or deformed beaks, splayed
legs, hard knobs on leg bones, difficulty walking or
complete inability to walk, twitches and jerking, crooked
feet and nails, softening of the carapace and plastron, and
diseases of internal organs.
In extreme cases the tail is shrunken from the turtle's body
trying to get more calcium in any way possible and the
turtle won't eat and may have bone fractures. Metabolic Bone
Disease is basically an umbrella term for a number of
disorders such as rickets, osteoporosis, fibrous
osteodystrophy, secondary nutritional hyperparathyroidism,
Doesn't this disease sound horrible? What can be done about
this terrible disease?
This disease is solely caused by an improper diet!
Granted, the poor care that results in this syndrome is
usually because of a turtle keeper's ignorance rather than
deliberate neglect, but with the wealth of information on
animal care available in books and on the Internet, there is
really no excuse. If you have pets of any kind, or want to
have pets, research the needs of the species you choose. A
pet is solely dependent on us for its needs, and we have a
responsibility to care for them properly.
Some common causes of Metabolic Bone Disease in Turtles
* The most common cause is a diet that is too low in calcium
and too high in phosphorus. This is most common in
carnivorous and insectivorous animals that are fed organ
meats without bone and/or insects that have not been "gut-
loaded" or dusted with reptile calcium supplement before
being fed to the turtle. Whole foods such as baby mice or
whole fish are the best diet choice for any reptile that
eats meat or insects.
Even with calcium supplementation, organ meats and insects
such as crickets have a negative Ca:P ratio (proportion of
calcium to phosphorus), but whole fish, birds, mice or rats
have a high Ca:P ratio because of their bones. Reptile
multivitamin and mineral supplements often have calcium in
them, but rarely enough to prevent Metabolic Bone Disease,
and many commercial diets for reptiles are far too low in
calcium for good turtle health. But, there are also health
issues caused by too much calcium or too much vitamin D, so
natural food rather than supplementation is the best path to
take. If you feed insects, remember that insects are
naturally high in phosphorus and buy a calcium dust for them
that is phosphorus-free.
* Other things that contribute to Metabolic Bone Disease in
turtles, tortoises and terrapins are:
a. Keeping the turtle at temperatures consistently lower
than temperatures in the turtle's native habitat can not
only depress the turtle's appetite but cause improper
digestion of the food it does eat.
b. Failure to provide adequate full-spectrum UVB light
prevents the turtle from properly absorbing and processing
the calcium and vitamin D3 in its diet. If UVB lights are
present there can still be a problem if the lights aren't
set up properly (too high, too low, aimed wrong, glass
between the turtle and the light) and the turtles can't get
under them for long enough periods, or if the light bulbs
are old and aren't really still emitting full-spectrum UVB
light. Even with good UVB fluorescents, you should try to
expose your turtles to unfiltered sunlight for short periods
whenever possible, but be sure to protect the turtle from
overheating by providing a shady spot also.