Beginning in the early 1980's, ultrasound scanning has been used to diagnose many disease processes in small animals. It is now considered to be an essential service in all veterinary teaching hospitals and large referral centers and many general small animal practices. The reason for this is simple, ultrasound offers a non-invasive, non-painful method for the diagnosis and staging of many diseases. Ultrasound is the best modality to evaluate fluid filled and soft tissue organs. Because ultrasound will not penetrate through air, ultrasound cannot be used to evaluate abnormalities if they are surrounded by gas.
Why Ultrasound?
Put simply, ultrasound allows us to visualize the internal architecture of many organs. Radiographically inapparent internal abnormalities such as nodules, masses, cysts and abscesses cannot only be seen, but can also be counted and measured. Although the ultrasound examination alone is in many cases non-specific for a particular disease, in conjunction with the animal's age, sex, breed, history, physical exam, radiographic findings and labwork, as well as ultrasound guided fine needle aspirates or true-cut biopsies, the specificity for disease can be high. Many organs that are difficult to see on plain film radiographs (prostate) can be easily seen with ultrasound. Real-time echocardiography (ultrasound examination of the heart) also allows us to see the heart in motion. From these images, measurements of cardiac contractility, areas of abnormal wall motion, chamber dilatation and wall thickening are made and compared to normal values. The typical ultrasound examination requires no tranquilization or anesthesia and is easily performed on awake animals. Prior fasting or water withholding is NOT required. The only patient preparation necessary is clipping of the hair overlying the area to be scanned (the ultrasound will not penetrate through hair) and placing coupling gel on the skin surface just prior to the exam process. The entire scanning process takes 30-40 minutes. Images are acquired on the monitor of the ultrasound machine as well as on film for later viewing.
What Can I See With Ultrasound?
Ultrasound is best at diagnosing abnormalities that are discrete. An example of this type of lesion would include a mass (tumor) in the liver. Once found, the mass can be accurately measured for later comparison. If the mass is found in an organ that is not required (such as the spleen), careful examination of the other organs (such as the liver) for the presence of metastatic disease (tumor spread) is needed prior to surgical removal of the "expendable" organ. Ultrasound is used to diagnose a variety of both benign and malignant diseases such as the presence of stones within the urinary bladder, kidneys or gall bladder, infection of the gall bladder, urinary bladder, prostate or kidneys, the presence of enlarged lymph nodes, abnormal blood vessels, or free fluid within the abdomen. It is especially good in diagnosing disease of the pancreas (pancreatitis), adrenal abnormalities, urinary bladder wall tumors, uterine infections (pyometra) and masses that are located behind the eyeball (retrobulbar masses). Ultrasound can often differentiate benign prostatic enlargement from prostatic cancer. In animals with a history of vomiting, ultrasound can be used to evaluate if the problem is within the liver, gall bladder or pancreas. It can often diagnose problems that are associated with the stomach or small intestinal wall, or see an intestinal foreign body, thus preventing a labor intensive and costly upper GI barium study. The diagnosis of pregnancy and fetal viability (heartbeats) are commonly seen by 21 days post-conception with ultrasound, which is much earlier than can be done with x-rays (42 days). In the heart, ultrasound is at it's best, as the heart is fluid filled organ. Abnormalities such as a diseased heart muscle (hypertrophic and dilatory cardiomyopathy), fluid around the heart (pericardial effusion), and congenital abnormalities can be diagnosed and the severity can be assessed. Heartbase tumors, which are rarely seen on radiographs, are easily visualized with ultrasonography. Ultrasound can easily differentiate fluid within the cranial mediastinum from a mass. Recently, ultrasound has been used to evaluate tendon abnormalities of the shoulder and knee (stifle). Ultrasound often diagnoses problems earlier than would otherwise be possible. This often affords an earlier diagnosis for better chance of successful treatment.
Why Am I Being Referred?
Although ultrasound capability is found in many general small animal clinics, many cases require the animal to be scanned (or re-scanned) by a board certified specialist with training in ultrasound. Many diseases can be diagnosed using ultrasound by your family veterinarian. Occasionally, however, there are questionable findings or the diagnosis is not "clear-cut" and a second opinion is in the best interest of the animal patient. This process is similar to human medicine where, for example, an internist or family practitioner will perform the initial ultrasound examination, but for a number of reasons may then refer you to a radiologist who is specifically trained in ultrasound, to get a second opinion. Your veterinarian must initiate the referral to Gulf Coast Veterinary Diagnostic Imaging and they will send any pertinent lab data or x-rays to the radiologist.
Why A Veterinary Radiologist?
Veterinary radiologists who are board certified by the American College of Veterinary Radiology (ACVR) are uniquely qualified to render first or second opinions on ultrasound examinations. These veterinarians have completed a formal 3-4 year residency in diagnostic imaging and have had intense formal training and practical experience in ultrasound of both small and large animal species. There are approximately 210 board certified veterinary radiologists in the world, with most practicing in the United States. Certification by the ACVR assures competency in ultrasound diagnosis and ultrasound guided tissue sampling.
What Can I Expect at the Referral Hospital?
At the time of your appointment, the radiologist will meet with you and your pet and explain the procedure to you. Most examinations will take 1-1.5 hours. If biopsies or aspirates are needed, the radiologist will inform you prior to obtaining them. If other procedures are needed before, during or after the ultrasound examination, these will be discussed with you. Following the examination, the radiologist will discuss the findings with you in detail, as well as discuss the "next step". If an ultrasound guided biopsy\aspirate was obtained, the results will be available within 2-3 days and the results will be faxed to your family veterinarian. Questions concerning the results can be addressed to both the radiologist and your veterinarian. In all cases, you and your pet will be instructed to return to your regular veterinarian for further treatment or surgery. If specialized treatment is required and your veterinarian wishes, your pet can be transferred to the appropriate service within our hospital.
Ultrasound