FUNDAMENTAL ISSUES. Clinical Approach to Respiratory Disease in the Dog and the Cat

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1 Clinical Approach to Respiratory Disease in the Dog and the Cat Philip Padrid DVM Medical Director VCA Vet Care Specialty Referral Center Regional Medical Director VCA SW Region Associate Professor of Molecular Medicine (Ret) University of Chicago Pritzker School of Medicine Associate Professor of Small Animal Medicine (adj) The Ohio State University School of Veterinary Medicine FUNDAMENTAL ISSUES Our patients are exposed to bacteria, viruses, fungi and yeast all the time.. These organisms are often commensal These organisms may be pathogenic but cleared by our patients natural defenses The overwhelming majority of the time! Dec 2009, staph spp

2 FUNDAMENTAL ISSUES Our patients are exposed to bacteria, viruses, fungi and yeast all the time.. These organisms are commensal, or they are cleared by our patients natural defenses The overwhelming majority of the time! So, the real questions are: 1. Does our patient have a respiratory tract infection? 2. Does the infection need to be treated with an anti-infective? 3. What infection are we treating? DIAGNOSTIC TECHNIQUES What is the most important tool we have to diagnose respiratory disease in dogs and cats? 1. History 2. Inspection 3. Palpation/percussion 4. Auscultation 5. Radiographs 6. CT/MRI 7. Pulse oximetry/arterial blood gasses DIAGNOSTIC TECHNIQUES What is the most important tool we have to diagnose respiratory disease in dogs and cats? 1. History 2. Inspection 3. Palpation/percussion 4. Auscultation 5. Radiographs 6. CT/MRI 7. Pulse oximetry/arterial blood gasses

3 DIAGNOSTIC TECHNIQUES Auscultation 1. Extremely valuable, necessary tool 2. Usually valuable 3. Occasionally valuable 4. Pretty useless 5. What is auscultation, take out the u!!! DIAGNOSTIC TECHNIQUES What is the second most important tool we have to diagnose respiratory disease in dogs and cats? 1. History 2. Inspection 3. Palpation/percussion 4. Auscultation 5. Radiographs 6. CT/MRI 7. Pulse oximetry/arterial blood gasses

4 DIAGNOSTIC TECHNIQUES History Physical exam Radiographs Pulse oximetry Respiratory internal medicine is cardiology without the ultrasound machine WHY DO WE RADIOGRAPH COUGHING ANIMALS WHY DO WE TAKE 2 VIEWS Vomiting?

5 WHY DO WE TAKE 2 VIEWS? The middle lobe is hidden on a lateral view What is this?

6 What is this? What is this? 1. neoplasia 2. pneumonia 3. lung collapse 4. mediastinum 5. normal variation DIAGNOSTIC TECHNIQUES Implications of RML atelectasis in dogs and cats? 1. Early death 2. Exercise intolerance 3. Chronic cough 4. Chronic infection 5. None - will re-expand

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9 THIS IS VERY EXCITING

10 THE CARINA IS AN UNDERAPPRECIATED AREA OF THE CHEST FILM DIAGNOSTIC TECHNIQUES IMPLICATIONS OF A NARROW CARINA? 1. big left atrium 2. chronic bronchitis 3. enlarged lymph node Doesn t necessary imply anything DIAGNOSTIC TECHNIQUES IMPLICATIONS OF A NARROW CARINA? 1. big left atrium 2. chronic bronchitis 3. enlarged lymph node Doesn t necessary imply anything

11 INSPIRATION This variation represents 1. bronchomalacia 2. heart failure 3. normal variation 4. cannot tell from this view EXPIRATION INSPIRATION This variation represents 1. bronchomalacia 2. heart failure 3. normal variation 4. cannot tell from this view EXPIRATION BRONCHO- MALACIA SECONDARY TO CHRONIC BRONCHITIS

12 CARDIOMEGALY We (dvm s) correctly guess the true nature of cardiac enlargement exactly 50% of the time.. John King DVM, DipACVP

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14 BNP (b type naturetic peptide) 1. B-type natriuretic peptide (BNP) is a 32 amino acid cardiac neurohormone 2. BNP is secreted from the ventricular cardiac muscle into the plasma in response to volume or pressure overload 3. The active BNP hormone (c-terminal brain natriuretic peptide [cbnp]) and the inactive N-terminal fragment of pro-bnp (NTproBNP) are released through enzymatic cleavage of pro-bnp Plasma BNP concentration is increased in people and dogs with CHF The magnitude of plasma BNP concentrations in humans positively correlates with worsening New York Heart Association class and prognosis. EFFECTS OF BNP cbnp binds to natriuretic peptide-a receptor, resulting in various biologic effects including: natriuresis (sodium excretion) vasodilation renin-angiotensin-aldosterone inhibition inhibition of myocardial hypertrophy inhibition of smooth muscle proliferation alteration of vago- sympathetic balance inhibition of bronchoconstriction

15 WHY IS IT NOT SIMPLE? Multiple studies in people have demonstrated the impact of various clinical non-cardiac disease states, especially renal insufficiency, sepsis, pulmonary hypertension, acute respiratory distress syndrome, and obesity, on both cbnp and NT-proBNP concentrations, either because of altered renal elimination or asyet undetermined reasons (AGE) There is a significant degree of interday variation (as much as 50%) in the same animal. This is especially found in animals with no heart disease or mild heart disease. BNP is falsely increased in animals with renal failure, systemic hypertension, and pulmonary hypertension. BNP is falsely decreased in animals on cardiac medications and in animals that are dehydrated or hypovolemic. JUSTINE LEE STUDY Neither our study, nor the study published previously examining the same assay, can be used to establish definitive reference intervals for the specific plasma cbnp immunoassay in normal dogs. Our findings in normal dogs concur with those of other investigators, who recently showed that a substantial proportion of normal dogs had increased NT-proBNP values at 1 or more time points over a 3-week period, with values exceeding the proposed diagnostic threshold value Our data suggest that this cbnp assay would reliably rule out CHF in our study population, but cannot unequivocally rule it in, on a patient- by-patient basis.

16 JVECC Study Conclusions JVECC Study Conclusions WHAT DOES IDEXX RECOMMEND? IDEXX suggests that veterinarians include Cardiopet probnp with their initial workup when any of the following clinical signs are present: An audible murmur, arrhythmia, exercise intolerance, lethargy, breathlessness, dyspnea, coughing, pale mucous membranes, visible signs of poor perfusion, Certain other situations may also indicate a need for the test. These include all cases of suspect congestive heart failure, to differentiate respiratory disease from heart disease, all patients with murmurs and arrhythmia, all cats over the age of four, all cats with a gallop rhythm, all breeds predisposed to heart disease and showing clinical signs

17 ANTECH TEST LITERATURE Love is Blind THIS IS THE QUESTION WE NEED TO UNDERSTAND CAN WE USE BNP TO DISTINGUISH CARDIAC FROM NON CARDIAC CAUSE OF clinically symptomatic animals ie; COUGH OR DYSPNEA? Answer: IN THE DOG: likely best use is to rule out CHF as cause of cough/dyspnea in patient with significant clinical signs

18 THIS IS THE QUESTION WE NEED TO ANSWER CAN WE USE BNP TO DISTINGUISH CARDIAC FROM NON CARDIAC CAUSE OF clinically symptomatic animals ie; COUGH OR DYSPNEA? Answer: IN THE CAT: asymptomatic but suspected cardiac disease. BNP is often more useful than the physical exam for this group. Many cats with cardiac disease will not have a heart murmur, gallop sound, or arrhythmia to clue-in the veterinarian that their heart is abnormal. The BNP is helpful here. (i.e. Is the cat having a pre-anesthetic evaluation and we want to know if there is significant cardiac disease? ) If the result is abnormal I would recommend an echocardiogram.

19 AIRWAY CYTOLOGY - 1. Technique TTW brush BAL 2. Interpretation macrophage neutrophil eosinophil BRONCHOALVEOLAR LAVAGE SAMPLES FROM CATS 4 yr old healthy cat 4 yr old cat with chronic cough

20 Typical Cytological Finding from TTW, Bronchial wash or BAL from Cats with Bronchial Disease AIRWAY CULTURES 1. What is normal? 2. What is abnormal? 3. How can we tell the difference? CCB IS NOT AN INFECTIOUS DISEASE

21 Padrid et al. AJVR 1990 Dye et al JVIM 1996 CCB IS NOT AN INFECTIOUS DISEASE Peters et al JVIM 2000:14: CCB 7/20 + aerobic culture 7/7 < 1 X 10 3 (100%) 4/7 single organism grown (57%) (included pseudomonas) LRTI 13/14 + aerobic culture 10/13 > 3 X 10 4 CFU/ml (77%) 9/13 single organism grown (70%)

22 DIAGNOSTIC TECHNIQUES IN RESPIRATORY MEDICINE Physical Exam Radiography Pulse Oxymetry PULSE OXYMETRY What exactly does it measure 1. Oxygen gas pressure in the blood 2. Oxygen supply to the lungs 3. Oxygen binding by red blood cells 4. Oxygen uptake by the heart 5. Oxygen supply to the entire body PULSE OXYMETRY What exactly does it measure 1. Oxygen gas pressure in the blood 2. Oxygen supply to the lungs 3. Oxygen binding by red blood cells 4. Oxygen uptake by the heart 5. Oxygen supply to the entire body

23 PULSE OXYMETRY What we really want to know.. What is the real value of this measurement How can I use it more effectively PULSE OXYMETRY So, if oxygen has a pressure of 80 mmhg or greater, about 95% of Hg is saturated 1. That s enough for dogs and cats to get around 2. Breathing is normal 3. Play behaviour is normal 4. Routine leash walks are easy

24 Pulse Oxymetry Indications Exercise Intolerance/panting Monitor and evaluate pneumonia asthma heart failure Should I hospitalize? Should I discharge? COUGHING CATS What tools do we have? Plain Film Radiographs

25 There area at least 4 significant radiographic findings They are?

26 There area at least 4 significant radiographic findings They are? YO DSH CHRONIC COUGH Initial presentation 3 weeks post antibiotic therapy

27 INITIAL PRESENTATION 6 weeks post antibiotic treatment FELINE COUGH Differentials? FELINE COUGH Differentials? 1. neoplasia 2. heart disease 3. fungal infection 4. chronic bronchial disease 5. I have no idea

28 7 YO CAT INTERMITTENT COUGH 1. HCM 2. DCM 3. Acc lobe neoplasia 4. Foreign body 5. Hernia FELINE COUGH 1. HCM 2. DCM 3. Acc lobe neoplasia 4. Foreign body 5. Hernia 9 YO SIAMESE CHRONIC COUGH 1. Asthma 2. Collapsed lung 3. Pneumonia 4. Heart failure 5. Heartworm infection 6. None of the above (ok,, then what is it?)

29 DIFFERENTIALS? 3 YO DSH CHRONIC COUGH 1. Asthma 2. Bacterial pneumonia 3. Fungal pneumonia 4. Neoplasia 5. Cannot tell from this view 2 MONTHS AFTER STARTING FLOVENT

30 GI ENDOSCOPY GONE VERY BAD