Hemorrhagic Tracheitis Standardized Submissions to Help Find Etiology Supported by SHIC

Hemorrhagic tracheitis syndrome (HTS) has been diagnosed in Canada for years, and recently increasingly recognized in the US. To date, no etiologic agent(s) has been definitively or consistently associated with the syndrome in the cases examined or reported. To investigate etiology, a joint project of the Iowa State University Veterinary Diagnostic Lab (ISU VDL), Animal Health Laboratory, University of Guelph (AHL-UG), and the Laboratoire de santé animale, MAPAQ,Québec has begun with support from SHIC. Diagnostic investigations at both ISU VDL and AHL-UG to date for tracheitis cases have been hampered by dependence on the submitter’s tissue sampling and diagnostic test selection. A standardized diagnostic test plan for swine tracheitis cases has been developed. This joint VDL project will facilitate thorough, consistent testing of these cases, allow staff to exclude common respiratory pathogens as the cause of tracheitis in individual animals and herds, and establish a tissue bank for future NGS to search for novel or emerging pathogens in those cases with no confirmed etiologic diagnosis.

This spring, the Swine Health Information Center (SHIC) and America Association of Swine Veterinarians co-hosted a webinar providing information on the syndrome, its signalments, tissues for postmortem assessment, and management. The webinar is available to view here.

Severe necrohemorrhagic tracheitis syndrome observed in finishing pigs and replacement breeding stock is characterized by severe erosive or ulcerative lesions. Transient outbreaks are reported, with herd resolution over a period of two to three weeks. Opportunistic bacterial infection is common among the tracheal lesions at the time of necropsy and evaluation. The temporal pattern, clinical signs, and gross and histologic lesions of severe necrohemorrhagic tracheitis, together with the failure to consistently identify any known respiratory pathogen in many of the cases, raises concern of either a novel infectious agent or a novel strain of a known infectious agent. Alternatively, the lesion may represent a stereotypic sequel to a variety of primary cause. Contribution of anatomic features (e.g. tracheal diameter, length) compressive effects of cervical lymphadenopathy, genetic factors, and environmental/air quality conditions to the development and severity of tracheitis must be considered.

Morbidity ranges from <1% to 10 to 50%, depending on the herd, with consistently low mortality (<1-3%). Clinical signs resolve over seven to 10 days, sometimes in response to antibiotic and/or anti-inflammatory therapy; however, resolution was noted in some herds with no or minimal treatment or interventions.

The following represents desired submissions for the HTS study at participating VDLs to develop a diagnostic investigation protocol and establishment of a tissue bank. Samples should be sent using each facility’s particular submission forms.

Clinical history
Percent morbidity/mortality, approximate weight of hogs, herd genetics
Gross images
Cervical region and pluck at time of necropsy
Intact plucks
Trachea from larynx to bifurcation, both lungs, from affected pigs
Tracheas should be partially opened during the field necropsy to confirm lesions compatible with necrohemorrhagic tracheitis
Further dissection and sampling of trachea and lung for diagnostic testing and lesion documentation will be done at the VDLs
Lymph nodes
Bilateral caudal deep cervical and costo-axillary lymph nodes
Intact, fresh, and labelled (right and left, anatomic site).
Control animals
Plucks and lymph nodes as above from two or three unaffected herdmates dying or euthanized during the same timeframe, potentially due to other causes, and without gross lesions of necrohemorrhagic tracheitis
Systemic samples
Fresh AND formalin-fixed: spleen, stomach, ileum, and heart
Oral fluids
From all affected pens, two unaffected pens in affected barn, and two pens in unaffected barns
Serum
From five animals in each of one representative affected pen, one unaffected pen, and one pen in an unaffected barn.

Additionally, environmental control records for affected barns for two weeks prior to outbreak, targeting sudden fluctuations in temperature or humidity are requested, including comments regarding barn air quality.

Tissues submitted towards this study should be clearly labeled with “SHIC Hemorrhagic Tracheitis Project,” or similar verbiage, and directed towards the attention of the diagnostician associated with this project at the respective institution (see below).

VDL Address Submission Form Link Attending Diagnostician
Iowa State University
Veterinary Diagnostic Laboratory
Iowa State University
1850 Christensen Dr
Ames, IA 50011-1134
Alyona Michael
(515-294-9019)
University of Guelph
Animal Health Laboratory
University of Guelph
Address: Building 89, 419 Gordon St.
Guelph, Ontario Canada N1G 2W1
Josepha DeLay
(519-824-4120 ext 54576)
MAPAQ
Laboratoire de santé animale :
2650, rue Einstein
Québec (Québec) G1P 4S8
Isabelle St-Pierre
418-643-6140 ext. 2626
[email protected]

As the world deals with the COVID-19 pandemic, SHIC continues to focus efforts on prevention, preparedness, and response to novel and emerging swine disease for the benefit of US swine health. As a conduit of information and research, SHIC encourages sharing of its publications and research. Forward, reprint, and quote SHIC material freely. SHIC is funded by America’s pork producers to fulfill its mission to protect and enhance the health of the US swine herd. For more information, visit https://www.swinehealth.org or contact Dr. Sundberg at [email protected].

July 14, 2020

Hemorrhagic Tracheitis Standardized Submissions to Help Find Etiology Supported by SHIC

Hemorrhagic tracheitis syndrome (HTS) has been diagnosed in Canada for years, and recently increasingly recognized in the US. To date, no etiologic agent(s) has been definitively […]
July 14, 2020

SHIC-Funded MSHMP Sequencing Project to Give Producers Edge in Responding to Emerging Virus Strains

Recent improvements have brought the Morrison Swine Health Monitoring Project (MSHMP)  closer to real-time monitoring of porcine reproductive and respiratory syndrome virus (PRRSV) sequence evolution and […]
July 1, 2020

Report on Influenza Variant in Swine in China Lacks Context

Significant attention is being paid to a study published in the Proceedings of the National Academy of Sciences this week. The study says a Eurasian avian-like […]
June 26, 2020

Pig Flow Connections, Mycoplasma, Database Enhancements Now in SHIC-Funded MSHMP

The Morrison Swine Health Monitoring Program MSHMP, partially funded by the Swine Health Information Center (SHIC), continues to expand its capacity and, as a result, delivers […]
June 23, 2020

SHIC Funded MSHMP Project Grows in Scope and Capability

Now in its fifth year, the Morrison Swine Health Monitoring Project (MSHMP) continues to monitor trends in pathogen incidence and prevalence. The basis of MSHMP is […]