Disseminated pleomorphic rhabdomyosarcoma in a horse.

An 8-y-old National Show Horse mare was presented for evaluation of pneumonia and laminitis. Harsh bronchovesicular sounds were auscultated throughout both lung fields, and the mare had signs of moderately painful laminitis. Thoracic ultrasonography revealed lung consolidation throughout the dorsal aspect of both lungs, and radiography revealed an extensive diffuse-to-patchy bronchointerstitial lung pattern. The mare's clinical condition rapidly deteriorated, and euthanasia was elected. On postmortem examination, the lungs, omentum, spleen, liver, adrenal glands, kidneys, and femur contained 0.5-2.5-cm, firm, tan nodules. Histologically, the lungs, spleen, liver, kidneys, adrenal glands, omentum, left eye, and femur were infiltrated by bundles and nests of pleomorphic polygonal-to-spindloid cells intermixed with frequent multinucleate cells. Lymphatic vessels in the affected tissues were frequently distended with tumor emboli. Neoplastic cells were diffusely positive for vimentin, desmin, sarcomeric actin, myoblastic differentiation protein 1, and myogenin, supportive of the diagnosis of rhabdomyosarcoma (RMS), which is a rare neoplasm in horses. Cross-striations were not evident with H&E or phosphotungstic acid-hematoxylin stains. Markedly pleomorphic neoplastic cells, multinucleate cells, and lack of cross-striations suggested the subclassification of pleomorphic RMS.

Head and neck squamous cell carcinoma with heterotopic ossification, lymphovascular invasion, and nodal and pulmonary metastases in a 23-year-old Morgan gelding.

Primary squamous cell carcinoma of the head and neck occurs in the skin or squamous epithelial lining tissues of the oral cavity, pharynx, larynx, and sinonasal tract. Although it is a common tumor in horses, distant metastatic spread to the lung is rare. This report describes a case of metastatic pulmonary squamous cell carcinoma in a 23-year-old Morgan gelding. The clinical signs displayed by this gelding in some ways mimicked the typical presentation of equine multinodular pulmonary fibrosis or thoracic lymphoma. The postmortem diagnosis in this case was head and neck squamous cell carcinoma, but a primary site of origin could not be ascertained. Cancer-associated heterotopic ossification (HO) was also identified in this case; this is an exceedingly rare finding with equine pulmonary neoplasia. Key clinical message: Careful physical examination should be undertaken in all horses presenting with clinical signs of intrathoracic disease. Clinical and radiographic abnormalities in this case of pulmonary metastatic disease resembled some of those associated with interstitial pneumonia. Rarely encountered in domestic animal species, there has been only 1 previous report of HO in a case of oronasal carcinoma in a horse.

Carcinome épidermoïde de la tête et du cou avec ossification hétérotopique, envahissement lymphovasculaire et métastases ganglionnaires et pulmonaires chez un hongre Morgan de 23 ans. Le carcinome épidermoïde primitif de la tête et du cou survient dans la peau ou les tissus épithéliaux squameux de la cavité buccale, du pharynx, du larynx et du tractus naso-sinusien. Bien qu'il s'agisse d'une tumeur courante chez les chevaux, la propagation métastatique à distance au poumon est rare. Ce rapport décrit un cas de carcinome épidermoïde pulmonaire métastatique chez un hongre Morgan de 23 ans. Les signes cliniques présentés par ce hongre imitaient à certains égards la présentation typique de la fibrose pulmonaire multinodulaire équine ou du lymphome thoracique. Le diagnostic post-mortem dans ce cas était un carcinome épidermoïde de la tête et du cou, mais un site d'origine primaire n'a pas pu être déterminé. L'ossification hétérotopique associée au cancer (HO) a également été identifiée dans ce cas; il s'agit d'une découverte extrêmement rare avec la néoplasie pulmonaire équine.Message clinique clé :Un examen physique attentif doit être entrepris chez tous les chevaux présentant des signes cliniques de maladie intrathoracique. Les anomalies cliniques et radiographiques dans ce cas de maladie pulmonaire métastatique ressemblaient à certaines de celles associées à la pneumonie interstitielle. Rarement rencontré chez les espèces animales domestiques, il n'y a eu qu'un seul signalement antérieur d'HO dans un cas de carcinome oronasal chez un cheval.(Traduit par Dr Serge Messier).

Concurrent chronic lymphocytic leukemia and primary hyperparathyroidism in a mule.

A 26-year-old mule gelding was evaluated for chronic weight loss and decreased appetite. The mule had been losing weight and intermittently hypophagic for approximately 7 months. Laboratory analysis of whole blood and plasma identified severe total hypercalcemia, marked hypophosphatemia, markedly increased parathyroid hormone concentration, and marked lymphocytosis. A sestimibi scan intended to identify parathyroid gland tissue was nondiagnostic. Results of flow cytometry and PCR for antigen receptor rearrangement (PARR) were consistent with a B cell lymphoproliferative disorder, likely chronic lymphocytic leukemia (CLL). Although not previously described concurrently, these conditions may sometimes arise together, complicating definition of the underlying mechanism for weight loss and hypercalcemia in aged equids.

Exodontia associated bacteremia in horses characterized by next generation sequencing.

Bacteremia resulting from dental surgery is increasingly recognized as a health risk, especially in older and immunocompromised patients. Dentistry-associated bacteremia can lead to remote infections, as exemplified by valvular endocarditis. Emerging evidence points to a novel role played by oral cavity commensals in the pathogenesis of diabetes, respiratory disease, cardiovascular disease, and adverse pregnancy outcomes. Whether dental extraction, a commonly undertaken procedure in old horses, causes bacteremia has not been reported extensively. In a prospective clinical study using next generation sequencing (based on bacterial 16S rRNA), the circulating blood microbiome was characterized before and at 1 h following extraction of incisor, canine or cheek teeth from 29 adult horses with dental disease. 16S rRNA gene sequencing results from the blood microbiome were compared with those from gingival swab samples obtained prior to extraction at the location of the diseased tooth. Bacteremia associated with translocated gingival commensals was demonstrated in horses undergoing exodontia and was, in some cases, still evident one hour post-operatively.