Bovine astrovirus and its role in lymphocytic encephalitis in cattle in Ontario, Canada, 1988-2019.

Astroviruses have been found in cattle and other species with encephalitis. Our objective was to determine the frequency of neurotropic bovine astrovirus (BoAstV) in cases of encephalitis in cattle ≥ 4-mo-old. Of 56 cases of idiopathic lymphocytic encephalitis examined retrospectively (1988-2019), fixed brain from 11 cases (19%) tested positive by semi-quantitative RT-PCR for BoAstV CH13/NeuroS1. None of the control cases tested positive, including 32 with other forms of encephalitis and 40 with no neurologic disease. Most astrovirus-positive cases were 1-2-y-old, with a range of 7 mo to 7 y, and affected both beef and dairy breeds with wide geographic distribution. BoAstV-positive cases had acute onset of neurologic signs of 12 h to 7 d before death or euthanasia. Affected cattle had lymphocytic inflammation throughout the brain including cerebrum, thalamus, midbrain, cerebellum, medulla oblongata, and spinal cord, and affecting gray and white matter. Further PCR testing identified a possible cause in 9 of the 45 (20%) remaining idiopathic cases of lymphocytic encephalitis, including eastern equine encephalitis virus, Listeria monocytogenes, bovine viral diarrhea virus, bovine alphaherpesvirus 1, and ovine gammaherpesvirus 2 (malignant catarrhal fever); we found no cases of infection by West Nile virus, rabies virus, or Chlamydia spp. No cause was identified in 36 of 56 (64%) cases of lymphocytic encephalitis. We frequently identified neurotropic BoAstV in cases of lymphocytic encephalitis that had no previously identified cause. Neurotropic BoAstV infections had gone undetected for decades, but the frequency of BoAstV infections has not increased among contemporary cases.

Identification of bovine astrovirus in cases of bovine non-suppurative encephalitis in eastern Canada.

Bovine astrovirus (BoAstV) was identified by reverse transcriptase polymerase chain reaction on brain tissue of 2 feedlot cattle that died of non-suppurative encephalitis. Sequencing demonstrated a high degree of identity with neurotropic US and Swiss BoAstV strains. To our knowledge, this is the first confirmed report of BoAstV-associated encephalitis in cattle residing in eastern Canada.

Identification de l'astrovirus bovin dans des cas d'encéphalite bovine non suppurative dans l'Est du Canada. L'astrovirus bovin (BoAstV) a été identifié par amplification en chaîne par la polymérase avec la transcriptase réverse sur des tissus du cerveau de 2 bovins de parcs d'engraissement qui étaient morts d'encéphalite non suppurative. Le séquençage a démontré un haut niveau d'homologie avec les souches neurotropiques américaine et suisse de BoAstV. À notre connaissance, il s'agit du premier rapport confirmé d'une encéphalite associée à BoAstV chez le bétail résidant dans l'Est du Canada.(Traduit par Isabelle Vallières).

Agreement among surgical pathologists evaluating routine histologic sections of digits amputated from cats and dogs.

Agreement among pathologists interpreting histologic specimens is an area of interest within human pathology, but little work in this area has been reported in the veterinary literature. Agreement among pathologists evaluating routine histologic sections of amputated digits from cats and dogs submitted to multiple diagnostic centers was examined. Histologic sections from surgical specimens were reviewed in a blinded fashion by two pathologists, and a comparison to the original diagnosis, as stated in the diagnostic report, was recorded. A total of 513 cases were reviewed, and complete agreement was reached in 409 (79.7%). Of the 104 instances of disagreement, 77 (74.0%) were considered to be of clinical significance. The diagnosis of keratoacanthoma was disagreed with in 19 of 21 diagnoses (90.4%). No other individual diagnosis was similarly disputed. The overall level of disagreement is large and is similar to that reported in human pathology and suggests that further study of this issue would be useful in veterinary pathology.