On-farm, diagnostic activities comprise routine sampling and investigations in line with health control programs. The diagnostic process originally shifted from the traditional veterinarian approach centered on individual birds to the health assessment of entire flocks. Flocks are commonly classified as “healthy” if they perform according to their genetic potential and are considered free from clinical disease.

Clinical examinations are time consuming and labor intensive and may fail to detect diseases; especially subclinical diseases can be challenging to be accurately diagnosed. The manifestation of an infectious disease can vary from subclinical to severe clinical illness, depending on various etiological factors and influences such as the causative agent, host and/or environment altogether complicating diagnosis. Diagnostic procedures continue with post mortem investigations, on farm or in the laboratory, which serve to identify gross pathologic changes in organs and tissues in order to further specify a tentative cause of impaired performance and clinical signs.

Sending diagnostic sample to laboratory:

 It is important to provide thorough and relevant flock information on the laboratory submission.

Diagnostic sample submissions include:

• Flock identification and location

• Age of flock

• Date of sample collection

 • Vaccination program

• Flock history, including pertinent health or production problems this information is vital to the flock veterinarian and diagnostician to make a meaningful interpretation of serological or diagnostic results and provide recommendations to improve flock health and/or production.

Equipment used for Blood Collection: 

-Disposable, sterile 3 or 5 cc syringes are used, depending on the size of the sample to be obtained.

-The size of needle depends on the anatomical site used for blood collection.

-Blood Collection Site Needle Length Needle Gauge Wing vein 0.5–1.0 (1.25–2.54 cm) 20–22 gauge Cardiac puncture 1.5 (3.81 cm) 18–20 gauge.

-Always use disposable needles and replace needles every 5 to 10 birds.

-Dull needles cause tissue trauma and make inaccurate punctures of veins.

- All blood collection equipment must be changed between flocks to eliminate the potential for disease transmission.