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Thiamine Deficiency in Cats: Our Vet Explains Signs & Causes

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By Dr. Iulia Mihai

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Dr. Iulia Mihai

DVM MSc (Veterinarian)

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Thiamine deficiency in cats is a clinical syndrome associated with vascular lesions and nervous disorders caused by vitamin B1 deficiency. This condition usually occurs due to an inadequate dietary intake of vitamin B1, which is found especially in cats that consume a lot of raw fish.

Thiamine is a component of the B vitamin complex, with a role in the metabolism of dietary proteins and carbohydrates, being indispensable for brain activity and the myelination of peripheral nerves. Thiamine deficiency usually results in nervous clinical signs that include muscle weakness, tremors, convulsions, and incoordination.

The 17 Clinical Signs of Thiamine Deficiency in Cats

In the case of thiamine deficiency in cats, you can notice two types of clinical signs:

  • Neurological: 12 Signs
  • Digestive: 5 Signs
vet checking up a cat
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The 12 Neurological Signs

Neurological signs are the most commonly seen type of signs of thiamine deficiency in cats and include:1

  • One: Bending the neck down or the head towards the floor (ventriflexion)
  • Two: Uncoordinated, unsteady gait or wobbly walk, your cat seems unable to stand (ataxia)
  • Three: Abnormal gait
  • Four: Your cat falls often
  • Five: Muscle weakness
  • Six: Dilated, fixed pupils
  • Seven: Vision loss
  • Eight: Paralysis of the muscles around the eyes
  • Nine: Head tilt
  • Ten: Arching of the head, neck, and spine—opisthotonus
  • Eleven: Stupor — when cats are unconscious but can be woken up by a very strong external stimulus
  • Twelve: Seizures

The 5 Digestive Signs

Digestive signs usually occur before neurological signs and include:

  • Thirteen: Loss of appetite
  • Fourteen: Excessive salivation
  • Fifteen: Nausea
  • Sixteen: Vomiting
  • Seventeen: Weight loss
sick stray cat drooling at the street
Image Credit: elwynn, Shutterstock

The 9 Causes of Thiamine Deficiency in Cats

Cats can suffer from thiamine deficiency for several reasons.

These include:
  • Raw fish: Consumption of raw fish—thiaminase is an enzyme that destroys vitamin B1 and is found in some fish species (cod, herring, catfish, carp, etc.)
  • Unbalanced diet: Feeding special pet food that is not completely balanced
  • Processed diet: Overprocessed food
  • Carnivore diet: Feeding an all-meat diet
  • Suppressed appetite: Prolonged lack of appetite
  • Nutrient absorption: Conditions that can cause nutrient malassimilation or malabsorption, such as pancreatic insufficiency and small intestine disease
  • Surgical resection: Extensive surgical resection of parts of the small intestine (jejunum and ileum)
  • Dietary preservatives (sulfites): Interfere with thiamine absorption
  • Excessive urination: Vitamin B1 is excreted through urine
cat at vet with owner and veternarian
Image Credit: 4 PM production, Shutterstock

Thiamine Deficiency Diagnosis and Treatment in Cats

The diagnosis of thiamine deficiency in cats is usually based on clinical signs and history. Complementary tests such as blood count, blood biochemistry, urinalysis, abdominal ultrasounds, and radiographs can be required to exclude other conditions with similar clinical signs.

The treatment of thiamine deficiency in cats involves the administration of injectable vitamin B1 over a period of several days to several weeks. The vet can also recommend feeding your cat a balanced diet and limiting or suspending giving them raw fish.

Thiamine Deficiency Prevention in Cats

To prevent thiamine deficiency in cats, you need to feed them a balanced diet.

Vitamin B1 is very heat-labile and is easily destroyed by heat. Therefore, it must be supplemented and balanced to compensate for the losses that occur in the heat treatments of some products. In the case of homemade diets, this aspect must be taken into account to avoid vitamin B1 deficiencies.


Thiamine deficiency is a consequence of insufficient vitamin B1 in your cat’s diet. Because thiamine is a vitamin necessary for the proper functioning of the nervous system and the brain, thiamine deficiency leads to neurological signs that may include muscle weakness, dilated pupils, tremors, and seizures. The treatment of thiamine deficiency involves injectable administration of vitamin B1.

Thiamine deficiency can be fatal if left untreated but the prognosis is favorable if the condition is treated early and if your cat’s diet is improved. Administer all the prescribed medication and feed your cat a well-balanced diet as recommended by your vet. Contact your veterinarian immediately if your pet does not respond to therapy or if the condition worsens.

Featured Image Credit: Alice Rodnova, Shutterstock

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