An MRI (magnetic resonance imaging) scan is similar to an X-ray in that it will provide the veterinarian images of the inside of your dog, but it provides more detail and it is safer because it does not use radiation. While an X-ray or an ultrasound scan will show the size and shape of an internal organ or tissue, an MRI scan will show what the inside of the organ or tissue looks like.
What Is Involved
The dog will need to be placed under general anaesthesia because it needs to remain perfectly still for up to two hours. The dog will be allowed only water on the day of the scan, and it will need about two hours after the scan to recover from the anaesthesia. The imaging specialist will usually be able to make a diagnosis while the dog is recovering.
When Is It Used?
MRI scans for dogs are normally reserved for diagnosing problems with the brain and spinal chord and they are only used when more traditional diagnostic techniques can't determine the problem with the dog. MRIs are also starting to be used for diagnosing problems with bones and joints in dogs.
How It Works
An MRI uses magnetic fields to create images of the dog's body. The dog is placed inside a giant magnet which sends radio waves into the body. When the magnet is turned off, the body releases the radio waves which the computer uses to make an image of the body.
The immense cost of owning, operating and maintaining MRI units is the biggest reason they are not commonly available. The machines can cost up to £0.6 million and are also very expensive to operate and maintain, so the average veterinarian will not have one. Usually, only large, well-funded veterinary institutions will provide MRI scans for dogs or other animals.
Dedicated MRIs are making MRI scans more available for animals. Dedicated MRIs are smaller machines that can take images of portions of the body, such as the brain, nasal cavity, or a joint. Large dogs may still need to use a normal MRI unit, especially if the spinal chord needs to be imaged. Because of their smaller size, dedicated MRIs are less expensive and it takes less time to take a scan, usually less than an hour. This means the dog won't need as much anaesthesia, which reduces the health risk to the dog and speeds up their recovery time.