Blackwell's Five-Minute Veterinary Consult: Reptile and Amphibian. Javier G. Nevarez
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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 storage of frozen fish by not keeping beyond 6 months of death/freezing.
Rapid thawing for five minutes in 80 degrees C (175 degrees F) water denatures thiaminase or thawing in refrigerator also avoids thiaminase activation.
An added level of protection would be to add thiamine 25 mg/kg fish.
Do not use vitamin supplements beyond expiration date or 6 months after opened.
CLIENT EDUCATION/HUSBANDRY RECOMMENDATIONS
Proper education about expiration dates/ opening dates of vitamin supplements, avoiding certain live fish species and carrying out proper thawing techniques for frozen fish.
Avoidance of too many thawed frozen vegetables.
DRUG(S) OF CHOICE
Thiamine administered at 50–100 mg/kg IM, SC, or PO q24h until resolution of clinical signs.
A vitamin B complex formulation is less ideal but can be used if a thiamine‐only supplement is not available.
PRECAUTIONS/INTERACTIONS
N/A
PATIENT MONITORING
Reassess diet
Diet processing/handling
Supplementation at every visit
EXPECTED COURSE AND PROGNOSIS
If thiamine deficiency without concurrent issues, should have immediate response to therapy, although repeated treatments may be needed.
In non‐piscivores, often not considered and diagnosed postmortem on histopathology.
COMMENTS
N/A
ZOONOTIC POTENTIAL
N/A
SYNONYMS
Thiamine deficiency
ABBREVIATIONS
IM = intramuscular
PO = per os
SC = subcutaneous
Suggested Reading
1 Mans C, Braun J. Update on common nutritional disorders of captive reptiles. Vet Clin North Am Exot Anim Pract 2014;17(3):369–395.
Author Eric Klaphake, DVM, DACZM
Iridoviruses
DEFINITION/OVERVIEW
Viruses in the family Iridoviridae are large, double‐stranded DNA viruses that contain a lipid component and can be enveloped. Viruses in the genus Ranavirus are the most common iridoviruses described in chelonians and have the greatest clinical importance. They can infect a wide range of ectothermic vertebrates including reptiles, amphibians, and bony fish.
ETIOLOGY/PATHOPHYSIOLOGY
Ranaviruses have been described in wild and pet chelonians, pet lizards, and occasionally in snakes.
Numerous ranavirus strains can be transmitted between different animal classes. In North America, the ranaviruses described in reptiles have all been closely related to FV3, the type species of the genus, while ranaviruses found in reptiles in other parts of the world (particularly Europe) have been more genetically diverse.
In infected reptiles, ranaviruses can cause severe disease, often associated with lesions in the mouth, liver, and blood vessels.
SIGNALMENT/HISTORY
Ranaviruses have been found in terrestrial and aquatic species.
Most chelonians appear to be highly susceptible to infection, and infection in these animals has been associated with large outbreaks.
Virus has been detected in free‐ranging box turtles in