Samples – how they help your veterinarian

As well as using tests to help veterinarians diagnose disease in sick animals, sometimes they’re also used as part of a routine health check to detect hidden disease before the development of obvious symptoms. This allows your guinea pig to be treated earlier and more effectively. Tests may be used to show whether a guinea pig is carrying infections that could pose a threat to other guinea pigs it comes into contact with.

Many veterinary practices have their own onsite laboratory where a 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 veterinarian by e-mail within 24 hours (although some tests may take 10 days or longer to complete). Commercial laboratories are able to advise your veterinarian on how to interpret difficult test results.

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

Blood tests

It is possible to tell a great deal about your guinea pigs 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 veterinarian how well your pet is fighting the disease. Samples can be difficult to obtain from guinea pigs, due to their anatomy. Sometimes sedation is also required, as the procedure can be stressful for them. Blood can be taken from a vein in front or back leg and sometimes from the jugular vein in the neck using a hypodermic needle and syringe. A patch of fur over the vein is shaved and cleaned with surgical spirit to clean the skin and allow your veterinarian to see the vein more easily. Some bruising may occur if your guinea pig has delicate skin or struggles when the sample is being taken. The puncture hole will heal quickly.

Urine tests

These are carried out to check for diseases such as cystitis, bladder stones and kidney disease. The presence of proteins or sugar in the urine will indicate whether the kidneys are functioning properly. Your veterinarian may be looking for signs of an infection in the kidneys or bladder. Urine samples can be collected by providing your guinea pig with a clean, empty litter tray and waiting! Collect the urine in a clean screw-top bottle (your veterinarian can provide you with these) and refrigerate – this needs to be taken to your veterinary practice soon as possible. When it is not possible to wait for a naturally produced urine sample your vveterinarianet may collect one using a needle inserted into the bladder through the skin over the abdomen. It may be possible to collect samples in this way without sedating your guinea pig.

Feces (droppings)

Small samples of feces often help to identify diseases of the digestive system. The sample can be tested (culture) to see if any unusual bacteria grow indicating an infection in the intestines. Checking for some parasites can also be done by examining the feces.

Swabs

A guinea pigs eyes, ears, 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 in the same way as a sample of feces. The results of a culture test may take a few weeks.

Skin scrapings

Guinea pigs 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 is important as some parasites live in the skin layers). This may cause minor discomfort to some guinea pigs 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 to a glass slide and examined under a microscope.

Hair plucks

Plucking of the hair may be necessary to look for ringworm. This is not a worm, it’s a fungus. Your veterinarian will pluck out a few strands of hair from the bald/red areas of skin and send these off for analysis. This does not hurt the guinea pig.

Tissue biopsies/fine needle aspirates (FNA)

If a guinea pig has a growth on its body it is normal to take a tissue biopsy – removing a small part of the lump which is examined under a microscope to see what sort of cells it contains. Alternatively, your veterinarian may insert a needle into the lump to draw off some of the cells for further analysis.

With many diseases it is not possible for your veterinarian to come up with an instant diagnosis. Your guinea pig may have to undergo a number of tests so that your veterinarian 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, for example, looking for changes in antibody levels in the blood over time.

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