ASSESSMENT OF PULMONARY FUNCTION IN RESPIRATORY AND CARDIAC DISORDERS OF DOG
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Date
2019-09-30
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COLLEGE OF VETRINARY AND ANIMAL SCIENCES MANNUTHY, THRISSUR
Abstract
Eighteen adult Labrador retriever dogs of either sex above 1 year of age
presented to the University Veterinary hospital, Mannuthy with history of clinical
signs suggestive of cardio-pulmonary disease were considered for the study.
Based on clinical, radiographic, electrocardiographic and echocardiographic
examination, respiratory and cardiac diseases were confirmed in 18 dogs. The
study consisted of four groups. Group A: Control (Apparently healthy animals)
(n=6), Group B: Animals with upper respiratory tract diseases (n=6), Group C:
Animals with lower respiratory tract diseases (n=6) and Group D: Animals with
cardiac involvement showing respiratory signs (n=6). These animals were
subjected to pulmonary function tests (spirometry and arterial blood gas analysis).
The different types of upper respiratory tract diseases diagnosed in canine
patients under study were tracheal stenosis (33.33 %), tracheitis (33.33 %),
tracheal collapse (16.66 %) and pharyngitis (16.66 %). The diseases were more
common in middle aged male dogs. The clinical signs included nasal discharge,
respiratory distress, dyspnoea, cough, syncope, snoring and anorexia.
Auscultation of trachea revealed inspiratory dyspnoea, stridor and stertor. The
radiographic findings were evidence of narrowing of trachea in the cervical region
and thoracic inlet, mild to moderate thickening of tracheal membrane and
enlargement of pharyngeal region.
In Group B, pneumonia, tracheobronchitis, pleural effusion and metastasis
were noted in 50, 16.66, 16.66 and 16.66 per cent of the cases, respectively. The
diseases were more common in middle aged male dogs. Respiratory abnormalities
like dyspnoea, tachypnoea, cough (productive or non productive), fever, cyanosis
and wheezing, crackles and harsh respiratory sounds on auscultation of lungs were
the common clinical examination findings recorded. Radiographic appearance of
lung pathologies in dogs with lower respiratory tract diseases showed bronchial,
alveolar, vascular and interstitial or mixed patterns, peribronchial markings,
increased soft tissue opacity, obscured cardiac silhouette and diaphragm, air
bronchograms, lobar sign, lung consolidation and multiple miliary lesions
depending upon the involvement of the anatomical structures.
The cardiac disorders diagnosed were dilated cardiomyopathy (66.66 %),
mitral valvular disease (16.66 %) and idiopathic pericardial effusion (16.66 %).
The main clinical signs included anorexia, dyspnoea, cough, exercise intolerance,
weak femoral pulse, ascites, limb oedema, syncope, tachycardia, murmurs,
pulmonary crackles and muffled heart sounds on thoracic auscultation.
Electrocardiographic and radiographic findings suggested of chamber
enlargement and pericardial effusion was confirmed by echocardiography.
The shape of the spirometric flow-volume loops obtained from control
group was similar to the alphabet ‘D’ in appearance. Flattening and prolonged
phase of inspiratory and expiratory portion of the loops were seen in dogs with
upper respiratory tract and lower respiratory tract diseases, respectively.
Flattening of both inspiratory and expiratory portion of the loops was observed in
dogs with cardiac diseases. Significant decrease was noticed in the mean values of
tidal volume in Group B, C and D in comparison to normal healthy animals. A
significantly higher values of respiratory rate were recorded in group C and D in
comparison to healthy animals and no difference was observed between Group A
and B. There was significant decrease in the mean values of inspiratory time in
Group C and D, whereas the mean values of inspiratory time in Group B was
significantly increased compared to healthy animals. The mean values of
expiratory to inspiratory time ratio in Group C and D showed significant increase,
whereas mean values of expiratory to inspiratory time ratio in Group B showed
significant decrease when compared to Group A.
Arterial blood gas analysis revealed significant evidence of hypoxemia in
affected dogs. Statistically significant decrease was noticed in the mean values of
partial pressure of oxygen and saturated oxygen and significant increase was
noticed in the mean values of Alveolar-arterial (A-a) gradient in Group B, C and
D compared to apparently healthy animals.
Description
Submitted in the partial fulfillment of the requirement for the degree of Master of Veterinary Science in Veterinary Clinical Medicine, Ethics and Jurisprudence.