Thiamine Deficiency in Dogs

Thiamine is used for carbohydrate metabolism and energy production, and since it is not stored in the body, it needs to be constantly replenished. A deficiency is most often due to an insufficient thiamine content in commercial pet foods, often because the vitamin is sensitive to heat and is destroyed in the cooking process. Vegetarian, homemade and raw meat diets can also suffer from insufficient thiamine levels. Also, foods that contain sulphur dioxide, sulphite preservatives, or thiaminases can break down thiamine and make it inactive and unable to be metabolized. Drugs that encourage fluid loss, such as diuretics, can deplete thiamine from the body, and intestinal disease can stop the body from absorbing this crucial vitamin. Supplemental thiamine treatments can lead to a full recovery in most cases.

A condition of thiamine deficiency can occur if enough thiamine, or Vitamin B1, is not included in the diet, or cannot be absorbed in the digestive system. This easily preventable condition can lead to serious health problems if not treated. Symptoms begin in the GI tract and can progress to the cardiovascular and nervous systems, with worst cases including hemorrhage and necrosis of brain tissue. If left untreated, this simple vitamin deficiency can become fatal.

Signs of a thiamine deficiency in your dog can take days to weeks to appear, and can include:

• Anorexia
• Vomiting
• Weight loss
• Lack of appetite
• Gastrointestinal issues
• Lethargy
• Decreased pupil light response
• Unequal pupil sizes
• Involuntary eye movement
• Eyeball protrusion
• Mental problems
• Abnormal behavior
• Nervous system issues
• Muscle spasms
• Neuromuscular weakness
• Loss of body movement control
• Seizures
• Heart problems
• Rapid heart rate

Reasons for a condition of thiamine deficiency to occur are:

• Insufficient thiamine in diet
• Diet including sulphur dioxide or sulphite preservatives
• Diet high in carbohydrates
• Malabsorptive intestinal disease
• Diseases that inhibit thiamine utilization, such as liver disease
• Diuretics

When coming to a diagnosis of thiamine deficiency, your veterinarian will take into account any present symptoms, a dietary history, results of tests, and a response to treatment. If a thiamine deficiency is suspected, plasma, blood, urine, or saliva can be tested for their concentrations of the vitamin. The most common test for this condition is the erythrocyte transketolase assay, which directly measures thiamine pyrophosphate in the red blood cells from a blood sample. Another test that also determines thiamine levels is a high pressure liquid chromatography, or HPLC, and can help to distinguish between thiamine deficient and normal animals.

Symptoms of this condition are similar to many other medical issues, and as such, your veterinarian may need to run many other tests to come to a conclusion that your dog’s problem is indeed a thiamine deficiency. These tests could include complete blood counts, serum biochemistries, bile acid concentration testing, folic acid and cobalamin concentration testings, liver function tests, and EKGs. MRIs of the brain may be performed if neurological issues are seen, and may lead to a thiamine deficiency diagnosis. A urinalysis is often performed to check for electrolyte and metabolic abnormalities. Gas chromatography-mass spectrometry can also be performed with a urine sample to look for levels of amino acids, organic acids, sugars, sugar alcohols, nucleosides, and most importantly, purine and pyrimidine bases.

Once a positive diagnosis confirms a thiamine deficiency, treatment aims to correct that imbalance by supplementing thiamine back into your dog’s system. An intramuscular injection of thiamine pyrophosphate for 3 to 5 days is generally given, followed by 2 to 4 weeks of oral treatments. Intravenous injection may be used, but is often avoided due to risk of hypotension and arrhythmias. A multi-vitamin that includes thiamine may be prescribed to ensure your dog receives balanced vitamin levels. Supplemental fluid therapy may be needed to balance electrolytes. MRI’s and urine testing may be performed after treatment to check for regression of symptoms.

Your veterinarian will also likely make dietary modifications to either exclude foods that affect thiamine levels or have insufficient vitamin amounts, or include more balanced ones. If an underlying condition has been identified, such as a gastrointestinal issue, your veterinarian will treat that as well. Response is generally good if treated early, but once neurological signs are exhibited, there may be residual conditions. In rare cases, euthanasia or death can occur.

After you return from the veterinary clinic, you may need to administer supplements to your dog. The most important measure to ensure proper nutrition is to cut out any foods containing sulphur. Check your dog food for appropriate and viable levels of thiamine. The AAFCO, (Association of American Feed Control Officials), has recommended 1 mg of thiamine per kilogram of food to be present in adult dog food.