Sixty-one horses were included in this study and classified into three groups based on the severity of colic, assessed by heart rate, oral mucous membrane color, and abdominal distension. The groups consisted of a strangulating colic (SC) group (n=21), a non-strangulating colic (NC) group (n=20), and a control group (n=20) of randomly selected healthy horses without colic. Serum concentrations of tumor necrosis factor α (TNFα), haptoglobin (Hp), nitric oxide (NO), malondialdehyde (MDA), zinc, iron, and copper were measured in all horses. Receiver operating characteristic (ROC) analysis was conducted to assess and compare the diagnostic performance of the analytes in terms of sensitivity, specificity, and area under the curve (AUC). TNFα demonstrated the highest diagnostic accuracy for non-strangulating colic at a cutoff value of >24 mg/l, with 100% sensitivity, 95% specificity, and an AUC of 0.996. For strangulating colic, TNFα also exhibited the best diagnostic performance at a cutoff value of >33 mg/l, achieving 100% sensitivity and specificity with an AUC of 1.00. Haptoglobin followed with a cutoff value of >52 µg/l, showing 95% sensitivity, 75% specificity, and an AUC of 0.898. This study provides new insights into the diagnostic performance of TNFα for detecting non-strangulating colic and TNFα and haptoglobin for diagnosing strangulating intestinal conditions in horses with colic.

We evaluated metabolic abnormalities in six neonatal Noma foals (Nos. 54–57, 62, and 66) that died shortly after birth, using laboratory tests, pathological examinations, serum amino acid (AA) analyses, gas chromatography/mass spectrometry (GC/MS), and genetic analyses. Nonspecific clinical symptoms, such as poor suckling and weakness, were commonly observed at birth. Sepsis caused by various bacterial infections was detected in foal Nos. 54, 62, and 66, while a heart malformation was identified in foal No. 57. Laboratory tests showed high aspartate transaminase, lactate dehydrogenase, and creatine kinase levels and low globulin and glucose levels in dead foals. The AA and GC/MS analyses revealed elevated levels of ammonia, orotic acid, and uracil in foal Nos. 54 and 55, while citrulline, arginine, and ornithine levels were low or within normal ranges, suggesting accelerated pyrimidine synthesis and suppressed urea cycle activity. Foal No. 56 had high uric acid and tyrosine levels, hypoglycemia, and liver dysfunction, suggesting glycogen storage disease. In foal No. 57, hypertyrosinemia was suggested because of high phenylalanine and tyrosine levels. We conducted a sequencing analysis of the ornithine transcarbamylase, argininosuccinatelyase, argininosuccinate synthase 1, uridine monophosphate synthase, G6PC1, and G6PT1/SLC37A4 genes associated with metabolic disorders. However, no mutations were detected. In conclusion, although metabolic pathways abnormalities resembling certain hereditary metabolic disorders were observed in neonatal foals that died in Noma horses, no specific mutations were identified in candidate genes, making hereditary disorders less likely.

The endemic situation of respiratory disease caused by equine herpesvirus type-1 (EHV-1) and type-4 (EHV-4) was investigated in a training facility for Thoroughbred yearlings in Japan. Vaccination typically starts in mid-September or early October—only after all yearlings have arrived—leaving those introduced earlier unprotected. To bridge this immunity gap, a revised vaccination program that started earlier was implemented. In 2021–2022 and 2022–2023, yearlings were allocated to three groups according to their introduction dates. Each group received a live EHV-1 vaccine (Equi N Tect ERP, Nisseiken, Tokyo, Japan) as early as possible after arrival, with a second dose administered two months later. Virus-neutralizing titers to EHV-1 rose significantly after the first vaccination in each group as anticipated. Virus type-specific enzyme-linked immunosorbent assays showed that, in 2018–2019 to 2020–2021, pyretic horses (≥38.5°C) infected with EHV-1/4 occurred more frequently between August and September than in other months: 15 cases with EHV-1, 9 cases with EHV-4, and 5 cases with both viruses across the three years. In 2021–2022 and in 2022–2023, only three pyretic horses with EHV-1 infection were confirmed in the corresponding period. The infection rates for EHV-1/4 in the entire population peaked between August and September in 2018–2019 to 2020–2021 (6.8‰–10.9‰). Under the new program, infection rates were much lower, at 2.6‰–3.8‰ in 2021–2022 and 1.2‰–1.7‰ in 2022–2023 (P<0.05). The reduction in these parameters was likely associated with the efficacy of the updated vaccination program.

A 17-year-old Thoroughbred stallion died suddenly after grazing. Necropsy revealed massive hemorrhage in the pericardial sac, suggesting cardiac tamponade. Aortic perforation was observed at the aortic origin, and hemorrhage was observed in and around the epicardium. Superficial observation of the aortic lumen revealed a transverse tear of the aortic wall at the bases of the right semilunar valve and septal semilunar valve. Fibro-osseous changes with calcification were histopathologically observed at the site of the rupture. A nodular goiter was observed in the left thyroid gland. The horse did not engage in strenuous exercise or activity likely to significantly elevate blood pressure during grazing. These results suggest that sudden death was caused by cardiac tamponade due to bone metaplasia and transverse aortic rupture with calcification, potentially triggered by a mild increase in blood pressure associated with normal activity during grazing.