Reptile Nutrition

Lower

The standard metabolic rate of reptiles is ___ [higher or lower] than mammals or birds of similar size.

Higher

In general, smaller reptiles have ___ [higher or lower] energy requirements than larger reptiles.

Overestimate

Most owners ___ [overestimate or underestimate] the nutritional needs of their pet reptile.

Slower

Gut transit time in reptiles is often ___ [faster or slower] than other species.

1-3 days

Gut transit time of small lizards

1-3 weeks

Gut transit time of turtles and tortoises

1 month

Gut transit time of large snakes

Faster

In general, increased temperature leads to ___ [faster or slower] metabolism.

Increased

GI transit time is faster with ___ temperature.

Improved

Immune function is ___ [improved or worsened] with increased temperature.

Enhanced

Endogenous production of vitamins is ___ [enhanced or diminished] by appropriate temperature.

Body temperature

Reptiles are ectothermic → ___ is completely dependent on environmental temperature

Slower

Reptiles kept at lower temperatures within their preferred range will have ___ [slower or faster] digestion.

Bloat, maldigestion, constipation

Keeping animals at suboptimal temperatures can lead to life-threatening medical problems such as ___, ___, and ___.

Calcium

Supports bone health, muscle, and nerve function

Life stage changes

What can impact homeostasis?

D3, bones

Calcium metabolism requires vitamin __ for gut absorption.

If it is not available, then it can be mobilized from the ___.

Endogenous production, exogenous (diet)

Two ways that reptiles get vitamin D3

Endogenous vitamin D3 production

• UV light starts conversion process at the level of the skin

  • Some species also need heat to complete this step

• Further conversion occurs in the liver and kidney

  • Might not be able to get to final active form if there is disease in these organs

• Final active form 1,25 hydroxyvitamin D3 maintains calcium homeostasis

1,25 hydroxyvitamin D3

What is the final active form of the vitamin that maintains calcium homeostasis and is produced endogenously?

UVA (320-400 nm), UVB (290-320 nm)

Components of UV light

UVA (320-400 nm)

Used for social/behavioral cues

UVB (290-320 nm)

Necessary for vitamin D (some species also need heat and UV light)

Nutritional secondary hyperparathyroidism

• AKA metabolic bone disease

• Herbivorous and insectivorous reptiles are most likely affected

• Etiology:

  • Need UVB light (295-315 nm) and heat to make vitamin D

• Signs:

  • Folding fractures, seizures, weakness, death

Intestinal tract, UV light

• Exogenous vitamin D3 sources:

  • Vitamin D can be absorbed from the ___ in usable (pre-converted) form from animal sources

    • However, even carnivorous animals may require ___ in managed care

Vitamin A

• Important fat-soluble vitamin

  • Roles in normal epithelialization

Hypovitaminosis A

• Clinical signs:

  • Squamous metaplasia and hyperkeratosis of epithelial tissues → epithelial tissues throughout the body

    • Insectivorous reptiles and aquatic turtles are most affected

Protein, fiber, water

Nutrient requirements of reptiles other than calcium, vitamin D, and vitamin A (although all will be variable depending on species and diet specificity)

Body condition assessment

• Visual assessment and score to determine animal’s condition

  • Combined with weight

• Numerous scoring methods available

  • Common schemes: 1-5 or 1-9

Tail, hips and back, internal fat pads (palpation or visualized by transillumination)

What body parts of the leopard gecko would you assess to determine its BCS?

Tail, hips and back, internal fat pads (palpation)

What body parts of the bearded dragon would you assess to determine its BCS?

Tail, back

What body parts of the snake (boa/python) would you assess to determine its BCS?

Limbs, axilla/inguinal folds

What body parts of the aquatic turtle would you assess to determine its BCS?

Limbs, axilla/inguinal folds, muscles over the head

What body parts of the tortoise would you assess to determine its BCS?

Iguanas, most turtles and tortoises, some lizards

Which species are herbivores?

Herbivorous diet

• May opportunistically eat insects or other protein sources but should not be fed these routinely

• Fiber

  • Fermentation in the large colon → think horses

  • Helminths, protozoa and bacteria help to break down fiber

• Protein

  • Higher requirements as juveniles than adults; oversupplementation can change growth patterns

• Calcium and phosphorus

  • Should be fed at 2:1 ratio

2:1

At what ratio should calcium and phosphorus be fed? (Ca:P)

Herbivorous lizards

Which animal and diet?:

• High in slowly digested carbohydrate (e.g. cellulose) and are low in quickly fermented sugars (e.g. low fruit content), fat

• Calcium (juveniles need higher concentrations than adults) and vitamin A

  • Remember that young may start out carnivorous/omnivorous and convert to herbivorous over time

High, low

Herbivorous lizard diets should be ___ in slowly digested carbohydrates (e.g. cellulose) and ___ in quickly fermented sugars (e.g. fruit) and fat.

Herbivorous lizards

What type of diet and animal would this diet be the right fit for?:

• 34% carotenoid-containing vegetables

• 24% green beans and peas

• 16% alfalfa hay

• 15% leafy greens (limit brassicas because they can be goitrogenic)

• 4% fruit (includes tomatoes)

Tortoises

Which herbivorous species requires a high hay component in their diet (as high as 70-75% hay)?

Shell pyramiding

Nutritional-related condition in turtles and tortoises

Can be stopped from progressing, but the damage that has already been done from this condition cannot be fixed

Inland bearded dragons, box turtles, blue-tongued skinks (many lizards, a few chelonians)

Which species are omnivores?

Omnivore diet

• Diet needs can be highly specialized

• Diet needs may change over time

• Likely evolutionary adaption to poor quality dietary items available in natural environment → Need to be able to use anything that comes along

• In captive setting, diets are typically rich

• Protein:

  • Useful protein sources may be variable for different reptiles (ex. Plant vs. animal vs. insect sources may have different digestibility)

    • Reducing protein may be helpful to slow growth, control obesity, and limit resources available for follicular development

Bearded dragons

This is an example of an evolution in the diet of which omnivorous species?:

• Juvenile: 60% insects, 40% veggies

• Adult: 20-40% insects, 60-80% veggies

All snakes, crocodilians, some lizards, a few turtles

Which species are carnivores?

Insectivores, vertebrate diets

Types of carnivorous reptiles

Rodent-based

Most common whole prey component of carnivorous reptile diet

Rodent bites, obesity

Two problems with carnivorous diets

Insectivorous diets

• Hardest to maintain in captivity; wild variety of insects is difficult to replicate in pet setting

  • Toxicity is possible

• Gut-loading

  • Can improve nutrition but hard to accomplish