VLD 421: Veterinary Clinical Biochemistry and Laboratory Diagnosis-II (0+1)

PRESERVATION

Preservation of Specimens

In many incidences, there may be a time gap between the collection of and  processing of specimens. During this period, the specimen should be maintained in an environment favorable for the preservation of organisms activities.

Various method of Preservation are

Refrigeration

• • The container containing the specimen should be placed in a larger container and the place between the smaller and the larger container should be filled with ice.
• Chemical preservation
  • Certain specimen can be preserved in 50% glycerol saline.
  • Specimen for histopathological examination should be preserved in 10% formal saline

Preservatives

• Serum
  • Sodium azide (0.1%) or methiolate (0.01%) preservation (Incase if it is used for ELISA sodium azide should not be added)
• Milk
  • One tenth volume of 5% boric acid as preservative
• Intestines
  • Ligate about 3 inches of the bowel tied at either ends and send the loop unopened for bacteriological examination of the intestinal flora, at once (in ice if it is to be transported for some distance).
• Heart blood swabs
  • For this sterile swabs, sterile scalpel, sterile forceps and a spatula. Before opening the chambers, singe the epicardium over the right ventricle with the host spatula are required (this is heated on a spirit lamp). Make an incision with the sterile scalpel, dilate the opening with the sterile forceps and then insert the sterile swab into the incision and collect the blood in the swab into the tube containing charcoal transport medium, carefully seal it and forward to the laboratory.
• Organs
  • Should be sent tightly packed in water proof sterile polythene pack and to be sent in ice pack.

Transport Medium and its Composition

• Buffered glycerol saline
  • Glycerol 300ml
  • Sodium chloride 4.2 gm
  • Disodium Hydrogen phosphate 10.0 gm
  • Na₂ H PO₄ Anhydrous 15.0 gm
  • Phenol red aqueous solution 0.02 per cent 15.0 ml
  • Water 700 ml
    • Dissolve NaCl in water and add glycerol.
    • Add disodium hydrogen phosphate to dissolve.
    • Add phenol red and adjust PH to 8.4.
    • Distribute 6 ml in universal containers (screw- capped bottles of 30 ml capacity).
    • Autoclave at 115⁰c minutes.
• Stuart transport medium
  • Thioglycolic acid 2 ml
  • Sodium hydroxide , (IN NaOH) 12-15 ml
  • Aqueous Calcium chloride 20%
  • Distilled water 900 ml
    • Mix the ingredients , adjust pH to 7.2 with IN sodium hydroxide solution.
• Charcoal transport medium
  • Sodium Chloride 4.00g
  • Potassium chloride 0.20 g
  • Dipotassium phosphate 1.70 g
  • Charcoal 10.0 g
  • Agar 4.00 g
  • Mix the ingredients in 1000ml of Distilled water adjust pH to 7.2 and autoclave at 121⁰ C for 15 mts.