Sample Collection and Submission Guidelines

Collecting and Submitting Only Obex and Lymph Nodes

• The obex (brain stem) and retropharyngeal lymph nodes (RPLN) must be collected in all cases, regardless of cervid species. Sample collection is also expected from European mounts. If operators need assistance, hands on training can be arranged through the Ministry of Agriculture at 306-539-4312.
• Packaging supplies can be provided to producers on request. Each supply kit includes one plastic specimen container with a screw-top lid, a waterproof label and one Ziploc bag:
1. Place both the obex and the RPLN in the specimen container. Write the animal ID on the outside of the container and on the label provided.
2. Place the specimen container and the label inside the plastic bag (do not attach the label to the specimen container or bag).
3. Place all animal ear tags inside the plastic bag.
4. Write the animal ID on the outside of the plastic bag.
• In total, the animal ID is recorded in three places (container, label and plastic bag) for added assurance.
• Tissue should be refrigerated or frozen to prevent sample deterioration if there will be a delay in delivery to the laboratory.

Sampling Resource Links

Proper sampling is extremely important. Resources to learn proper sampling techniques to remove the obex and lymph nodes are provided.

Disclaimer: The below content contains graphic material. Discretion is advised.

• YouTube videos:
  • Ministry of Environment, information on CWD Head Collection
  • How to Take Your Own CWD Sample
• Instructional sheets:
  • CWD Sample Collection Guidance
  • CWD for Hunters
  • Guidelines for Collecting Tissues

Submitting Whole Heads for Testing

• Wear protective clothing and plastic or rubber gloves when removing the head.
• Cut the head off and leave all ear tags attached. The head should be cut between the skull and the first vertebrae. The antlers or rack can be removed as long as the majority of the brain, including all of the brain stem, remains in the head.
• Cause of death must be indicated on the submission form as follows:
  • Hunt: cervid killed from licensed hunting
  • Slaughter: cervid humanely killed at an abattoir
  • Euthanized: any cervid that was humanely killed when found down, diseased or dying
  • Found Dead: cervid death occurred on farm
• In addition, all ear tags (unique identification tags, as well as any other ear tags) must be recorded on the submission form, or as a list that accompanies the form in the case of slaughter animals. If IDs cannot be confirmed this can have serious consequences for NON-NEGATIVE results.

If you want results faxed or phoned, ensure you write down the appropriate contact number(s).

Chronic Wasting Disease (CWD) not Detected in "Secondary Tissue"

• Whether submitting targeted tissue samples or whole heads for testing, both the obex and RPLN must be present, regardless of cervid species. This helps increase the chances of testable tissue being present.
• For elk and reindeer, the obex is the target tissue for CWD sampling. If the obex is not available for testing and only the lymph nodes are, then a "chronic wasting disease not detected in secondary tissue" is reported. This means the obex could not be identified and CWD cannot be ruled out. Inconclusive results may lead to further action from the Canadian Food Inspection Agency or the Ministry of Agriculture.
• For white-tailed deer and mule deer, the RPLN is the target tissue. If the RPLN is not tested and only the obex is, then a “chronic wasting disease not detected in secondary tissue” is reported as above.
• The obex (elk and reindeer) and RPLN (white-tailed and mule deer) need to be identified by Prairie Diagnostic Services (PDS) in Saskatoon to report a negative result of "chronic wasting disease not detected."

How to Avoid Getting Non-Negative “not detected in secondary tissue” Results

• The quality of the sample is important. The fresher the brain tissue, the more likely the result will be a confirmed finding if the disease is present.
• Submit cervid heads to PDS as soon as possible or freeze the heads until they can be dropped off (regulatory requirement is within 15 days, or as approved).
• Cut the neck off between the back of the skull and the first vertebrae before freezing the head. If a large portion of the neck remains, it takes a long time for the sample to thaw, which can lead to deterioration of the obex.
• Make sure to cut through the spinal cord when removing the head of a dead animal. Do not twist the head off as this can damage the brainstem and obex, affecting sample quality.

Whole Head Delivery to Prairie Diagnostic Services (PDS)

• It is best to phone ahead and let the staff know when you will be arriving and the number of heads you are bringing in for testing.
  • Normal business hours are 8 a.m. to 5 p.m. Monday to Friday.
    • Call PDS at: 306-966-7316.
  • After-hours services can be arranged at 306-291-9281 for an additional fee at the responsibility of the producer.
• Do not drop heads off on a Thursday or Friday unless you have phoned ahead of time so that PDS can accommodate the request based on storage and staffing availability, especially if it's a long weekend. Deterioration of the brain tissue over the weekend can affect test results.

If You Find a Dead Animal with Only Bones Remaining

• If you find a dead animal with only bones remaining, the head should still be submitted to PDS regardless of its condition; or at minimum, examined by a veterinarian.
• In some circumstances good quality photographs may be taken in place of an examination. Photographic submissions must be approved by the Animal Health Program Officer first at 306-787-6469.
• It is important to submit all head types or have adequate photographic documentation of heads unsuitable for testing, because these animals will be considered submitted/verified as “unsuitable” in assessments for compliance.

Animals Less than 12 Months of Age

• Calves (elk) that die after May 1 in the year following their birth can be submitted for testing to PDS.
• Fawns (white-tailed deer, mule deer, and reindeer) that die after June 1 in the year following their birth can be submitted for testing by PDS.

Storage, Packing and Shipment of Samples

• Brain tissue deteriorates quickly. The head must be refrigerated or kept at refrigerator-like temperatures (no warmer than four Celsius) using ice (cooler) packs, until delivery; if delivery is going to be delayed more than six hours, the head should be frozen.
• Double- or triple-bag the head and tie it tightly to prevent leakage. Use an absorbent material (e.g., newspaper) between bags to absorb any fluids that may leak out.
• The head can be delivered directly to PDS in Saskatoon (address is on the PDS submission form that must be completed).
• If the head is sent by courier, the specimen must be double- or triple-bagged as described above and put into a solid-sided, sturdy, leak-proof container, such as a Styrofoam cooler. Ice (cooler) packs should be included to keep the head cool in warm weather. Seal the container so there is no risk of leakage during transit. These containers will not be returned.
• Make sure the container is properly labelled and the submission form is included. Enclose the submission form in a water-tight plastic bag and place it on top of the bagged samples in the container, or place it in an envelope and tape it to the outside of the container.
• Ensure heads do not arrive at PDS on Thursdays, Fridays, the weekend, or statutory holidays.

Cleaning and Disinfection

• Instruments and protective clothing used during the sampling process should be cleaned of organic material and then disinfected with a two per cent concentration of available chlorine for a one-hour period.
• Rinse with water afterward to prevent corrosion of instruments.
• Most commercial bleaches have a concentration of six per cent available chlorine. A two per cent solution can be obtained from six per cent available chlorine bleach by mixing one part of the bleach with two parts water. Read the label on the bottle to determine the concentration and dilute as required.
• Proper cleaning and disinfection are important to help prevent the spread of disease and contamination of the environment in cases of positive results.