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Thiamine Deficiency 969

Clinical Presentation prompt initiation of treatment. Response to Nutrition/Diet
DISEASE FORMS/SUBTYPES treatment strongly supports the diagnosis. Dietary correction:
VetBooks.ir multiple organ systems may be involved. Differential Diagnosis • Discontinue suspected deficient diet. Diseases and Disorders
• Eliminate any raw food, especially raw fish.
Primarily affects nervous system, although
• Feed an appropriate, balanced commercial
• Intoxication
• Induction stage: within 1 week of severe
or home-cooked diet.
deficiency
disease
• Critical stage: if not identified and reversed • Inflammatory or infectious central nervous Assisted feeding if diminished food intake:
during the induction stage • Multifocal intracranial neoplasia • Veterinary therapeutic critical care diet
• Terminal stage: after approximately 1 month • Other nutritional disease offered orally or administered through
of severe deficiency; death occurs. Most cases • Metabolic disease feeding tube
are diagnosed in terminal stage. • Introduce food gradually; begin at one-fourth
Initial Database to one-third of the patient’s resting energy
HISTORY, CHIEF COMPLAINT • Nutritional assessment, including body weight, requirement (RER), increase to one-half to
• Diet and medical history compatible with body condition score, muscle condition score, two-thirds after 24 hours, and so forth to
risk factors food intake and diet history, followed by full RER.
• Clinical signs are variable and nonspecific. assessment of nutritional risk factors.
○ GI signs initially: hyporexia or anorexia, • Question owners about possibility of toxin Possible Complications
lethargy, depression, weight loss, hyper- ingestion. • Animals can experience discomfort during or
salivation (cats), vomiting, and diarrhea • CBC, serum biochemical profile, urinalysis, after SC or IM thiamine injection. Rarely,
or constipation. and CSF analysis are generally unremarkable. allergic reactions to SQ thiamine have
○ Progression to neurologic signs: blind- occurred.
ness, ataxia, paresis, weakness, cervical Advanced or Confirmatory Testing • Thiamine supplementation IV should
ventroflexion (cats), tremors, seizures, • Treatment with thiamine results in rapid be avoided because severe hemodynamic
and coma response in 12-48 hours; response is con- effects (hypotension, cardiac arrhythmias,
○ In terminal stage, rapid worsening of signs sidered confirmatory for suspected diagnosis. neuromuscular and ganglionic blockage,
until death occurs. • Erythrocyte transketolase activity: indicator of apnea, and death) have been reported.
thiamine status; limited availability; requires
PHYSICAL EXAM FINDINGS specific blood sample preparation. PROGNOSIS & OUTCOME
• Dogs: tachypnea, tachycardia, weak femoral • High-performance liquid chromatography
pulses; cats: sinus arrhythmia, bradycardia for whole blood and serum thiamine Clinical signs begin to resolve within hours
• Neurologic exam (p. 1136): altered menta- analyses: limited availability; lack of reference after supplementation, although some signs may
tion, poor proprioception, abnormal postural ranges persist for days to months. Full recovery may
reaction, absence of deep and superficial pain • Elevated plasma pyruvate and urinary lactate not be possible if severe neurologic damage has
in all limbs, and hyperesthesia concentrations in dogs occurred. Exercise intolerance and some degree
• Cats: spastic ventroflexion of head and neck • MRI of the brain: symmetrical bilateral of ataxia can persist for years after treatment.
that worsens and persists despite being held lessons in the brainstem; primarily affects
upside down gray matter PEARLS & CONSIDERATIONS
• Ocular exam (p. 1137): nystagmus, anisoco- • Histopathology: lesions may be spongy or
ria, mydriasis, unresponsive dilated pupils, may involve cell degeneration and hyper- Prevention
and lack of menace response. Fundic exam trophy; especially occur in the nuclei of the • Feed a balanced commercial diet in accor-
may reveal retinal venous dilatation and caudal colliculi dance with the patient’s life stage, or feed
hemorrhage. • Laboratory analyses of diet for thiamine a balanced homemade diet formulated by
• Electrocardiographic changes (p. 1096): (± sulfur dioxide) board-certified veterinary or PhD nutritionist
flattening or inversion of the T wave, QRS • Do not feed raw food, especially raw fish.
prolongation, or prolongation of the ST TREATMENT • Note the “best before” date on pet food
segment packaging and ensure proper pet food storage
Treatment Overview (original packaging, avoid exposure to heat
Etiology and Pathophysiology Parenteral thiamine supplementation is and light).
• Thiamine can be obtained only from the recommended; acute treatment with oral
diet and is not stored in the body. Excess supplementation is considered for longer-term Technician Tips
thiamine is excreted in the urine. use. Dietary correction is indicated if nutritional Nutritional assessment and diet history are most
• Thiamine exists in the blood as free form or thiamine deficiency is suspected. important tools to diagnose thiamine deficiency.
phosphorylated (thiamine monophosphate,
diphosphate, and triphosphate). Acute General Treatment Client Education
• Critical role in carbohydrate metabolism and • Crystalloid fluids IV Explain the dietary risk factors associated
energy production; clinical signs of deficiency • Anticonvulsant medications, if required (p. with thiamine deficiency and the importance
may relate to dependence of neuronal and 903) of feeding a balanced diet in accordance with
cardiac tissue on energy • Thiamine hydrochloride 100-250 mg IM the pet’s life stage.
• Role in neural function (synaptic transmission or SQ q 12-24h until neurologic signs
and cell membrane conductance and stimulates subside (3-5 days). The ideal dose is currently SUGGESTED READING
activity in the spinal cord and cerebellum). unknown. Dosages described after improve- Kritikos G, et al: The role of thiamine and effects of
ment of neurologic signs are 25-150 mg in deficiency in dogs and cats. Vet Sci 4(4):59, 2017.
DIAGNOSIS cats, 100-600 mg in dogs PO q 12h. AUTHOR: Adronie Verbrugghe, DVM, PhD, DECVCN
Diagnostic Overview Chronic Treatment EDITOR: Jennifer Larsen, DVM, PhD, DACVN
Thiamine deficiency is suspected based on • Continue with oral thiamine supplementa-
clinical signs and presence of risk factors on tion for an additional 2-4 weeks.
nutritional assessment. These findings justify • Correct dietary or medical issues.

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