Chronic Wasting Disease (CWD) is a prion disease that affects farmed and free-ranging white-tailed deer, mule deer, elk, red deer, sika deer and moose. CWD was confirmed in mule deer from the trans-Pecos region of Texas in 2012. Texas deer producers and the Texas Parks and Wildlife Department routinely submit cervid samples for CWD testing. The Texas A&M Veterinary Medical Diagnostic Laboratory (TVMDL) receives approximately 15,000 samples annually for CWD testing.
Proper sample preservation and shipment is imperative for an accurate diagnostic result. The primary test for CWD is immunohistochemistry (IHC), a specialized staining technique performed on specific histologic sections of the obex area of the brain stem and the retropharyngeal lymph nodes. TVMDL often receives the entire deer head for CWD testing.
When sending a deer head, remember:
- Triple-bag all samples individually: If you have multiple deer heads in one shipment container, ensure they are separately preserved.
- Send the head with cold packs – not frozen – and use cold packs instead of ice cubes. The cubes may melt and water can affect the structure of the brain, which may cause an inconclusive test. This is also the reason for not freezing the deer heads. If freezing is necessary, we will make every effort to obtain a valid test but the submitter must realize that freezing decreases the chance of a valid test result.
- Use absorbent material in the package to prevent leaking.
- Label each sample bag with indelible marker; place the same ID on the form.
- Fill out a TVMDL submission form for each sample and place them together in a plastic bag. Do not package the form with the deer head.
- For cash customers, place payment in the bag with the forms.
- Call TVMDL for forms and/or instructions when necessary. Visit tvmdl.tamu.edu to download the submission form and for shipping or delivery information.
Only laboratories approved by the United States Department of Agriculture may perform diagnostic testing for CWD; TVMDL conducts approved testing at both the Amarillo and College Station labs. If a complete deer head is sent for testing there is a fee to remove the brain stem for testing ($20 for in-state clients; $30 for out-of-state clients) and a $20 head disposal fee will apply. TVMDL recommends the more cost effective option of two tissue testing, which includes both the obex and retrophayngeal lymph nodes. Occasionally, testing one tissue (obex) results in an inconclusive test, which will then result in a second one-tissue test charge to test the retropharyngeal lymph nodes. Detailed test information is available online. Laboratory professionals are always available to answer questions or concerns regarding testing.
For more information on CWD, visit the Texas Parks & Wildlife Department website at tpwd.state.tx.us.