Investigation of the disease problem
The initial important step is history taking. We have developed a history questionnaire which we ask owners to fill in on arrival. This forms the framework for our questions, with some answers giving leads that have to be explored in greater depth.
Evaluation of the aquatic environment is often an essential part of the investigation, this involves analysing the owners water testing records and may necessitate further testing. Temperature and dissolved oxygen levels can only be measured on site.
The fish are examined both in and out of the water. Samples are collected from live fish as dictated by the examination. Some of these have to be tested immediately in the clinic laboratory but some tests need to be carried out in external laboratories.
Radiography is a commonly used to investigate disease problems in individual fish. Contract materials are often given to allow better evaluation. For example evaluation of the kidneys require intravenous injection of positive contrast material while for evaluation of the gut appropriate contrast material can be gavaged orally or given rectally. Negative contrast as is commonly used in mammals (i.e. the introduction of air into a body cavity to enhance contrast in the radiograph) is not available for fish due to the resulting disturbance to buoyancy.
Ultrasound and endoscopy are other important clinical tools often used in the investigation of disease diagnostic techniques in fish medicine. Ultrasound can provide information about organ location, size and pathological changes.
Endoscopy allows us to look inside the body and with modern equipment a magnified view is obtained. The mouth, pharynx, gills oesophagus stomach and vent are commonly examined in fish. The body cavity can be entered to examine internal organs and take samples in live fish under anaesthetic through a tiny puncture hole. However in koi as in all the members of the carp family there are limitations of endoscopy. Their well developed pharyngeal teeth limit access to the oesophagus, and examination of the internal organs is severely restricted by the extensive adhesions normally present between their organs and the body wall.
Due to cost constraints CT and MRI are rarely used however if costs come down these techniques would be very useful in some cases