AHL Newsletter, March 2014

For a pdf copy of AHL Newsletter, March 2014 click here

Triplex PCR for bovine respiratory viruses

We have developed and validated a new test that can simultaneously detect 3 major bovine respiratory viral pathogens: bovine herpesvirus 1/ infectious bovine rhinotracheitis virus (BoHV-1), bovine respiratory syncytial virus (BRSV) and bovine parainfluenza 3 virus (BPIV-3).  Test fee is $29.00.  Expected turnaround time of next business day.

Fine-tuning of AHL lab reports:

• Sample numbers are now included with case numbers.
• Bacteriology results have been reorganized, and PCR displays have been expanded.
• A brief Communication history is now appended to each report.
• A Case summary can be added to multi-lab section reports.
• AHL mastitis results can be incorporated in DairyComp records.
• Final cumulative reports for non-pathology cases are being investigated

Practical tips - spotlight on Clinical and Anatomic Pathology

• Cases submitted with a request for histopathology or postmortem are assigned to a case coordinator pathologist, who integrates all test results for the case in a final comment.
• A duty pathologist is always available to answer questions regarding in-clinic/field postmortem examinations and ancillary test selection, and assist with interpretation of tests performed at the AHL.

Selected zoonotic pathogens and diseases 2013 

• We ALWAYS appreciate a heads-up call on incoming postmortem cases.  It helps us plan our day and staffing needs.
• If an animal dies unexpectedly, please include information about the last time seen alive as well as the housing, location, and posture of the animal when found dead.
• Include a history with all submissions.  This will allow us to make meaningful, case- specific comments.
• Telling us what you want will ensure that specific tests are performed, but telling us what you saw (clinically AND grossly) helps the pathologist place the histologic lesion in clinical context and assists interpretation.
• Photos from incoming cases can be emailed to ahlhisto@uoguelph.ca and will then be directed to the pathologist assigned to the case.
• Visit the ‘Disease Conditions’ section of the AHL User’s Guide, which provides a standardized approach to diagnosing common problems such as abortion, diarrhea, and respiratory disease.  If you follow these guidelines, your diagnostic rate should improve.  You may not need to request all tests listed, but if you collect and freeze samples, you can always go back when ancillary tests are needed.
• When performing a PM in-clinic, every minute can be significant; some organs (particularly the intestinal tract) begin to autolyze almost immediately after death, and even mild autolysis can obscure subtle lesions.
• Combined cytologic and histologic examination can be very helpful for biopsies, especially for round cell tumors.  Impression smears can be made from biopsies prior to fixation in formalin, and submitted in slide holders.  Always remember to gently blot excess blood from the tissue sample before making the impression smears.  Package air-dried smears in SEPARATE plastic bags from formalin-fixed samples, as formalin is detrimental to preservation of cytology samples.
• Submit air-dried, unstained blood smears with all comprehensive CBC submissions.  This will allow accurate morphological assessment of cells, which is particularly crucial when toxicity or atypical cells are of concern.
• When submitting fluid for cytological interpretation (e.g., urine), please include air-dried direct or sediment smears prepared at the time of collection.  This will preserve cellular morphology, especially if transit time is prolonged.
• Ensure at least a 10:1 ratio of formalin:tissue for histopathology samples.  Tissues placed in insufficient formalin will not fix adequately and will autolyze, and your results will be compromised.
• Use wide-mouthed sample containers for formalin fixation.  Tissues harden following fixation, and biopsies that easily slip into a narrow-necked container (e.g., water bottle) when fresh will be impossible to extricate after fixation.
• To prevent formalin freezing and tissue artefact in cold weather, add 1 mL of ethanol per 10 mL of formalin.
• Endometrial biopsies should be fixed in 10% buffered formalin, not Bouin's fixative.  Bouin's produces over-hardening and tissue artifact if the biopsy is not removed within 24 h and transferred to either 70% alcohol or 10% formalin.  Bouin's fixative contains picric acid, a hazardous chemical = health and safety concerns and complex disposal.
• Enucleated eyes can be better preserved for histopathology by gently injecting a small amount of formalin (0.25 mL for small animals, 2 mL for large animals) into the posterior cavity prior to immersion in formalin.

When investigating multifocal or generalized skin disease, submission of multiple skin biopsies (particularly early in the progression of disease, prior to treatment) are more likely to yield a helpful definitive diagnosis.  The same holds for endoscopic enteric biopsies.   

Selected zoonotic pathogens and diseases from Ontario identified at the AHL, 2013

Beverly McEwen, Durda Slavic, Davor Ojkic, Josepha DeLay, Hugh Cai, Margaret Stalker, Murray Hazlett, Andrew Brooks, Kristiina Ruotsalo, Brent Hoff

Many new, emerging, and re-emerging diseases of people are caused by pathogens originating from animals, or are shared between people and animals.  The AHL plays an important role in public health by identifying zoonotic pathogens in about 1,000 cases annually (Tables 1 and 2).  These are numerator data reliant upon submission biases to the diagnostic laboratory and cannot be regarded as population prevalence estimates.  Monitoring programs are not included.    

Table 1.  Cases with selected zoonotic pathogens isolated and/or identified at the AHL, 2013

*All C. abortus except for 1 case of C. psittaci in a pet bird.

Table 2.  Leptospira spp. seropositive cases identified at the AHL, 2013, microscopic agglutination test (MAT).