Clinical findings and outcome predictors for multinodular pulmonary fibrosis in horses: 46 cases (2009-2019).

BACKGROUND: Prognostic indicators for equine multinodular pulmonary fibrosis (EMPF), an interstitial fibrosing lung disease, are poorly described. HYPOTHESIS/OBJECTIVES: Describe diagnostic findings and outcome predictors for EMPF. ANIMALS: Forty-six adult horses with EMPF. METHODS: Retrospective multicenter case series from 2009 to 2019. Radiographic (n = 27) and ultrasonographic studies (n = 19) from EMPF horses and bronchoalveolar lavage fluid (BALF) cytology from 6 EMPF and 13 asthma cases were independently reviewed and blinded to diagnosis and outcome. Associations between predictor variables and survival were assessed by predictor screening followed by Fisher's exact and Wilcoxon rank sum tests. RESULTS: Primary clinical findings were weight loss (36/46, 78%), increased respiratory effort (33/46, 72%), tachypnea (32/46, 70%), and fever (18/46, 39%). Macrophage atypia was seen in more EMPF than asthmatic horse BALF (67% vs. 8%; P = .02). Equine herpesvirus 5 (EHV-5) was detected in 24 of 30 (80%) and hyperfibrinogenemia in 25 of 28 (89%) cases. Twenty-seven of 46 horses (59%) and 11 of 45 (24%) survived to discharge and to 3 months, respectively. Three-month survival was associated with lower median (range) respiratory rates (30 [24-36] vs. 41 [30-60] breaths per minute; P = .04), and higher BALF lymphocyte:neutrophil ratios (4.7 [1.4-22] vs. 0.47 [0.11-1.9]; P = .01) and blood lymphocyte counts (1.25 [0.93-2.55] vs. 0.90 [0.70-1.24] × 109/L; P = .03). Imaging findings, EHV-5 detection, and corticosteroid treatment were not associated with survival. CONCLUSIONS AND CLINICAL IMPORTANCE: Fever is not a sensitive clinical sign of EMPF. Diagnostic testing should be pursued for horses with increased respiratory rate and effort and weight loss. The prognosis for EMPF horses is poor. Corticosteroid treatment does not improve 3-month survival.

Diagnosis, management and genetic analysis of a cat with primary copper hepatopathy.

Case summary: A 2-year-old spayed female domestic longhair cat was presented for evaluation of chronic ocular discharge and occasional vomiting. While physical examination findings were consistent with an upper respiratory infection (URI), serum chemistry results revealed increased liver enzyme activities. Histopathologic examination of a liver biopsy identified substantial centrilobular accumulation of copper in hepatocytes - strongly suggestive of primary copper hepatopathy (PCH). Retrospective cytologic examination of a liver aspirate also identified copper aggregates in hepatocytes. After transitioning to a low-copper diet, 1 year of chelation therapy with D-penicillamine achieved normalization of liver enzyme activities and resolution of persistent ocular signs. Subsequently, a long-term regimen of zinc gluconate has been successfully managing the cat's PCH for almost 3 years. Sanger sequencing of the cat's ATP7B gene, which encodes a copper-transporting protein, revealed a novel, 'likely pathogenic', single nucleotide variation (c.3670t/a [p.Trp1224Arg]), for which the cat is heterozygous. Relevance and novel information: Recommendations are described for the long-term clinical management of feline PCH - a previously attainable but unreported outcome - with considerations for mitigating the speculated oxidation-exacerbated ocular risks of concurrent URI. This report is the first to include identification of copper aggregates in a liver aspirate from a cat - evidence that liver aspirates from cats could be routinely examined for copper as is standard practice for those from dogs. The cat is also the first reported with PCH and a 'likely pathogenic' heterozygous ATP7B genotype, which suggests that normal ATP7B alleles could be recessive to or incompletely/co- dominant with deleterious ATP7B alleles in cats, as has been reported in other species.

Cytochemical staining of leukocytes and platelets in the Florida manatee (Trichechus manatus latirostris): identification of a bilobed monocyte similar to other members of the Paenungulata.

Manatees (Antillean-, Amazonian, and African-) and dugongs belong to the Order Sirenia, and when combined with elephants and rock hyraxes, form the Paenungulata. A bilobed mononuclear cell has previously been identified in elephants and rock hyraxes, but not in manatees and dugongs, with cytochemical staining identifying these cells as bilobed monocytes in elephants. The objective of this study was to characterize leukocytes (white blood cells, WBC) and platelets in blood films of Florida manatees (Trichechus manatus latirostris; n = 8) using one routine hematological (Wright-Giemsa) and eight cytochemical stains: alkaline phosphatase (ALP), α-naphthyl butyrate esterase (ANBE), chloroacetate esterase (CAE), Luna, myeloperoxidase (MPx), periodic acid-Schiff (PAS), Sudan black B (SBB), and toluidine blue (TB). Heterophils and lymphocytes comprised most of the WBC, with low numbers of eosinophils, basophils, and monocytes. Additionally, 1-3% of the WBC were bilobed mononuclear cells. Bilobed mononuclear cell proportions were similar to rock hyraxes, but lower than elephants (approximate range 20-60%). Heterophils and eosinophils were positive for MPx, ALP, SBB, and PAS, with heterophils also being positive for CAE. Most of the lymphocytes were positive for ANBE and they were variably positive for CAE. Monocytes and bilobed mononuclear cells had similar cytochemical staining reactions (variably positive for all stains, except Luna and TB), supporting a monocytic origin, like elephants. Platelets were ANBE- and PAS-positive. Luna stain was useful for identifying eosinophils and TB was uninformative. This study provides new information on the morphological features and cytochemical staining characteristics of WBC and platelets and will aid in obtaining accurate hematological data of Florida manatees.

Transient increases in glutamate dehydrogenase (GLDH) activity occur in neonatal foals.

BACKGROUND: Liver analyte measurement is important in the evaluation of sick animals. Liver injury in horses is recognized by increased glutamate dehydrogenase (GLDH), sorbitol dehydrogenase (SDH), and aspartate aminotransferase (AST) activities, whereas biliary pathology is identified by increased alkaline phosphatase and γ-glutamyl transferase (GGT) activities or bilirubin concentrations. We have observed high GLDH, but not SDH, activities in neonatal foals admitted for conditions other than liver disease. Only one previous study have evaluated GLDH activity over time in healthy neonatal foals; however, SDH activity was not measured. OBJECTIVE: We aimed to evaluate changes in liver analytes in neonatal foals over time. METHODS: We measured serum liver analytes (GLDH, SDH, GGT, AST, total, direct, and indirect bilirubin) and creatine kinase activity of 11 clinically healthy foals before and at various times after suckling until 46 days of age. Analytes were also measured in colostrum and mare serum. RESULTS: Median GLDH activities increased after birth to peak at 3-4 days of age (106 U/L, reference interval, 0-8 U/L). Median SDH activities had a lower peak at 3-4 days (15 U/L, reference interval, 0-11 U/L) and were frequently discordant with GLDH. There was no association between foal and mare serum or colostral enzyme activities. AST activity plateaued at 5-6 days, whereas GGT activity and total and indirect bilirubin concentrations peaked at 14 and 3-4 days of age, respectively. CONCLUSIONS: Transient increases in GLDH, SDH, and GGT activities and total and indirect bilirubin concentrations occur in clinically healthy neonatal foals and do not necessarily indicate relevant liver disease.

Granular variant of a histiocytic tumor on the toe of a cat: Case report and literature review.

A 16-year-old female spayed domestic shorthaired cat was examined for lameness and a mass on the fourth digit of the right hindlimb. Cytologic examination of an aspirate of the mass revealed large discrete cells admixed with low numbers of well-granulated mast cells. The discrete cells contained single to many variably sized light pink to purple granules in their cytoplasm and had pleomorphic nuclei, with intranuclear cytoplasmic inclusions. Karyomegalic, binucleated and multinucleated cells were seen. Histologic examination of formalin-fixed sections of the excised mass showed a mildly infiltrative, unencapsulated, multinodular dermal mass that extended into the subcutis and consisted of similar discrete cells. On immunohistochemical staining, the tumor cells expressed ionized calcium-binding adapter molecule 1 (Iba1) and CD18. The tumor cells did not express CD3, CD20, CD117, pancytokeratin (AE1/AE3), melanoma antigen (Melan-A), multiple myeloma oncogene-1 (MUM1), melanoma-associated antigen (PNL-2), and S-100. Low numbers of tumor cells expressed CD204 and protein gene product 9.5 (PGP9.5). Granules were variably positive for Periodic-acid Schiff (PAS) and Alcian blue. On transmission electron microscopy, the cells contained filopodia, abundant endoplasmic reticulum, and moderate numbers of low-density membrane-bound granules. This case documents a previously undescribed granular variant of a histiocytic tumor in a cat.

Case-control exercise challenge study on the pathogenesis of high serum gamma-glutamyl transferase activity in racehorses.

BACKGROUND: High serum γ-glutamyl-transferase (GGT) activity syndrome in racehorses has been associated with maladaption to exercise. Investigation of affected horses before and immediately after standard exercise may provide critical insight into the syndrome's pathophysiology. OBJECTIVES: To investigate blood biomarker changes in actively competing racehorses with high GGT activity associated with an exercise challenge. STUDY DESIGN: Case-control study. METHODS: High GGT case (age: 2-3 years) and normal GGT control (age: 2-7 years) pairs (3 Thoroughbred, 4 Standardbred pairs) at least 3 months into their training/racing season were included. Horses with a recent history of high GGT activity (≥50 IU/L) without additional biochemical evidence of liver disease were identified by veterinarians. Horses were tested again in the week prior to a planned exercise challenge to confirm persistent increases in GGT activity. Controls from the same stable with similar training/racing intensity and serum GGT activity ≤36 IU/L were matched with each case. Blood samples were obtained immediately before, 15 and 120 min after exercise. Pre-exercise serum samples were analysed for baseline select serum chemistries, selenium and vitamin E concentrations. Cortisol concentration and markers of oxidative status were measured in serum or plasma for all time points. Individual serum bile acid and coenzyme Q10 concentrations, plasma lipid mediator (fatty acids, oxylipids, isoprostanes) concentrations and targeted metabolomics analyses were performed using liquid chromatography-mass spectrometry. Serum viral PCR for equine hepaci- and parvovirus was performed in each animal. RESULTS: Cases had higher baseline concentrations of total glutathione, taurocholic acid, cortisol and cholesterol concentrations and higher or lower concentrations of specific oxylipid and isoprostane mediators, but there were no case-dependent changes after exercise. MAIN LIMITATIONS: Small sample size. CONCLUSIONS: Results indicated that glutathione metabolism was altered in high GGT horses. Enhanced glutathione recycling and mild cholestasis are possible explanations for the observed differences.

Hemostatic Testing in Companion Exotic Mammals.

The mammalian hemostatic system is highly conserved, and companion exotic mammals are commonly used as biomedical models for normal and disordered hemostasis. Challenges associated with sample collection, test validation, and test interpretation have limited the use of these tests in clinical exotic animal practice. However, evaluation of platelet counts, coagulation screening times, and fibrin(ogen) degradation products can be valuable for monitoring exotic patients with a range of disease presentations including intoxications, anemia, systemic viral disease, hepatopathy, and endocrinopathy.

A Urinary Drug-Disposing Approach as an Alternative to Intravesical Chemotherapy for Treating Nonmuscle Invasive Bladder Cancer.

The standard treatment of nonmuscle invasive bladder cancer (NMIBC) is transurethral resection of the tumors, followed by intravesical therapy (IT), which comprises a direct instillation of a solution of Bacillus Calmette-Guérin vaccine or chemotherapy into the bladder. However, the recurrence rate in this disease remains unacceptably high. IT is a local treatment that fails to reach tumors developed in the upper urinary tract (ureter and renal pelvis). The catheterization procedure required for IT is invasive, painful, and poses an increased infection risk, resulting in poor patient quality of life and compliance. There is an unmet need for a potent, comprehensive, and noninvasive option. Without chemical modifications, peptides are rapidly removed by renal clearance. This "shortcoming" can be advantageous when used as a drug carrier for directing therapy to NMIBC. Here we develop a urinary drug-disposing (UDD) approach to improve NMIBC treatment. A 12-amino acid bio-inert peptide (Bdd) that can be exclusively eliminated via renal filtration was generated for delivering the microtubule inhibitor DM1 to NMIBC with minimal nonspecific accumulation in other organs. The UDD approach prolonged survival of mice bearing human bladder tumors. Unlike IT, the treatment was given noninvasively (intravenously). Furthermore, it was more effective at suppressing tumor growth than clinically used IT (mitomycin) and safer than free DM1. The application of this UDD approach to treat kidney tumors and deliver other drugs such as doxorubicin was also demonstrated. Overall, the rapid renal clearance of peptides can be exploited to direct cancer therapies to the urinary system. SIGNIFICANCE: A noninvasive drug delivery approach that targets the urinary system overcomes the current barriers facing effective treatment of bladder cancer.

Investigating the pathogenesis of high-serum gamma-glutamyl transferase activity in Thoroughbred racehorses: A series of case-control studies.

BACKGROUND: High-serum γ-Glutamyl Transferase (GGT) activity has been associated with and thought to be a marker of maladaptation to training and possibly poor performance in racehorses, but the cause is unknown. OBJECTIVES: To investigate possible metabolic and infectious causes for the high GGT syndrome. STUDY DESIGN: Pilot case-control study and nested case-control study. METHODS: The case-control study in 2017 included 16 horses (8 cases and 8 controls with median [range] serum GGT 82 [74-148] and 22 [19-28] IU/L, respectively) from the same stable. In 2018, similar testing was performed in a nested case-control study that identified 27 case (serum GGT 50 ≥ IU/L)-control pairs from three stables for further testing. Serum liver chemistries, selenium measurements, viral PCR and metabolomics were performed. RESULTS: No differences were found in frequency of detection of viral RNA/DNA or copy numbers for equine hepacivirus (EqHV) and parvovirus-hepatitis (EqPV-H) between cases and controls. Mild increases in hepatocellular injury and cholestatic markers in case vs control horses suggested a degree of liver disease in a subset of cases. Metabolomic and individual bile acid testing showed differences in cases compared with controls, including increased abundance of pyroglutamic acid and taurine-conjugated bile acids, and reduced abundance of Vitamin B6. Selenium concentrations, although within or above the reference intervals, were also lower in case horses in both studies. MAIN LIMITATIONS: Observational study design did not allow us to make causal inferences. CONCLUSIONS: We conclude that high GGT syndrome is likely a complex metabolic disorder and that viral hepatitis was not identified as a cause for this syndrome in this cohort of racehorses. Our results support a contribution of oxidative stress and cholestasis in its pathophysiology.

Hematologic and Biochemical Reference Intervals and Urinary Test Results for Wild-caught Adult Southern Giant Pouched Rats (Cricetomys ansorgei).

Southern giant pouched rats (Cricetomys ansorgei) are muroid rodents native to subSaharan Africa. They are increasingly used as service animals because of their keen sense of smell and are primarily known for clearing minefields in Africa. The objectives of this study were to determine hematologic and biochemical reference intervals from clinically healthy wild-caught captive adult rats, to describe the cytochemical staining reactions of peripheral blood leukocytes, and to document urinalysis findings. Blood samples were collected from the coccygeal artery of 60 isoflurane-anesthetized rats (36 males and 24 females) and analyzed with automated hematologic and biochemical analyzers; manual differential cell counts were performed on modified Wright-stained blood smears. Urine was collected by cystocentesis, and dipsticks were analyzed on a urine analyzer, with visual examination of unstained sediments. Samples from a male rat with chronic renal disease were excluded from analysis. Reference intervals were determined according to guidelines established by the American Society of Veterinary Clinical Pathology. Lymphocytes were the dominant leukocyte in peripheral blood and granular lymphocytes were identified in most animals. Male rats had significantly higher RBC, absolute reticulocyte counts, and MCV than did female rats. Minor sex-associated differences in urea nitrogen concentration and GGT activity were noted. Leukocytes showed unique cytochemical staining characteristics. Small amounts of protein and bilirubin were found in the urine of rats of both sexes and of female rats, respectively, particularly in concentrated urine. These results will provide benchmarks for determining health status and identifying disease in this species of rat.

Assay variability and storage stability of the myeloperoxidase index of the ADVIA 2120i hematology analyzer in canine and equine whole blood samples.

BACKGROUND: The myeloperoxidase index (MPXI), on ADVIA hematology analyzers, reflects the mean neutrophil myeloperoxidase staining. It is used as a marker of inflammation in animals and people, but assay variability and storage stability are unknown. OBJECTIVE: We aimed to determine MPXI precision and stability with refrigerated storage of canine and equine EDTA-anticoagulated blood and compared MPXI results between two analyzers. METHODS: Inter-assay coefficients of variations (CVs) were determined from three human-based controls assayed before and after a 20- or 21-day calibration. Blood from 14-16 dogs and 26 horses was assayed 4-10 times within 1 day for intra-assay CV measurements. Median control and single run results from 18 canine and 35 equine samples were compared between analyzers. Blood from 10-12 dogs and 10-11 horses was analyzed after collection, and 24, 48, and 72 hours of refrigerated storage. RESULTS: Inter-assay CVs of controls were 10.7%-15.9% and 6.4%-9.6% before and 4.3%-7.7% and 2.8%-17.5% after calibration, for ADVIA 1 and 2, respectively. Calibration altered peroxidase gain settings and improved precision. Intra-assay CVs were 0.6%-64% and 3%-350% for canine and equine samples, respectively. Median MPXI results differed significantly between the analyzers, likely from calibration-associated changes in gains. MPXI decreased with storage, and with variable changes between animals and analyzers. Platelet clumps and lipid contributed to the variability in replicate MPXI measurements. CONCLUSION: MPXI has a higher variability in equine samples than in canine samples. Equivalent results might not be obtained between analyzers. Results change unpredictably with repeated analyses over 72 hours. MPXI measurements might only be useful in controlled research settings.

Detection of Epithelial Cell Adhesion Molecule in Feline Normal and Tumor Cell Lines and Tissues With Selected Commercial Anti-human EpCAM Antibodies.

Epithelial cell adhesion molecule (EpCAM) is a transmembrane protein expressed at intercellular junctions in epithelial cells. As an epithelial biomarker, it used for immunologic-based capture of epithelial-derived circulating tumor cells (CTCs) in human patients with different carcinomas. EpCAM expression has not been described in normal or neoplastic epithelial tissues in cats. Our goal was to find a commercial antibody that recognizes surface EpCAM expression for CTC detection. We tested two anti-human EpCAM antibodies, designated for use with flow cytometry, for detection of surface EpCAM expression on feline cell lines derived from normal mammary and renal epithelia and mammary and oropharyngeal squamous cell carcinomas in cats. Only one of the antibodies, a goat polyclonal antibody, labeled normal and neoplastic feline mammary epithelial cells and oropharyngeal squamous cell carcinoma cells; no labeling was observed for normal feline kidney epithelial cells. At low dilution, this antibody immunohistochemically stained the intercellular junctions of normal pancreatic, intestinal and mammary epithelium, as well as neoplastic mammary epithelium in feline tissues; however, oral mucosa, skin, and an oropharyngeal squamous cell carcinoma showed no positive immunostaining. The antibody only weakly bound feline squamous cell carcinoma cell lines under static adhesion. Our results indicate that EpCAM is expressed in specific epithelia in cats but is variably expressed in feline mammary tumors and oropharyngeal squamous cell carcinoma. A higher avidity cross-reactive or feline-specific antibody will be required to further investigate EpCAM expression in normal and neoplastic feline tissue or for detecting CTCs in the blood of tumor-bearing cats.

SARS-COV-2 INFECTION AND LONGITUDINAL FECAL SCREENING IN MALAYAN TIGERS (PANTHERA TIGRIS JACKSONI), AMUR TIGERS (PANTHERA TIGRIS ALTAICA ), AND AFRICAN LIONS (PANTHERA LEO KRUGERI) AT THE BRONX ZOO, NEW YORK, USA.

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) emerged as the cause of a global pandemic in 2019-2020. In March 2020, New York City became the epicenter in the United States for the pandemic. On 27 March 2020, a Malayan tiger (Panthera tigris jacksoni) at the Bronx Zoo in New York City developed a cough and wheezing with subsequent inappetence. Over the next week, an additional Malayan tiger and two Amur tigers (Panthera tigris altaica) in the same building and three lions (Panthera leo krugeri) in a separate building also became ill. The index case was anesthetized for diagnostic workup. Physical examination and bloodwork results were unremarkable. Thoracic radiography and ultrasonography revealed a bronchial pattern with peribronchial cuffing and mild lung consolidation with alveolar-interstitial syndrome, respectively. SARS-CoV-2 RNA was identified by real-time, reverse transcriptase PCR (rRT-PCR) on oropharyngeal and nasal swabs and tracheal wash fluid. Cytologic examination of tracheal wash fluid revealed necrosis, and viral RNA was detected in necrotic cells by in situ hybridization, confirming virus-associated tissue damage. SARS-CoV-2 was isolated from the tracheal wash fluid of the index case, as well as the feces from one Amur tiger and one lion. Fecal viral RNA shedding was confirmed in all seven clinical cases and an asymptomatic Amur tiger. Respiratory signs abated within 1-5 days for most animals, although they persisted intermittently for 16 days in the index case. Fecal RNA shedding persisted for as long as 35 days beyond cessation of respiratory signs. This case series describes the clinical presentation, diagnostic evaluation, and management of tigers and lions infected with SARS-CoV-2 and describes the duration of viral RNA fecal shedding in these cases. This report documents the first known natural transmission of SARS-CoV-2 from humans to nondomestic felids.

PAR1 regulation of CXCL1 expression and neutrophil recruitment to the lung in mice infected with influenza A virus.

BACKGROUND: Protease-activated receptor 1 (PAR1) is expressed in various immune cells and in the lung. We showed that PAR1 plays a role in Coxsackievirus B3 infection by enhancing toll-like receptor 3-dependent interferon- ß expression in cardiac fibroblasts. OBJECTIVES: We investigated the role of PAR1 in a mouse model of influenza A virus (IAV) infection. METHODS: We used mice with either a global deficiency of PAR1, cell type-specific deficiencies of PAR1, or mutation of PAR1 at the R41 or R46 cleavage sites. RESULTS: PAR1-deficient mice had increased CXCL1 expression in the lung, increased neutrophil recruitment, increased protein levels in the bronchoalveolar lavage fluid, and increased mortality after IAV infection compared with control mice infected with IAV. Results from mice with cell type-specific deletion of PAR1 indicated that PAR1 expression by hematopoietic cells suppressed CXCL1 expression, whereas PAR1 expression by endothelial cells enhanced CXCL1 expression in response to IAV infection. PAR1 activation also enhanced polyinosinic:polycytodylic acid induction of interleukin-8 in a human endothelial cell line. Mutation of the R46 cleavage site of PAR1 was associated with increased CXCL1 expression in the lung in response to IAV infection, which suggested that R46 signaling suppresses CXCL1 expression. CONCLUSIONS: These results indicate that PAR1 expression by different cell types and activation by different proteases modulates the immune response during IAV infection.

Severe Acute Respiratory Syndrome-Coronavirus-2 (SARS-CoV-2): A Perspective Through the Lens of the Veterinary Diagnostic Laboratory.

The SARS-CoV-2 pandemic has resulted in unprecedented challenges to veterinary diagnostic laboratories. These challenges include partial or complete shutdowns, interrupted courier services, disruptions in workflow and diagnostic testing, new physical distancing practices, protocol development or enhancement for handling samples from high-risk or susceptible species, and fulfilling requirements for pre-test permission approval from state and federal veterinary agencies, all of which have been implemented to prevent or minimize exposure and transmission of SARS-CoV-2 locally or regionally. As in people, SARS-CoV-2 infects animals through direct animal-to-animal contact and aerosol transmission between animals. Humans can also infect pets or other animals in their care and, although human-to-human transmission is the main route of viral spread in people, infected animals and specimens of their bodily fluids or tissues are a potential source of infection for veterinarians and technical or laboratory personnel that are handling them. In this perspective, we discuss how SARS-CoV-2 has necessitated rapid changes in laboratory operation to minimize zoonotic risk to personnel and to implement tests for identifying the virus in animals. The pandemic has highlighted the adaptability and quick response of veterinary diagnosticians to an emerging infectious disease and their critical role in maintaining animal health, while synergizing with and protecting human public health.

From People to Panthera: Natural SARS-CoV-2 Infection in Tigers and Lions at the Bronx Zoo.

Despite numerous barriers to transmission, zoonoses are the major cause of emerging infectious diseases in humans. Among these, severe acute respiratory syndrome (SARS), Middle East respiratory syndrome (MERS), and ebolaviruses have killed thousands; the human immunodeficiency virus (HIV) has killed millions. Zoonoses and human-to-animal cross-species transmission are driven by human actions and have important management, conservation, and public health implications. The current SARS-CoV-2 pandemic, which presumably originated from an animal reservoir, has killed more than half a million people around the world and cases continue to rise. In March 2020, New York City was a global epicenter for SARS-CoV-2 infections. During this time, four tigers and three lions at the Bronx Zoo, NY, developed mild, abnormal respiratory signs. We detected SARS-CoV-2 RNA in respiratory secretions and/or feces from all seven animals, live virus in three, and colocalized viral RNA with cellular damage in one. We produced nine whole SARS-CoV-2 genomes from the animals and keepers and identified different SARS-CoV-2 genotypes in the tigers and lions. Epidemiologic and genomic data indicated human-to-tiger transmission. These were the first confirmed cases of natural SARS-CoV-2 animal infections in the United States and the first in nondomestic species in the world. We highlight disease transmission at a nontraditional interface and provide information that contributes to understanding SARS-CoV-2 transmission across species.IMPORTANCE The human-animal-environment interface of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is an important aspect of the coronavirus disease 2019 (COVID-19) pandemic that requires robust One Health-based investigations. Despite this, few reports describe natural infections in animals or directly link them to human infections using genomic data. In the present study, we describe the first cases of natural SARS-CoV-2 infection in tigers and lions in the United States and provide epidemiological and genetic evidence for human-to-animal transmission of the virus. Our data show that tigers and lions were infected with different genotypes of SARS-CoV-2, indicating two independent transmission events to the animals. Importantly, infected animals shed infectious virus in respiratory secretions and feces. A better understanding of the susceptibility of animal species to SARS-CoV-2 may help to elucidate transmission mechanisms and identify potential reservoirs and sources of infection that are important in both animal and human health.

Correction: Equid Herpesvirus Type 1 Activates Platelets.

[This corrects the article DOI: 10.1371/journal.pone.0122640.].