Case Studies

These case studies contain detailed information on the diagnostic and treatment process for each individual animal.

Riley

Case Background

Name: Riley
Age: 12 years old
Sex: Male, Castrated
Breed: Shih Tzu
Weight: 6 kg
Reason for visit: Presented two days ago to your colleague for a complaint of respiratory difficulty for one week. Now the owner, Mr. Brown, has brought him back to you because he has noticed a distended abdomen and is concerned because Riley is not eating well. During the initial visit a murmur was identified and Riley was tentatively diagnosed with CHF and started on Furosemide, enalapril and spironolactone.
Medications: Heartworm prevention: Heartgard® plus and Frontline®

Clinical History

Please review Riley’s clinical history.

Attitude/demeanor: Bright and alert
Coughing: None reported
Respirations: Increased inspiratory effort with shallow breathing
Exercise intolerance: Has generally been slowing, but is now more reluctant to exercise
Sleep patterns: Sleeping well, but he prefers to sleep on his belly and not on his side
Weight change (loss or gain): Significant abdominal distension
Appetite: Not eating as well for the last 2 days
Usual diet: Science Diet® maintenance dry
Vomiting: None reported
Diarrhea: None reported
Syncope: None reported
Change in urinary habits: Increase in urinating since meds started yesterday
Change in drinking habits: Increase in drinking since meds started yesterday
Other symptoms or signs: None reported

Physical Exam - General

Please review the results of Riley’s physical exam.

Body condition: Good, BCS 6/9
Attitude: Alert, somewhat anxious
Mobility | gait: Normal gait on inspection
Posture: Standing or sitting
Hydration: Normal
Body temperature: 100.3 F
Arterial pulse – rate, regularity, intensity: 132 beats/min, occasional premature beat, pulses fair
Respiratory rate & effort: 24 breaths per minute, normal
Mucous membranes – color & CRT: Normal color and CRT
Jugular venous pulse & pressure: Pulsations present to the level of the mandible bilaterally
Abdominal palpitation: Severe abdominal distension, fluid wave suspected, internal organs difficult to palpate
Lymph nodes: Normal
Oral cavity: Mild dental calculus
Other abnormalities: None

Physical Exam - Auscultation

Let’s auscult Riley’s heart & lungs. (Recommend high-end headphones)

The following recording is taken when the stethoscope is placed over the left apex. Similar sounds are heard when the stethoscope is placed over the right mid-heart.
Listen to Riley's heart sounds
Direct HR: 140
Heart rhythm:  Regular
Intensity of heart sound: Heart sounds audible, but reduced
Extra sounds – clicks or gallops: None
Precordial palpation: No thrill detected

Physical Exam ‑ Differential Diagnosis

The following are potential diagnosis for you to consider at this time. Based on the history and the physical examination, please indicate the likelihood of each as:
  • High (could explain most or all of the signs)
  • Possible (less likely to explain most of the signs)
  • Unlikely
STAGE C MVD (MYXOMATOUS VALVULAR DEGENERATION)
STAGE C DCM
RIGHT SIDED CHF SECONDARY TO HEARTWORM DISEASE
PERICARDIAL EFFUSION CAUSING ASCITES (TAMPONADE)
The CEG considers the following differential diagnosis as most likely (and why):CHF secondary to chronic valvular disease (CVD) is the most likely underlying etiology of the clinical signs because Riley is a small (<20Kg) older dog with a loud heart murmur characteristic of mitral regurgitation (MR). Dilated cardiomyopathy (DCM) cannot be ruled out but would be very unlikely in a Shih Tzu. CHF secondary to heartworm (HW) disease is less likely because of the history of heartworm prevenative, but should be considered in endemic areas especially if dogs are not on preventative. Pericardial effusion with tamponade is less likely because his heart sounds (murmur) are loud.

Diagnostic Test Selection

BLOOD PRESSURE

Non-invasive blood pressure

CLINICAL LABORATORY

CBC with platelet count
Serum biochemical profile (includes electrolytes)
Urinalysis
Serum thyroxine (T4)
Heartworm antigen test
Heartworm antibody test
NT-PROBNP

DIAGNOSTIC IMAGING (some may require a referral)

Thoracic radiographs
Abdominal radiographs
Echocardiogram with doppler studies
Abdominal ultrasound

ELECTRODIAGNOSTICS (some may require a referral)

ECG rhythm strip or 6 lead ECG
Ambulatory ECG - holter ECG or event monitor
The CEG considers the following diagnostic tests as the highest priority:Thoracic radiographs must be considered as the most important diagnostic test in a patient with respiratory signs suspected of having congestive heart failure. An echocardiogram should be performed to confirm that there is enough underlying heart disease present to make the clinical signs likely to be attributable to heart failure. In addition, an echocardiogram is the definitive diagnostic test to document the presence of pericardial effusion, pulmonary hypertension and severe heartworm disease. Obtaining a serum chemistry is also important in this case, as the owner complained that Riley’s appetite has suffered after starting the cardiac therapy. Impairment of renal function and resulting azotemia is an important cause of decreased appetite in patients receiving therapy for CHF. Similarly, a blood pressure evaluation is important to rule out systemic hypertension and to identify adverse effects of current therapy. This is especially important if additional therapy is contemplated. An ECG should be obtained in any patient where an arrhythmia is identified/suspected (Riley had premature beats detected on auscultation). NT-proBNP is less useful if significant heart disease has been identified by echo; however this may be a very useful test if an echocardiogram cannot be obtained. A heartworm test can also be considered in a patient presented with signs of heart disease and right-sided heart failure; while still appropriate in this case, it may be less important given the rest of the case history. Evaluation of the abdomen (e.g. use of ultrasound, radiographs and/or fluid analysis) can also be considered, but would be most important if significant heart disease is not identified. In some cases, abdominal evaluation may be more important, especially if an acute abdomen (hemoabdomen, peritonitis, etc.) is suspected based on clinical findings. Similarly, a complete blood count can be considered a higher priority if infection/bleeding is a concern.

Blood Pressure

Systolic blood pressure: 110mmHg
Diastolic blood pressure: Not available for this case
Mean blood pressure: Not available for this case
Consensus Statements of the American College of Veterinary Internal Medicine (ACVIM) provides the veterinary community with up-to-date information on the pathophysiology, diagnosis, and treatment of clinically important animal diseases. In 2018, ACVIM published guidelines for the identification, evaluation, and management of systemic hypertension in dogs and cats in the the Journal of Veterinary Internal Medicine.

Click here to view and download a PDF of the ACVIM consensus statement, guidelines for the identification, evaluation, and management of systemic hypertension in dogs and cats.

Radiography

Please review Riley’s radiographs

Click here for Riley’s radiograph viewer (measure VHS and VLAS here) View the ventral dorsal radiograph

View the right lateral radiograph Click here to see the CEG’s recommendation on evaluating heart size on radiographs
Is there evidence of pleural effusion or pulmonary edema to explain the respiratory signs?
Is Riley's heart enlarged?
Technical quality: Good
Pulmonary venous congestion: No pulmonary venous congestion seen
Pulmonary infiltrate: No convincing interstitial changes are seen on the VD. Increased opacity is seen on the lateral, but may be due to the expiratory nature of the film.
Other findings: Loss of serosal detail is noted on the abdominal portion of the film.

Clinical Labs

Please review Riley’s lab results

SERUM CHEMISTRIES
BUN: 29 mg/dL, Normal: 6 – 25 mg/dL
Creatinine: 0.8 mg/dL, Normal: 0.5 – 1.6 mg/dL
Sodium: 145 mmol/L, Normal:139 – 154 mmol/L
Potassium: 4.5 mmol/L, Normal: 3.6 – 5.5 mmol/L
Chloride: 4.5 mmol/L, Normal: 3.6 – 5.5 mmol/L
ALT: 33 IU/L, Normal: 12 – 118 IU/L
ALP: 185 IU/L, Normal: 5 – 131 IU/LHEARTWORM
Heartworm test results: Negative within the last 6 monthsURINALYSIS
Urinalysis – USG: Not performed
Urinalysis – protein: Not performed
Urinalysis – biochemical: Not performed
Urinalysis – sediment evaluation: Not performedCBC
White blood cells: Not evaluated
Red blood cells: Not evaluated
Platelets: Not evaluated

Echocardiography

Please review the results of Riley’s echo. The images and videos were obtained by a cardiologist.

Subjective – lesions of valves, myocardium, pericardial space: No pericardial effusion; thickened mitral leaflets
LV chamber size and thickness:Mild left ventricular enlargement
Left atrial size: Moderate to severe dilation
LVIDd & LVIDs: Diastole (3.22 cm); Systole (1.41 cm)
LV shortening fraction: Normal to hyperdynamic ~ 56%
RA, RV and pulmonary artery: Moderate right atrial and ventricular enlargement, moderately dilated main pulmonary artery
Effusions: Moderate ascites seen
Doppler results: Mitral and tricuspid regurgitation; velocity of MR predicts normal systemic pressures; increased velocity of TR (~5.2 m/s) predicts severe pulmonary artery hypertension (~110 mmHg)Click here to view an M-mode of Riley's LV and RV Watch Riley's 4 chamber echo Watch Riley's MR echo Watch Riley's pulmonary artery echo Click here to view Riley's tricuspid regurgitation velocity  

Referral

Under most circumstances, the identification of severe pulmonary hypertension as a cause for right sided congestive heart failure would require a referral to obtain the echocardiographic imaging found in this case.

Diagnosis & Treatment

With the information obtained from the diagnostic testing above, please choose a diagnosis and treatment plan for Riley.
What is Riley’s cardiac diagnosis?
What treatments are recommended for Riley? Riley’s weight is 6kg
THE CEG RECOMMENDS:
Riley has been diagnosed with Stage C Myxomatous valvular degeneration with concurrent, severe pulmonary hypertension. The CEG recommends therapy with sildenafil to address the pulmonary hypertension, as well as pimobendan and furosemide to relieve the signs of congestive heart failure. An ACE-inhibitor and spironolactone are also helpful adjuncts to help suppress the renin-angiotensin-aldosterone system and control signs of congestive heart failure.

ACTUAL TREATMENT:
Initial therapy-

Sotalol is a class III anti-arrhythmic drug that is useful in treating life-threatening or clinically important ventricular and supraventricular arrhythmias in dogs. Riley does not currently have evidence of important or life-threatening arrhythmias, and disease and pulmonary hypertension. Although sotalol may be helpful in the future, it is not currently indicated.

Pimobendan 1.25 mg: 1 tablet every 12 hours.
Based on ACVIM Consensus statement guidelines, pimobendan is indicated in patients with congestive heart failure secondary to myxomatous valvular degeneration (Stages B2, C, and D). Pimobendan is also a phosphodiesterase III inhibitor with some vasodilatory properties that also affect the pulmonary vasculature.

Digoxin is a positive inotropic agent with negative chronotropic properties and may be indicated for adjunctive therapy in refractory congestive heart failure or in the management of tachyarrhythmias. However, it is a relatively weak positive inotropic agent relative to pimobendan and has a narrow therapeutic window, making it more difficult to use. Although it may be useful for Riley in the future, it is not considered first-line therapy for Riley that should be initiated at this time.

Continue spironolactone 25mg: ¼ tablet every 12 hours.
Based on ACVIM consensus statement guidelines, pimobendan is indicated in patients with clinically important mitral regurgitation and congestive heart failure secondary to myxomatous valvular degeneration (Stages C and D). Care should be taken to monitor renal function in patients already receiving diuretics if this medication is added to the treatment plan.

Sildenafil 20mg tablets: ¼ tablet every 8 hours.
Sildenafil is a phosphodiesterase V inhibitor with vasodilatory properties that is relatively selective for the pulmonary vasculature. Based on ACVIM Consensus statement guidelines, sildenafil is indicated in the management of patients with severe pulmonary hypertension such as Riley.

Benazepril. Based on ACVIM Consensus statement guidelines, an ACE-inhibitor is indicated in patients with congestive heart failure secondary to myxomatous valvular degeneration (Stages C and D). Care should be taken to monitor renal function in patients already receiving diuretics if this medication is added to the treatment plan.

Amlodipine is a calcium channel blocker with vasodilator properties that is useful in the management of systemic hypertension in dogs and cats. Although it also may cause some dilation of pulmonary arteries, this effect is much less pronounced than its effect on systemic arteries or the effects of sildenafil.

Continue furosemide 12.5 mg: 1 tablet every 12 hours.

Continue enalapril 2.5mg: 1 tablet every 12 hours.

Follow-up plan:
1. Recheck examination in 7-14 days.
    • Physical examination and weight
    • Renal profile with electrolytes
    • Echocardiogram to assess pulmonary pressures via tricuspid regurgitation velocities
    • Adjust diuretic therapy as necessary for persistent ascites
    • Palliative abdominocentesis if clinically important ascites that is non-responsive to diuretics (or in patients that cannot tolerate escalating diuretic therapy)
2. Lifestyle adjustments:
    • Avoid high sodium treats and foods such as processed meats, hot dogs, cheese, some table scraps. If Riley is eating well, encourage transition to a prescription low-sodium diet.
    • Avoid stress or strenuous exertion
3. Long-term: Recheck every 3-4 months or as needed for symptoms or recurrent heart failure, syncope, or other signs of deteriorating quality of life.  
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