Knowledge Sharing | Proper Sampling, Effective Testing — Workflow for Collecting and Submitting Diagnostic Samples from Large-Scale Pig Farms

Diagnostic testing can be used to identify the etiology of disease outbreaks on pig farms and to monitor potential pathogens that may cause illness. Only by accurately determining the root cause of a disease can targeted treatment and precise prevention and control measures be implemented. The accuracy of diagnostic results, in turn, depends on the quality of the samples submitted for testing; only a rigorous, scientifically sound, and safe sampling and submission process can provide high-quality specimens that ensure accurate test outcomes, thereby offering valuable guidance for effective disease prevention and control.

Pathogen detection sampling: Select 5–10 sick or debilitated pigs in the early to mid stages of illness, which are either alive or near death and exhibit common pathological changes. For pigs requiring necropsy, collect deep nasal swab samples and oral fluid samples (or cut off the tip of the tongue) using cotton swabs prior to euthanasia. Collect 4–5 mL of blood (separate 2–3 mL for serum), then euthanize the animals and immediately perform necropsy to collect tissue samples for diagnostic testing, preferably within 2 hours. Diarrheal feces, aborted fetuses, or mummified fetuses must be sampled without delay.

“To do a good job, one must first sharpen one’s tools.” Before sampling, be sure to prepare in advance latex gloves, protective suits, masks, shoe covers, syringes, scalpels, scissors, forceps, a hacksaw, 75% alcohol swabs, marker pens, and other necessary supplies.

(1) External Inspection: 
 

Inspect the limbs, conjunctival color, and skin for any abnormalities, paying particular attention to whether the mandibular lymph nodes are swollen and congested. Examine all areas of the skin for changes in color, as well as for scars, petechiae, or other irregularities. Inspect the hoof capsules, interdigital spaces, anus, and external genitalia. Perform a head examination, with special focus on the muzzle and eyes.

(2) Incision of the skin and subcutaneous tissue:

Make a skin incision along the line connecting the midpoints of the two mandibular rami to the anus, taking care not to penetrate too deeply; carefully dissect the skin from the subcutaneous tissue and perform a thorough examination.

(3) Laparotomy and organ examination:

The abdominal wall is incised from anterior to posterior along the midline of the abdominal wall, starting behind the xiphoid process and extending to the pubic symphysis. Subsequently, incisions are made along the posterior margins of the ribs on both sides, extending from the xiphoid process to the transverse processes of the lumbar vertebrae, thereby dividing the abdominal wall into two equal wedge-shaped flaps. These flaps are then retracted laterally, fully exposing the intra-abdominal organs.

(4) Examination of intra-abdominal organs:

When examining the viscera, the primary focus is on assessing the size, color, and consistency of the liver, spleen, and kidneys; the thickness of the intestinal wall and whether the mucosa shows sloughing or hemorrhage; as well as the characteristics and color of the gastric contents and the condition of the gastric mucosa.

(5) Thoracic examination:

Make an incision from posterior to anterior at the level of the costal cartilages, then apply pressure on the ribs to expose the thoracic cavity. Inspect the pleural effusion (color, volume, and presence of exudate) as well as the trachea, bronchi, mediastinal lymph nodes, and major blood vessels within the thoracic cavity. Open the pericardium, examine its contents and the epicardium, then make an incision from the cardiac apex to the base of the heart to inspect the right ventricle, left ventricle, and all cardiac valves.

(6) Pulmonary tissue examination:

Examine the lung tissue for consistency, color, and any surface lesions. Perform several transverse sections throughout each lung lobe to obtain a comprehensive view of pulmonary lesions.

Tissue samples for pathological examination should be collected in accordance with the anatomical sequence. The primary organs to be sampled include the spleen, kidneys, liver, lymph nodes, lungs, and brain tissue (in cases with neurological signs). Each tissue block should measure 2–5 cm on each side, and 1–5 mL of fluid should be collected. Lesional tissue samples must include both the affected area and adjacent normal tissue. For cases presenting with diarrhea, collect intestinal segments (with the proximal and distal ends of the affected small intestine ligated; each segment should be approximately 10 cm long), fecal samples, or anal swabs.

(1) When bacterial isolation, identification, and antimicrobial susceptibility testing are required, antibiotics must be discontinued 5 days prior to pig necropsy. During sample collection, care must be taken to ensure sample integrity, and samples should be cooled gradually in a stepwise temperature reduction to minimize ice crystal formation.

(2) Precautions for temperature-based sample preservation: For bacterial samples, collect specimens whenever possible before antibiotic treatment; avoid freezing and maintain refrigerated storage at 2–8°C; submit samples for testing as soon as possible. For samples intended for pathogen nucleic acid detection, freeze at −15°C and submit for testing promptly.

(3) Sample Transportation: Package the samples in multiple layers to prevent leakage. Place the samples in a foam-insulated container for low-temperature transport, adding an adequate number of ice packs based on ambient temperature and transit time. Fill any remaining empty space with crumpled waste paper to minimize the risk of sample damage due to overturning during transit, and arrange for expedited delivery to the laboratory.

Diagnostic testing can be used to identify the etiology of disease outbreaks on pig farms and to monitor potential pathogens that may cause illness. Only by accurately determining the root cause of a disease can targeted treatment and precise prevention and control measures be implemented. The accuracy of diagnostic results, in turn, depends on the quality of the samples submitted for testing; only a rigorous, scientifically sound, and safe sampling and submission process can provide high-quality specimens that ensure accurate test outcomes, thereby offering valuable guidance for effective disease prevention and control.

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Official consultation phone numbers: 020-66377266 / 135 3988 6748, Ms. Dai

Guangzhou Weiboxin Biotechnology Co., Ltd. is located in the national-level innovation park—Guangzhou Science City—and is a provincial-level “Little Giant” high-tech enterprise specializing in the forward R&D, manufacturing, sales, and technical services of diagnostic reagents for animal epidemics. The company is also recognized as a “Contract-Honoring and Credit-Keeping Enterprise” by Guangdong Province and a provincial demonstration unit for intellectual property, as well as a industry–university–research collaboration base of Guangdong Food and Drug Vocational College and an executive director unit of the Veterinary Diagnostic and Biological Products Committee of the Guangdong Society of Animal Husbandry and Veterinary Medicine. It has been designated as an innovative, high-potential enterprise by multiple research institutes, including the Entrepreneurship College of Jinan University in Guangdong Province, and has been awarded the titles of “Specialized, Refined, Distinctive, and Innovative” enterprise at both municipal and provincial levels. The company has received the “Most Investment-Valuable Enterprise” award and the annual title of “ASF and Swine Disease Testing Service Provider.” In addition, it has obtained veterinary drug product approval numbers from the Ministry of Agriculture and Rural Affairs: Veterinary Drug Registration No. 191438923 (Fluorescent PCR Test Kit for African Swine Fever Virus), Veterinary Drug Registration No. 191438213 (ELISA Antibody Test Kit for Porcine Reproductive and Respiratory Syndrome Virus), and Veterinary Drug Registration No. 191438875 (Blocking ELISA Antibody Test Kit for Classical Swine Fever Virus). The company was awarded the Excellence Prize in the Growth Category of the Biopharmaceutical Industry at the 11th China Innovation and Entrepreneurship Competition, the Provincial Second Prize in the Growth Category of the Nanotechnology Industry Technology Competition within the Science and Technology Innovation and Entrepreneurship Contest, and the National Third Prize in the Growth Category of the National Finals of the Nanotechnology Industry Technology Innovation Special Competition at the China Innovation and Entrepreneurship Competition. Furthermore, the company has consecutively received the A-Level Tax Credit Honor Certificate, the Four-Star Trademark Brand Certification, and the Two-Integration Management System Assessment Certificate each year, along with ISO 9001 International Quality Management System Certification, ISO 14001 International Environmental Management System Certification, and GMP certification from the Ministry of Agriculture. Since its establishment, the company has been granted a total of 24 patents, including 5 invention patents, 15 utility model patents, and 4 design patents, as well as more than ten trademarks.

The company boasts robust technical capabilities and a team of world-class professionals, including dozens of masters, doctors, and returnees who studied abroad, as well as numerous senior-title technical experts. Currently, the company’s primary focus is on the research and development of molecular diagnostic reagents. Its core R&D team has developed more than 600 products spanning molecular diagnostics and immunoassays, including public-health–oriented fluorescent PCR test kits, animal disease–control–oriented fluorescent PCR test kits, clinical and research–grade fluorescent quantitative PCR kits, and transgenic identification test kits (ZL2006). The company has also established a nationwide distribution network covering more than ten major cities, such as Beijing, Shanghai, Hangzhou, Nanjing, Xi’an, Chongqing, Lanzhou, Zhengzhou, and Qingdao.

Looking ahead, Weiboxin will remain steadfast in its commitment to continuously enhance product quality and service standards. Leveraging a rapid and efficient research platform and abundant biomedical resources, we will conduct extensive and in-depth R&D and scientific research in the biomedical field, thereby contributing to human health and advancing life sciences. Quality is our lifeline; innovation is our soul. Upholding this guiding principle, we will relentlessly strive to become the premier supplier of rapid diagnostic reagents and instruments.