Ultrasound (Scan)

Ultrasound has been used in veterinary medicine since the early 1970’s. Until the 90's ultrasound was reserved for veterinary teaching hospitals only. Today ultrasound is commonly used in private veterinary hospitals.

Ultrasound technique uses high frequency sound (not audible to the human ear). The ultrasonographic waves emitted from a transducer are then re-captured and digitally converted to a visible image on a screen. The waves are confined to a narrow beam. These waves are absorbed, refracted or reflected by the tissue. Tissues vary - bone, fat, fluid, and muscle all have different characteristics that vary in appearance on the screen from black to almost white in image. These differences in the grey scale allow the interpreter to form an image of what is being scanned.

When an ultrasound is performed on a patient, structures and characteristics of those structures can be seen.
Ultrasonography is particularly useful in abdominal and cardiac examinations.
Abdominal organs such as the liver, spleen, kidney, intestinal tract, bladder, prostate, uterus, adrenal gland and pancreas can be visualised with ease. No invasive techniques are required. The size and characteristics of the structures or organs can be compared to normal structures/organs. If an abnormal looking structure is seen it may be possible to take a sample by fine-needle aspiration, or a larger tissue sample can be obtained by tru-cut biopsy. This sample can be evaluated at the practice, or sent to a pathologist for interpretation.

Ultrasonography of the heart (echocardiography) is very useful part of cardiac examinations. The different chambers of the heart, valves and great blood vessels can be visualised. The flow between narrowing valves or blood vessels, etc., can be measured and compared to a normal patient. Subtle abnormalities, otherwise undetected, can be found in this way. The appropriate therapy can be selected for patients with cardiac failure. Echocardiography can also be used to monitor response to therapy.

Pregnancy ultrasound is often used to diagnosis and confirm the viability of a litter. This examination can be carried out from 21 days after conception. It allows us to roughly count the foetuses and estimate the litter’s due date.

To have an ultrasound examination carried out, the patient often has to be starved for 12 hours. The hair is clipped over the area of interest. The ultrasound procedure is non-painful, although sometimes sedation is required if the animal cannot be restrained. Occasionally, the veterinarian needs to take a tissue sample of an organ, and light sedation may then be needed. Ultrasound examinations form part of a diagnostic process. In addition, blood tests, X-rays and surgery may form some of the steps needed to reach a diagnosis.

Like any procedure, the information and quality of the ultrasound examination, and hence also the information or outcome, is dependant on several factors:

Patient factors

• obese patients often have poorer ultrasound images.
• Aggressive and fractious animals do not allow a proper ultrasound examination.

The experience of the sonographer, their ability to interpret the image, and the quality of the equipment also plays a role.

The latest machines on the market have multiple frequencies, therefore multiple uses. At Valley Farm Animal Hospital we have an Aloka α6 ultrasound machine. This machine has multiple probes with frequencies from 2 – 12 MHz , which allows us to scan large, medium and small animals with the frequency we prefer. There is also a comprehensive cardiac application, which allows usage of continuous Wave, Colour flow Doppler, as well as pulsed Wave Doppler