Does your dog need an MRI? How and when it is a good idea to have a magnetic resonance imaging procedure to help diagnose your dog.

Shelley’s vet suspected her dog might have a brain tumor and suggested an MRI to determine if that was indeed the case. “I asked him to repeat himself, as I’d never heard of MRIs for animals and thought maybe I’d heard him wrong,” says Shelley. Her surprise is understandable. MRIs are often performed on people but rarely done on dogs, although they’re becoming more common and have a variety of applications in veterinary medicine. This article will introduce you to the MRI, and most importantly, give you the information you need to help you decide if and when your dog might benefit from this important diagnostic test.

Magnetic Attraction

MRI stands for “magnetic resonance imaging”. Unlike a traditional radiographic procedure or CT scan, the MRI does not use ionizing radiation so there is no harm to the dog undergoing the procedure. Instead, it uses magnetic fields and radio waves to form an image of the body part being scanned. The technology is therefore considered less invasive than traditional radiography, which uses potentially harmful x-rays to make images of the body.

For an MRI, the dog is given a general anesthetic to keep him still and is placed inside a giant magnet that sends radio waves into his body. When the magnet is turned off, the body releases the radio waves, and the computer uses them to make an image of the body. More specifically, MRI technology utilizes subatomic particles called protons. If you imagine these protons as spinning tops, they’re spinning in a random manner within the body. When your dog is placed in the magnetic field, all the protons in his body start spinning in a synchronized fashion, creating a low energy field. When the MRI unit’s radio waves reach the animal, the protons move to a high energy level as they absorb the waves. Simply stated, the patient is absorbing energy in the form of radio waves. When the magnet is turned off, the “excited” protons release the energy they have absorbed as more radio waves, which are recovered by the MRI unit’s computer. The computer then turns them into a visible image.

What Are MRIs Used For?

MRI scans are normally reserved for diagnosing problems and not typically prescribed as a screening procedure for dogs in good health. Most commonly, MRIs are used to diagnose problems with the brain and spinal cord after other tests fail to determine the cause of the animal’s illness.

Brain diseases diagnosed with an MRI include tumors, infarcts (lack of blood to an area of the brain), abscesses, and inflammation of the brain’s covering (meninges).

Spinal disorders that may be diagnosed with an MRI include herniated discs, stenosis (narrowing of the vertebral column), nerve root impingement, and spinal tumor

I typically refer animals with neurological problems such as seizures or an abnormal gait for an MRI, to help determine the cause and rule out organic brain lesions such as tumors. An MRI might also be helpful for diagnosing problems with the bones and joints when traditional radiographs fail to reveal a cause.

A Look at the Drawbacks

While an MRI can be quite helpful for the right patient, there are a few downsides.

  • Availability is limited. Only advanced diagnostic centers, usually located in larger cities and at veterinary schools, have the proper equipment (the scanners are very expensive). A referral from your veterinarian is needed in order to set up the procedure at a specialty center.
  • An MRI is expensive, with costs often running $2,500 and up per scan. However, this cost, which includes the scan, anesthesia, and monitoring, is covered by many pet insurance plans.
  • Another consideration (not necessarily a drawback) is that the dog can’t move during the scan. Humans can be told to stay still, but in the case of an animal, complete anesthesia is required.

In conclusion, an MRI test can help your dog’s doctor pinpoint the cause of certain health problems when other tests fail to reveal a source and provide vital information to help your dog receive proper treatment.