Thiamine (Vitamin B1) for Dogs and Cats

Overview of Thiamine for Canines and Felines

• Thiamine is vitamin B1. It is a water-soluble vitamin used for dogs and cats to treat thiamine deficiency.
• Natural sources of thiamine include brewer’s yeast, legumes, beef, pork, milk, liver, nuts, whole grains, enriched flour, and cereals.
• The functions of thiamine include metabolism of carbohydrates, maintenance of normal growth, transmission of nerve impulses, and acetylcholine synthesis.
• Following absorption, thiamine is quickly converted to its active form, thiamin pyrophosphate (TPP), by a specific enzyme, thiamin diphosphotransferase.
• Clinical signs of thiamine deficiency include anorexia, vomiting, depression, stunted growth, loss of body hair, coprophagy, wide-based hind limb stance, crouching gait, kyphosis, vestibular ataxia, progressive spastic paraparesis [“Chastek paralysis”], ventroflexion of the neck, circling, exophthalmos, seizures, muscle weakness, recumbency, opisthotonus, coma, and death. Neurological signs may include exaggerated reflexes, proprioceptive deficits, mydriasis, reduced or absent menace reflex, tremors, and nystagmus. Cats tend to show vestibular signs, head tremor, ataxia, persistent crying, mydriasis, progressive paraparesis/paralysis, seizures, depression, coma, opisthotonus, and death. Various electrocardiographic abnormalities are seen in dogs and cats with thiamine deficiency.
• Thiamine deficiency has been reported in dogs and cats fed uncooked meat containing sulphur dioxide (SO2) as a preservative. Such food may induce thiamine deficiency when mixed with thiamine-replete commercial pet foods. Thiamine is broken down by thiaminase found in certain types of raw fish (tuna, salmon, shellfish) and rice bran. Tannins (found in coffee and tea) inhibit the absorption of thiamine. Excess feeding of foods rich in thiaminase or ones than impair thiamine absorption will lead to thiamine deficiency.
• Depending on the product, methionine may be available as a prescription drug or as an over-the-counter medication. However, it should not be administered to animals except under the supervision and guidance of a veterinarian.

Brand Names and Other Names of Thiamine

• This drug is registered for use in humans, horses, dogs, and cats.
• Human formulations: Thiamilate® (Tyson) and various generic preparations.
• Veterinary formulations: Numerous generic preparations.

Uses of Thiamine for Dogs and Cats

Thiamine may be used for:

• Treatment of thiamine deficiency
• Adjunctive treatment in lead poisoning and ethylene glycol toxicity

Precautions and Side Effects

• Thiamine is generally safe and effective when prescribed by a veterinarian, an side effects are rare.
• Thiamine should not be administered to animals that are hypersensitive to it.

Drug Interactions with Vitamin B1

Thiamine may interact with other medications. Consult with your veterinarian to determine if other drugs your dog or cat is receiving could interact with thiamine. Such drugs may include:

• Amprolium (a coccidiostat) inhibits thiamine absorption
• Thiamine may enhance the action of neuromuscular blockers

How Thiamine is Supplied

• Thiamine is available in 20mg (enteric-coated); 50 mg; 100 mg; 250 mg tablets.
• Thiamine is available as an oral powder: 500mg/oz in 1.5 lb, 4 lb, and 20 lb containers.
• The injectable forms includes a human product containing 100 mg/mL (1 mL in 2mL Tubex and 2mL multidose vials) and veterinary preparations containing 200 and 500 mg/mL in 100 or 250 mL vials.
• Thiamine is also included in several B-complex vitamin preparations.

Dosing Information of Thiamine for Dogs and Cats

• Medication should never be administered without first consulting your veterinarian.
• The dosage prescribed may vary depending on the reason for prescribing.
• The duration of administration depends on the condition being treated, response to the medication and the development of any adverse effects. Be certain to complete the prescription unless specifically directed by your veterinarian. Even if your dog or cat feels better, the entire treatment plan should be completed to prevent relapse.
• In dogs, the usual dose is 0.5 to 1 mg per pound (1 to 2 mg/kg) every 24 hours orally, subcutaneously, or intramuscularly.
• In cats, the usual dose is 1 to 2 mg per pound (2 to 4 mg/kg) every 24 hours orally, subcutaneously, or intramuscularly.