Signalment & History
A 3 year old MN Domestic Short Haired Cat presents with a history of increased breathing effort and coughing. The owner reports intermittent dysorexia and coughing. On physical examination, the patient is bright, alert and responsive. His heart and respiratory rate are 150 bpm and 80 bpm, respectively. His temperature is 101.7 F. Mucous membranes are pink and moist and CRT is <2”. Femoral pulses are strong and synchronous. Wheezes are heard on auscultation. When palpated, lymph nodes and abdomen are within normal limits.
Findings
There is a mild, diffuse, bronchial pulmonary pattern throughout the lung lobes. In addition an increase in opacity of the right middle lung lobe is seen. This increased opacity within the right middle lung lobe border effaces the adjacent cardiac silhouette on the ventrodorsal view. Moreover, a lobar sign between the right middle and the right caudal lung lobes is noted on the left lateral view. Also, a cavitated lesion, measuring approximately 7 x 4 mm, is seen superimposed over the peripheral aspect of the right middle lung lobe. The remainder of the study is within normal limits.
Diganosis
You found mild diffuse bronchial pulmonary pattern, right middle lung lobe collapse and right middle lung lobe cavitation. The radiographic findings are suggestive of feline asthma with presence of right middle lung lobe collapse likely secondary to chronic bronchial obstruction/inflammation and right middle lung lobe cavitation (consider abscess formation or emphysema). Differential diagnoses such as allergic or infectious bronchitis are not ruled out.
Conclusions
This patient underwent medical therapy for feline ashtma and soon returned to his normal activity and appetite. Evidence of a bronchial pattern is usually related to bronchial inflammation (peribronchial edema is less common). Chronic bronchial diseases can lead to different consequences that may be visible radiographically as lobar collapse, bronchiectasis, spontaneous rib fractures, pulmonary hyperinflation, and bronchial mineralization. Lobar collapse secondary to chronic bronchial obstruction, even though not common, is most frequently observed in asthmatic cats, and the right middle lung lobe is often the lobe being affected. The collapsed right middle lobe usually appears as a homogeneous, triangular opacity, more conspicuous in the left lateral view.
Asthma is a common lower airway inflammatory disease in cats thought to be allergic in cause. The median age at presentation is 4-5 years, even though many cats have an history of chronic signs, and the Siamese breed seems to be overrepresented. The three major features of asthma are: airway inflammation, airway hyperresponsiveness and airflow limitation, and airway remodeling. The 2 major common clinical presentation are the asthmatic crisis with open mouth breathing, tachypnea, and increased expiratory effort, and the chronic presentation of cough and increased breathing effort. Classic findings on PE are: cough, expiratory wheeze and tachypnea. Often cough is easy to elicit with gentle tracheal palpation in these patients. Common radiographic findings are: bronchial/bronchointerstitial pattern and collapse of a lung lobe(+++ R middle) likely secondary to mucus trapping and atelectasis. Lack of radiographic changes does not rule out feline asthma. Feline asthma is most commonly treated with lifelong steroids with or without bronchodilators. Nowadays different experimental therapies targeted to reverse the underlying immunopathology are under investigation.
References
Update on Feline Asthma.Trzil JE, Reinero CR. Vet Clin Small Anim. 2014; 44, 91-105.
