Ultrasound and Your pet
by Graham Peck
What is ultrasound?
Ultrasound is a technique for looking at tissues within the body by using high frequency sound waves. Many people will be familiar with its use in monitoring human pregnancies. A hand held probe is placed against the body adjacent to the site to be investigated. The probe emits bursts of sound waves (inaudible to the human ear) and these sound waves are echoed back from the tissue to be picked up by the same probe. Some seriously clever electronics then converts these sound waves into a picture that represents a "slice" through the tissue. This is displayed on a small TV screen as a "real-time" moving image.
With increasingly complex ultrasound machines further techniques of doppler ultrasound and colour flow mapping can be used to actually watch and measure blood flow through an organ such as the heart.
When is Ultrasound Used in Veterinary Practice?
Ultrasound is most commonly used as a diagnostic-imaging tool or for pregnancy diagnosis. Confirmation of pregnancy is usually undertaken from 28 days (this may vary depending on the operator). Your own vets will normally do this if they have an ultrasound machine or inform you of a local practice that has one for you contact to organise a scan. In other types of cases where your veterinary surgeon is considering the use of ultrasound. He or she will have probably undertaken other procedures such as blood tests and x-rays but needs further information about the affected tissues before they can discuss treatment and prognosis of the condition affecting you pet.
How Will Ultrasound Help My Pet?
Ignoring the obvious use of ultrasound for pregnancy diagnosis the majority of ultrasound investigations in veterinary practice are to either confirm or rule-out problems that the initial clinical exam and tests have suggested. Commonly this may involve examination of the heart, also the liver, spleen, kidneys, bladder, prostate, intestines and other abdominal structures.
Less commonly ultrasound of the eye make be undertaken where a clinical condition prevents the normal direct visualisation of the contents of eye.
Unlike x-rays where it is often impossible to appreciate subtle changes in these organs, ultrasound excels in differentiating changes in soft tissues that make up these structures and provides the vet with a wealth of useful diagnostic information.
Ordinary radiography is also unable to assess the dynamic aspect of organs such as the heart where subtle changes in the cardiac muscle tissue, the way it contracts and other associated structures may have profound effect on the heart's function.
Occasionally ultrasound may detect a problem deep within a tissue such as the liver. In this case the veterinary surgeon may suggest undertaking an ultrasound-guided biopsy of the affected area. This is a much quicker technique that allows tissue samples to be taken with minimum trauma to your pet.
Once a condition has been diagnosed with ultrasound further scans and measurements over a period of time either allow the progress of a condition to be monitored or more hopefully the beneficial response to treatment will be appreciated.
How is it done?
Regardless of where the ultrasound examination is done most will follow a fairly standard pattern.
The hair over the area to be scanned is clipped off as the hair prevents the intimate contact of the probe with the skin and poorer ultrasound image results. The clipped skin is cleaned and a special gel applied to again enhance the transmission of the ultrasound waves though the skin into the deeper tissues. Scanning is painless but some pets may get sufficiently anxious that a tranquillizer is administered to reduce anxiety. The vet undertaking the procedure will normally discuss this possibility with you. If ultrasound guided biopsies are going to be undertaken then we often recommend a full general anaesthetic.
What are the risks of ultrasound?
Although there is some element of risk involved with sedation or biopsies using ultrasound, the scan itself is completely pain free and safe. Aside from having to have their hair cut, you pet will not show any outward signs of the scan.
