Disseminated Rhodococcus equi infection in two goats.

Rhodococcus equi infection was diagnosed in two goats from the same herd. At necropsy, numerous caseating granulomas were disseminated throughout the liver, lungs, abdominal lymph nodes, medulla of right humerus, and the right fifth rib of goat No. 1, and the liver of goat No. 2. Histopathologic examination confirmed the presence of multiple caseating granulomas in these organs. Numerous gram-positive and Giemsa-positive coccobacilli were identified within the cytoplasm of macrophages. Aerobic bacterial cultures of the liver and lung from both goats yielded a pure growth of R. equi. R. equi antigens were immunohistochemically identified in caseating granulomas from both goats. However, the 15- to 17-kd virulence antigens of R. equi were not detected, suggesting possible infection by an avirulent strain of this organism.     

Disseminated Rhodococcus equi infection in dromedary camels (Camelus dromedarius)

Rhodococcus (R). equi, a recognized pathogen in horses, is emerging as a human opportunistic pathogen, especially in immunocompromized people. It affects also New World camelids, but there are no reports of R. equi infection in Old World camelids yet. Four cases of disseminated R. equi infection in adult breeding dromedaries occurred at one camel farm near Dubai within 16 months of each other. At necropsy the lungs were diffusely consolidated with large caseous areas. Histology revealed severe suppurative to necrotising pneumonia with multiple encapsulated abscesses. Immunohistochemistry enabled the detection of 15- to 17-kDa antigens (VapA) of R. equi in the lung sections. High numbers of R. equi were isolated from the lung lesions as well as from liver, spleen and mediastinal lymph nodes, indicative of septicaemia. The isolated strains were PCR-positive for the specific virulence plasmid (VapA-Gen) of R. equi, indicating virulent strains and containing an 85-kb type I plasmid. This is the first report of disseminated R. equi infection in Old World camelids. Since adult camels in general do not suffer from bacterial caused pneumonia (except tuberculosis), this is a new emerging disease for camels.     

Rhodococcus equi pleuropneumonia in an adult horse

A 10-year-old warmblood gelding was evaluated for intermittent pyrexia, dullness, weight loss, and progressive respiratory disease. Multifocal necrotic pneumonia and pleuritis due to Rhodococcus equi infection was diagnosed. Case management is discussed, as well as factors that may have led to this rare cause of pleuropneumonia in an adult horse.     

Osteomyelitis of the scapulohumeral joint associated with Rhodococcus equi and unresponsive to antibiotherapy in a foal

This case report describes the treatment and outcome of a 3.5-month-old lame foal, with a history of pneumonia associated with Rhodococcus equi. Clinical examination identified osteomyelitis of the scapulohumeral joint. The unusual location of the Rhodococcus equi osteomyelitis unresponsive to prevention and adequate treatment led to euthanasia of the patient. Post-mortem findings confirmed bronchopneumonia due to Rhodococcus equi as well as the osteomyelitis of the scapulohumeral joint. This case highlights that Rhodococcus equi should be considered as a pathogen in extrapulmonary locations such as septic arthritis and osteomyelitis in foals with history of bronchopneumonia. Early and aggressive treatment should be considered.     

Rhodococcus equi pneumonia in an adult horse

A 20‐year‐old, Thoroughbred mare in the fifth month of gestation was examined for weight loss, pyrexia and lethargy. Physical examination, ultrasonography and radiography revealed a severe abscessing pneumonia and a dead fetus. The mare did not respond to symptomatic treatment and died suddenly. Necropsy revealed multifocal pulmonary abscessation. Rhodococcus equi was isolated from the lungs, liver and kidneys. Specific immune function of the mare and presence of the virulence associated protein A (VapA) of the R. equi isolated was not determined. It is likely that immunosuppression is required for systemic R. equi infections in adult horses; however, it is unknown if VapA is necessary to produce disease in adult horses.     

Multiple extra-pulmonary disorders associated with Rhodococcus equi infection in a 2-month-old foal

A 2-month-old Thoroughbred filly was referred to Hagyard Equine Medical Institute for further evaluation of acute pyrexia and a suspected intra-abdominal abscess based on abdominal ultrasonography performed in the field. Initial examination revealed bilateral uveitis, polysynovitis, a large internal abdominal abscess and pneumonia. A transtracheal wash confirmed the presence of a multi-sensitive strain of Rhodococcus equi. Anaemia and thrombocytopenia were noted during hospitalisation. Results of a Coombs test were consistent with an immune-mediated haemolytic process. Recurrent pyrexia, abdominal discomfort and severe respiratory distress unresponsive to intensive medical support motivated euthanasia followed by necropsy after 30 days of treatment. Overall, six extra-pulmonary disorders were simultaneously diagnosed despite the lack of pulmonary pyogranulomas.     

Rhodococcus equi occipital bone osteomyelitis,septic arthritis and meningitis in a neurological foal

This case report describes a 3‐month‐old female Thoroughbred foal that presented following the acute onset of apparent respiratory distress, abnormal head carriage and severe neurological deficits referable to the brainstem or cranial cervical spinal cord. Ultrasonography revealed an abscessing pneumonia. Radiographs did not show evidence of bony pathology at the atlanto‐occipital region, an area consistent with the observed neurological deficits. With magnetic resonance imaging, atlantal and occipital osteomyelitis, atlanto‐occipital septic arthritis, and atlanto‐axial synovitis were diagnosed. Brainstem meningitis and extradural compression were also revealed. Culture of the right occipitoatlantal joint and cerebrospinal fluid yielded a pure culture of Rhodococcus equi. These findings and multifocal R. equi abscessation were confirmed at necropsy.     

Medical management of a large intra-abdominal mass caused by Rhodococcus equi in a foal

A 4-month-old Thoroughbred filly presented with pyrexia, inappetence and diarrhoea. Abdominal ultrasonography revealed a multilobulated abdominal mass that was determined to be associated with the caecum using computed tomography. Computed tomography also identified mesenteric lymphadenopathy and a pulmonary mass in the left caudal lung lobe. Percutaneous aspiration of the abdominal mass yielded pure growth of Rhodococcus equi. The filly responded in a positive fashion to the administration of clarithromycin, rifampin and gallium maltolate. Follow-up computed tomography revealed complete resolution of the abdominal mass and lymphadenopathy. Extrapulmonary disorders associated with R. equi should be considered even when thoracic ultrasonography reveals no evidence of pulmonary pathology. Although intra-abdominal abscesses have a grave prognosis, successful treatment is possible. Gallium maltolate can be safely administered to foals and may improve patient outcomes.     

Acute noncardiogenic pulmonary edema in an anesthetized Nubian goat kid

ObservationsA 1-month-old Nubian goat presented for sialocyst resection. Physical examination and bloodwork were unremarkable. While pre-oxygenating, the goat was sedated with midazolam and morphine (0.1 mg kg^?1 each) intravenously (IV). General anesthesia was induced 5 minutes later with 1.7 mg kg^?1 propofol. Sevoflurane was administered in oxygen without assisted ventilation via a cuffed orotracheal tube. Throughout the first 85 minutes of anesthesia, the goat was well-oxygenated (SpO₂, ≥97%), ventilating adequately (Pe′CO₂, 36–48 mmHg), and had normal mean arterial blood pressure (MAP, 60–85 mmHg). Blood-gas values at 45 minutes were consistent with adequate ventilation on oxygen. At 75 minutes, the goat moved in response to surgical stimulation, requiring additional propofol (0.4 mg kg^?1). After 10 minutes, MAP dropped precipitously to 40 mmHg and frequent multiform premature ventricular contractions (PVCs) were observed. Crystalloids, hetastarch, and dopamine (5 μg kg^?1 minute^?1) were administered to correct the hypotension. Arterial blood-gas analysis revealed that the goat had become hypoxemic (PaO₂, 50 mmHg). Intermittent positive pressure ventilation (IPPV) was initiated. Subsequent blood-gas analysis did not show significant improvement in PaO₂ (53 and 56 mmHg, respectively). Occasional PVCs were observed thereafter. Surgery ended, and sevoflurane and IPPV were discontinued. The goat was extubated within 7 minutes and received 100% oxygen by mask. Diffuse crackles were ausculted over both hemithoraces. Suspecting pulmonary edema, furosemide (1 mg kg^?1) was administered IV. Radiographs taken immediately post-operatively revealed a severe, caudodorsal airspace (alveolar) pattern, confirming the diagnosis. Respiration improved considerably within an hour with nasal oxygen and two additional doses of furosemide.ConclusionsThe goat developed acute, drug-induced, noncardiogenic pulmonary edema in response to the second dose of propofol.     

Presumed immune‐mediated hemolytic anemia in two foals with Rhodococcus equi infection

Objective – To describe the clinical presentation, case management, and outcome in 2 foals with Rhodococcus equi infection associated with presumptive severe immune‐mediated hemolytic anemia. Series Summary – Two foals diagnosed with R. equi pneumonia on the basis of tracheal wash cultures, thoracic radiographs, and thoracic ultrasonography were concurrently diagnosed with hemolytic anemia. Both foals required whole blood transfusions, and were treated with the antimicrobial combination of rifampin and a macrolide (eg, clarithromycin, erythromycin, or azithromycin). Dexamethasone was used to prevent further hemolysis in both foals, and to treat acute lung injury/acute respiratory distress syndrome in 1 of the foals. Both foals survived, and required prolonged antimicrobial therapy. New or Unique Information Provided – Although extra‐pulmonary disorders are commonly diagnosed in foals infected with R. equi, hemolytic anemia is rarely described. Dexamethasone is considered the treatment of choice for immune‐mediated hemolytic anemia, but may be contra‐indicated in foals with severe bacterial infections. In these foals, a relatively low dose and short duration of dexamethasone was utilized in an attempt to minimize immune suppression, although early discontinuation in 1 foal precipitated a second hemolytic crisis.     

Effect of prepubertal nutrition on cellular apoptosis and proliferation in at term placenta of Anglo‐Nubian goats

The aim of this study was to evaluate the effect of feed restriction with or without monensin supplementation, followed by a re‐feeding period on cellular apoptosis and proliferation in at term placenta of Anglo‐Nubian goats. To evaluate the induction of apoptosis through the intrinsic pathway, proteins Bax and Bcl‐2 were determinated. The apoptosis was related with the cell proliferation indices through Ki67 determination. The treatments were applied for 250 days and were (a) ad libitum feeding (control; n = 5); (b) restricted feeding at 70% of control (restricted; n = 7); and (c) restricted with monensin supplementation (monensin; n = 7). After treatments, all the animals were fed to support their requirements. After parturition, 27 placentas were gathered. The placental cellular structure was studied by high‐resolution light microscopy and transmission electron microscopy; the cellular proliferation was determined by Ki67 index, and Bax and Bcl‐2 proteins were localized by immunohistochemical analysis. Differences in cell proliferation through the Ki67 index were found in monensin group placentas. Monensin supplementation stimulated the placental cell proliferation reversing the effect of feed restriction during the peripuberal period. A significant increase of Bcl‐2 in placentas of restricted group was found, and it would provide a protective effect on the placental structure. A lack of the Bcl‐2 protective effect was observed in control and monensin group placentas, probably meaning that the observed apoptosis would be induced through the intrinsic signalling pathway. A balance between apoptosis and cell proliferation is necessary to maintain tissue homoeostasis during caprine placental development.     

Rhodococcus equi (Prescottella equi) vaccines; the future of vaccine development

For decades researchers have been targeting prevention of Rhodococcus equi (Rhodococcus hoagui/Prescottella equi) by vaccination and the horse breeding industry has supported the ongoing efforts by researchers to develop a safe and cost effective vaccine to prevent disease in foals. Traditional vaccines including live, killed and attenuated (physical and chemical) vaccines have proved to be ineffective and more modern molecular‐based vaccines including the DNA plasmid, genetically attenuated and subunit vaccines have provided inadequate protection of foals. Newer, bacterial vector vaccines have recently shown promise for R. equi in the mouse model. This article describes the findings of key research in R. equi vaccine development and looks at alternative methods that may potentially be utilised.     

Cervical vertebral osteomyelitis in a 4‐month‐old foal

Vertebral body osteomyelitis in the cervical spine secondary to Rhodococcus equi has been treated both medically and surgically. This Case Report describes a 4‐month‐old foal exhibiting severe neurological signs from R. equi vertebral body osteomyelitis. Rapid, significant resolvement of neurological signs was noted in this case with surgical debridement and use of synthetic bone filler. The outcome suggests that aggressive surgical therapy in conjunction with synthetic allograft may be indicated in treatment of cervical vertebral body osteomyelitis.     

Radiographic and computed tomographic appearance of caseous lymphadenitis in a goat

A 2‐year‐old Boer doe was presented with respiratory distress and severe inspiratory dyspnea. Cervical and thoracic radiographs revealed a marked retropharyngeal soft tissue mass effect, several mineralized pharyngeal and retropharyngeal structures, and a pulmonary mass. Computed tomography (CT) revealed a severely enlarged right medial retropharyngeal lymph node, which caused laryngeal compression, leading to upper airway obstruction. Multiple cervical and thoracic lymph nodes, and the pulmonary mass had an irregular layered/laminated pattern of mineralization. Imaging findings were consistent with caseous lymphadenitis, and further confirmed with culture, necropsy, and histopathology. This is the first report of CT appearance of caseous lymphadenitis in a goat.     

Hereditary xanthinuria in a goat

A 2‐year‐old mixed breed goat was presented for a 1‐day history of anorexia and 1 week of weight loss. Serum biochemistry disclosed severe azotemia. Abdominal ultrasound examination showed decreased renal corticomedullary distinction, poor visualization of the renal pelves, and dilated ureters. On necropsy, the kidneys were small, the pelves were dilated, and the medulla was partially effaced by variably sized yellow nephroliths. Histologically, cortical and medullary tubules were distended by yellow‐brown, multilayered crystals. Stone composition was 100% xanthine. Exonic sequencing of xanthine dehydrogenase (XDH) and molybdenum cofactor sulfurase (MOCOS) identified 2 putative pathogenic variants: a heterozygous XDH p.Leu128Pro variant and a homozygous MOCOS p.Asp303Gly variant. Variant frequencies were determined in 7 herd mates, 12 goats undergoing necropsy, and 443 goats from genome databases. The XDH variant was not present in any of these 462 goats. The MOCOS variant allele frequency was 0.03 overall, with 3 homozygotes detected. Hereditary xanthinuria is a recessive disorder in other species, but the XDH variant could be causal if the case goat is a compound heterozygote harboring a second variant in a regulatory region not analyzed or if the combination of the XDH and MOCOS variants together abolish XDH activity. Alternatively, the MOCOS variant alone could be causal despite the presence of other homozygotes, because hereditary xanthinuria in humans often is asymptomatic. Ours is the first report describing the clinical presentation and pathology associated with xanthine urolithiasis in a goat. The data support hereditary xanthinuria, but functional studies are needed to conclusively determine the causal variant(s).     

MAGNETIC RESONANCE IMAGING IN FOALS WITH INFECTIOUS ARTHRITIS

The magnetic resonance (MR) imaging findings of foals with infectious and noninfectious arthritis are described. Six foals with infectious arthritis and three foals with noninfectious arthritis were grouped based on synovial fluid analysis results and examined with radiography and MR imaging. Four out of six foals with infectious arthritis had osseous lesions in MR images indicative of osteomyelitis and only 4/19 lesions were detected on digital radiographs. The three foals with noninfectious arthritis had no osseous lesions in MR images or radiographically. Of the six joints that had osseous lesions detected with MR imaging, three had at least one lytic lesion detected radiographically. Osseous lesions in the epiphysis, metaphysis, and physis appeared in MR images as T2W, short tau inversion recovery, and proton density hyperintense foci with a hypointense halo. The same lesions appeared hyperintense in the 3D RSSG water excitation pulse sequence but lacked a surrounding hypointense halo. Most joints of foals with infectious arthritis had heterogenous signals within the synovial fluid whereas all of the nonseptic joints had homogenous synovial fluid signals. MR imaging appears to be better than radiography in the detection of osseous lesions in foals diagnosed with infectious arthritis and may be a valuable screening test for the presence of osteomyelitis.