Disease

Collection of Various Samples for Routine Laboratory Investigation of Animal Diseases

June 30, 2023
SR Publications

Harsh R Jogi1, G.K. Sharma1, Nabaneeta Smaraki2, Sonalika Mahajan2, Mayank Patel3

Introduction:

Laboratory investigation of animal disease is solely dependent on the quality and suitability of the specimens collected for analysis. One of the most frequent problem that is faced in clinical cases related to microbial aspect is the inaccurate specimen submission implying impertinence in specific disease diagnosis. The above mentioned lacuna in specimen submission can be overcomed by upgrading the existing information and knowledge regarding diseases. Microbial invasion in the host tissues prior to and after the death is mandatory for initiation of putrefication. Thus, the assessment of specific microbial infection becomes cumbersome because of tissue degradation resulting to improper diagnosis of causative pathogen. To deliver valid results, the collected specimens must be suitable along with adequacy in quality, volumeand number for the proposed testing. Furthermore, the sampled specimens must be true representative of the disease condition being investigated. In order to prevent contamination of the surrounding, animal handlers and individuals involved in sampling, specimens must be collected by using appropriate biosafety measures. Proper packaging and labelling of the biological materials should be done by following standard guidelines. It is critical not only to collect the specimens showing diagnostic accuracy, but also to inform the laboratory assistants regarding associated disease epidemiologyfor accuracy in testing.The collected samples should include different stages of the disease progression in an animal (viz. pre-clinical, clinical, chronic and convalescent phases).

Listed below are various specimens collected for diagnosis of animal diseases:

  1. Blood: Whole blood samples can be collected for haematology, clinical chemistry, toxicology, direct examination of bacteria or parasites, PCR , immunological tests, or for culture of bacteria or viruses. Usually, for the blood collection from animals various veins such as jugular vein, ear vein, caudal vein, mammary vein and vena cava can be used. However, sites for the blood collection is varies according to species of animals.To perform the whole blood collection a proper anticoagulant is require. For the selection of appropriate anticoagulant, the collector must be aware withbeneficial and harmful effects of specific anticoagulant. The collected blood sample should be thoroughly mixed with the chosen anticoagulant during or immediately following its sampling from the animal. The blood sample should be collect and dispense gently to prevent haemolysis.
  2. Serum: Serum samples can be collected for various serological tests such as SNT, ELISA, IFA etc. To obtain serum, whole blood is collected without anticoagulant and the clot is allowed to contract at ambient temperature for some time. Clear serum can be collected by pipette following physical removal of the clot or by using gentle centrifugation to separate cell components from the serum.
  3. Faeces: Faeces can be collected directly from the rectum in case of animals, while in poultry cloaca is preferred site of collection. Usually, faecal samples are collected to perform the investigation of parasitic infection. However, it can also use for the culture of microorganism such as virus and bacteria. Faecal specimens should be kept in chilled conditions (e.g. refrigerated at 4°C or on ice) and tested immediately after the collection to avoid the negative impacts on test results. For the collection of faecal samples screw cap or sealable containers should be used to prevent leakage and cross contaminations.
  4. Epithelium: Epithelial tissues can be collected to identity the surface parasites such as mites and lice. However, it can also helpful in the detection of various viral, bacterial, fungal infections and allergic reactions. To identity the burrowing mites deep skin-scrapping should be performed. Epithelial tissues associated with vesicular lesions can be collected in viral transport media.
  5. Ocular sample: Ocular samples can be collected by swabbing or scarping. To collect the ocular sample cotton, dacronor gauze swab should be used that has been pre-moistened with sterile saline.
  6. Genital sample: To perform the investigation of reproductive diseases preputial and vaginal swabs can be used as specimens. Antiseptic or detergent solutions should be applied on sampling site to avoid the contamination of specimens.
  7. Milk: Milk samples can be collected from individual animals to investigate various microbial disease conditions. For the collection of milk samples, teats should be properly cleaned and rinsed off. During the collecting the milk sample, initial stream must be discarded and subsequent stream sampled.
  8. Nasal discharge and Saliva: Nasal and oral secretions can be collected into vial or tube. For the collection of cellular material and mucus from the pharynx of livestock, probang cups can be used.
  9. Samples collected at necropsy: To conduct the necropsy only qualified veterinarian or pathologist must be allowed. Based on the suspected disease, condition of the carcass and facilities available for necropsies post-mortem specimens can be collected from one or multiple organs and submitted to the laboratory. To preserve the post mortem specimens, it should be collected into vials containing formalin solution.

Information to be sent with sampled specimens

Collected specimens must be properly labelled prior to transportation. It is advisable to contact the receiving laboratory to obtain an appropriate submission form and other relevant shipping and handling information. Details regarding necessary information that can be sent along with sampled specimens are listed below.

  1. Location and contact information
    • Name and address of owner of the animal and the geolocation (latitude and longitude, if available) where disease occurred, with appropriate contact information (telephone and fax numbers, e-mail address).
    • Name, postal and e-mail address, telephone and fax numbers of the sender
  2. Case information
    • Disease agents were suspected and tests requested.
    • Species, breed, sex, age and identity of the animals sampled and trackability number when available.
    • Date of samples were collected and submitted.
    • List and type of samples submitted with transport media used.
    • Case history: clinical signs, temperature, condition of mouth, eyes and feet, list and description of animals examined, date of first cases etc.
  3. Epidemiological information
    • A description of the spread of infection in the herd or flock.
    • The number of animals on the premise by species, the number of animals dead, the number showing clinical signs, and their age, sex and breed.
    • The type and standard of husbandry
    • Introduction of animals from other countries or regions.
    • Any medication given to the animals and when given.
    • Vaccination history describing the type of vaccines used and dates of application