Animal radiography or radiology uses the same technology that is used on humans as a tool to diagnose injury and disease in animals. Veterinarians use computed tomography scans (CTs), digital fluoroscopy, nuclear imaging, ultrasound and magnetic resonance imaging (MRIs) to diagnose and treat animals, both small and large. The machines used in animal radiography are almost exactly like the machines used for humans, but many have modifications to accommodate animals of varying sizes, from hamsters to horses.
Radiography uses specific types of electromagnetic radiation to create an image. The most common type of radiography is an x-ray. The shadowy image of an x-ray is created when certain organs and bones, which are relatively dense, absorb x-rays more readily than other body parts. When exposed to the x-rays, the denser tissues or bones show up as white, while the less dense areas are black. The x-ray is perhaps one of the first tests a veterinarian will administer for a sick or injured animal in order to assess and diagnose its condition.
Animal radiography often requires modifications to human radiology equipment. For vets to perform an x-ray on a small animal, the x-ray machine can be positioned over a table, while free-floating machines can be used for larger, standing animals. A free-floating x-ray machine can move up and down, so it can also x-ray the lower extremities. This can accommodate cows, horses and other large animals.
A CT is another commonly used test in animal radiography. CTs provide hi-resolution cross section images of the inside of an animal. The image is much like an x-ray, but it is three dimensional and provides a clearer picture than a traditional x-ray.
Since an animal must lie on a table during the scan, the CT procedure poses a problem for large animals. A large animal CT table can accommodate animals up to 2,000 pounds (about 907 kg). MRIs are also used in animal radiography, but they can be very expensive and are consequently not used as often.
Digital fluoroscopy allows vets to conduct tests including venography, vascular studies and contrast GI studies. A radiocontrast agent is either injected or ingested and used to map the digestive tract or blood vessels. In nuclear imaging, vets use a gamma camera to document how a radioactive tracer that has been injected travels through the animal. In animal radiography, the camera may be attached to a stacker crane, which moves the camera up and down to scan both small and large animals.
Ultrasounds, another common test used in animal radiography, bounce sound waves off of organs and translate them into images on an ultrasound monitor. These tests are usually performed on the abdomen and thorax of animals. Because ultrasound machines are relatively mobile and easy to use, they generally don’t have to be modified for use in animal radiography.
Because animals are often uncooperative or dangerous, they are usually sedated for some of the more delicate diagnostic tests. Ultrasounds can usually be performed while the animal is awake, but if the animal is dangerous or in severe pain, the vet may administer anesthesia or a sedative to make the procedure easier on both the vet and the animal. For tests that require the patient to be still, anesthesia is usually administered in order to get a clear picture.
Like general physicians, veterinarians are trained in animal radiography, and as in human medicine, vets can also choose a specialty. One can become a board certified veterinary radiologist — a vet who studies to become a specialist in animal radiology. These specialists are available for more difficult diagnoses that require their expertise. Veterinary technicians can also specialize in small and large animal radiology by taking extra classes during their coursework.