Journal of Veterinary Diagnostic Investigation

Gallibacterium spp., particularly G. anatis, have received much attention as poultry pathogens in recent years. We report here the presence and antimicrobial resistance profile of 69 Gallibacterium isolates obtained from 2,204 diagnostic submissions of broiler and layer chickens in 2019–2021. Gallibacterium-positive chickens had lesions primarily in the respiratory tract, reproductive tract, and related serosal surfaces. Gallibacterium spp. were initially identified based on their typical cultural characteristics on blood agar. The isolates were confirmed by a genus-specific PCR spanning 16S-23S rRNA and MALDI-TOF mass spectrometry. Phylogenetic analysis based on 16S rRNA gene sequence revealed distinct clades. Of the 69 isolates, 68 clustered with the reference strains of G. anatis and 1 with Gallibacterium genomospecies 1 and 2. Antimicrobial susceptibility testing of 58 of the 69 isolates by a MIC method showed variable responses to antimicrobials. The isolates were all susceptible to enrofloxacin, ceftiofur, florfenicol, and gentamicin. There was a high level of susceptibility to trimethoprim–sulfamethoxazole (98.0%), streptomycin (98.0%), amoxicillin (84.0%), sulfadimethoxine (71.0%), and neomycin (71.0%). All of the isolates were resistant to tylosin. There was resistance to penicillin (98.0%), erythromycin (95.0%), clindamycin (94.0%), novobiocin (90.0%), tetracycline (88.0%), oxytetracycline (76.0%), and sulfathiazole (53.0%). A high rate of intermediate susceptibility was observed for spectinomycin (67.0%) and sulfathiazole (40.0%). Our findings indicate a potential role of G. anatis as an important poultry pathogen and cause of subsequent disease, alone or in combination with other pathogens. Continuous monitoring and an antimicrobial susceptibility assay are recommended for effective treatment and disease control.

Lymphoma diagnosis in dogs and cats is continually evolving as new subtypes and human correlates are being recognized. In humans, T-cell lymphomas with MUM1 expressed and plasma cell neoplasia or B-cell lymphomas with CD3 expressed aberrantly are reported only rarely. We report here a case series of tumors in dogs and cats with CD3 and MUM1 co-expressed as determined by immunocytochemistry or immunohistochemistry. Lineage was assigned for these tumors by 3 board-certified pathologists and a veterinary immunologist based on review of clinical and cellular features and the results of ancillary testing including PCR for antigen receptor rearrangements, flow cytometry, and serum protein electrophoresis with immunofixation. In cats, 7 of 7 tumors, and in dogs, 3 of 6 tumors with CD3 and MUM1 co-expressed had clonal rearrangement of the immunoglobulin gene or serum monoclonal immunoglobulin, consistent with a diagnosis of a plasma cell neoplasia or myeloma-related disorder with CD3 expressed aberrantly. Disease was often disseminated; notably, 3 of 7 feline cases had cutaneous and/or subcutaneous involvement in the tarsal area. In dogs, 3 of 6 cases had a clonal T-cell receptor gamma result and no clonal immunoglobulin gene rearrangement and were diagnosed as a T-cell tumor with MUM1 expressed. The use of multiple testing modalities in our series of tumors with plasma-cell and T-cell antigens in dogs and cats aided in the comprehensive identification of the lymphoproliferative disease subtype.

Radial immunodiffusion (RID) is used to quantify IgG concentration in neonatal beef or dairy calf serum; variability has been noted that may affect the precision and accuracy of assay results. We determined the source, range, and homogeneity of variance in the results of a commercial bovine IgG RID assay (Triple J Farm). To estimate the variance in the precipitin ring diameter, we used 6 sera, measured 28 times across 8 plates and 4 lots, and 3 standards with known IgG concentrations, measured 75 times across 69 plates and 5 lots. The source of diameter variance was determined using variance partition coefficients for lot, plate, and repetition. We used 11 different methods to generate standard curves to convert RID precipitin ring diameters to IgG concentrations. The Levene test of homogeneity of variance (α = 0.1) was used to evaluate the equality of variance between the standards or serum precipitin ring diameters and calculated IgG concentrations. Lot and plate contributed minimally to the diameter variance. Precipitin ring diameters had equal variance. Calculated IgG concentrations for serum not requiring dilution had equal variance. A linear equation from aggregated standards, performed within the same day, had greater accuracy for the calculated IgG concentrations of the standards compared to other equation methods. Regardless of standard curve methodology or IgG concentration, variability inherent to the assay limits its clinical usefulness.

A 14-y-old, castrated male, diabetic, domestic longhaired cat was presented for investigation of anemia. General examination revealed widespread cutaneous erythematous macules and patches. Hematology and bone marrow aspiration revealed severe regenerative anemia and marked erythroid hyperplasia, respectively. Low numbers of intermediate-to-large, atypical lymphocytes were observed in the blood smear and bone marrow aspirates. Various imaging modalities demonstrated a diffuse pulmonary bronchial pattern, multifocal mural thickening of the urinary bladder, splenomegaly, and mild tri-cavitary effusion. Skin biopsies and cytologic examination of the pleural effusion demonstrated round-cell neoplasia consistent with lymphoma. Autopsy confirmed disseminated T-cell lymphoma, mostly affecting the urinary bladder, stomach, lymph nodes, and interscapular subcutis and muscles. Angiocentrism and nerve infiltration were present. The cutaneous erythematous patches, characterized by perivascular neoplastic lymphocytic infiltrates and angiodestruction, were a manifestation of the disseminated lymphoma in this cat, similar to the lesions reported in humans affected by angioimmunoblastic T-cell lymphoma.

Gastrointestinal disorders are among the most common disease processes in captive elephants. Colic is a frequent clinical presentation and may have several infectious and noninfectious causes. Ingestion of sand has been reported in elephants living in enclosures with loose sandy soils. Similar to the situation in horses, sand ingestion can cause intestinal impaction and colic in elephants. Here we describe a case of colonic sand impaction with cecal rupture and peritonitis in an African savanna elephant from a zoologic collection that died after several days of colic. On autopsy, abundant, gritty, sandy material was found within a segment of colon immediately aboral to the cecum. There was a full-thickness tear in the cecal wall, free intestinal contents within the abdominal cavity, and peritonitis. To our knowledge, the postmortem examination of an elephant with sand impaction and cecal rupture has not been reported previously; this condition should be included among the differential diagnoses in elephants with colic. We review the reports of noninfectious causes of gastrointestinal disease in elephants, which include cases of small intestinal and colonic torsion and of intestinal obstruction by fecal boluses.

A 12-y-old Himalayan black bear suddenly developed depression, anorexia, cough, and dyspnea and died at the Ordos Zoo, China. At autopsy, the mesenteric and cranial mediastinal lymph nodes (LNs) were enlarged; the largest cranial mediastinal LN was ~13 cm in diameter. Scattered-to-diffuse, rounded-or-oval, gray, firm 1–6-mm nodules were observed on the surfaces of the spleen, liver, lungs, and small intestine. Histologically, the enlarged cranial mediastinal and mesenteric LNs, spleen, small intestine, lungs, and liver contained dense populations of neoplastic lymphoid cells (NLCs). The NLCs were round-or-oval with small amounts of mildly eosinophilic cytoplasm and round-or-oval hyperchromatic nuclei with indistinct nucleoli; the mitotic count was 55 in 2.37 mm². Immunohistochemically, cell membranes and the cytoplasm of NLCs were CD3+, CD79a−, CD20−, CD15−, CD30−, and CD45RA−; hence, the NLCs were derived from T lymphocytes. To our knowledge, T-cell lymphoma has not been reported previously in a Himalayan black bear.

Testing platforms that leverage automation, require minimal sample volume, and enable various tests to be performed simultaneously on a single sample have the potential to improve workflow and efficiency in veterinary diagnostic laboratories. We evaluated a barcoded magnetic bead (BMB) technology using established immunoassays for detection of feline leukemia virus (FeLV) p27 antigen and antibody against feline immunodeficiency virus (FIV). Analytical sensitivity, limit of blank, and limit of detection were used to establish a functional sensitivity of 1.00 ng/mL of inactivated FeLV antigen and 35.7 ng/mL of anti-FIV monoclonal antibody. Common interferents, such as hemoglobin, lipid, and bilirubin, were not found to interfere with the performance of the assay. Intra- and inter-assay CVs were <13% for both assays using manufactured samples. Using a set of 116 feline samples, the diagnostic accuracy of our multiplex assay was 100% compared to reference assays. Performance in a convenience set of 1,000 feline samples submitted to a commercial diagnostic laboratory revealed a proportion of positive results of 1.3% for FeLV and 3.7% for FIV. BMB technology should enable rapid screening of samples for various markers in a single immunoassay well.

Neorickettsia risticii, an obligate intracellular bacterium, is the causative agent of Potomac horse fever (PHF). Diagnosis of PHF is based on demonstration of serum antibodies, isolation of N. risticii, and/or detection of nucleic acid by a PCR assay. An existing real-time PCR assay targeting the N. risticii 16S rRNA has been validated using blood samples from horses with colitis, and snails; to our knowledge, the performance of the assay for other sample types has not been reported. We describe here a modification of the 16S rRNA gene assay by the addition of a set of primers and probe targeting the N. risticii p51 gene to form a duplex assay. We validated the new assay using diagnostic specimens from 56 horses with suspected PHF. The assay consistently detected down to 5 copies of synthetic targets, and did not show any cross-reaction with common equine enteric pathogens. Although we did not establish the diagnostic sensitivity and specificity of the duplex assay, results for both gene targets were in complete agreement, with the exception of 4 fecal samples that tested positive for the 16S rRNA gene only. Further analysis indicated that testing of fecal samples using our 16S rRNA gene assay alone can produce a false-positive result.

Four Indian ringneck parakeets (Psittacula krameri; syn. ringneck parrots or rose-ringed parakeets) were submitted by 2 private owners for autopsy following a history of dyspnea and death. Gross findings were varied and included thickening of the left caudal thoracic air sac, white spots throughout the liver, mild dilation of the proventriculus, coelomic effusion, splenomegaly, and pulmonary congestion and edema. Microscopically, the submitted parakeets had significant lesions in the lower respiratory tract, including necrotizing bronchitis, parabronchitis, and interstitial pneumonia with numerous syncytia containing eosinophilic intranuclear inclusions. Electron microscopy of the lungs was compatible with a herpesviral infection and Psittacid alphaherpesvirus 5 (PsAHV5) was detected via PCR and sequencing. There has been inconsistent terminology used with Psittacid alphaherpesvirus 3 and PsAHV5; we attempt here to clarify the reported history of these viruses.

The Asian small-clawed otter (Aonyx cinereus) is an endangered species that is common in zoologic collections. A 17-y-old female Asian small-clawed otter under human care, with a clinical history of chronic renal disease, was euthanized because of deteriorating health. Histologically, the jejunal wall was infiltrated by a monomorphic population of small neoplastic lymphocytes that expanded the lamina propria of the villi and crypts, and on rare occasions invaded the submucosa. The tumor was composed of T cells (CD3+) with a proliferation index of 16%. Based on the World Health Organization (WHO) Classification of Hematopoietic Neoplasms in Domestic Animals, this lymphoma was classified as an enteropathy-associated T-cell lymphoma (EATL) type 2. We also present here a review of the literature on intestinal lymphoma in the subfamily Lutrinae (otters).

Salivary gland neoplasia is uncommon in veterinary species and has rarely been reported in cattle. Adenocarcinoma, squamous cell carcinoma, and pleomorphic carcinoma have been described in the parotid gland of dairy cows. Here we describe a case of high-grade mucoepidermoid carcinoma in a bull. The bull had a chronic history of caudal mandibular soft tissue swelling. Postmortem examination revealed a 30 × 30-cm mass with a caseonecrotic center, hemorrhage and necrosis of the ipsilateral cervical musculature, osteolysis of the right paracondylar process of the skull and right horn base, pulmonary nodules, and enlarged tracheobronchial lymph nodes. Histology of the mass, lungs, and lymph nodes revealed an invasive neoplasm composed of epithelial cells arranged in nests and ductular structures supported by a spindle cell stroma, with frequent central necrosis. Immunohistochemistry revealed that epithelial cells were diffusely positive for pancytokeratin and p63 with multifocal vimentin positivity; stromal cells were diffusely positive for vimentin and α-SMA. A salivary gland mucoepidermoid carcinoma was diagnosed based on these findings. Although rare, salivary gland neoplasia should be considered a differential diagnosis for mandibular masses in cattle.

Perivascular wall tumors (PWTs) are common well-known canine mesenchymal tumors. The term PWT has not yet been applied to cats; only 2 cases of feline soft tissue hemangiopericytomas (HEPs) are available. In human medicine, sinonasal HEP-like tumor/glomangiopericytoma (SHPCL/GP) and intranasal solitary fibrous tumor (SFT) are well-known mesenchymal tumors with staghorn vasculature and low malignant potential; however, these entities have not been described in small animals. We describe here the pathologic and immunohistochemical features of 2 cases of feline intranasal mesenchymal tumors consistent with PWTs and resembling human SHPCL/GP (case 1), and human intranasal SFT (case 2). Both cats developed intranasal, unilateral, polypoid, expansile neoplasms with a mostly patternless growth of spindle cells, minimal stroma, and prominent staghorn vessels. The stroma was PAS negative, which excludes a glomus tumor. Immunohistochemistry identified diffuse vimentin and PDGFRβ expression. Case 1 was α-SMA positive (as is human SHPCL/GP); case 2 was negative (as is human intranasal SFT). Both tumors were incompletely excised, leading to recurrence in case 1. Case 2 was lost to follow up. To our knowledge, intranasal PWTs have not been reported previously in cats. The frequency of the lesions is not known, but awareness of these entities may assist in their recognition and better characterization in the future.

Here we characterize 6 cases (4 autopsies and 2 biopsies) of histiocytic sarcoma in the CNS of cats. All affected cats had chronic, progressive clinical signs. Three autopsied cats were euthanized because of a poor prognosis, and one died. The clinical outcome for the biopsy cases remains unknown. Tumors occurred in the brain (4 cases), spinal cord (1 case), and brain and spinal cord (1 case). Neoplasms were restricted to the CNS in 3 cases. Reported gross changes in the 4 autopsy cases consisted of neuroparenchymal swelling with or without tissue pallor or gray discoloration (2 cases) and a yellow or dark-gray mass (2 cases). Histologically, pleomorphic, round-to-elongate neoplastic cells with typical histiocytic morphology effaced the neuroparenchyma and leptomeninges. Multinucleate neoplastic cells were observed in all cases. The mitotic count was 1–24 in 2.37 mm² (10 FN22 40× fields). Neoplastic cells in all cases had positive immunolabeling for Iba1; immunolabeling was negative for E-cadherin, CD3, CD79, and MUM1, confirming their histiocytic origin.