Understanding the Use of Ultrasound in Cats
Ultrasound, a high-tech tool long used in human medicine, is bringing new benefits to an increasing number of animals every year. Veterinarians in growing numbers have begun using ultrasound to diagnose illnesses and chart a course of treatment – often at less risk and suffering to the cats and less cost to their owners.
Veterinarians are using ultrasound as a complementary tool in radiology. It enables them to peer inside a cat’s body and to view more detailed images of tissues than provided by X-rays. It can also be used without placing an animal under anesthesia. Cats must sometimes be anesthetized to be X-rayed.
An estimated 10 percent of the veterinary clinics in the United States now use the tool. “Ultrasound is a diagnostic tool that complements X-rays and other imaging without side effects and offers tremendous information about soft tissues,” said Dr. Jon Rappaport, original founder of PetPlace.com. Rappaport believes that ultrasound, combined with other advances in veterinary medicine, can often extend a pet’s life significantly.
Dr. Jennifer Lowry, a veterinary radiologist at the College of Veterinary Medicine and Biomedical Sciences at Colorado State University, added that ultrasound has been in use in veterinary medicine since the early 1980s, but it has really just increased. “Now it is part of a routine diagnostic work-up in both large and small animals,” she said.
How Ultrasound Works
Ultrasound is perhaps most familiar in human medicine in studying fetal development in pregnant women. It works by sending sound waves, beyond the range of human hearing, through tissue and recording the waves as they are reflected back. Those reflections are then transformed into images of organs and other body systems for veterinarians to study.
In simplest terms, ultrasound produces two-dimensional pictures of, say, the heart, kidney or spleen as they are actually functioning. The pictures enable veterinarians to see even the pulsing of blood vessels. It is not used, however, for diseases of the bone or muscle
“If you take an X-ray of the heart, all you see is the shape and size of the heart. Is it small, normal or large, or is it enlarged at a certain spot?” explained Rappaport. “With ultrasound you can see inside the heart, see the valves and measure the thickness of the walls of the heart. It is the same with the kidney. With an X-ray you will see a bean-shaped kidney. With ultrasound, you can see the structure of the organ.”
The Benefit of Ultrasound to Cats
The benefits to pets can be enormous. For example, many dogs suffer from mitral valvular heart disease, a condition in which the heart’s mitral valve stops functioning properly, allowing blood to flow forward and backward. As a result, the body does not get an adequate blood supply and the heart enlarges to compensate for the shortage, eventually leading to heart failure.
“Before ultrasound without a contrast study of the heart, a veterinarian could only guess at the problem based on X-rays and EKGs,” said Rappaport. “Now we can clearly and quickly diagnose the problem, get the animals on medication and monitor them. Before ultrasound and some new drugs we would give dogs with mitral valvular heart disease six months to live. Now some live three, four and five years.”
Ultrasound Helps Avoid Surgery
Ultrasound can also keep animals from having exploratory surgery, as can happen when they undergo chemotherapy for cancer. In those cases, veterinarians need to know whether a tumor is continuing to grow or has stopped. Ultrasound can determine that, provided that the tumor is not too small.
“The nice thing about ultrasound is a lot of times you can avoid surgery,” said Lowry. “We use ultrasound to reassess a cancer patient to see if the medication is working. We may evaluate your dog every three months to make sure the tumor has not recurred.”
Why aren’t all veterinary clinics equipped with ultrasound? One reason is cost. Ultrasound equipment requires an investment of $30,000 to $250,000, depending on its complexity. The investment can make performing ultrasound more expensive than doing an X-ray, but the expense can be more than offset by reduced costs for surgery and other forms of care.
Training is another reason that ultrasound is not yet more widely available. It takes experience to use the equipment properly and read the images accurately, but a growing number of veterinarians are mastering the skill. And some are bringing radiologists into their practices as they are needed on a case-by-case basis.