Journal of Veterinary Diagnostic Investigation最新文献

A 13-y-old Vietnamese Pot-bellied sow (Sus scrofa) was presented because of blood-tinged mucoid vulvar discharge of 5-d duration and a 4-mo history of intermittent coughing and weight loss. Computed tomography revealed diffuse, multilobulated cystic and mineralized uterine masses, numerous lung nodules, and abdominal lymphadenopathy. Malignant neoplasia was suspected. Gross and histologic findings were diffuse cystic endometrial hyperplasia and endometrial adenocarcinoma of the mid-body of the left uterine horn. Metastatic foci were evident in the lungs, liver, and spleen. Neoplastic cells were immunoreactive for pan-cytokeratin. Metastatic endometrial adenocarcinoma and diffuse cystic endometrial hyperplasia have not been previously reported antemortem using computed tomography in a sow, to our knowledge.

African swine fever virus (ASFV) is a highly transmissible pathogen affecting swine, causing a devastating disease with high mortality rates in naive populations. Given the likelihood of significant economic impacts associated with an ASF outbreak, considerable resources have been allocated in the United States to safeguard the swine industry against this threat. Ongoing outbreaks of ASF in the Dominican Republic and Haiti further threaten the U.S. swine industry, given their proximity and involvement in movement to and from North America. Although surveillance programs are ongoing, limited point-of-care (POC) tests are available during outbreaks with the sensitivity and specificity standards of laboratory testing (e.g., real-time PCR [rtPCR]). However, the recently developed CRISPR-Cas-based testing systems may offer comparable high-quality results. We sought to develop a low-cost visual detection method for ASFV by employing a recombinase polymerase amplification (RPA)-dependent CRISPR-Cas12a technique that can be utilized in the field as a POC assay. Our CRISPR-Cas12a assay had comparable sensitivity and specificity to rtPCR, both visually and when quantified using a fluorescence reader. In whole blood samples from ASFV-suspect or ASFV-negative cases, our CRISPR assay achieved a sensitivity of 98.3% (10² DNA copies) and a specificity of 100%. Test results of our RPA-CRISPR assay can be visualized in as few as 7 min, with peak fluorescence at 40 min (RPA and CRISPR steps). Our results lay the groundwork for a large-scale POC assay assessment for ASFV detection and offer a robust workflow that works with commonly submitted diagnostic samples.

A multi-state outbreak of equine botulism occurred between December 2022 and March 2023 in the United States. Follow-up and testing were performed on 42 horses, including 24 that died or were euthanized in the outbreak that affected ~98 horses. Affected horses had all been exposed to the same commercial feed. Clinical signs included progressive muscle weakness and tremors, recumbency, and colic. No significant gross or microscopic abnormalities were observed on autopsy. Feces and gastrointestinal content were tested for various infectious agents, including botulinum toxin; fecal samples from 2 horses tested positive for botulinum neurotoxin (BoNT) type C using the mouse bioassay (MBA). Feed samples, as well as mammalian tissue found within the feed, were collected and tested; 2 samples were positive for BoNT type C by MBA. Based on these results, a diagnosis of botulism was established, and the contaminated feed was identified as the source of exposure. We highlight the diagnostic challenges associated with equine botulism and the importance of regulatory agencies and interagency collaboration during outbreaks.

Digital microscopy is increasingly used in veterinary diagnostic pathology. However, limited independent research has been published on its use, especially for the purpose of evaluating blood films. Hence, determining the potential limits of blood film assessments obtained via digital microscopy is needed. We compared the agreement of digital and optical cytology for the detection of common cellular morphology changes and abnormalities in veterinary blood films. Twenty-two veterinary clinical pathologists and residents evaluated canine, feline, and equine blood films on glass slides via optical microscopy and digitized blood film slides, with a ≥8-wk washout period between evaluations. One of the equine cases was a patient experimentally infected with Theileria haneyi. Using a standardized rubric, 16 erythrocyte features, 2 platelet features, and 2 leukocyte features were scored from absent to 4+. Additional comments at pathologist discretion were recorded. Changes in erythrocyte shape, platelets, and leukocytes were readily identified on both digital and glass slides. T. haneyi organisms were identified on significantly fewer digitized blood film slides than glass slides. Additionally, intra-observer consistency was low between digitized blood film slide and glass slide evaluation. Relative to glass slides, digitized blood film slides appear generally adequate for identifying erythrocyte, leukocyte, and platelet morphology changes, but may be inadequate for identifying intracellular T. haneyi organisms; however, more studies are needed. Clinicians should exercise caution when interpreting results from digitized blood film slides in which blood-borne infectious disease may be present.

Fluorescence in situ hybridization (FISH) can be used to detect intracellular bacteria in formalin-fixed paraffin-embedded (FFPE) tissues. However, this technique has rarely been applied to samples of feline heart, liver, or kidney to investigate the relationship between intracellular bacteria and chronic inflammation within these organs. Our objective was to develop a robust FISH protocol to detect intracellular bacteria within medium-density FFPE feline tissue samples. Cy3-labeled eubacterial and non-eubacterial probes were applied to samples of monkey intestine, feline intestine, and feline liver, in which bacteria had been visualized on routine histopathology. Although initial tests failed, the addition of pepsin pre-digestion to the test protocol and the adjustment of stringency ensured consistent results. All positive results were confirmed using Gram staining and non-eubacterial probes applied to sequential samples of the 3 tissues. Our FISH protocol using Cy3-labeled eubacterial probes reliably and consistently detected bacteria within FFPE samples of the 3 tissues. The addition of 20-min pepsin pre-digestion and the adjustment of the formamide concentration within the hybridization buffer to 40% were pivotal to the successful use of the protocol. Species-specific probes, along with PCR, culture, and special staining, could be considered to increase sensitivity and specificity of FISH when used for the detection of organisms within tissues.

Sparganosis, a zoonotic infection caused by the plerocercoid (sparganum) larval stage of Spirometra spp., is rarely reported in domestic cats. Sparganosis is typically seen as subcutaneous or visceral granulomatous lesions and has been associated with Spirometra mansonoides in North America. A proliferative form of sparganosis, with tissue invasion and widespread dissemination, has always been associated with Sparganum proliferum. However, emerging molecular evidence challenges this distinction. Here, we report a confirmed case of proliferative sparganosis in a domestic cat caused by Spirometra decipiens complex 2 (also referred to as Spirometra sp. 3). The cat had widespread lesions in multiple tissues, with gross and histologic lesions resembling those attributed to S. proliferum. Molecular identification of larval cestode DNA demonstrated a 99% match to S. decipiens, confirming its role in severe disseminated disease. Our case broadens the understanding of the pathogenic capacity of S. decipiens (Spirometra sp. 3) in felids and emphasizes the critical role of molecular detection for accurate species identification. To our knowledge, proliferative sparganosis attributable to Spirometra sp. 3 has not been reported previously in domestic cats. Given the zoonotic potential of sparganosis, our findings have important implications for both veterinary care and public health surveillance.

Several etiologic factors contribute to bovine respiratory disease, the primary cause of feedyard mortality. We performed a cross-sectional observational study to determine the frequency and chronicity of lesions in fatal feedyard pneumonia cases. Postmortem examinations were performed (n = 443), and 2 lung samples were collected from each animal. Histologic sections were scored using 10 classifications: 5 types of bronchopneumonia (BP; 3 acute, 2 chronic), 4 types of interstitial pneumonia (IP; 2 chronic, 2 acute), and 1 category for other findings. Cases with chronicity in either section were classified as chronic. Results from both lung sections were combined into a case-level diagnosis of BP, IP, or BP with IP (BIP). After exclusions because of autolysis or missing data, our diagnosis frequencies for 352 cases were: BP (150; 42.6%), IP (86; 24.4%), BIP (71; 20.2%), and Other (45; 12.8%). Of cases with an IP component, chronic lymphoplasmacytic IP (CLIP) was identified in 59 of 157 (37.6%) cases. A generalized linear model was used to evaluate the probability of case-level chronicity and potential associations with diagnosis and days on feed. Model-estimated probability of chronic lesions was higher in cases with IP (51% IP; 60% BIP) compared with BP (38%). Of 71 BIP cases, 27 had acute BP and acute IP; 18 had acute IP and chronic BP; 0 had chronic IP and acute BP; 5 had chronic IP and chronic BP; 14 had CLIP and acute BP; and 7 had CLIP and chronic BP. In our final dataset of 352 feedyard pneumonia cases, IP was found histologically in the lungs of 157 cases, either alone or in conjunction with BP; cases with an IP component were more likely to have chronic lesions.

Diagnosis of canine bacterial bronchopneumonia (bBP) is challenging and mostly based on bronchoalveolar lavage fluid (BALF) cytology and bacterial culture (BC) results. However, bacterial contamination of BALF is frequent, intracellular bacteria are not always visualized on BALF cytology, and BC results may not be related to antimicrobial requirements. Based on local expression of C-reactive protein (CRP) by alveolar macrophages, we aimed to evaluate whether CRP was detectable in canine BALF, and to determine whether BALF-CRP detection could assist in differentiating bBP from non-bacterial bronchopneumopathy (nbBP) in dogs. We used surplus BALF material collected from 24 dogs. Final diagnosis of bBP (n = 3) versus nbBP (n = 21) was retrospectively achieved by 2 board-certified internists. CRP was measured in BALF using an Idexx Catalyst One analyzer. Agreement between a detectable BALF-CRP (≥1 mg/L) and a diagnosis of bBP was assessed using the Cohen kappa coefficient. Five dogs had detectable BALF-CRP, including 3 dogs with bBP and 2 dogs with nbBP. Substantial agreement (κ = 0.7) was found between BALF-CRP and the final diagnosis. BALF-CRP had a test sensitivity of 100% (95% CI [29, 100]) and a specificity of 90% (95% CI [69, 98]) for bBP. Only a fair and not significant correlation was found between plasma CRP and BALF-CRP concentration (rho = 0.3; p = 0.3). Our results suggest that CRP is detectable in canine BALF. The BALF-CRP may be a potential in-house biomarker for bBP in dogs, without being influenced by the plasma CRP concentration.

Emphysematous gastritis is a rare, serious infection with very few reported cases in veterinary species. Gas-producing bacteria are most often implicated in both animals and humans. Here, we describe a case of emphysematous gastritis in a 7-y-old dog that was diagnosed with ileus of 12 d, chronic pancreatitis, and exocrine pancreatic insufficiency. Histologically, the gastric submucosa was markedly expanded by emphysema, and the mucosa had multifocal necrosis, hemorrhage, and gram-positive bacilli. Anaerobic culture of the stomach wall yielded 3+ growth of Clostridium perfringens, Enterococcus faecalis, and Escherichia coli. PCR typing identified the C. perfringens isolate as type C, further characterized as a beta2 toxin-producing strain. Fluorescence in situ hybridization using a C. perfringens probe identified bacilli within the gastric mucosa and submucosa. C. perfringens type C causes enteritis necroticans in humans and necrohemorrhagic enteritis in livestock when levels of endogenous trypsin are low or dietary levels of trypsin inhibitors are high. The exocrine pancreatic insufficiency in our case likely allowed C. perfringens type C to exert cytotoxic effects on the gastric mucosa and contributed to the unique emphysematous gastritis.