Nutritional metabolic bone disease is a condition seen only in captive reptiles due to husbandry and dietary mismanagement. In Denver, most of the problems stem from keeping reptiles that are not native to Colorado.
Inappropriate husbandry practices result in anorexia and a decrease in mineral uptake. In most cases this is secondary to stress, therefore, misguidance in pet care has an influence on calcium metabolism.
Tropical and semi-tropical species
Most tropical reptiles are tree climbers. Housing them in an aquarium or other unit that’s longer than it is tall doesn’t allow them to climb. If these reptiles stay on or near the ground, they won’t obtain the appropriate amounts of UV radiation and they will consider predators a consent threat. Humidity levels that are too low cause chronic dehydration and stress, while high levels are a breeding ground for bacteria and other organisms that can cause infection.
Incorrect temperatures cause several problems. If temperature ranges are too low, proper digestion and other metabolic functions will not occur, and temperatures too high can burn pets. Lack of appropriate temperature ranges in the environment, or temperature gradients, do not allow reptiles to establish normal ectothermic behaviors.
Lighting systems are a major problem with reptile keeping. Tropical species have specific needs that can not be met with regular household light bulbs. Many reptile bulbs also do not meet the requirements for most of these species. Basking bulbs and most broad spectrum bulbs are designed for the sole purpose of providing heat and light. They do not provide UVA or UVB radiation needed by these reptiles unless they are specifically labeled. The amount of time an animal spends in the sunlight, or the photoperiod, can’t be too long or too short, otherwise future medical problems will occur.
Desert and grassland species
Reptiles from desert and grassland habitats that are housed in units that are not high enough can result in over heating of the enclosure or serious damage from the bulbs. If the unit doesn’t have plenty of floor space for moving around, reptiles can’t maintain appropriate internal temperatures. Humidity levels don’t have to be extreme for these habitats, however, water needs to be accessible and low levels of humidity provided for proper shedding.
Incorrect temperatures, and temperature gradients, for any reptile will affect digestion and other metabolic functions. Regardless of whether the levels are too high or too low, serious consequences result. It shouldn’t be assumed that all desert reptiles require high heat; this simply is not the case.
Both desert and grassland reptiles can not be maintained with the same light bulbs. Some species require UVA and UVB bulbs, while some can do well with only basking bulbs. Household bulbs are inappropriate as are any bulbs that are not specifically designed for reptile keeping. Household plant bulbs do not provide specific radiation and light needed by certain species. Photoperiods can not be too long or too short, they must be appropriate for the species and the season.
Problems associated with diet are based on several misconceptions. First, outdated information that is considered to be of value continues to be used. Second, modern conveniences allow for compromise of natural diets, and third, misguidance from the internet, pet stores, and other misinformed leaders in the pet industry.
Juvenile reptiles develop NMBD more often than adults due to their rapid growth rates. Lack of supplementation during this time promotes hypocalcemia due to the increased demands for calcium and other vitamins and minerals.
The dietary needs of these reptiles are the most misunderstood and present with the most problems. Many keepers believe that commercial reptile diets, dog food, and cat food are balanced and complete. Many of these processed foods are high in fat, provide animal source proteins instead of plant based ones, contain artificial ingredients, high amounts of grains, and offer no variety or water.
A diet rich in dark leafy greens, vegetables, and small amounts of fruit are optimum for these reptiles. Mistakes are made with lack of variety, the wrong types of produce, such as tomatoes or oranges, and fruits and vegetables in the wrong proportions.
Offering meats such as hamburger, infant mice, crickets, or other meat sources in any amount is the most detrimental practice. This not only leads to NMBD but other health conditions that can be fatal.
Reptiles that eat mostly crickets and worms are at a disadvantage because these insects are low in calcium and other nutrients. Feeding them on a regular basis without supplementation contributes to deficiencies in vitamins and minerals. Wax worms in particular, are high in fat and can lead to weight gain along with vitamin and mineral deficiencies.
Feeding juveniles infant or young adult prey can lead to nutrient deficiencies due to their uncalcified bones. For adults, large prey can be nutrient deficient if their diet was insufficient before being fed to the pet.
Part 3 of this series on MBD will discuss clinical signs, diagnosis and treatment..