Emerging outbreaks associated with equine coronavirus in adult horses

The purpose of this study was to describe clinical, hematological and fecal PCR results from 161 horses involved in outbreaks associated with ECoV. The outbreaks happened at four separate boarding facilities between November 2011 and April 2012 in the States of CA, TX, WI and MA. Following the molecular detection of ECoV in the feces from the initial index cases, the remaining herdmates were closely observed for the development of clinical signs. Fecal samples were collected from sick and healthy horses for the PCR detection of ECoV. All four outbreaks involved primarily adult horses. Fifty-nine horses developed clinical signs with 12–16 sick horses per outbreak. The main clinical signs reported were anorexia, lethargy and fever. Four horses from 3 different outbreaks were euthanized or died due to rapid progression of clinical signs. The cause of death could not be determined with necropsy evaluation in 2 horses, while septicemia secondary to gastrointestinal translocation was suspected in 2 horses. Blood work was available from 10 horses with clinical disease and common hematological abnormalities were leucopenia due to neutropenia and/or lymphopenia. Feces were available for ECoV testing by real-time PCR from 44 and 96 sick and healthy horses, respectively. 38/44 (86%) horses with abnormal clinical signs tested PCR positive for ECoV, while 89/96 (93%) healthy horses tested PCR negative for ECoV. The overall agreement between clinical status and PCR detection of ECoV was 91%. The study results suggest that ECoV is associated with self-limiting clinical and hematological abnormalities in adult horses.     

Outbreak of equine coronavirus infection among riding horses in Tokyo,Japan

In 2020, an outbreak of equine coronavirus (ECoV) infection occurred among 41 horses at a riding stable in Tokyo, Japan. This stable had 16 Thoroughbreds and 25 horses of other breeds, including Andalusians, ponies and miniature horses. Fifteen horses (37 %) showed mild clinical signs such as fever, lethargy, anorexia and diarrhoea, and they recovered within 3 days of onset. A virus neutralization test showed that all 41 horses were infected with ECoV, signifying that 26 horses (63 %) were subclinical. The results suggest that subclinical horses played an important role as spreaders. A genome sequence analysis revealed that the lengths from genes p4.7 to p12.7 or NS2 in ECoV differed from those of ECoVs detected previously, suggesting that this outbreak was caused by a virus different from those that caused previous outbreaks among draughthorses in Japan. Among 30 horses that tested positive by real-time RT-PCR, ECoV shedding periods of non-Thoroughbreds were significantly longer than those of Thoroughbreds. The difference in shedding periods may indicate that some breeds excrete ECoV longer than other breeds and can contribute to the spread of ECoV.     

Equine coronavirus: An emerging enteric virus of adult horses

Equine coronavirus (ECoV) is an emerging virus associated clinically and epidemiologically with fever, depression, anorexia and less frequently colic and diarrhoea in adult horses. Sporadic cases and outbreaks have been reported with increased frequency since 2010 from Japan, the USA and more recently from Europe. A faeco‐oral transmission route is suspected and clinical or asymptomatic infected horses appear to be responsible for direct and indirect transmission of ECoV. A presumptive clinical diagnosis of ECoV infection may be suggested by clinical presentation, haematological abnormalities such as leucopenia due to lymphopenia and/or neutropenia. Confirmation of ECoV infection is provided by specific ECoV nucleic acid detection in faeces by quantitative PCR (qPCR) or demonstration of coronavirus antigen by immunohistochemistry or electron microscopy in intestinal biopsy material obtained ante or post mortem. The disease is generally self‐limiting and horses typically recover with symptomatic supportive care. Complications associated with disruption of the gastrointestinal barrier have been reported in some infected horses and include endotoxaemia, septicaemia and hyperammonaemia‐associated encephalopathy. Although specific immunoprophylactic measures have been shown to be effective in disease prevention for closely‐related coronaviruses such as bovine coronavirus (BCoV), such strategies have yet not been investigated for horses and disease prevention is limited to basic biosecurity protocols. This article reviews current knowledge concerning the aetiology, epidemiology, clinical signs, diagnosis, pathology, treatment and prevention of ECoV infection in adult horses.     

Splenic abscessation in the horse: A retrospective study of 12 cases

This paper summarises the clinical findings of 12 cases of splenic abscessation in horses presented to Texas A&M University Veterinary Medical Teaching Hospital from 1993 to 2015. The objective of this study was to describe the signalment, clinical and laboratory findings, diagnostics, treatment and outcome of horses affected with splenic abscessation. Only horses in which a splenic abscess was confirmed by microbiological or cytological confirmation from a percutaneous, surgical, or necropsy sample were included in this study. No apparent breed or sex predilection was identified. The mean age of presentation was 9 years, with a range of 1–21 years of age. The most common presenting clinical signs were nonspecific signs including fever, anorexia and lethargy. A variety of bacterial organisms were identified and treatment with antimicrobial agents or surgical exploration was attempted in several of the cases. None of the cases survived to discharge from the hospital.     

Clinicopathologic Characterization of Six Cases of Equine Granulocytic Anaplasmosis In a Nonendemic Area (2008-2011)

Six adult horses (four geldings and two intact mares; age range, 4-22 years) were evaluated for acute development of nonspecific malaise during a 3-year period. Clinical signs included lethargy, anorexia, fever, limb edema, and ataxia. Physical examination findings included depression, anorexia, tachycardia, fever, poor body condition, hind limb ataxia, and dehydration. Hematologic examination in these horses most commonly revealed thrombocytopenia, mild anemia, and leukopenia. Inclusion bodies consistent with the presence of Anaplasma phagocytophilum morulae were observed within circulating neutrophils in all horses. Clinical biochemistry findings were nonspecific. Infection of each horse with A. phagocytophilum was confirmed by polymerase chain reaction. All horses showed resolution of clinical signs after initiation of treatment with intravenous oxytetracycline or oral doxycycline, combined with flunixin meglumine and additional supportive care as needed. Hematologic parameters paralleled clinical recovery and returned to reference limits in patients that underwent repeated analysis. Equine granulocytic anaplasmosis is likely under-recognized in regions where it has not been previously reported; therefore, equine practitioners should be cognizant of relevant clinical signs and laboratory findings in acute infection. Additionally, horses may represent sentinels for infection in other species, including humans.     

Black walnut toxicosis in ten horses

Black walnut toxicosis was diagnosed in 10 horses at one stable. The time from exposure to shavings to development of clinical signs was 8 to 12 hours. Most common clinical signs were moderate to severe laminitis (Obel grade 2 or 3), pitting edema of the distal portion of the limbs, and rapid respiratory rate. Two horses had clinical signs of colic and 2 other horses had anorexia and lethargy. All 10 horses recovered without complications.     

Intestinal neoplasia in horses

BACKGROUND: Intestinal neoplasia of horses is inadequately described. HYPOTHESIS: Intestinal neoplasia of horses has characteristic clinicopathologic features. ANIMALS: Thirty-four horses with intestinal neoplasia. METHODS: Retrospective study. RESULTS: Anamnesis, clinical signs, clinicopathologic and pathologic findings in 34 adult horses diagnosed histologically with intestinal neoplasia were reviewed. The horses ranged in age from 2 to 30 years (mean 16.6 years at presentation). The Arabian breed was most represented and there was no sex predisposition. The most common presenting complaints were weight loss, colic, anorexia, and fever. The most consistent clinical signs were poor body condition, tachycardia, tachypnea, fever, and diarrhea. Useful diagnostic tools included rectal examination, routine blood analyses, abdominocentesis, ultrasonographic examination, rectal biopsy, and exploratory laparotomy. Alimentary lymphoma was the most common intestinal neoplasia identified, followed by adenocarcinoma and smooth muscle tumors. The small intestine was the most common segment of intestine affected for all neoplasms. Intestinal neoplasia was diagnosed antemortem in 13 of 34 (38%) horses. The median time from onset of clinical signs to death or euthanasia was 1.9 months. The discharge rate was 15%. Although the longest survival was observed in horses with jejunal adenocarcinoma, all horses were eventually euthanized because of intestinal neoplasia. CONCLUSIONS: Arabian horses were 4.5 times more likely to have intestinal neoplasia diagnosed than were other breeds.     

Evaluation of clinical characteristics, diagnostic test results, and outcome in horses with internal infection caused by Corynebacterium pseudotuberculosis: 30 cases (1995-2003)

OBJECTIVE: To determine clinical signs, results of diagnostic testing, and outcome in horses with internal Corynebacterium pseudotuberculosis infection. DESIGN: Retrospective study. ANIMALS: 30 horses. PROCEDURE: Information pertaining to clinical data, results of diagnostic tests, and costs of hospitalization and treatment was extracted from medical records of affected horses. RESULTS: Internal C. pseudotuberculosis infection was diagnosed on the basis of clinical signs, diagnostic imaging, and clinicopathologic data, including results of serologic tests and bacterial culture. The most common clinical signs were concurrent external abscesses, anorexia, fever, lethargy, weight loss, and signs of respiratory tract disease or abdominal pain. Clinicopathologic abnormalities included a geometric mean reciprocal serum synergistic hemolysin inhibition titer > or = 512, leukocytosis with neutrophilia, hyperglobulinemia, hyperfibrinogenemia, and anemia. Specific organ involvement was diagnosed in 27 of 30 horses. Affected organs included the liver (18 horses), lungs (12), kidneys (7), and spleen (3); multiple organs were affected in 10 horses. Treatment with antimicrobials for a median of 36 days (range, 7 to 97 days) was usually successful, yielding an overall survival rate of 71%. CONCLUSIONS AND CLINICAL RELEVANCE: Early diagnosis and long-term antimicrobial treatment were important for a successful outcome in horses with internal C. pseudotuberculosis infection. Ultrasonographic imaging was an important technique for identifying specific organs affected, aiding in obtaining samples for a definitive diagnosis, and monitoring response to treatment. Pregnant mares with internal infections are at risk for fetal loss. Preexisting chronic organ disease may be associated with a poor prognosis.     

Treatment of proliferative colitis in ferrets

Proliferative colitis associated with intracellular Campylobacter sp was diagnosed in 10 ferrets. The ferrets had a history of diarrhea (often blood-tinged or mucoid), dehydration, and chronic weight loss. Additional clinical signs included rectal prolapse, lethargy, fever, and a palpably thick colon. In 5 ferrets, the diagnosis was confirmed by colonic biopsy, via endoscopy. Supportive treatment in 5 ferrets did not alleviate the clinical signs or the proliferative intestinal disorder. oral chloramphenicol treatment (50 mg/kg of body weight, q 12 h for 10 to 21 days) resulted in marked clinical improvement and eradication of proliferative intestinal lesions in 5 ferrets.     

Gastric Neoplasia in Horses

Background: Gastric neoplasia of horses is incompletely described.
Objective: Provide history, clinical signs, and clinicopathological and pathological findings associated with gastric neoplasia in horses.
Animals: Twenty-four horses with gastric neoplasia.
Methods: Retrospective study. History, clinical signs, and clinicopathological and pathologic findings in horses diagnosed histologically with gastric neoplasia were reviewed.
Results: Horses ranged in age from 9 to 25 years (median 18 years at presentation). There was no apparent breed or sex predisposition. The most common presenting complaints were inappetance (17/24), weight loss (14/24), lethargy (7/24), hypersalivation (7/24), colic (5/24), and fever (5/24). The most consistent clinical signs were tachypnea (10/19), decreased borborygmi (8/19), and low body weight (7/17). Useful diagnostic tests included rectal examination, routine blood analysis, gastroscopy, abdominocentesis, and transabdominal ultrasound examination. Anemia was the most common hematologic abnormality encountered (7/19), and hypercalcemia of malignancy was seen in 4/16 horses. Squamous cell carcinoma was the most common tumor identified (19/24), and was most often (14/19) found as a single ulcerated, necrotic mass in the nonglandular portion of the stomach. Other gastric neoplasms encountered were leiomyoma (n=2), mesothelioma (n=1), adenocarcinoma (n=1), and lymphoma (n=1). Metastatic neoplasia was found in 18/23 horses. The median time from onset of clinical signs to death was 4 weeks, and all horses died or were euthanized because of gastric neoplasia.
Conclusions: Squamous cell carcinoma is the most common primary gastric neoplasia in horses. The survival time after diagnosis of gastric neoplasia in horses is short.     

Gastric squamous cell carcinoma in three horses

Gastric squamous cell carcinoma was diagnosed in three horses. Clinical signs observed in all cases were weight loss, anorexia and lethargy. Respiratory signs were prominent in one case. All three horses had depressed albumin and elevated globulin and fibrinogen concentrations. Two horses were mildly anaemic. Inflammatory exudates were present in peritoneal cavities in all cases, and cytological evaluation provided a positive diagnosis of squamous cell carcinoma in two cases. Pleural fluid samples taken from two cases were also classified as inflammatory exudates, but no neoplastic cells were detected on initial examination. In all cases the neoplasms had arisen from the oesophageal region of the stomach, and had metastised throughout the abdomen. Two cases had metastatic lesions within the pleural cavity.     

Identification of an enzootic diarrhea (“Shasta river crud”) in Northern California as potomac horse fever

A disease entity known as the “Shasta River crud” (SRC) has been recognized for at least 25 years in areas of Siskiyou and Shasta counties, in far northern California. It is characterized by anorexia, lethargy, diarrhea, variable fever, and in some cases laminitis, and is tetracycline responsive. The incidence is seasonal, with cases occurring in the spring and summer months near the Shasta and Klamath rivers. Limited serologic testing has provided some suggestion that the illness may be linked to Ehrlichia risticii, the agent of Potomac horse fever. Here we report the identification of E. risticii genomic DNA in blood buffy-coat cells from horses with SRC, and so provide the first definitive evidence that this enzootic diarrhea is in fact Potomac horse fever.     

Clinical Presentation,Progression, and Management of Five Cases of Ross River Virus Infection in Performance Horses Located in Southeast Queensland: A Longitudinal Case Series

Ross River virus (RRV), a mosquito-transmitted alphavirus prevalent in Australia, is believed to cause poor performance, lethargy, and muscle stiffness in Australian horses. However, disease progression and management is poorly documented. A better understanding of disease presentation, acute therapy, and long-term management is required. The aim of the study was to describe clinical presentation, diagnosis, acute treatment, and long-term management of RRV infection in horses. This study is a series of retrospective case reports. Clinical and diagnostic data were obtained from both veterinary records, and owner interviews for five performance horses that presented with acute poor performance coupled with serologic evidence of RRV exposure. Clinical and owner reports were evaluated from the time of presentation until the horses appeared asymptomatic and had returned to normal performance. Ross River virus was suspected to be the cause of generalized muscle stiffness and poor performance in five performance horses located in southeast Queensland between 2011 and 2015. Clinical symptoms included pyrexia, tachypnea, exercise intolerance, generalized muscle stiffness, synovial effusion, and edema of the lower limbs. Serologic investigations (ELISA and/or virus neutralization assay) detected antibody responses to RRV. Horses were treated with nonsteroidal anti-inflammatory drugs (n = 5) and disease-modifying osteoarthritis drugs (n = 2). Most horses returned to previous athletic capabilities between 7 and 12 months after the onset of symptoms. Not all horses in the study had preclinical serology or submitted paired blood samples for serology, meaning assumption of acute infection in those horses was made based on clinical signs coupled with positive serology. Ross River virus is a significant but poorly understood cause of poor performance in Australian horses. This report is the only one to document longitudinal management of performance horses affected by RRV infection. Much more research is needed to gain a better understanding of this infection in horses.     

Clinical and epidemiologic features of an epizootic of equine leukoencephalomalacia

A herd of 15 mature riding horses with a history of anorexia, weight loss, and lethargy was examined. The animals had been fed a 50/50 mixture of commercial sweet feed and corn screenings contaminated with a heavy growth of Fusarium moniliforme. Thirteen of the horses had one or more neurologic signs. The most characteristic signs were profound depression and mild ataxia. Over the 19-day course of the epizootic, the horses had increasing severe neurologic deficits, including unilateral blindness and delirium. Despite the clinical appearance of dehydration, 12 horses had low PCV (16 to 27%), hematocrit (21.2 to 31.0%; determined by automated cell counter), and RBC counts (3.76 to 5.5 x 10(6) RBC/microliters). White blood cell counts were variable (4,900 to 17,000 WBC/microliters). Necropsy findings included diffuse malacia of the white matter of the frontal cortex and severe multifocal perivascular hemorrhage in the white matter of the temporal cortex, basal ganglia, anterior medulla, and pons. One horse had a hepatic lesion consisting of a mixed inflammatory cell infiltrate and bile duct proliferation. The attack rate of this epizootic was 100%. The course of disease was unusually long in some animals. In an experiment, the fusarium-infected corn screenings were fed to horses and did not cause clinical signs or alterations in blood or serum biochemical values.     

Disease features in horses with induced equine monocytic ehrlichiosis (Potomac horse fever)

Fifty-five horses were inoculated IV and/or SC with materials containing Ehrlichia risticii, ie, infected whole blood, buffy coat cells, or cell culture, to study clinical and hematologic features of equine monocytic ehrlichiosis (Potomac horse fever). Major clinical and hematologic features of induced E risticii infection were biphasic increase in rectal temperature with peak increases of 38.9 C and 39.3 C on postinoculation days (PID) 5 and 12, respectively; depression; anorexia; decreased WBC count (maximal decrease of 47% on PID 12); and diarrhea from PID 14 to PID 18. Increased WBC count was an inconsistent feature, with a maximal increase of 51.5% on PID 20. During times of decreased and increased WBC counts, lymphocyte/neutrophil ratios remained fairly constant. However, not all horses had all clinical and hematologic features, and these features were present in different degrees among horses. Increased rectal temperature, depression, anorexia, and decreased WBC count were more consistent features, whereas diarrhea developed in 73% of the horses. Of 55 horses, 39 (71%) had all clinical and hematologic features of the disease (classic disease), whereas 16 (29%) horses did not have greater than or equal to 1 of these features (nonclassic disease). The E risticii titer in the blood (ehrlichemia) was maximum during the peak increase in rectal temperature. In 55 horses, mortality was 9%. Significant differences (P greater than 0.5) in clinical and hematologic features were not detected between horses that survived and those that died of E risticii infection.     

Ehrlichial diseases.

Equine granulocytic and monocytic ehrlichiosis caused by Ehrlichia equi and E. risticii, respectively, are seasonal diseases in horses that occur throughout the United States E. equi is transmitted by lxodes ticks and causes high fever, depression, anorexia, limb edema, petechiation, icterus, ataxia, and stiffness in gait. E. risticii, also known as the agent of Potomac horse fever, causes a febrile illness with a colitis of variable severity. Its occurrence is associated with aquatic habitats. The natural route of transmission is oral, through the ingestion of E. risticii infected trematode stages either free in water or in an intermediate host, such as aquatic animals.     

Nonhematopoietic hepatic neoplasms in cats: 21 cases (1983-1988).

Nonhematopoietic hepatic neoplasms (n = 25) were diagnosed in 21 cats during a 5.5-year period. Thirteen of the neoplasms were benign bile duct adenomas and 12 were malignant, 6 of which were bile duct adenocarcinomas. All cats were greater than or equal to 10 years old, and 14 were male. Main clinical signs were anorexia and lethargy, and 15 of 21 cats had hepatomegaly. All 21 cats were feline leukemia virus-test negative. Although there was a trend toward high activities of serum alanine transaminase and aspartate transaminase, neither clinical signs nor enzyme activity were specific for diagnosis of hepatic neoplasia in the cats of this study.     

Nonlymphomatous Hepatobiliary Masses in Cats: 41 Cases (1972 to 1991)

The medical and necropsy records of 41 cats diagnosed with nonlymphomatous hepatobiliary (NLHB) masses, including neoplasia and cysts, were reviewed. Overall, benign masses (n = 27) were more common than malignant ones (n = 14). The single most common malignancy was cholangiocellular carcinoma. The median age at diagnosis was significantly lower ( P < .01) for cats with malignant rather than benign disease. Clinical signs associated with hepatobiliary neoplasia were usually vague and included lethargy, vomiting, and anorexia, often present for at least 2 weeks before presentation. Benign masses were an incidental finding in significantly more ( P < .01) of the cases than were malignant masses. Median values for alanine aminotransferase (ALT), aspartate aminotransferase (AST), and total bilirubin were significantly higher ( P < .05) in cats with malignant versus benign masses. The prognosis for malignant disease was poor, with 86% of the cats dying or being euthanatized during hospitalization. Cats with benign disease that underwent exploratory celiotomy were more likely to recover and warranted a more favorable prognosis than cats with malignant tumors. Factors associated with malignancy included age at presentation, presence of clinical signs at presentation, and specific serum chemistry changes.     

Diagnostic challenges: Equine thoracic neoplasia

The diagnosis of thoracic neoplasia in the horse can be difficult due to the nonspecific nature of the clinical signs and their overlap with other pulmonary diseases. Haematological and serum biochemical evaluation, thoracic ultrasonography, radiography, endoscopic examination, and, where appropriate, thoracocentesis and pleural fluid cytology may all be helpful in reaching a diagnosis. Granular cell tumours are the most frequently reported primary pulmonary tumours of horses. They occur as single or multiple masses adjacent to bronchi and bronchioles, and the mass typically extends into the airway, resulting in partial or complete occlusion of the lumen. Thymic tumours are classified as benign or metastatic, based on evidence of tissue invasiveness, even though they uniformly appear benign histologically. These tumours are derived from epithelial reticular cells of the thymus and are rare in horses. Other primary thoracic neoplasms originate from various pulmonary tissues and are primarily reported as single case reports: pulmonary and bronchial carcinoma and adenocarcinoma, bronchogenic squamous cell carcinoma, bronchial myxoma, pulmonary chondrosarcoma, pulmonary leiomyosarcoma and pleuropulmonary blastoma. Clinical signs of these primary pulmonary neoplasms are dependent on the tumour type and location, but commonly include chronic cough, weight loss, anorexia, fever and respiratory difficulty; ventral oedema, pleural effusion and epistaxis are also frequently observed. Mesothelioma is a rare primary pleural tumour arising from the mesothelium of the pleura, pericardium and peritoneum. The clinical presentation in horses includes weight loss, respiratory difficulty and large volume pleural effusion. The tumour appears ultrasonographically as multiple small nodules on a thick serosal surface and pleural biopsy is diagnostic. Lymphoma is the most common haematopoietic neoplasm in horses, which can present with 4 main manifestations of lesions: mediastinal, multicentric, alimentary and cutaneous. Common clinical features include chronic weight loss, lethargy, anorexia, subcutaneous oedema, lymphadenopathy, colic, bleeding tendency and diarrhoea. Coughing and laboured respiratory effort are often apparent in individuals suffering from mediastinal masses. In such instances, pleural effusion may result in severe pulmonary atelectasis and pulmonary function is significantly compromised. Haemangiosarcoma is the second most common metastatic thoracic neoplasm in horses. Disseminated haemangiosarcoma is aggressive and rapidly progressive. The clinical presentation often includes tachypnoea, pale or icteric mucous membranes, respiratory distress, epistaxis, and subcutaneous, cutaneous or intramuscular masses. Other tumour types that metastasise to the thoracic cavity include adenocarcinoma, squamous cell carcinoma, fibrosarcoma, metastatic melanoma, mastocytoma and undifferentiated sarcoma. The clinical features of these tumours are generally nonspecific and often relate more to the primary site of tumour formation.     

Ultrasonographic characteristics of splenic and hepatic lymphosarcoma in three horses.

Splenic and hepatic ultrasonography were beneficial for diagnosis of lymphosarcoma in 3 horses with anorexia, weight loss, and lethargy. Ultrasonographic abnormalities of the spleen included a large, complex, hypoechoic mass in 1 horse, multiple well-marginated, hypoechoic nodules in 1 horse, and diffuse hyperechogenicity in another horse. Ultrasonographic abnormalities of the liver included a spherical, hypoechoic nodule in 1 horse and diffuse hyperechogenicity in another. Histologic examination of ultrasound-guided biopsy specimens or aspirates revealed lymphosarcoma. Necropsy findings confirmed diagnosis of lymphosarcoma in all horses. Necropsy findings of the liver and spleen correlated well with antemortem ultrasonographic images.