Internal Medicine Diagnostics-Thoracic Cavity

Sheila M. McGuirk, D. V.M., M.Sc. Department of Veterinary Physiology and Pharmacology College of Veterinary Medicine The Ohio State University Columbus, Ohio 432 JO

The most valuable tools of the trained veterinarian are the tic evaluation is based in part on the acoustic accuracy of the ability to perform a complete physical examination, inter­ stethoscope. However, the acoustics of any stethoscope will pret the findings, make some logical conclusions based on reflect the acoustics of the human when it is worn. 1 The these findings, and design a course of therapy to return the diaphragm of the stethoscope amplifies high frequency patient to normal function. The successful diagnostician sounds while attenuating low frequencies. 2 Poor quality or may perfect his clinical exam by perfecting his ability to cracked diaphragms will attenuate all frequencies. The bell is interpret what he finds or by employing more sensitive used to amplify low frequency sounds. The shallow, bowl­ diagnostic tools in order to gain more specificity in defining shaped bells have no useful high frequency response at all. and treating the problems he sees. Diagnosis of problems in The tu bing of the currently available stethoscopes are either the thoracic cavity are often overlooked. More often than single or double. Although the single tube is more compact not the problem stems from the failure to perform a good and subject to less extraneous noise, it is subject to examination of the chest. Avoidance of the thoracic cavity, irregular distortion patterns and suffers from considerable however, is the result of confusion over i~terpretation of loss of output at high frequencies. The double tube stetho­ what is seen and heard. The purpose of this paper is to scopes amplify high frequency sounds but they are often review some of th~ diagnostic methods used in physical more cumbersome to use. The stethoscope with fused double examination of the thoracic cavity. The focus will be on tubes has the same acoustical advantage of the double tubes auscultation since this is the most useful diagnostic while being more compact. With tubes of increasing length procedure every veterinarian can perform. both high and low frequency sounds will become progress­ 0 "'O Physical examination of the begins with inspection ively more damped. The earpieces should be tight fitting to (D of the animal. At this time a decision can oftentimes be made avoid air leaks and admission of extraneous noise. Only ~ ~ whether the problem is thoracic or abdominal. Hallmarks of when one auscults the thoracic cavity in relative quiet can the (") (D disease in the chest are: labored breathing (prolonged trained ear distinguish sounds generated in the chest from 00 00 inspiration or expiration), marked thoracic or abdominal extraneous noise. 0-...... 00 excursions with each breath, flared nostrils, or open mouth The acoustic system is made up of: (I) the source ,-+- '"i breathing. Cardiovascular disease may be heralded by producing vibrations within the body which are transmitted ~ distended jugular , abnormal jugular pulsations or through tissue to the wall of the chest; (2) the stethoscope, ~...... edema. Palpation of the thoracic cage may reveal thrills (in which receives vibrations at the surface of the skin and 0p the cardiac dullness area), friction rubs, fractured , or transmits them to the ear; and (3) the ear, itself, which . permits one to hear vibrations as sounds. Auscultation is the most important tool used in the By auscultating the cardiac area of either the left or right diagnosis of diseases of the chest. The majority of clinical side, one should always hear 2 distinct sounds for each car­ conditions involving the chest can be diagnosed by careful diac cycle. The normal range for the rate of the cow is auscultation alone. Under the best circumstances other between 60 and 80 beats per minute. The first heart sound dianostic procedures (ECG, radiograph, ultrasound, (S 1) occurs at the onset of ventricular contraction (systole) endoscopy) can be implemented for confirmation of the and is produced basically by the closure of the tricuspid and diagnosis but the bovine practitioner must rely on the stetho­ mitral (AV) valves and partially by the opening of the scope alone. Besides being the most useful diagnostic pulmonic and aortic (semilunar) valves. 3 procedure available, auscultation takes a small amount of The second heart sound (S2) follows S 1 and marks the end time, it yields a great amount of information, and it is cost of systole. It is generated mainly by closure of the semilunar effective. The drawbacks are few. Skill is required for inter­ valves but the opening of the A-V valves may also contribute pretation of information gained by using the stethoscope to genesis of the sound. This sound may be variably split and communication is often difficult because of confusing with respiration in the normal animal. Consistent splitting of terminology, which is especially true of sounds. the S 2 with every cardiac cycle may be suggestive of pulmo­ The requirements for productive auscultation are a good nary hypertension, the most common cause of the latter in quality, comfortable stethoscope. The accuracy of diagnos- cattle being hypoxia (high altitude or brisket disease).

APRIL, 1983 69 The first heart sound is louder, longer, and lower pitched are rare in cattle but may be associated with valvular than S 2 and is heard best at the apex of the heart. The second endocarditis. In cases such as the latter, the diastolic heart sound is heard best at the base of the heart, the murmur is also accompanied by a systolic murmur ("to and location of which is reached by forcing the stethoscope be­ fro murmur"). In the young calf a continuous (systolic and tween the elbow and thorax and moving dorsally up under diastolic) murmur is the sign of a patent ductus arteriosus. (Q) the triceps. The intensity of both sounds depends on the n The murmurs or sounds which occur with pericarditis 0 vigor of ventricular contraction, valve structure, chest (traumatic) are distinctive in cattle. The "washing machine" '"a '-< conformation, and type of disease process (if any) present. or splashing sounds can be heard at the left base and at the ...... '"i (JQ In addition to S 1 and S 2, the astute practitioner may hear apex during systole and diastole. Distinct cardiac sounds are g S 4, which precedes S 1, or S3, which follows S 2. The fourth often muffled by the pericardia) effusion. heart sound is a low frequency sound generated by atrial Cardiac arrhythmias in cattle are rarely primary signs of contraction, and heard best at the heart base. It may be cardiac disease. They usually occur with gastrointestinal timed very closely to S 1, giving a sound which is difficult to disease (atrial fibrillation, bradycardia) electrolyte disorders distinguish from a split S 1. The third heart sound is also a (atrial or ventricular premature beats), excitement, viral low frequency sound, which is heard best at the apex of the infection (myocarditis), or other disorders characterized by heart, and is generated by ventricular filling. •Auscultation of severe metabolic derangement (hypocalcemia, hypercalce­ 3 distinct cardiac sounds is termed a gallop rhythm. A mia). The arrhythmias usually resolve with correction of the presystolic gallop (S 4-SrS2) is normal in cattle. The primary condition and therefore require no specific therapy. significance of a protodiastolic gallop (S 1-S 2-S 3) is The atrial arrhythmias which are present in adult questionable if no other signs of heart disease are present. lymphosarcoma usually indicate specific involvement of the Interpretation of cardiac murmurs is relatively easy if the heart. practitioner is familiar with the origin of heart sounds, can Auscultation of the can also be rewarding in the locate the position (apex vs. base) and side (left vs. right) information that it yields. However, interpretation of lung where the murmur is loudest, and knows the age and medical sounds and the confusing terminology used to describe lung history of the animal. Congenital murmurs, the most sounds often leads to a reluctance to complete this part of common of which is the ventricular septal defect (VSD) in the physical exam. The bovine practitioner must cultivate cattle, are heard in young animals, whereas acquired his ability to auscultate since radiography and the other murmurs occur most commonly in adults. Acquired more sophisticated diagnostic tools of the small animal murmurs are commonly caused by vegetative endocarditis, veterinarian are not always practical. The practitioner .§ usually involve the tricuspid valve, and occur in cows with begins his examination of the lungs by distinguishing nor- g intermittent fever, and other signs of a persistent infection. ma! breath sounds from the added (adventitious) sounds ~ Cardiac murmurs which occur between S and S are generated by pathologic processes. Evaluation of lung (") 1 2 (D 00 systolic murmurs. In cattle early systolic low intensity sounds is best during deep respiratory efforts, especially 00 murmurs at the left heart base are not uncommon and are when optimal quiet is not possible. Deep breathing can be 0...... 00 ,-+- considered "functional" or ejection sounds. The functional transiently produced by holding off the nostrils for a minute '"i murmur is often associated with fever, excitement, or and then ausculting the chest immediately after release. Sus­ ~ anemia. The defects of pulmonic stenosis (PS) and aortic tained deep respiratory efforts can be produced by putting a ~...... stenos is (AS) may produce a similar murmur at the left heart plastic bag loosely over the muzzle of the cow, thereby 0p base but are rare in cattle unless they are caused by valvular forcing the cow to rebreathe her expired air. Variations in endocarditis. A "relative" pulmonic stenosis murmur may lung sounds will occur with differences in age, respiratory accompany a harsh right sided murmur in young calves and pattern, chest thickness, area of the chest being auscultated, is very suggestive of a VSD. and the amount of di sease present. 4 The systolic murmur heard best at the left apex of the Normal lung sounds can be divided into bronchial heart is usually mitral valve regurgitation. This lesion is (tracheal), vesicular, and bronchovesicular sounds.4 Bron­ uncommon in cattle compared to horses and dogs and, when chial breath sounds are those heard with the stethoscope it occurs, is generally a sign of severe myocardial disease and over the trachia. The sounds are characterized by having dilation of the ventricle, such as with Vitamin E-Se clearly audible inspiratory and expiratory sounds. They deficiency. have been likened to harsh, tubular sounds. 4 Vesicular A right-sided systolic murmur in cattle is generally found sounds are also normal breath sounds heard over the lungs. with either a VSD or tricuspid valve insufficiency. Tricuspid These soft, "sipping" sounds are thought to be generated by insufficiency (Tl) will occur most often in older animals with the lobar and segmental bronchi normally. Smaller airways chronic infection who have acquired vegetative valvular may contribute to sound production in disease conditions. endocarditis. The murmur of TI is heard best at the right Under conditions of quiet respiration, vesicular sounds may base. The murmur produced by a VSD occurs most often at become inaudible in late expiration. The term "broncho­ the right sternal border and is accompanied by a left basilar vesicular" is applied to sounds with characteristics which are 5 murmur of relative PS. Diastolic murmurs ( occur after S 2) intermediate between bronchial and vesicular sounds.4,

70 THE BOVINE PROCEEDINGS-No. 15 Bronchovesicular sounds may be heard when the patient is tinguished from the case in which extraneous sounds (hair breathing deeply. It is not uncommon to hear the descrip­ and skin sounds, heart sounds, gastrointestinal sounds) tion of harsh or rough lung sounds used. This term usually render the normal breath sounds inaudible. refers to an increased intensity of normal breath sounds, When auscultation of the chest has been completed, most particularly those of low frequency. The clinical significance practitioners will have completed the thoracic cavity exam. of harsh sounds is questionable. The animal breathing Following will be a brief review of some other diagnostic rapidly from heat or excitement will have harsh lung sounds. aids which may be useful for examination of the thoracic The cow with IBR may also have harsh or rough breathing cavity and the indication for their use. sounds. Percussion of the chest is a useful diagnostic tool when it Adventitious or added lung sounds are sounds produced is performed frequently. The tools for percussion by pathologic processes which can be further classified into (percussion hammer and spoon) are inexpensive and easy to discontinuous and continuous sounds. Discontinuous transport. The percussion border of the cow is very steep sounds, known also as crackles, were formerly called rales. compared to other species. At the fifth intercostal (IC) The confusion over interpretation of such things as dry rales space, the border is at the costochondraljunction. From this for interstitial pulmonary edema has led to the recent change space it moves dorsally in a straight line to the level of the in nomenclature. Crackles are intermittent, non-musical scapulo-humoral at the seventh IC space, mid thoracic sounds which have been described as clicking, popping, and level at the ninth IC space, and parallel with the ileum at the bubbling.4 The sounds may be generated by a number of eleventh IC space. Percussion is useful when pleural fluid, mechanisms such as bubbling of secretions in airway (in pulmonary consolidation, or emphysema is suspected. The severe pulmonary edema or bronchopneumonia or by the normal resonance will be replaced by dull, solid sounds in sudden opening of a diseased airway late in inspiration in the case of fluid or consolidation. The line between dullness lungs that inflate asynchronously such as in fibrinous and normal resonance may be uniform in the case of pleural pneumonia, fibrosis, or interstitial pulmonary edema. fluid. On the other hand, emphysema is accompanied by an Crackles can be further subdivided into coarse and fine increased or drum-like resonance and extension of the crackles, a distinction formerly used for dry and moist rales, percussion border beyond normal limits. respectively. Coarse crackles are louder than fine crackles Radiography of the chest for most bovine practitioners is and have been described as gurgling or bubbling. These relatively impractical except for calves. In calves, a chest sounds are heard in bronchopneumonia and late pulmonary radiograph is an extremely useful prognostic tool. It is not 5 edema.4, Fine crackles are likened to the cracking of only helpful to clarify the meaning of sounds which are 0 "'O cellophane and may be heard with interstitial edema, difficult to interpret but to define distribution and severity (D interstitial pneumonia, or chronic fibrosis. of pulmonary disease. It can be utilized to evaluate progress ~ Adventitious sounds of the continuous type are known as ~ with therapy in the valuable calf. (") (D wheezes or formerly as rhonchi. They are produced when a Electrocardiography is used almost exclusively for the 00 narrowed airway oscillates between being opened and determination of aberrant cardiac rhythms since limb lead 00 0.. 5 ...... nearly closed as air passes through it.4, The pitch of the criteria for cardiac enlargment patterns are not well defined 00 ,-+- sound produced is related to the velocity of the air moving in the cow. Three attachment sites only are used for the '"i ~ 6 through it rather than the size of the airway. Wheezes can be base-apex lead. Electrocardiography is used when one ~...... high pitched (sibilant) or low pitched (sonorous). Most wishes to be more specific about the diagnosis of a cardiac 0 p wheezes occur during expiration, though severe upper arrhythmia, such as following calcium therapy. An respiratory obstruction ( occlusive tracheal mass) can important indication for use is to distinguish supraventric­ produce an inspiratory wheeze also known as stridor. ular from ventricular rhythms. The latter have a much more Wheezes are heard in disease conditions such as guarded prognosis and may require therapy. A further use bronchospasm (allergic), mucosal inflammation, mucous for electrocardiography is in monitoring patients being plugging, or through external compression of airways by treated for atrial fibrillation. 6 The use of quinidine tumors, abscesses, or lymphademopathy. 4 · 5 The wheeze intravenously in this group can predispose to a number of produced by secretions in the airway will change after a deep rhythm disturbances which warrant an effective monitoring cough. The pleural friction rub is a distinctive loud, coarse system for the detection. Electrocardiographic monitoring rubbing sound which often is more localized than in these patients will also allow early detection of the return pulmonary crackles. Interpretation of the silent lung, on the to normal sinus rhythm so that therapy can be discontinued. other hand, is more difficult. Fluid and air are 2 media Aspiration and biopsy are probably the most underused through which loss of sound energy is great. Therefore, diagnostic aids available to the bovine practitioner. Rela­ pleural effusion and are causes of a silent tively simple techniques with inexpensive tools can yield a lung. Other reasons for silent lung may be diaphragmatic great amount of information about disease. The transtra­ hernia or other space occupying lesions, extreme obesity, cheal wash, for example, in a herd outbreak of pulmonary pulmonary emphysema, severe small airway disease and disease or in an individual who has not responded to routine neuromuscular weakness. The truly silent lung must be dis- therapy can give new insight into etiology, severity and

APRIL, 1983 71 microbial sensitivity. Pericardia) centesis at the left 5th IC skills required to perform and interpret the exam will limit space below the elbow can make a diagnosis between its applicability to private practice. infectious effusion (traumatic), benign effusion (heart In conclusion, a number of diagnostic tools are available failure), or neoplasia (lymphosarcoma). Pleural centesis can for use in evaluation of diseases of the thoracic cavity. The be similarly rewarding in distinguishing the cause of silent most important of these tools is the art of auscultation. lung, i.e. between fluid, emphysema, or solid lung. All of Knowledge of the origin and mechanism of production of these techniques, though relatively simple, require surgical cardiac and lung sounds will allow the practitioner to accu­ preparation of the site and laboratory assistance in cytologic rately diagnose the majority of the diseases he sees in the evaluation, culture, etc. The most common complication is field. A number of other diagnostic procedures such as local infection at the site of puncture which can be avoided radiography, aspiration, and percussion are then used to by improved technique and local infusion of antibiotics as further define or confirm the tentative diagnosis made by the needle is withdrawn. auscultation. Endoscopy is not used frequently by the bovine practitioner because of infrequent use of costly equipment. When the equipment is available, it is indicated for use in the case of upper airway obstruction. Skillful manipulation of References the flexible endoscopes can also aid in obtaining tracheal fluid aspirates for bacterial culture when pneumonia is I. ErteL P.Y .. Lawrence. M .. Brown, R.K. and Stern, A.M.: Stethoscope diagnosed. Acoustics: I. The doctor and his stethoscope. Circulation 34:898-890, 1966. 2. Ertel, P .Y., Lawrence, M., Brown, R. K. and Stern, A.M.: The use of ultrasound in will probably Stethoscope Acoustics: 11. Transmission a nd filtration patterns. Circula­ never become a tool of the general practitioner but it has tion 34:899-909. 1966. 3. Raphel, C.F. and Fregin, G.F.:Clinical examina­ yielded invaluable information about the detection of tion of the cardiovascular system in cattle. The Compendium on Continu­ cardiac disease for the academician. Detection of abnormal ing Education. Vol. 2( 12): Dec. 80, 5259. 4. Roudebush, P.:Lu~g sounds. valves (vegetative endocarditis), dilated or hypertrophied JAVMA 181 (2):122-126, 1982. 5. Forgacs, P.: Appliedcardiopulmonary physiology: the functional basis of pulmonary sounds. Chest 73(3):399-405, cardiac chambers and effusions (pleural or pericardia!) by 1978. 6. McGuirk, S.M., Muir, W.W ., Sams, R.A., and Rings, D. M .: non-invasive techniques are definite advantages over other Atrial fibrillation in cows: clinical findings and therapeutic considerations. methods. However the cost of the equipment and technical JA VMA (accepted for publication).

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72 THE BOVINE PROCEEDINGS-No. 15 Rediscover respiratory vaccination with Norden~ Resbdline

Right or wrong, respiratory lOx Dosage Test vaccines often catch the blame To further establish safety, when clients report problems with we intramuscularly vaccinated a their conditioning programs. group of cattle at 10 times the And that's unfortunate. Because recommended field dose. We took this protection can be critical to temperature readings for 14 days cattle health. and made clinical observations To help return respiratory protec­ for 21 days. All animals were tion to its rightful and important reported normal. place in vaccination schedules, Real World Situation Testing 0 Norden researchers outlined "'d We supplied our new 'Resbo' (D some vaccine objectives. They BYD fraction. We reasoned that ~ vaccines for field use observation ~ set major guidelines for vaccine introducing vaccine directly into () () safety. They applied the latest in three herds. There were no (D this natural route of infection r.r, technology and now all vaccine would allow greater opportunity reports received of either injection r.r, 0...... virus fractions are propagated site or systemic reactions. All r.r, for potential reactions. There were .-t-­ on our established cell line ... no reported clinical signs of reports were favorable. >--1 g5-= a technique in which Norden has respiratory infection in any of the Protect cattle ... and reputations ...... long been an industry leader. 0 animals during a 2 week post­ Rediscover respiratory vacci­ p The result- an exclusive new inoculation period ... an impressive nation! Our new 'Resbo' line can 'Resbo' line that met four strin­ test of safety! help you and your clients schedule gent standards we selected that protection with less concern would be required toward about vaccination stress and unto­ reaching a goal of maximum ward reactions. Your Norden vaccine performance. representative has further details Leukopenia Study or phone your Norden Branch. In a Norden study, leukopenia, believed by some to be an impor­ tant sign of immunosuppression, Norden's was not observed. Cattle were vac­ cinated, then tested daily for three Resbdline weeks without any significant drop in white blood cell counts. Intranasal Inoculation Test N NORDEN Although recommended for aSmlthKltnec...,_ intramuscular administration, Resbo BVD, Resbo BVD-LP, Resbo IBR-BVD, we experimentally vaccinated test Resbo IBR-BVD-LP. Resbo 3 (IBR-BVD-P/3), Resbo 4 (IBR-BVD-P/_1-LP), Resbo 8 animals intranasally with the (IBR-BVD-PI_rLS), Resbo IBL5 (IBR-BVD-LS).