You should seek the advice of your veterinarian if your pet is ill as only he or she can correctly advise on the diagnosis and recommend the treatment that is most appropriate for your pet.

Vitamin B12 (cobalamin) is an essential water soluble vitamin for cats. Determination of serum concentrations may be useful in diagnosis.

Studies at Cornell University (n=80 cats) have demonstrated that measurement of serum cobalamin concentrations using a solid-phase boil radioimmunoassay can be useful in gastrointestinal cases. Subnormal concentrations were found in middle aged to old cats (n=49) with the following clinical signs:

• Anorexia
• Diarrhoea
• Vomiting
• Thickened intestines on palpation
• Weight loss

Confirmed diagnoses (n=22) in these patients included :

• Intestinal lymphoma
• Inflammatory bowel disease
• Cholangitis and cholangiohepatitis 
• Pancreatitis

The half-life of cobalamin in cats was :

• 12.75 days - normal cats
• 5 days - cats with inflammatory bowel disease

The "normal" reference range for healthy cats was 900-2800pg/ml mean 1775 +/- 535 pg/ml

One cat in the study had methylmalonic acidaemia which resolved after treatment with vitamin B12 - suggesting a true cobalamin deficiency. 

As in dogs, some cats may also have altered folate or TLI concentrations

Reference.

J Vet Intern Med 2001;15:26–32 Subnormal Concentrations of Serum Cobalamin (Vitamin B12) in Cats with Gastrointestinal Disease Kenneth W. Simpson, John Fyfe, Angelyn Cornetta, Amy Sachs, Dalit Strauss-Ayali, Stephen V. Lamb, and Thomas J. Reimers

Last updated : January 2016