Case Studies

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

Arco

Case Background

Name: Arco
Age: 10 years
Sex: Male
Breed: Male German Shorthaired Pointer
Weight: 32 kg
Reason for visit: Heart murmur detected prior to anesthesia for neutering due to history of prostatitis and prostatic hypertrophy (intact male). Arco is negative for heartworm disease based on a yearly antigen test and year-round monthly preventative.
Medications: None

Clinical History

Attitude/demeanor: Quiet, alert and appropriate to surroundings
Coughing: None
Abnormal respirations: None
Exercise intolerance: None
Sleep patterns: No changes, normal
Weight change (loss or gain): None
Appetite: Has become somewhat more picky in past 6 months
Vomiting: One episode 3 days before presentation
Diarrhea: No
Syncope: No
Change in urinary habits: Some straining to urinate noted by owners, resulted in suspicion of prostatic disease
Change in drinking habits: Mildly increased water consumption in past year

Physical Exam - General

Body condition: Lean, BCS 4/9
Attitude: Quiet and alert, slightly anxious
Mobility | gait: Normal
Posture: Normal
Hydration: Adequate, based on mucous membrane examination and normal capillary refill time
Body temperature: 101.2° F
Arterial pulse – rate, regularity, intensity: Strong pulses, no deficits
Rate & respiratory effort: 36 per minute, eupneic
Mucous membranes – color & CRT: Pale pink, moist
Jugular venous pulse & pressure: No jugular distention noted
Abdominal palpatation: Mildly tense, non-painful, no organomegaly or mass lesions identified
Lymph nodes: Peripheral lymph nodes symmetric, normal in size and texture
Oral cavity: Moderate dental tartar
Other abnormalities: Rectal exam revealed that prostate gland was out of reach of digital examination, no evidence of pain during exam

Physical Exam - Auscultation

Listen to Arco’s heart (Recommend high-end headphones)


Heart murmur intensity is usually graded on a scale of 1-6, where grades 5 & 6/6 are very loud murmurs with a precordial thrill (a palpable buzzing sensation on the thorax). Arco's thoracic palpation reveals no precordial thrill. This indicates that the heart murmur is likely to be graded as:
Careful auscultation allows localization of the heart murmur to the left cardiac apex. What is the timing of the murmur?
Direct HR: 100 bpm
Heart rhythm: Irregular with respiration, suspect respiratory sinus arrhythmia
Intensity of heart sound: 2/6 systolic murmur over the left cardiac apex, murmur is barely audible at the right cardiac apex.
Extra sounds – clicks or gallops: None
Precordial palpation: No precordial thrill

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
Myxomatous mitral valve disease with mitral regurgitation
Aortic stenosis or subaortic stenosis, previously undetected
Vegetative endocarditis of the mitral valve
Vegetative endocarditis of the aortic valve
The CEG considers the following differential diagnosis as most likely (and why):Mitral valve regurgitation due to valvular disease is the most likely diagnosis based on the location of the heart murmur over the left cardiac apex. However, other reasons for mitral valve regurgitation, such as a vegetative lesion, are possible. Aortic or subaortic stenosis is considered as a differential due to breed predilection for this congenital abnormality, but a Grade 2 heart murmur due to aortic or subaortic stenosis would be more likely to be detected at the left heart base. A grade 2/6 murmur of aortic stenosis would typically be associated with mild stenosis so may have normal pulse strength and minimal outward clinical effects on the patient. Vegetative endocarditis was thought to be less likely in this dog because of the lack of overt clinical signs of sepsis or fever, but a mitral valve vegetation could cause or exacerbate mitral regurgitation. Aortic stenosis, if present, may increase Arco’s susceptibility to endocarditis of the aortic valve, which may cause a systolic heart murmur.

Diagnostic Test Selection

BLOOD PRESSURE

Non-invasive blood pressure

CLINICAL LABORATORY

CBC with platelet count
Urinalysis
Serum thyroxine (T4)
NT-ProBNP
Cardiac troponin-I
Blood culture

DIAGNOSTIC IMAGING (some may require a referral)

Thoracic radiographs
Abdominal radiographs
Echocardiogram doppler studies
Abdominal ultrasound

ELECTRODIAGNOSTICS (some may require a referral)

ECG rhythm strip or 6 lead ECG
The CEG considers the following diagnostic tests as the highest priority: The highest priority test for determining the cause of the heart murmur in this patient is Doppler-echocardiography to both identify the cause of the murmur and assess systolic function, and to identify any additional cardiac abnormalities that may be present.
Other tests that can be considered for pre-anesthetic evaluation of this patient include a baseline ECG recording to identify any arrhythmias that may change the anesthetic protocol – this test is a higher priority in patients with an irregular rhythm on auscultation, or heart rates that are inappropriately high or low.
Thoracic radiography aids in staging of heart disease and can help rule out non-cardiac pulmonary lesions that may affect anesthesia. Thoracic radiographs area high priority in patients with any pulmonary-related signs (e.g. cough) and may also be more strongly recommended in older patients, who are at higher risk for concurrent diseases.
Some of Arco’s historical findings (picky appetite, possible increased water consumption, history of disease), make general laboratory screening, including a CBC, serum biochemistry analysis and urinalysis indicated.
After discussion, Arco’s owners elected to have Arco undergo most of the suggested tests (thoracic radiographs, Doppler-echocardiography, CBC, serum biochemistry and urinalysis). Blood pressure assessment is considered part of the standard cardiac evaluation but was not obtained in this patient at this time.

Radiography

Please review Arco’s radiographs

Click here for Arco’s radiograph viewer (measure VHS and VLAS here) View the right lateral radiograph View the ventral dorsal radiograph
What is the vertebral heart size?
Which cardiac chambers/structures appear to be enlarged?
The VD view is slightly rotated, and the dorsal spinous processes are cut off on the lateral view but both views are still usable for cardiovascular assessment. The VHS of 11 is considered within the expected range for a deep-chested, athletic breed like the German short-haired pointer. This finding is supported by a lack of identifiable cardiac chamber enlargement. The slightly small caudal vena cava is suggestive of hypovolemia (dehydration). The apparent enlargement of the ascending aortic may represent post-stenotic dilation, true aortic enlargement or be an artifact in this thin patient. Arco has some mineralization of his large airways, consistent with his age. Pulmonary vasculature is normal.

Clinical Labs

Serum chemistries

BUN: 113 mg/dL Normal: 7-32 mg/dL
Creatinine: 7.1 mg/dL Normal: 0.5 – 1.5 mg/dL
Sodium: 150 mm0l/L Normal:141 – 150 mm0l/L
Potassium: 3.9 mm0l/L Normal: 3.9 – 5.3 mm0l/L
Chloride: 121 mm0l/L Normal: 109 – 119 mm0l/L
ALT: 37 IU/L Normal: 14 – 87 IU/L
ALP: 47 IU/L Normal: 20 – 157 IU/L

Urinalysis

Urinalysis – USG: 1.012
Urinalysis – protein: 3
Urinalysis – biochemical: Not Done
Urinalysis – sediment evaluation: RBCs: 5-10/hpf, WBC: rare, casts: none, crystals: few amorphous

CBC

White blood cells: 9.0 x 10^3/uL (5-14 x 10^3/uL)
Red blood cells: Hct 39% (39-57%)
Platelets: 283 x 10^3/uL (175-500 x 10^3/uL)

Echocardiography

Please review Arco’s echocardiogram results

Subjective – lesions of valves, myocardium, pericardial space: 1. The mitral valve leaflets are mildly thickened. There are several jets of mitral regurgitation noted; overall severity appears to be mild to moderate. 2. The aortic valve is structurally normal. There is no evidence of aortic or subaortic stenosis. Mild to moderate aortic regurgitation is present. 3. The tricuspid valve is normal and there is no tricuspid regurgitation. 4. The pulmonary valve is normal. There is no evidence of pulmonic stenosis or pulmonic regurgitation.
LV chamber size & thickness: The left ventricle is severely thickened, globally. The LV diameter in diastole is normal compared to weight-based references. Both the LV wall and the interventricular septum are severely thickened compared to weight-based reference ranges.
Left atrial size: Left atrial diameter is normal subjectively. LA: Ao ratio is normal (1.11).
LVIDd & LVIDs: Both within normal reference ranges.
LV shortening fraction: 37%
RA, RV & pulmonary artery: All within expected size ranges.
Effusions: None
Doppler results: Aortic systolic velocity: 1.59 m/s, gradient ~10 mmHg (normal). Pulmonic systolic velocity: 0.87 m/s, gradient ~3 mmHg (normal).

ECG

Click here for Arco's ECG Technical quality, leads, paper speed, calibrations: Good quality recording, lead 2 rhythm strip, 50 mm/sec, 10 mm/mV
Artifacts: None
Rhythm- regular or irregular/ patterns: Irregular rhythm
P Wave abnormalities- morphology, amplitude, duration: P wave height and width are normal. Some P waves are notched. There is variable P wave morphology (complexes 1 and 6)
QRS abnormalities- axis, morphology, amplitude, duration: QRS height and width are normal
Abnormal intervals- PR, QRS, QT: All intervals are within reference ranges
Other: The T wave is biphasic
What is the heart rate and rhythm diagnosis? (black dots mark 1 sec. Intervals)
What is the likely cause of the variable p wave morphology noted here?
Interpretation: HR: 120 bpm. Sinus rhythm with respiratory sinus arrhythmia and wandering pacemaker.

Summary of Current Test Results

Based on Arco’s laboratory assessment, severe azotemia with isosthenuria and proteinuria is present, making renal dysfunction likely. The urine sediment reveals proteinuria with an inactive sediment, making urinary tract infection less likely, but does not rule infection out completely. Arco’s echocardiographic findings combined with his radiographic findings indicate the presence of ACVIM Stage B1 mitral regurgitation, likely secondary to myxomatous valve disease. These findings are consistent with Arco’s age and breed. Severe left ventricular hypertrophy and aortic regurgitation without evidence of aortic/subaortic stenosis are suggestive of systemic hypertension. Protein-losing renal disease (glomerular disease) is common in older dogs and often associated with systemic hypertension. Additional diagnostic testing is indicated.

Additional Diagnostic Selection

Which of the following additional diagnostic tests are indicated for Arco?

Blood Pressure

Non-invasive blood pressure

Clinical Laboratory

Ocular/retinal examination
Coagulation profile
Urine protein: creatinine ratio
Serum thyroxine (T4)
Heartworm antigen test
Blood culture
Urine culture
Serology for tick-borne disease

Diagnostic imaging (some may require a referral)

Abdominal radiographs
Abdominal ultrasound
Arco has mitral regurgitation and aortic regurgitation with severe left ventricular hypertrophy. His findings are suggestive of systemic hypertension, so blood pressure assessment and ocular examination to rule out ocular target organ damage (e.g. retinal hemorrhage, retinal detachment, hyphema) are the highest priorities. Investigation of proteinuria includes quantification of the proteinuria with a urine protein:creatinine ratio. A urine culture is indicated to rule out infection (renal, bladder, prostate) as a cause of protein in the urine. The CEG recommends repeating heartworm antigen test to rule out occult heartworm infection, which can lead to proteinuria. If in an endemic area, screening for tick-borne diseases that may be associated with proteinuria, such as Anaplasmosis and Borreliosis, is recommended. An abdominal ultrasound examination is highly recommended to assess the urinary tract and prostate for evidence of stones, infection, renal dilation and prostatic abnormalities; an abdominal radiograph could be assessed if ultrasound is not available but would provide less information.

Blood Pressure Results

Systolic blood pressure: 254 mmHg
Diastolic blood pressure: 138 mmHg
Mean blood pressure: 190 mmHg
Consensus Statements of the American College of Veterinary Internal Medicine (ACVIM) provide the veterinary community with up-to-date information on the pathophysiology, diagnosis, and treatment of clinically important animal diseases. In 2018, ACVIM updated 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.

BLOOD PRESSURE

What is your assessment of Arco's blood pressure results?
Arco’s blood pressure is severely elevated. Normal blood pressure measured non-invasively in dogs is considered to be less than 160/95 mmHg. Click here to read the recommendation article “Diagnosis and management of systemic hypertension in cats and dogs”.

Additional Diagnostic Results

TEST RESULTS

Ocular/retinal examination: Pinpoint retinal hemorrhages OU, no evidence of retinal detachment or hyphema.
Urine protein creatinine ratio: 5.28 (normal < 0.5)
Heartworm antigen test: Negative
Serology for tick-borne diseases: Negative
Urine culture: Negative
Abdominal ultrasound: Cystic benign prostatic hyperplasia with concurrent paraprostatic cysts. Bilateral adrenomegaly. Renal findings consistent with bilateral chronic renal disease with cortical dystrophic mineralization. No evidence of renoliths or uroliths.

Diagnosis

You’re ready to form a diagnosis for Arco! Please select your answer to each question below.

What is your cardiac diagnosis for Arco?
Which of the following systemic findings is least likely to be related to Arco's severe systemic hypertension?
Arco was suspected of having chronic renal disease based on the findings of severe azotemia, non-concentrated urine and compatible findings on abdominal ultrasound. His severe systemic hypertension has resulted in target organ damage (retinal hemorrhage, left ventricular hypertrophy). Arco’s proteinuria may be both a cause (protein-losing renal disease) and an effect (due to increased intraglomerular pressure) of his systemic hypertension. Despite being presented for a cardiac evaluation, Arco’s heart disease is not severe and not a clinical problem at this time. The aortic regurgitation may be exacerbated by increased aortic diastolic pressure, and his mitral regurgitation may be exacerbated by elevated left ventricular systolic pressure.
Because Arco has evidence of target organ damage and severely elevated systemic blood pressure, immediate therapy for systemic hypertension is indicated. In addition, Arco’s severe azotemia may respond to fluid administration. When fluid administration is indicated in a patient with systemic hypertension, a slow rate of infusion should be chosen initially, since hypertensive patients with left ventricular hypertrophy may develop pulmonary edema at higher fluid administration rates due to diastolic dysfunction in the hypertrophied ventricle. No evidence of prostatitis or urinary tract infection was identified in this patient.

Click here to learn more about the stages of MMVD.

Treatment

You’re ready to form a treatment plan for Arco.

What treatment(s) would you recommend for Arco?
THE CEG RECOMMENDS:
The CEG recommends treatment with amlodipine and an ACEi (enalapril or benazepril).
ACTUAL TREATMENT
Initial therapy:
Amlodipine – 12.5 mg – (0.4 mg/kg) PO q 24 hrs
Amlodipine is recommended as an effective anti-hypertensive agent.
Benazepril – 15 mg – (0.5 mg/kg) PO q 12 hrs
Benazepril is recommended as an anti-hypertensive agent and for its anti-proteinuric effects.
Lifestyle adjustment: No specific changes recommended.
Diet: A renal-specific diet was recommended.

Follow Up

Please review Arco’s follow up

Arco’s castration surgery was postponed until his systemic condition had been stabilized. After a short hospitalization for fluid therapy, Arco’s creatinine stabilized at 4.9 mg/dL but his appetite was improved. At discharge, Arco’s blood pressure was improved at 178/102 (127) mmHg. Arco’s target systolic blood pressure is approximately 140 mmHg. An increase in the amlodipine dose may be needed if systolic blood pressure remains ≥ 160 mmHg 5-7 days post-initiation of antihypertensive therapy. Click here to view the updated ACVIM Systemic Hypertension Consensus Statement.

Post Test - CE

Please answer the following questions.

What is normal systolic blood pressure in dogs (when measured noninvasively)?
What target organ change might be a result of severe systemic hypertension?
Which of the following tests can be used to investigate proteinuria?
A precordial thrill indicates that a heart murmur is at least what grade (on a standard grading scale of 1-6)?
Systemic hypertension may be associated with findings of mitral regurgitation and aortic regurgitation.

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    The CEG is funded through an educational grant from Boehringer Ingelheim Vetmedica, Inc., IDEXX Laboratories, Inc. and Nestle Purina PetCare.

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