Texas Equine Veterinary Association

www.texasequineva.com • 22 to determine poisoning by Pyrethroids or Avermectins (10 g minimum). Bromethalin is best detected in body fat, next best in kidney, then liver and finally brain tissue. Anticoagulant Rodenticide poisoning can be determined from 2 cc serum (whole blood is second best) or 2 g liver tissue (no added liquid). Other toxins are available for testing and we encourage you to contact the lab should you have questions on how to properly submit the preferred samples for these tests. Q: What is the best way to handle and submit samples for serology testing? Collection As the name implies, most of the testing within the serology section utilizes serum. Ideally, blood should be collected in such a manner as to avoid bacterial contamination and hemolysis. For best results, blood should be centrifuged soon after formation of a clot, usually after around an hour at room temperature. The serum should then be removed to another tube without any additives. The sample should be stored in the refrigerator until it can be shipped, or frozen if shipping will be delayed (note: do not freeze serum still on the clot). Serum collected for regulatory testing (i.e., equine infectious anemia and piroplasmosis) should be submitted to the lab as soon as possible, as regulatory requirements prohibit performing these tests on samples older than 30 days from collection. The one exception to use of serum in tests performed on horses is the ELISA test for Clostridium difficile toxins A&B. This test requires a minimum of 2 g of feces. The feces should be freshly passed or rectally collected and placed in an airtight container without preservative. Fecal samples should be tested within 72 hours of collection. As with serum, the sample should be stored in the refrigerator or frozen until shipping. Shipping Overnight couriers are strongly recommended when submitting samples to a diagnostic laboratory. If Saturday delivery is needed, then this must specifically be requested of the courier. While shipping serum can be done without the use of icepacks if they are sent by overnight courier, the use of icepacks is still recommended during the extreme heat of Texas' summers. Feces should be shipped on cold packs regardless of the time of year. Test schedule Please refer to the TVMDL catalog for the complete testing schedule. As some tests are only run certain days of the week, knowing the day of testing can help you plan to get samples to the lab in time for testing. Note that samples reaching TVMDL is not the same as samples reaching the individual testing sections. In general, samples must arrive the day prior to testing. For tests performed daily (EIA and piroplasmosis), these samples must reach the serology section by noon to be tested the day they are received. STAT testing is available only for EIA samples received before 3 p.m. and may incur an additional fee. Regulatory paperwork The required federal and/or state forms for equine infectious anemia (EIA) and piroplasmosis testing must be filled out completely, including the veterinarian's signature or samples will not be tested until corrections are made. Please note while the serology lab section will attempt to contact submitting veterinarians to secure permission to correct an incomplete form (can't sign it for you), this may delay testing of the sample. Further, as of April 15, 2020, the USDA has revised the guidelines for EIA testing, which now require use of the February 2018 revision of the VS 10-11 EIA form or approved electronic alternative such as GlobalVetLINK or USDA's Veterinary Services Process Streamlining (VSPS) system. Q: What do I need to do to get the most out of virology/virus isolation requests? The selection, handling, and submission of specimens is critical to provide the best possible chance for identification of a viral infection. The greatest chance of success is when samples are collected at the earliest stages of infection or quickly after death. Specimen or tissue selection is based upon the tropism of the suspect virus and the organs or tissues visibly involved in the disease process. In general, blood specimens from live animals, both unclotted (collected with an anti-coagulant such as EDTA) and clotted (serum) are recommended. Primary samples should be collected from affected areas, for example if skin lesions are present samples should include vesicular fluid and epithelium underlying vesicles, and scrapings of the lesions. For respiratory symptoms, nasal swabs or washings and transtracheal aspirates are appropriate specimens. Post- mortem samples should include trachea, lung and bronchial and mediastinal lymph nodes. For animals with diarrhea, feces should be submitted; post-mortem should include mesenteric and gastric lymph nodes and segments of diseased intestine. For neurological cases, portions of brain, spinal cord, tonsil, and cerebrospinal fluid should be collected. Autolyzed tissues are not recommended for either virus isolation or PCR testing. If swabs are used, they should be Dacron or polyester with a plastic shaft and submitted in either viral transport media or in a sterile, leak- proof container (e.g. red top tube) with two to three drops of saline. Swabs submitted in bacterial transport media, such as gel or Amies (liquid or charcoal), are not appropriate for virus isolation or PCR testing. All samples should be collected and sent to the laboratory as soon as possible, preferably overnight with cold packs. Collection and transport system with gel for bacterial culture (not for PCR).

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