What is Your Diagnosis? Dyspnoeic Cat

A 4-year-old, 3.5-kg, entire male cat was presented with severe lethargy and increasing dyspnoea and respiratory distress, nasal discharge, excessive salivation, loss of appetite and weight loss, over the past few days. He was an indoor-outdoor cat and was fed a homemade diet. 
On physical examination, severe laboured abdominal breathing, nasal discharge and excessive salivation were evident. Mucous membranes were slightly hyperaemic, with no jaundice or cyanosis observed. There was no jugular distension. Gingival capillary refill time was 2 seconds. Body temperature was 39.2 °C. On palpation, the mandibular lymph nodes were mildly enlarged, while no abdominal mass was detected. On thoracic auscultation, bronchial crackles in the right lung lobe and dysphonia in the left lobe were noted. The cat was initially stabilised with oxygen therapy (10 L/min) by oxygen chamber. Venous blood (jugular venepuncture), urine (mid-stream free-flow) and faecal samples (rectal swab) were taken for laboratory analysis. Abdominal ultrasonography, thoracic and abdominal radiography, and thoracic computed tomography (CT) were performed.


Anamnestic data
A four-year-old male cat weighing 3.5 kg was brought with severe lethargy and increasing dyspnoea and respiratory distress, nasal discharge, excessive salivation, loss of appetite and weight loss that were persisting for a few days. It was an indoor cat with access to the outdoors and it was fed homemade diet.
In physical examination, severe laboured abdominal breathing, nasal discharge and excessive salivation were established. Mucous membranes were slightly hyperaemic, with neither jaundice nor cyanosis. Th ere was no jugular distension. Gingival capillary refi ll time was determined to be 2 seconds. Body temperature was 39.2 °C. During palpation, mildly enlarged mandibular lymph nodes were observed and no abdominal mass was detected. On thoracic auscultation, bronchial crackles in the right lung lobe and dysphonia in the left lobe were noted. Th e cat was initially stabilised with oxygen therapy (10 liters /minute) by oxygen chamber. Venous blood (jugular venepuncture), urine (mid-stream free-fl ow) and faecal samples (rectal swab) were taken for laboratory analysis. Abdominal ultrasonography, thoracic and abdominal radiography, and thoracic computed tomography (CT) examinations were performed.

Laboratory Results
A complete blood count (using a MS4e®, Melet Schloesing Laboratoires, France), serum biochemistry (using a BT 3000® plus analyser, Biotecnica Instruments SpA, Rome, Italy), and acid/base, blood gas and electrolyte measurements (using an ABL90 Flex® blood gas analyser, Radiometer Medical ApS, Bronshoj, Denmark) were performed. Th e results are presented in Tables 1 -3 respectively.  Feline leukaemia virus (FeLV) antigen, feline immunodefi ciency virus (FIV) antibody and feline coronavirus (FCoV) antibody tests (ASAN PHARM® Co. Ltd, South Korea) were performed according to the manufacturer's instructions and were all negative. Urinalysis using a refractometer revealed specifi c gravity of 1035. Th e urine was transparent and dark yellow in colour. Urine dipstick (URIT-31®, India) revealed a pH of 6.0, protein 1+, trace amount of glucose and negative bilirubin and ketones. Microscopic examination of urine

Diagnostic Imaging
Abdominal ultrasonography revealed no abnormalities in the morphology and echogenicity of the abdominal organs and no eff usion was detected. Ventrodorsal and lateral thoracic radiographs are shown in Figure 1. CT was performed using a Toshiba® Asteion machine (Asteion, Toshiba Medical Systems Corporation, Japan) in helical thoracic scanning mode, using 120 kV, 100 mA and 3 mm section thickness values. Prior to the CT, the cat was sedated with dexmedetomidine (Domitor®, Zoetis) at 40 mcg/kg dosage according to the patient's weight. Representative CT images are shown in Figure 2. Dyspnoea is a common fi nding in cats and is oft en the only symptom of a thoracic disease. A wide variety of conditions such as viral and bacterial diseases, neoplasms, mycotic infections, tracheal diseases such as collapse and stenosis, cardiac diseases and tracheal diseases such as collapse, stenosis were reported to be causative (Blaxter, 1986;Sharp, 2013). Aft er all the above-mentioned information and applied diagnostic tests and methods, the following questions arise: What is your interpretation of these laboratory tests and imag-

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ing results as they relate to this case? What are your diff erential diagnoses? Are there any further tests that you would perform?

Clinical Pathology
Polycythaemia with a moderate to severe prerenal azotaemia was noted. Th ese combined fi ndings support the presence of signifi cant dehydration (Pavelski et al., 2018). In the leukogram, an increase in granulocytes, lymphocytes and monocytes were observed. Further interpretation was required such as assessment of a blood smear in order to determine the types of granulocytes, like whether there was a left -shift and to evaluate cell morphology, especially of the lymphocytes. An infl ammatory leukogram was highly likely. Th erefore, lymphocytes may refl ect antigenic stimulation or lymphoid leukaemia (Wang et al., 2014). Th rombocytopenia in the presented case was the result of clumping of thrombocytes (pseudo thrombocytopenia) which is a common issue in cats and might be secondary to blood sampling technique and handling of peripheral blood (Sumner and Rozanski, 2013). Th e mild increase in creatine kinase and aspartate aminotransferase were likely the result of muscle ischaemia from dehydration and recumbency, while marginal hypocholesterolaemia was probably due to inanition. Th e importance of the marginal increases in alkaline phosphatase and total bilirubin were moot (Bart et al., 2000). Acidbase results revealed a marked metabolic acidosis (decreased pH and bicarbonate concentration and increased base defi cit), with secondary respiratory alkalosis (decreased pCO2). Th e metabolic acidosis explains the hyperkalae-mia. It was likely due to dehydration, which also explains the hyperchloraemia (Sumner and Rozanski, 2013). Apart from hypersthenuria, the urinalysis was unremarkable.

Radiographs and CT images
A severe left mediastinal shift , hyperinfl ation of the right lung lobe, diff use infi ltration of bronchial tissue and a stomach dilated with gas are shown in Figure 1A (ventrodorsal view). In Figure 1B (left lateral view), a radiopaque tumour-like granulomatous structure in the carina is shown. No cardiomegaly was apparent.
A solitary tumour-like structure (red arrow) with mineralized opacity in the left medial lung lobe and carina and heterogeneous hypodense areas (orange arrows) interpreted as necrotic and granulomatous lesions are shown in Figure 2A. Severe mediastinal shift is apparent in Figure 2B. Total consolidation of left lung lobe is shown in Figure 2C (left lung lobe and heart). No pleural, pericardial, or pulmonary eff usions were evident.

Diff erential diagnoses
Based on the pulmonary imaging fi ndings, diff erential diagnoses considered were focal pneumonia, granulomatous lesions, primary or metastatic lung tumors. Th e most common causes of pneumonia in cats are bacterial. However, fungal, parasitic and viral pneumonia should also be considered (Blaxter, 1986;Cohn, 2009). For further diff erential diagnosis, it was decided to take bronchoalveolar lavage fl uid (BALF) and fi ne needle aspiration from the aff ected lung and to prepare the collected sample for culture. Due to the exacerbated respiratory distress in the patient during imaging examinations, the planned further diff erential diagnostic methods could not be performed and the treatment phase was initiated immediately.

Treatment and Outcome
Th e cat was hospitalized and intravenous (IV) fl uid therapy (0.9% isotonic saline, with vitamin-amino acid supplements; Duphalyte®, Zoetis, 10 mL/kg), antibiotics (ceft riaxone, 25 mg/kg IV), corticosteroids (prednisolone, 1 mg/kg IV), nebulization (salbutamol, 100 mcg) and oxygen therapy (oxygen chamber, 10 L/min) were administered. Despite the treatment, the general condition of the cat did not improve. Humane euthanasia was performed at the re-quest of owner aft er 2 days aft er admission to the hospital. Cat necropsy was performed.

Pathological Examination
During the necropsy, multiple grey-white granulomatous foci (approximately 1 cm, between 0.75 -1.55 cm) on the lungs were observed. Th e bronchial lymph nodes in the middle of both lung lobes were markedly enlarged (approximately 4.5 cm). Th ere was a white-coloured mucopurulent exudate in the trachea and on the left caudal lobe aft er sectioning. Th ere were large whitish grey areas, which were more severe in the cranial lobe of the right lung, oval-round foci characteristics spreading over large areas in the caudal lobes, without exudate leakage on cross-sectioning. Th e enlarged lymph nodes were whitish in colour on sectioning with solid consistency. Cardiac examination revealed clotted blood in both ventricles ( Figure 3). Although there were minimal and insignifi cant macroscopic changes in other organs, sampling for histopathology was considered to be useful.
Diff use necrosis in the lungs and typical granuloma structures consisting of a small number of lymphocytes, many plasmacytes and epithelioid histiocytes, fi brocytes, fi broblasts and collagen threads around these necrotic foci were determined during routine HE staining of histopathologic examination. In some parts of the lungs, alveolar structures were completely defi cient, and were fi lled with neutrophil leukocytes, alveolar macrophages and shed epithelial cells. Similar fi ndings were observed in the bronchi and bronchioles. In addition, degeneration of bronchial epithelium and severe hyperplasia and desquamation of glands were detected. Th rombus and severe haemorrhagic leaks were noted in the pulmonary vessels. In addition, pale eosinophilic structures with oval-spheroid structure (approximately 20 μm), especially surrounding the necrotic areas in the lung, were observed. Th ese structures were determined to be positive using PAS and GMS staining. No acid-resistance bacteria were found in the ZN staining. Granulomatous lesions were observed both in the aff ected lymph nodes and in the lungs. Degeneration and desquamation in the tubular epithelium of the kidneys, protein-rich fl uid in the lumen, plasmahistiocytic cell infi ltration in the interstitium and an increase in the fi brous tissue were detected. Congestion in the liver, atrophy of hepatocytes and compensation hypertrophy of the vena centralis were observed. In addition to the increase in the connective tissue of the pancreas, degeneration and desquamation were observed in the duct epithelium ( Figure 4). It was reported that no bacterial agent could be isolated in microbiological analyses (48 hours, routine set of culture media was Mac-Conkey agar as the tissue materials were mostly purulent).

DISCUSSION
In the present case, a defi nitive diagnosis of a diff use granulomatous pneumonia with severe mediastinal shift caused by pulmonary Cryptococcosis was established based on clinical, laboratory and necropsy fi ndings.
Th e fi rst approach of dyspnoeic cats is to determine the localization of the lesion in the respiratory tract, lung lobe or pleural space and to make diff erential diagnosis on the basis of the patient's anamnesis, signalment, physical, laboratory and imaging fi ndings. Since the mediastinum is in contact with the facial surfaces of the neck and retroperitoneal space, pneumomediastinum, diaphragmatic hernia, pleural eff usion, atelectasis and masses can be detected in the presence of mediastinal shift (Blaxter, 1986;Cohn 2009). Although the exact etiology of this pathological condition is unclear in many cases, it is known to be highly correlated with viral infections such as feline leukaemia and feline immunodefi ciency virus (Newman and Schaible, 2019). Studies have reported that fi xed shift of mediastinum is associated with mass lesions such as scoliosis, pneumonectomy, atelectasis, pleural operations, eff usion or granulomatous structures (Pavelski et al., 2018). In our case, histopathological examination confi rmed that mediastinal shift detected in radiographic examination was associated with diff use granulomatous lesions.
As stated by various researchers (Bart et al., 2000;Cohn, 2009), radiographic examination is one of the most useful diagnostic tools in cats with respiratory distress and should be done with caution in dyspnoeic cats. Lateral and dorsoventral or ventrodorsal imaging is essential for complete evaluation (Elsmo et al., 2018). Radiopaque areas were seen in the left thoracic region on ventrodorsal radiological examination. Radiopaque granulomatous appearance in the mediastinal and carina regions was noted on lateral radiography. Although the use of CT in feline thorax has been rarely described, feline CT anatomy has been reported by Samii et al. (1998). In the present case, unilateral lymph node enlargement and mediastinum invasion were detected in the CT examination. In addition, patterns with diff erent opacity as a result of air loss in the lungs were detected. Hypodense areas refer to necrotic debris. With CT imaging of feline thorax, diff erential diagnosis of granulomatous lesions, pulmonary abscesses, primary lung tumours, metastatic lung tumours, pneumonia, congenital or parasitic cysts can develop. Necrotic areas in granulomatous lesions are generally observed in a heterogeneous structure on CT images (Foster and Martin, 2011). Th e structures interpreted in the CT image of our case are the following: thoracic spine, ribs, sternum, muscular thoracic wall, pleural space and diaphragm, respectively. Subsequently, the mediastinum was evaluated along with the trachea, oesophagus, thymus and the heart. Finally, bronchi and lungs were examined. As a result, heterogeneous necrotic areas were detected within diff use granulomatous lesions with severe mediastinal shift . With this systematic examination, not only was the obvious pathological condition determined, but the changes that could aff ect the treatment and prognosis were also observed. In addition to bacterial, viral, fungal and parasitic pneumonia and bronchopneumonia, allergic and idiopathic infl ammatory changes in the lung are oft en manifested as marked changes in density and diff erent distribution patterns of the alveolar space. Specifi c CT fi ndings of diff erent infl ammatory lung diseases have not yet been established in dogs and cats, but some general characteristics have been identifi ed. CT fi ndings oft en show a tendency to soft tissue opacifi cation, which is evident in fungal pneumonia, and associated perihilar lymphadenopathy (Roden and Schuetz, 2017). In the present case, the lesions detected by CT imaging are similar to the reported fi ndings of fungal pneumonia.
Feline necrotic pneumonia has been reported before (Sharp, 2013). Although cats and dogs with necrohemorrhagic pneumonia associated with extraintestinal Escherichia coli and Bartonella henselae (Sharp, 2013;Sumner and Rozanski, 2013) are generally evaluated as subclinical, various clinicopathological abnormalities such as anaemia, fever, neurological dysfunction, endocarditis and pyelogranulomatous myocarditis and diaphragmatic myositis may be evident. In addition, Elsmo et al. (2018) reported that necrotic interstitial pneumonia and suppurative myocarditis developed due to B. henselae infection in their study on three Florida pumas, diff use tracheal haemorrhage, thoracic eff usion, lung colour change, pulmonary edema, and duodenal haemorrhage and lymphadenomegaly developed in necropsy fi ndings. Th ey also reported that the most important microscopic fi nding was acute, fi brinonecrotic, and haemorrhagic interstitial pneumonia. In the present case, alveolar collapse with mediastinal shift , diff use granulomatous structures and surrounding necrotic areas, severe haemorrhage in the lung parenchyma, mucopurulent leakage in the respiratory tract were detected in the necropsy, and the diagnosis of diff use granulomatous pneumonia with mediastinal shift was confi rmed. In addition, fungal agents were observed with GMS and PAS staining of spheroid structures around the necrotic areas.
Fungal infections are generally characterized by granulomatous or pyogranulamatous pneumonia (Sumner and Rozanski, 2013). Th e lungs are considered the primary site for human Cryptococcal infection. Although pulmonary Cryptococcal infections have rarely been reported in cats, pulmonary lesions were reported in 29% of cats with radiographic abnormalities and 38% in necropsy in a previous study (Sura et al., 2007). In the lung histopathology of pulmonary Cryptococcus infection, pathogens can be detected within the transparent areas that are not stained around the necrotic lung tissue. Th ese pathogens appear as an oval fungal organism of various sizes, with a shell-like blue-grey or red staining. Th e necrotic area surrounded by many macrophages with vacuoles and also fi brosis with minor lymphocyte infi ltration may be seen. It was reported that in the necrotic areas, with PAS staining eosinophilic, with GMS staining brown-black stained fungal cell walls can be seen (Vogl et al., 2015). In the present case, the histopathological examination fi ndings of necrotic areas in the lung tissue were consistent with the fi ndings of previously reported Cryptococcal infections. Roden and Schuetz (2017) reported that this type of infections may be accompanied by necrotized or non-necrotized granulomas. In some cases, the organism may not be detected in GMS or PAS staining and, in these cases, polymerase chain reaction (PCR) or fungal serology can be performed from tissue samples. Lack of BALF sampling, PCR analysis, or fungal serology are the limitations of this clinical report.
Dyspnoeic cats are usually cause emotional distress to their owners. Minimizing patient stress is very important and it can be diffi cult to apply the appropriate diagnostics to decide the best treatment protocol for the patient. A composed, logical approach that involves clinical observation, laboratory analysis, thoracic radiography and ultrasonography, CT and, where necessary, echocardiographic examinations are vital. In most cases, the protocol that was followed in our case is suffi cient -applying empirical treatment, achieving successful stabilization and retrenching the list of diseases to be considered in diff erential diagnosis.
In this clinical report, the diagnosis of diff use granulomatous pneumonia, which was established aft er imaging techniques were performed following by non-specifi c clinical and laboratory fi ndings, was confi rmed in histopathological examination and it was found that it was complicated with fungal pneumonia as a result of positive GMS and PAS staining. Th e histopathological fi ndings were consistent with Cryptoccocosis infection. No bacteria were detected in the culture of tissue samples. Although a systemic examination protocol is important for a successful diagnosis and treatment in dyspnoeic cats, this is very diffi cult for clinicians. In this presented manuscript, the diagnostic diffi culty of dyspnoeic cats was stated over a cat case with respiratory distress due to diff use granulomatous pneumonia accompanied by necrotic areas and complicated with Cryptoccocosis infection. It was concluded that the management protocol which was followed in the present case would be useful for the diff erential diagnosis and management of dyspnoea in cats for clinicians.