COMPANION ANIMALS

Clonality testing/PARR update

Stefan Keller

Clonality testing or PCR for antigen receptor rearrangement (PARR) is a molecular test that can help diagnose lymphoid neoplasia when light microscopy-based methods are equivocal (see testing algorithm below). The test is now available in concert with the Keller lab (Department of Pathobiology), which will allow for faster turnaround and more direct communication between clients, AHL pathologists, and the clonality lab.

Species: Cats and dogs.

Specimens: Stained/unstained cytology slides, FFPE tissues, fluids.

Testing schedule: Once a week, cut-off is Monday at noon.

Turnaround time: Thursday noon, if samples were submitted before Monday noon.

Immunophenotyping: Clonality testing is an interpretive test and requires prior immunophenotyping (IHC, ICC, flow cytometry).

Pricing: Depending on the sample type (histopathology, cytopathology, fluids) between $212-$230.

For more information regarding sample submission and proposed testing strategy of suspected lymphoid proliferations, please see AHL LabNote 44 - Testing algorithm for suspected lymphoid neoplasms

http://www.guelphlabservices.com/files/AHL/AHL%20LabNotes/Labnote%2044%20Testing%20algorithm%20for%20suspect.pdf

Clonality testing can help distinguish reactive from neoplastic lymphoid proliferations if other methods are equivocal. Clonality results must be interpreted in conjunction with clinical, morphologic, and immunophenotypic data, and should hence be done as the last step in the diagnostic algorithm. Clonality testing is not suitable for immunophenotyping. Clonality testing from cytology samples is feasible if a biopsy cannot be obtained readily (e.g., CSF, effusions without primary mass, etc.). Ideally, additional material should be obtained for immunophenotyping (flow cytometry, immunochemistry). The latter information is required for the interpretation of clonality results. Samples without immunophenotyping will not be accepted.

Fatal babesiosis in a dog imported into Canada

Andrew R. Vince

The body of a 10-week-old mixed-breed puppy was received at the Animal Health Laboratory for postmortem examination after dying unexpectedly during importation to Canada from the Dominican Republic. Grossly, there was mild generalized icterus of mucous membranes and soft tissues. The spleen was enlarged and fleshy (rather than congested) on cut section. The liver was generally pale, both renal cortices were dark red-grey, and the urinary bladder contained moderate quantities of red-tinged urine. A tentative gross diagnosis of hemolytic anemia was made. Histologically, there was diffuse interstitial pneumonia with capillary thrombi, and most intravascular erythrocytes contained small (1-2 µm) round-to-pyriform, faintly-basophilic Giemsa-positive, PAS-negative organisms suspicious for Babesia spp. (Fig. 1). There were lesions of acute hypoxic injury in the liver and kidney, and some renal tubular epithelium contained hemoglobin-like pigment globules. Fresh-frozen lung was submitted to the Vector-Borne Disease Lab at North Carolina State University for PCR panel assessment for Babesia, Anaplasma, Bartonella, Ehrlichia, Rickettsia, and hemotropic Mycoplasma spp. DNA consistent with Babesia canis vogeli was identified within lung, and a final diagnosis of acute Babesia-associated hemolysis was made.

Babesia spp. are hemoprotozoan parasites transmitted by ticks within the US and South America, particularly the tick Rhipicephalus sanguineus. Internationally, these are of great economic concern, particularly their impact on animal health and productivity. Dogs have been reportedly infected with B. vogeli, B. conradae, B. gibsoni, B. vitali, B. rossi, B. canis, and an unspeciated Babesia species. In dogs, clinical babesiosis varies from mild to severe forms, manifesting as hemolysis and secondary systemic hypoxic and inflammatory organ injury, organ dysfunction, shock, and death. The prognosis of clinically ill dogs infected with Babesia canis may be negatively predicted by hyperlactatemia, leukopenia, hyperphosphatemia, hypertriglyceridemia, and hypoproteinemia, hypoglycemia, increased serum cortisol, and clinically compromised circulation/consumptive coagulopathy.

Trends indicate that importation of domestic dogs to Canada from overseas is becoming more common, although this is not well-tracked and reliable statistics are not available. This pattern of importation provides a greater risk of infectious diseases being imported along with them, and because many of these pathogens depend on environments or vectors not seen in Canada, recognition is often delayed. Moreover, because of the presence of competent tick vectors in regions of Canada, the importation of dogs with babesiosis may provide a risk to other dogs. Hemotropic parasites such as Babesia, Anaplasma, Mycoplasma, Bartonella, Ehrlichia, and Rickettsia spp. should be considered as differential diagnoses in imported dogs, and blood testing (including review of blood smears) prior to importation of dogs from endemic areas is recommended to avoid undue loss of life and to reduce the risk of establishing infection within Canadian tick populations.   

Figure 1. Lung, 600x magnification, Giemsa stain. Hypochromatic erythrocytes in blood vessels contain Giemsa-positive, roughly round, 1-2 µm diameter Babesia organisms, often in pairs (arrowheads). 

An update on PCR testing for dogs  

Davor Ojkic

The AHL has been increasing the number of real-time PCR tests designed for detection of viruses affecting dogs. In addition to single-target tests for detection of Canine parvovirus 2 and Canine distemper virus, we have developed and validated a triplex real-time PCR test for detection of Canid herpesvirus 1, Canine adenovirus 2, and Canine parainfluenza virus.

Although influenza A viruses have not been detected in dogs in Canada, the risk of influenza cannot be underestimated – for rapid detection of influenza A viruses we also offer an influenza A virus PCR. All tests are run daily and typical turnaround time is the next business day.