CT vs MRI

in Veterinary Medicine

MRI vs. CT in Pets: What’s the Difference and When Are They Needed?

If your pet needs advanced imaging, your veterinarian may recommend either an MRI or a CT scan. These tests help diagnose conditions that regular X-rays or ultrasounds might not fully detect. While both provide detailed pictures of the inside of your pet’s body, they work in different ways and are best suited for different types of health problems. This article is written with pet owners in mind. If you have a medical background or just want all the nitty gritty details, there will be a link to the other version at the bottom of this page.

What Is the Difference Between MRI and CT?

How They Work

  • MRI (Magnetic Resonance Imaging) uses a strong magnet and radio waves to create highly detailed images of soft tissues like the brain, spinal cord, muscles, and nerves.

  • CT (Computed Tomography) uses X-rays to create 3D images of bones, lungs, and other dense structures in the body.

Time and Sedation Requirements

  • MRI scans take longer (30–90 minutes) and require general anesthesia so the pet stays completely still.

  • CT scans are much quicker (a few seconds to minutes), and in some cases, only mild sedation is needed.

Radiation Exposure

  • MRI does not use radiation, making it safer for repeated imaging.

  • CT uses X-rays, so radiation exposure is a factor, but it is minimal and carefully controlled.

When Does a Pet Need an MRI?

MRI is the best choice for diagnosing problems in soft tissues, especially the brain, spinal cord, and muscles. Your veterinarian may recommend an MRI if your pet has:

  • Seizures or other unexplained neurological symptoms

  • A suspected brain tumor or stroke

  • Spinal cord injuries or diseases like intervertebral disc disease (IVDD)

  • Muscle, ligament, or tendon injuries (common in athletic dogs)

When Does a Pet Need a CT Scan?

CT scans are ideal for imaging bones, lungs, and complex structures like the nose and sinuses. Your pet might need a CT scan if they have:

  • A bone fracture that isn’t visible on X-rays

  • Lung disease or suspected tumors in the chest

  • Chronic nasal discharge, sinus infections, or a possible nasal tumor

  • Cancer, to check for spread (metastasis)

  • A suspected middle or inner ear infection

  • A need for detailed surgical planning, such as for orthopedic or cancer surgeries

Which One Is Right for My Pet?

  • If your pet has a neurological issue (brain, spinal cord, nerves), MRI is usually the best choice.

  • If your pet has bone fractures, lung disease, nasal problems, or cancer staging, CT is usually better.

Your veterinarian will help determine which imaging test is best based on your pet’s symptoms and medical history. Both MRI and CT can provide critical information to guide treatment and improve your pet’s health.

Do you want the more detailed, medically-focused version of this document? Check it out here.