Case Description—An 8-year-old 38-kg (84-lb) castrated male German Shepherd Dog cross was evaluated because of respiratory distress secondary to pneumothorax (detected radio-graphically prior to referral).
Clinical Findings—CT of the thorax confirmed the presence of pneumothorax and revealed pulmonary blebs without evidence of infiltrative pulmonary changes. A tentative diagnosis of primary spontaneous pneumothorax was made.
Treatment and Outcome—Exploratory median sternotomy revealed emphysematous changes along the margins of all lung lobes, with the ventral margins of the left cranial, right cranial, and right middle lung lobes most affected. Partial lobectomies of the ventral aspects of these lobes were performed. Histologic examination of tissue samples from the lung lobes revealed diffuse smooth muscle hypertrophy of the terminal and respiratory bronchioles with moderate numbers of peribronchiolar eosinophils. Mucus plugs and mucous cell metaplasia within the airway epithelium were also evident. After surgery, clinical signs resolved and the dog was discharged from the hospital 2 days later. Eight months after surgery, the dog developed a mild cough, and treatment with prednisolone (tapering dosage starting at 0.5 mg/kg [0.023 mg/lb], PO, q 12 h) was initiated. Dosage reduction resulted in recurrence of coughing; however, with continued prednisolone treatment at a dosage of 0.5 mg/kg, PO, once daily, the dog was not coughing at 10 months after surgery.
Clinical Relevance—Reactive bronchopneumopathy should be included as a differential diagnosis for spontaneous pneumothorax in dogs.
Objective—To determine the effects of 2 weeks of intense exercise on expression of markers of pulmonary venous remodeling in the caudodorsal and cranioventral regions of the lungs of horses.
Procedures—Tissue samples of the caudodorsal and cranioventral regions of lungs were obtained before and after conditioning and 2 weeks of intense exercise. Pulmonary veins were isolated, and a quantitative real-time PCR assay was used to determine mRNA expression of matrix metalloproteinase-2 and −9, tissue inhibitor of metalloproteinase-1 and −2, collagen type I, tenascin-C, endothelin-1, platelet-derived growth factor, transforming growth factor (TGF)-β, and vascular endothelial growth factor (VEGF). Protein expression of collagen (via morphometric analysis) and tenascin-C, TGF-β, and VEGF (via immunohistochemistry) was determined.
Results—Exercise-induced pulmonary hemorrhage was detected in 2 horses after exercise. The mRNA expression of matrix metalloproteinase-2 and −9, tissue inhibitor of metalloproteinase-2, TGF-β, and VEGF was significantly lower in pulmonary veins obtained after exercise versus those obtained before exercise for both the caudodorsal and cranioventral regions of the lungs. Collagen content was significantly higher in tissue samples obtained from the caudodorsal regions of the lungs versus content in samples obtained from the cranioventral regions of the lungs both before and after exercise. Exercise did not alter protein expression of tenascin-C, TGF-β, or VEGF.
Conclusions and Clinical Relevance—Results of this study indicated 2 weeks of intense exercise did not alter expression of marker genes in a manner expected to favor venous remodeling. Pulmonary venous remodeling is complex, and > 2 weeks of intense exercise may be required to induce such remodeling.
Case Description—5 horses were evaluated because of decreased appetite, weight loss, fever, cough, tachypnea, and respiratory distress.
Clinical Findings—Tachycardia, tachypnea, increased respiratory effort, lethargy, fever, poor body condition, and nasal discharge were detected in various combinations on initial physical examination. Evaluation of the lower portion of the respiratory tract via radiography and ultrasonography revealed a severe nodular interstitial pattern. Histologic examination of lung tissue revealed interstitial expansion of alveolar parenchyma with collagen, intraluminal accumulation of neutrophils and macrophages within the alveoli, and occasional intranuclear inclusion bodies within alveolar macrophages. Equine herpesvirus type 5 was detected in samples of lung tissue, bronchoalveolar lavage fluid, or both via polymerase chain reaction assay in all cases. A diagnosis of equine multinodular pulmonary fibrosis (EMPF) was established.
Treatment and Outcome—Horses were provided supportive treatment and were administered a variety of medications including corticosteroids and acyclovir. Two horses survived and returned to their previous level of activity. Three horses were euthanized because of either deterioration of clinical condition (n = 2) or failure to improve within 4 weeks of initiation of treatment (1).
Clinical Relevance—EMPF should be considered as a differential diagnosis for adult horses with interstitial pneumonia and should be suspected on the basis of characteristic radiographic, ultrasonographic, and histopathologic findings. Equine herpesvirus type 5 is found in association with EMPF; although the exact pathogenic role this virus plays in EMPF is unknown, equine herpesvirus type 5 may be an etiologic agent or cofactor in the development of EMPF.