months with most manifestations resolving, though renal damage may be permanent.
COMMENTS
N/A
ZOONOTIC POTENTIAL
N/A
SYNONYMS
N/A
ABBREVIATIONS
IM = intramuscular
UVB = ultraviolet B
Suggested Reading
1 Chen LP, Huang CH. Estimation of dietary vitamin A requirement of juvenile soft‐ shelled turtle, Pelodiscus sinensis. Aquacult Nutr 2015;21:457–463.
2 Li H, Vaughan MJ, Browne RK. A complex enrichment diet improves growth and health in the endangered Wyoming toad (Bufo baxteri). Zoo Biol 2009;28:197–213.
3 Mans C, Braun J. Update on common nutritional disorders of captive reptiles. Vet Clin North Am Exot Anim Pract 2014;17(3):369–395.
4 Miller EA, Green SL, Otto GM, Bouley DM. Suspected hypovitaminosis A in a colony of captive green anoles (Anolis carolinensis). Contemp Top Lab Anim Sci 2001;40:18–20.
Author Eric Klaphake, DVM, DACZM
Hypovitaminosis B
DEFINITION/OVERVIEW
Hypovitaminosis B generally refers to hypothiaminosis and is a health concern in reptiles that are fed fish—whether live or frozen thawed. Other cases have been reported in herbivorous reptiles and reptiles fed vitamin supplements lacking in thiamine.
ETIOLOGY/PATHOPHYSIOLOGY
In humans, thiamine deficiency can occur rapidly and advance to metabolic coma and death; causes being malnutrition, a diet high in thiaminase‐rich foods (raw freshwater fish, raw shellfish, ferns), chronic gastrointestinal diseases, and diabetes mellitus.
Thiamine derivatives and thiamine‐ dependent enzymes are present in all cells, but the nervous system is very sensitive, leading to nerve fiber myelin sheath degeneration causing necrotizing encephalopathy and peripheral neuritis.
Bilateral vision loss due to optic neuropathy can occur.
Thiamine is a water‐soluble vitamin synthesized by bacteria, fungi, and plants.
Captive fish‐eating garter snakes and semi‐aquatic turtles, and captive and free‐ ranging crocodilians are most commonly affected.
Feeding fish high in thiaminase—goldfish and fathead minnow, improperly thawed fish (thawing too slowly), or fish that has been frozen a long time can all be factors.
Some frozen thawed vegetables containing phytothiaminases lead to thiamine deficiency in green iguanas.
Insectivorous anoles developed thiamine deficiency due to lack of any thiamine in the multivitamin supplement because of extensive storage before use.
Thiamine is a rapidly deteriorating vitamin so it is important to ensure that supplements are stored and used properly.
SIGNALMENT/HISTORY
Fish as primary diet
Thawed frozen vegetables
Using same container of vitamin supplement/powder beyond expiration date or past 6 months after opening.
CLINICAL PRESENTATION
Can present with non‐specific signs such as anorexia, dehydration, and lethargy, but suspicions of thiamine deficiency are greater with torticollis, opisthotonus, muscle tremors, incoordination, blindness, jaw gaping, and sudden death.
RISK FACTORS
Husbandry
N/A
Others
Piscivores
Thawed frozen vegetables
DIFFERENTIAL DIAGNOSIS
Trauma
Infectious encephalitis
Toxins
Metabolic bone disease
Hepatoencephalopathy
Neoplasia
Cardiac disease
Renal disease
Ruptured aneurysm
DIAGNOSTICS
Usually based upon history, clinical signs, and response to parenteral thiamine (B‐complex vitamins).
PATHOLOGICAL FINDINGS
Cerebral cortical necrosis
• Peripheral neuritis
APPROPRIATE HEALTH CARE
N/A
NUTRITIONAL SUPPORT
Avoid feeding fish known to have high thiaminase levels, such as goldfish and fathead minnows.
Proper
