Why do dogs and cats develop cobalamin deficiency?

Cobalamin deficiency is often linked to intestinal malabsorption, chronic enteritis, or long-term use of medications that impair absorption. The exact cause requires a veterinary examination and blood testing to determine.

How is cobalamin deficiency diagnosed?

Your vet will recommend a blood test to measure serum cobalamin (vitamin B12) levels, and may also perform faecal or imaging tests to identify the underlying cause.

Does cobalamin deficiency affect my pet's prognosis?

If the underlying cause is identified and treated, most pets show clinical improvement. Ongoing supplementation and regular monitoring are important — follow your vet's schedule for follow-up visits.

What information should I bring to the appointment?

Bring the date symptoms began, a weight log, a record of vomiting and diarrhoea frequency, a list of current medications and supplements, and photos of any past test reports.

How much do the tests and treatment usually cost?

Costs vary by clinic and region — ask your vet for an estimate before proceeding.

Disease Guide

Cobalamin Deficiency in Dogs & Cats: Symptoms, Diagnosis & Treatment [2025]

Cobalamin deficiency affects digestion and neurological function, and is common in pets with gastrointestinal disease — supplementation can effectively improve symptoms.

Take 1 minute to check the symptoms first

Last updated: 2026/01/05

Pethealthmap Editorial Team

Sources: ACVIM, WSAVA, National Taiwan University Veterinary Hospital

When to See a Vet

Seek immediate veterinary care (emergency)

•Persistent inability to eat or refusal to eat for more than 24 hours
•Frequent vomiting that cannot be stopped after multiple episodes
•Severe lethargy, slow response, or inability to stand

Schedule a clinic visit as soon as possible (within 24-72 hours)

•Appetite is clearly reduced and persists for several days
•Noticeable weight loss over a short period
•Persistent diarrhea or abnormal changes in stool consistency

01What symptoms indicate something is wrong?

Cobalamin (vitamin B12) deficiency in dogs and cats often presents as lethargy and gastrointestinal problems. Symptoms tend to be chronic or gradual in onset, and diagnostic testing is needed to identify the underlying cause.

Lethargy, reduced activity, and less interest in interaction
Changes in appetite — often decreased, occasionally abnormally increased
Recurrent vomiting or obvious discomfort after meals
Persistent diarrhoea or changes in stool consistency (soft stools, poor digestion)
Gradual weight loss or a noticeable drop in weight over a short period
If symptoms persist or worsen, schedule a veterinary appointment for assessment

Seek emergency care immediately if you notice the following symptoms:

⚠️ Persistent vomiting with inability to eat
⚠️ Significant weight loss over a short period
⚠️ Becoming very lethargic or noticeably unresponsive

02How can I assess the situation at home? Key observations and when to seek emergency care

Keeping a systematic record at home helps your vet quickly understand the course of illness and likely causes, and guides further testing and treatment.

Note any changes in energy levels and activity during the day and night
Weigh your pet morning and evening and record any changes
Log the number of vomiting episodes, what was brought up, and when they occurred
Photograph or record the frequency of diarrhoea and the appearance of stools
Track daily food intake, food type, and feeding times
If abnormalities continue, take a short video and arrange a vet visit as soon as possible

03How does the vet make a diagnosis? Common tests and examinations

At the clinic, the vet will start with a physical examination and proceed to blood work or imaging as needed to identify the underlying cause of the deficiency and any complications.

Physical examination

assessing alertness, body condition, and hydration status

Complete blood count and biochemistry panel

evaluating overall nutritional status and organ function

Specific blood test

measuring serum cobalamin (vitamin B12) levels

Faecal examination or infection screening

ruling out parasitic or bacterial infections

Abdominal ultrasound or advanced imaging (e.g. CT) if indicated

04How is it treated and managed after diagnosis? Medications, diet adjustments, and care guide

Treatment will be tailored based on test results, addressing both cobalamin supplementation and the underlying cause, alongside dietary adjustments and regular monitoring of blood markers and clinical progress.

Your vet will develop a supplementation and treatment plan based on test results
Adjust diet and continuously monitor changes in appetite and body weight
Schedule regular follow-up visits to track blood markers and clinical improvement
Continue recording vomiting and bowel movements at home and report to your vet
If improvement is limited, a specialist referral or further testing is recommended

05What should I prepare before the appointment? Key information to help your vet quickly identify the cause

Note the date symptoms began and how they have changed over time

Prepare a log of daily food intake and type of food given

Record the frequency and timing of vomiting and diarrhoea episodes

List the names of all current medications and supplements

Bring photos or digital copies of past blood test or imaging reports

Book an appointment with a vet experienced in gastrointestinal evaluation

This content is for reference only and cannot replace a professional veterinary diagnosis. If your pet shows signs of illness, please seek veterinary care promptly.