Cat Fred was a well-nourished animal all his life with a shiny coat and strong nerves; nothing could disturb the cozy room tiger. Now at the age of fifteen, he is unrecognizable: he has become frightened, hectic and nervous. Although he eats with cravings, he is getting thinner, he is already really thin. Even his digestion is out of balance: diarrhea and vomiting are commonplace. Fred drinks much more than before and urinates accordingly. He looks very ill with his shaggy coat!
After a thorough check-up with the veterinarian, it is clear that Fred is suffering from an overactive thyroid. This is the most common hormonal disorder in cats over the age of 12 years. In younger animals, this hormone disorder is very rare and in velvet paws under four years not at all. Many cat owners first believe that their four-legged friends are getting thinner, despite hunger and good food intake, but age is not a disease.
Early detection allows early treatment
Older cats should be brought to the check-up twice a year. The result is that not only the liver and kidney levels and sugar are determined, but also the thyroid hormone thyroxine (T4). If this is increased, this is a sure indication of an overactive thyroid. To further define the extent and cause of hyperthyroidism, one relies on a more advanced examination method, scintigraphy.
What happens during scintigraphy?
Scintigraphy is an imaging technique in the field of nuclear medicine. It is an examination method in which the patient is administered a small and harmless amount of a radioactive substance, and then their distribution is tracked in the body. Unlike other imaging techniques, such as X-rays or computed tomography, the result of scintigraphy is not a high-resolution representation of body structures, but a picture or sequence of images that represents bodily functions. These may be general functions such as the circulation of a specific body region or special organ functions such as kidney excretion. Depending on the direction of the examination, the patient is given various radiopharmaceuticals. These are special drugs bound to scintigraphic radioactive isotopes. In most cases, these substances are injected into the patient, spread throughout the body and taken immediately after administration or waiting for up to three hours.
The picture is created because of radiation from the radioactive isotopes (ionizing radiation). This radiation is registered with a gamma camera and converted into an image. From the distribution pattern in the image, that is from the increased or decreased occurrence or absence of radiation in an organ, then its function or malfunction is inferred. The most common applications in the small animal are, as in human medicine, thyroid studies, kidney function tests and bone examinations.
Scintigraphy of the thyroid gland
With the help of thyroid scintigraphy it is possible to determine an over- or under-function of the thyroid gland. When hyperthyroidism (hyperthyroidism) and unclear cases, it is important to locate where the trigger is located. Because especially in cats with hyperthyroidism, it may happen that not the thyroid alone, but also additional outside of the thyroid tissue lying (ectopic thyroid tissue) is the trigger for hyperthyroidism. Such ectopic tissue may be at various locations in the body, e.g. in the ribcage. If, as a treatment for hyperthyroidism, surgical removal is now selected and the ectopic tissue is not taken into account, therapy success is lost.
Bone scintigraphy Bone scintigraphy is used to visualize metabolic reactions of the bone to certain diseases. Inflammations, fractures, hairline cracks, tumor metastases and other diseases can be detected as often as days to months earlier than in X-rays. In addition, it is possible to represent the entire skeleton in an examination step. This is e.g. then a great advantage if the origin of lameness in the clinical examination can not be determined in a particular area. With the X-ray you would have to make countless pictures to get an overview.
Scintigraphy of the kidney
Kidney scintigraphy is mainly used in dogs and cats to determine renal function. The so-called isotope nephrography allows a much more accurate determination of renal function as pure blood tests and has the advantage that the performance of the right and left kidney can be determined separately. This is especially important if a kidney is to be removed, as only scintigraphy can be used to determine if the remaining kidney is really working properly.
Mostly short anesthesia needed
In order to obtain evaluable results, it is important that the patient remains absolutely silent during the examination. An examination lasts between one and twenty minutes, which is why most patients are given either soothing medication or under anesthesia for the duration of the study. After the examination, patients must remain at the clinic for 12-48 hours. The reason: Part of the radiopharmaceutical is eliminated with the urine and feces, the rest remains in the body and decays slowly. Thus, both the patient and his excretions emit radioactive radiation for a short time. In order to protect the pet owner against this minimal radiation exposure, the patients remain in the radiation protection area until they can be discharged safely.