1/ Take a history and develop an understanding of the nature of the problem.
2/Conduct a thorough clinical exam, make an assessment of the birds general clinical condition, undertake a microscopic exam of a fresh faecal smear, conduct a faecal flotation, undertake a microscopic exam of a fresh crop aspirate, check pharyngeal tonsils and laryngeal mound (redness, swelling, abscessation, sialoliths, etc.) in particular.
3/Collect throat, conjunctival (eye) and choanal ('slot') swabs for Chlamydia and Mycoplasmal PCRs.
4/Collect blood for full haematology and biochemistry – this gives valuable information about nutrition, the level of training and overall fitness, hydration, organ function, the immune system and infection. This information cannot be gathered from autopsy. An autopsy and histopathology identifies structural problems. Blood profiling identifies functional problems.
5/ Euthanise bird by giving lethal injection ( IM pectoral).
6/ Wait 2 hours to do the autopsy; earlier leads to passive bleeding, identified as "congestion" by pathologists, which can make interpretation of tissues microscopically difficult or impossible.
7/ Autopsy within 4 hours of death, later can lead to early autolytic (decomposition) changes and altered bacterial populations, decreasing diagnostic value.
8/ Collect full set of tissues for histopathology including -- whole head (after removal make a longitudinal incision along the top and back of the skull and crack the skull open to allow formalin to run into the brain case), the anterior oesophagus (sometimes this is the only place you will find Herpes), sections of crop wall, proventriculus, gizzard, several sections of gut, caeca (vestigial) and bursa of Fabricius if visible (i.e. bird <5 months old), trachea, syrinx, lungs, air sac, spleen (often best to collect on first opening the abdomen, if there is bleeding the spleen can later be hard to find), liver (left and right lobes), kidney, middle-third of femur (for bone marrow), sciatic nerve, section of spine, skin, heart and pectoral muscle. Please note that birds that have been frozen are unsuitable for histopathology
9/ Collect PCR from the liver for Rota in case you get hepatocellular necrosis of unknown cause; Birds can be negative for Rota on faecal PCR and positive on hepatic PCR. Collect kidney, pancreatic and bowel PCRs for PMV PCR testing.
10/ Collect a second set of the main tissues and freeze these. These are used if further viral identification and testing are required
11/ If anything looks abnormal, target that and make sure a section/sample is collected.
12/ If anything looks infected, collect a swab for MC and S (microscopic examination, culture and antibiotic sensitivity) testing. Collect a similar swab of the gut content.
13/ Collect further swabs for PCR and culture as indicated.

Please note :- It is important that the client's money is spent wisely and so the samples collected in points 3, 9, 10,12 and 13 above are held and available if the other tests, in particular the blood profiling and histopathology, are not diagnostic. These samples cost nothing to collect, store well and some can only be collected from a dead pigeon. Overlooking the collection of these may not only compromise the diagnostic process but may necessitate killing another bird unnecessarily to subsequently collect these samples.