Vet Lab Manual

Genetics

The field veterinarian should follow the links below for details on the specimens required for diagnosis of the specific disease suspected.

Where DNA based tests have been developed for genotyping at a defined locus the preferred sample is hair roots. DNA can also be isolated from anticoagulant-treated blood and from semen; however the tests will be significantly more expensive than with those that exploit hair roots as a source of DNA. Only with prior arrangement with the laboratory can other tissue samples be utilised as the source of DNA for routine tests.

Where DNA tests are not available, diagnosis may be possible by histological examination of suitable tissues and findings used to complement historical observations, breeding data and clinical findings.

Standard Containers and Equipment

Vacuum blood tubes (5mL or 10mL with anticoagulant EDTA or heparin)

For blood samples.

Paper envelope or prelabelled "ziplock" plastic bags

For tail hairs.

Collection of Specimens

Hair: Tease out 20 to 25 hairs growing at the distal end of the tail. Select hairs that are free of visible faecal contamination. Tie a knot in the hair shafts approximately one quarter of the distance from their proximal end. Firmly grasp the knotted hairs and pull with a quick action. Ensure roots are present at the proximal end of the hair shafts. If desired, cut off and discard the distal half of the shafts. Place the shafts (with roots) in an envelope labelled with the animals identity, and post to EMAI. See Collection of hair samples for DNA testing

Use of forceps or artery clamps may facilitate collection of suitable samples from newly-born calves.

Clearly state the breed of the subject and DNA test required.

Blood: Fill evacuated blood tubes, to end of draw, from the coccygeal vessels or the jugular vein. Immediately after drawing the sample ensure mixing of anticoagulant and blood by repeated but gentle inversion of the tubes. Label each tube with the identity of the subject.

Semen: A semen straw or 0.5mL of raw semen in a serum vial.

Storage and Despatch of Specimens

Samples of tissues other than hairs must be chilled until despatch.

Do not freeze blood samples.

Clean, dry hairs are stable at ambient temperature for an extended period of time.

Specimens other than hairs should be forwarded in an insulated container with an "icebrick". Use sufficient "icebricks" to ensure samples arrive at least chilled. Refer to Guidelines for Packaging Specimens for more detail.

Always seal the specimen advice form in a separate plastic bag.