Category: veterinary-procedures-rabbits

X-rays and ultrasound

Veterinary medicine has made many advances in the last 10 years and many local veterinary practices are now able to perform x-ray and ultrasound examinations.

Your vet can get a lot of information about what might be wrong with your rabbit from talking to you and examining your rabbit. Sometimes your vet may need to take a blood, urine or faeces sample to test for diseases. X-ray and ultrasound allow your vet to look at the organs inside your rabbit’s body without having to perform an operation.

X-rays are like light except they can travel through the body. For an x-ray your rabbit will lie under the x-ray machine which sends a beam of x-rays through your rabbit’s body onto a photographic plate. When the film is developed your vet will have a picture of the inside of your rabbit. This is called a radiograph.

Veterinary ultrasound machines are just like the ones used by human doctors to scan babies in the womb. As its name suggests ultrasound is a form of sound. Just as sound waves can pass through solid objects (like doors and walls when your neighbour has a party!), ultrasound can pass through the skin into your rabbit’s body.

The sound waves are directed through the area your vet wants to look at and some of them are reflected back like an echo. These echoes are detected by a special computer which uses them to produce a map of the inside of your rabbit which your vet can read.

No, it is not possible to feel x-rays or ultrasound. For ultrasound examinations, fur will need to be shaved over the area where your vet is taking the picture. The ultrasound machine must be in contact with skin to let the sound waves get into the body. The hair should grow back quickly after the examination.

Taking an x-ray is a bit like taking a photograph of the inside of your rabbit. For x-ray examinations it is important that your rabbit lies still as the exposure is made or the final picture will be blurred. Nurses and vets take many x-rays every day and so they cannot hold all the patients or they would also be exposed to the x-rays which can be dangerous over a long period of time.

Ultrasound examinations can take up to an hour to perform. Although your pet can be held by a nurse while the vet performs the examination, many rabbits do not like to be held still for this length of time. Giving them a sedative makes them relax so that they are not worried by the examination.

X-rays, when used to produce pictures of your pet, will not cause side effects. Exposure to high doses, or over long periods of time, can be dangerous and this is why your vet cannot hold your cat for the examination.

There is no evidence that ultrasound examinations carry any risk at all.

The risk associated with the tests is that of upsetting a sick rabbit or one with breathing difficulties by struggling with it, or the risk of the anaesthetic or sedation in an ill animal. Your vet will explain the risks to you and if you are in any doubt about the risks please ask your vet to explain why they need to do the tests. In almost all cases the risk of not finding out what is wrong with your rabbit (and therefore not being able to treat it) is far worse than the risk of the anaesthetic.

Although your vet will be able to get the pictures from these examinations on the same day, they may want to send them to a specialist for a second opinion before giving you a final diagnosis. Some vets specialise only in reading x-rays and ultrasounds and may be less likely to miss some information on the pictures. Some veterinary practices now have a specialist in the practice or one who visits the practice regularly to perform these examinations.

Your vet will be happy to explain to you why they need to do tests on your rabbit. If you do not understand the reasons please ask someone to explain the tests to you. If you are interested, your vet will probably be able to show you the pictures of your rabbit after the examination and explain what they can see.

Scanning – the inside picture

Until a few years ago, diagnostic imaging was limited to radiography (x-rays), ultrasound and endoscopy. Although these are still very useful diagnostic tools, there are now far more advanced diagnostic imaging methods, such as Magnetic Resonance Imaging (MRI) and Computed Tomography (CT), that are being more commonly used in rabbit medicine.

MRI is also a non-invasive imaging modality that scans the rabbit using a magnetic field to produce high-quality images of the animal which can be used to evaluate anatomy, function and pathology of many structures.

In rabbits, MRI is usually used to look at soft tissue structures, including organs within the body, and is especially useful when diagnosing brain tumours.

An MRI scanner consists of a box-like machine with a tunnel through the centre that is open at both ends. Your rabbit will be placed onto the motorised table in the centre of the tunnel. This moves inside the machine to create the scan with a small receiving device placed behind/around your rabbit.

An MRI scan relies on a strong magnetic field to move around and react with different atoms within the body to create the image.

The operator is located in a different room, and the veterinary team will also monitor your rabbit from here.

MRI scanners are very noisy which is another reason why your rabbit is very likely to be sedated or placed under general anaesthesia, and can take around half an hour to complete, during which there must be minimal movement to prevent blurring of the scan images.

CT, also known as CAT scanning, is a non-invasive imaging modality that uses x-rays to scan the rabbit to create cross-sectional pictures of the animal which can be used to evaluate anatomy, function and pathology of many structures.

In rabbits, CT is particularly useful for viewing bony changes, such as those associated with advanced dental disease.

A CT scanner is a large box-like machine with a short tunnel or hole running through the centre. Your rabbit will be placed on the examination table which then moves in and out of the tunnel.

The x-ray tube and electronic x-ray detectors are located opposite each other in a ring, called a gantry, and rotate around your rabbit to create the scan image.

The CT scan is controlled from a separate room, where the information is processed and from where the veterinary team can monitor your rabbit.

  • Tumours, especially brain tumours
  • Abscesses within the body/skull
  • Fluid within the tympanic bullae or the ear (inner and middle ear disease)
  • Tumours within bone or the chest/abdomen
  • Central nervous disease, such as epilepsy
  • Assessing the vertebral column
  • Upper respiratory tract disease

CT scanning is normally the technique of choice for assessing the skull and calcified structures, whereas MRI is mostly used for evaluating soft tissue.

During the scanning process of both CT and MRI, your rabbit must stay totally still to get a good diagnostic image. Therefore, to ensure your rabbit is immobile during the procedure, your vet will need to either sedate or anaesthetise your rabbit. General anaesthesia is usually required, even in the most relaxed and well behaved rabbit.

Samples and tests – how they help your vet

Laboratory tests are used by vets to help them diagnose disease in animals that are ill. Increasingly, they are also used as part of a routine health check to detect hidden disease before the development of obvious symptoms. This allows your rabbit to be treated earlier and more effectively. Tests may be used to show whether a rabbit is carrying infections that could pose a threat to other rabbits it comes into contact with.

Many veterinary practices have their own small laboratory where a limited range of tests can be carried out. Results are obtained quickly which allows rapid decisions on treatment. Often a quick test is carried out in the practice and a sample is then sent to the commercial laboratory to check that the results tally.

If a broader range of tests is required, samples will be sent to a commercial laboratory which will usually send results of routine tests back to your vet by fax, telephone or e-mail within 24 hours (although some tests may take 10 days or longer to complete). Commercial laboratories are able to advise your vet on how to interpret difficult test results.

Occasionally, especially if samples are delayed in the post, they may deteriorate and your vet may need to repeat the test.

There are a whole battery of tests which can be done on different types of samples, although not all are used to investigate every disease. Some samples are more easy to obtain than others and the effects that testing has on your rabbit will vary.

It is possible to tell a great deal about your rabbit’s health or disease from the concentration of different chemicals in the blood. The proportion of different types of blood cells and the presence of proteins called antibodies (which are produced as part of the body’s defence against disease), may tell your vet how well your pet is fighting the disease.

Samples are usually taken from a vein in the ear using a hypodermic needle and syringe. A patch of fur over the vein is shaved and the skin disinfected with surgical alcohol to clean the skin and allow your vet to see the vein more easily. A few millilitres (about a teaspoon) of blood are put into special containers to prevent it clotting.

Blood sampling is not painful although some rabbits don’t like being held whilst the sample is taken. Some bruising may occur if your rabbit has delicate skin or struggles when the sample is being taken. The puncture hole will heal quickly.

These are carried out to check for diseases such as diabetes or cystitis. Urine can be checked to see if it contains proteins, sugar or signs of infection.

Urine samples can be collected by catching a few drops of urine in a thoroughly cleaned container as the cat empties its bladder. However, this is sometimes difficult and it may be easier to take urine from the bottom of a clean litter tray. The sample should be kept in a sealed bottle inside a refrigerator and tested as soon as possible.

When it is not possible to wait for a naturally produced urine sample your vet may collect one using a catheter (a special tube) passed directly into the bladder through the urethra, or using a needle inserted into the bladder through the skin over the belly. It may be necessary for your vet to sedate your cat to collect a sample in this way, but these techniques are no more complicated or dangerous than taking a blood sample.

Small samples of faeces often help to identify diseases of the digestive system. The sample may be tested to see if any unusual bacteria are growing that indicate an infection in the intestines. Further tests may be carried out to see if your cat is unable to digest certain foods or if its faeces contain eggs from parasitic worms.

A cat’s eyes, ears and nose or skin can often become infected with disease-causing bacteria,viruses or fungi. Swabs are taken by gently rubbing the affected area with a small piece of cotton wool. The swab is then either transferred onto a glass slide for examination under a microscope or cultured and tested to see if bacteria can be grown. The results of a culture test may take a few weeks or longer, (in the case of some slow growing bugs).

Cats with skin disease will be tested to see if they are infected with parasitic mites. The skin is scraped gently with the edge of a scalpel blade until bleeding occurs. This may cause minor discomfort to some cats although others tolerate it fairly well. There are usually only small numbers of mites and a large number of scrapings may have to be taken from several areas before finding them. The skin sample is transferred onto a glass slide and examined under a microsope.

If a cat has a growth on its body it is normal to take a tissue biopsy. This involves removing a small part of the lump which is then examined under a microscope to see what sort of cells it contains. Cell samples may also be collected by putting a needle into the lump and sucking out some cells.

Fluid samples may be taken from the airways via a tube placed in the throat, or the digestive system via an endoscope passed into the stomach. In this way your vet can obtain more information without performing a full operation on your cat.

With many diseases it is not possible for your vet to come up with an instant diagnosis. Your animal may have to undergo a number of tests so that the vet can rule out possible causes of the illness. While some diseases can be confirmed using a single test, others will need a large number (profile) or a sequence of tests on one or more tissues or body fluids. There are occasions when repeat tests may be needed to be taken over a period of time, eg looking for changes in antibody levels in the blood over several weeks.

Your vet may need to perform diagnostic tests on your cat, or on samples from your cat, to help provide the best possible care for your pet. If you are unsure what a test involves or why your vet needs to do it, please ask for a more detailed explanation.