Journal of Veterinary Diagnostic Investigation最新文献

Staphylococcus aureus is one of the most important bacteria responsible for clinical bovine mastitis globally, leading to significant economic losses in the dairy industry. Antimicrobials used to treat and prevent mastitis can lead to antimicrobial resistance (AMR) in S. aureus. We retrospectively evaluated AMR of S. aureus isolates from clinical bovine mastitis cases submitted to the Animal Health Centre in British Columbia from 2013 to May 2024. S. aureus was isolated from 15.0% of submitted bovine milk samples. Antimicrobial susceptibility testing was done on 611 of 1,347 S. aureus isolates. No methicillin-resistant S. aureus isolates were detected based on cefoxitin susceptibility test results, which is encouraging. The highest frequencies of resistance were found for penicillin (46.6%) and ampicillin (42.1%). The lowest frequencies of resistance were to ceftiofur and sulfamethoxazole-trimethoprim (0.2% each) and cephalothin (0.3%). AMR trends over our study period were generally stable, except for penicillin and ampicillin; penicillin resistance increased from 15.2% to 71.1%, and ampicillin resistance increased from 18.2% to 70.1%. The information in our study could help guide clinicians when choosing antimicrobial treatments to treat mastitis caused by S. aureus, particularly in the province of British Columbia. Because S. aureus has a broad host range and is of importance to both human and veterinary medicine, continued monitoring to detect the emergence of resistance is warranted.

African rhinoceros undergo chemical immobilization and prolonged transport during translocations for conservation purposes and, hence, experience several pathophysiologic changes, including skeletal muscle injury. Potential concurrent myocardial injury has not been investigated due to a lack of validated immunoassays. We aimed to use inferred cardiac troponin I (cTnI) amino acid sequences of southern white (Ceratotherium simum simum) and southern-central black (Diceros bicornis minor) rhinoceros to assess the potential usefulness of several commercial cTnI immunoassays for detecting cTnI in African rhinoceros. We extracted RNA from the myocardium of deceased rhinoceros (2 white, 1 black rhinoceros) followed by primer design, cDNA synthesis via RT-PCR, and Sanger sequencing. The inferred cTnI amino acid sequences were obtained from the mRNA transcript sequences. The homology of epitope binding sites recognized by capture and detection antibodies in 6 human immunoassays was visually evaluated using aligned inferred rhinoceros cTnI amino acid sequences. Percentage identity between white and black rhinoceros cDNA nucleotide sequences was 99%; inferred amino acid sequences were identical. There were 5 amino acid differences between humans and rhinoceros in the epitope binding sites of immunoassay antibodies; 5 assays contained antibodies against epitopes that were not conserved. For one assay, the single capture antibody targeted a short heterologous epitope (residue 87-91), and cross-reactivity with rhinoceros cTnI was deemed unlikely. For the other 5 assays, complete antibody-epitope homology, or the inclusion of multiple detection or capture antibodies, or targeting of long epitopes, indicated that these assays could be suitable for further investigation of cTnI measurement in African rhinoceros.

Cases of sodium toxicosis (ST), although reported infrequently, can result in acute morbidity and mortality and extensive losses in affected poultry. We analyzed the clinical, pathologic, and toxicologic findings of 7 diagnosed cases of ST in chicken autopsy submissions at the California Animal Health & Food Safety Laboratory System (CAHFS), University of California-Davis, from 2014 to 2023. We also evaluated the brain sodium concentrations in 10 clinically normal broiler chickens to elucidate potential differences with salt-intoxicated chickens, and reviewed the literature of field cases of ST in chickens and turkeys. Lesions of anasarca described in the 7 ST cases (66 chickens) identified from the CAHFS database included: ascites (62 of 66; 6 of 7 cases); hydropericardium and cardiomegaly (54; 6 of 7); edematous, congested lungs (24; 6 of 7); enlarged, pale kidneys (24; 6 of 7); subcutaneous edema (17; 4 of 7); cystic testes (14; 6 of 7); and cerebral edema (7; 4 of 7). Brain sodium concentrations exceeded 1,800 ppm in only 4 of 24 brains analyzed in our case series. In the feed samples analyzed from 5 ST cases, sodium concentrations exceeded the recommended 2,000 ppm; concentrations detected were 2,500-12,000 ppm. In brains from the 10 clinically normal chickens evaluated, brain sodium concentrations were 1,500-1,700 ppm.

Prompt diagnosis of equine septic arthritis is crucial for successful treatment. Serum amyloid A (SAA) has been suggested as a reliable biomarker. However, we previously found that synovial fluid SAA increases in nonaffected joints of horses with septic arthritis. We hypothesized that systemic SAA may leak into the nonaffected joints. If this is the case, we also hypothesized that locally produced joint SAA isoforms may be better candidates for septic arthritis biomarkers. Thus, our objectives were 1) to evaluate the temporal kinetics of systemic and synovial fluid SAA in horses with septic arthritis (n = 5), non-septic synovitis (n = 5), and systemic inflammation (n = 5), examining both affected and contralateral joints; and 2) investigate putative locally produced joint SAA isoforms and detect amino-acid differences between them. We confirmed that SAA increases significantly in synovial fluid in nonaffected joints of horses with systemic inflammation (≤352 mg/L), as well as in contralateral nonaffected joins in horses with septic arthritis (≤1,830 mg/L) compared to baseline at time 0 (<0.2 mg/L). We also identified a putative locally produced joint SAA peptide in synovial fluid (FGDSGHGAADSR) that differed in 1 amino acid from 2 systemic peptides found both in plasma and synovial fluid. The putative joint SAA isoform was present in joints of horses with both septic arthritis and systemic inflammation (ion intensities 10⁴-10⁶). Thus, the increase of synovial fluid SAA may be both due to the leakage of SAA from serum into joints and local production of joint SAA isoforms.

The 1890s marked a significant milestone with the introduction of antibody-based agglutination and precipitation assays, revolutionizing the detection of bacterial pathogens in both animals and humans. This era also witnessed pivotal contributions to our understanding of humoral immunity, as researchers elucidated the structure and functions of antibody molecules, laying the groundwork for diagnostic applications. Among antibody isotypes, IgG is of paramount importance in diagnostic investigations given its definitive indication of infection or vaccination, coupled with its widespread presence and detectability across various specimen types, such as serum, colostrum, milk, oral fluids, urine, feces, and tissue exudate. Despite their resilience, immunoglobulins are susceptible to structural alterations induced by physicochemical and enzymatic processes, which can compromise the reliability of their detection. Here we review comprehensively the historical milestones, underlying mechanisms, and influencing factors (e.g., temperature, pH, storage) that shape the structural integrity and stability of IgG antibodies in aqueous solutions and various clinical specimens.

The ingestion of cotyledons or seeds of cocklebur (Xanthium strumarium) causes poisoning as a result of acute liver failure. Here we describe a spontaneous outbreak of X. strumarium toxicity in dairy cows in Uruguay. The outbreak occurred in the winter when the cows were fed sorghum silage contaminated with X. strumarium seeds. Clinical signs of depression, anorexia, paddling, opisthotonos, muscle tremors, sternal recumbency, and death were observed 2-12 h following ingestion. Of 160 Holstein cows, 30 (19%) animals were ill, and 6 (4%) died. At autopsy, the liver had a diffuse mottled appearance with intercalated red and yellow areas. Histologically, centrilobular hemorrhagic coagulative necrosis was found. The diagnosis of this natural outbreak of intoxication was based on the clinical signs observed, finding the fruits of X. strumarium in the silage, and the characteristic macroscopic and histologic lesions.

We estimated the Leptospira seroprevalence in dogs, cats, and horses from Tennessee, USA, using the microscopic agglutination test (MAT) against 12 Leptospira serovars. We observed Leptospira seropositivity in 110 of 374 (29.4%) dogs, 21 of 170 (12.4%) cats, and 42 of 88 (47.7%) horses. The highest seroprevalence was observed for serovars Autumnalis (74.6%) in dogs, and Bratislava in cats (42.9%) and horses (95.2%). We found a significant level of potential cross-reactivity between multiple Leptospira serovars tested, with highest cross-reactivity to serovar Autumnalis in dogs. Leptospira seroprevalence was significantly higher in vaccinated dogs (45 of 98 [46%]) compared to unvaccinated dogs (14 of 86 [16%]; p < 0.001). A significant difference in seroprevalence was observed in vaccinated and unvaccinated dogs to all 4 serovars included in canine leptospiral vaccines (p < 0.001). We also evaluated the Leptospira testing results from our diagnostic laboratory submissions from 2021-2023; 103 of 252 (40%) canine serum samples were positive, with the highest positivity rate for serovar Autumnalis. On Leptospira real-time PCR, 35 of 325 (10.7%) urine samples and 15 of 257 (5.8%) blood samples were positive. The cross-reactivity between the Leptospira serovars used in the MAT and vaccination status should be considered when estimating seroprevalence.

In March 2024, highly pathogenic avian influenza A(H5N1) virus, clade 2.3.4.4b, was detected in dairy cows in the United States, and at the same time in resident cats on affected farms. To help guide sample collection and diagnosis in cats, here we report the distribution of lesions and detection of H5N1 clade 2.3.4.4b influenza A virus (IAV) infection by PCR, immunohistochemistry (IHC), and serology in samples from 4 deceased and 2 living cats from 3 separate affected dairy farms. Although gross lesions were not diagnostic, histologically, all 4 deceased cats had nonsuppurative and necrotizing encephalitis and subtle interstitial pneumonia, and some also had significant myocarditis (3 of 4), chorioretinitis (2 of 4), and sialadenitis (1 of 2). The virus was detected by IHC in the aforementioned tissues, and by PCR in each brain (Ct = 9.9-25.1), lung (17.4-32.7), oropharyngeal swab (28.3-30.5), urine (30.3-34.4), and nasal swab (33.5-34.1) collected postmortem; fecal swabs were PCR-negative. In the antemortem samples, the virus was detected by PCR in the oropharyngeal swabs (34.1-36.1), whole-blood samples (30.8-36.6), and one serum sample (31.7). Seroconversion was detected in one cat. Our results support histologic evaluation of brain, lung, eyes, and heart, and PCR testing of brain and lung for postmortem diagnosis, and show that oropharyngeal swabs, urine, serum, and whole blood are suitable samples for antemortem detection of IAV infection in clinically affected cats.

Two methods of measuring triacylglycerol (TG) in the blood are used in clinical laboratories. The glycerol-blanked TG analysis method is used primarily in Japan; the total glyceride measurement method is used in most countries, including the United States. The latter method includes free glycerol in the blood, which is known to be slightly higher in humans. However, the extent to which the 2 methods differ in companion animals is unknown. We used cryopreserved blood from dogs and cats that visited a secondary veterinary hospital to investigate the relationship between the data obtained using the 2 TG analysis methods. The median ratio (5th and 95th percentiles) of total glyceride measurement:glycerol-blanked TG measurement ratios was 1.24 (1.08 and 1.77) for dogs and 2.00 (1.44 and 3.66) for cats, with the total glycerol method clearly having higher values. The Passing-Bablok regression equation comparing the total glyceride method (y) and glycerol-blanked method (x) was y = 1.049x + 0.119 for dogs and y = 1.476x + 0.177 for cats. The estimated free glycerol value calculated from the difference between the 2 TG measurements was strongly correlated with the measured free glycerol value (dog, r = 0.7905; cat, r = 0.8708), indicating that free glycerol in the blood was the cause of the TG measurement discrepancy. Therefore, the TG concentrations obtained from total glyceride assays in dogs and cats may contain non-negligible levels of free glycerol.