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ISU Student Experience

Left-Sided Heart Failure

Written by: Grace Mercer • 2022 Scholar

Josie is a 1 1⁄2 year old spayed female miniature Labradoodle. She presented to Iowa Veterinary Specialties (IVS) in respiratory distress. Any animal in respiratory distress is immediately triaged and rushed to the treatment area to be stabilized. Only the most pertinent information is acquired from the owner by a vet tech at the time. Josie was immediately put on oxygen therapy, and a physical exam was conducted. The top three differentials for a dog presenting in respiratory distress are cancer, heart failure, and pneumonia.

Physical Exam

Heart Rate: 86 (normal: 80-140 bpm)
Respiratory Rate: 80, with increased effort (normal: 10-40 bpm) Temperature: 100.8 (normal: 100-102.5°F)
MM/CRT: Cyanotic, <2 (normal: pink, <2 s)

Respiratory and Cardiovascular System Assessment

Grade 4/6 heart murmur Weak femoral pulses Clear bilateral lung sounds SpO2: 83%

T-FAST: Left atrial enlargement, fluid present in thorax (pericardial or pleural effusion possible) with b-lines present.


A vet tech obtained a history from the owner while the patient was being stabilized. The owner first acquired Josie from a vet who had diagnosed her with a grade 3 heart murmur. The owner stated Josie is normally short of breath with exercise. Josie was left with a pet sitter for a week while the owners were out of town. The pet sitter stated that Josie was lethargic off and on throughout the week. Josie had been eating and drinking less after the owners brought her home and had small amounts of intermittent diarrhea that the owner believed was anxiety related.

The summation of the history, physical exam, and cardiovascular assessment led to the conclusion that Josie was in left-sided congestive heart failure. Heart failure is not a diagnosis but a collection of clinical signs caused by some other disease. The most likely cause was Myxomatous Mitral Valve Disease (MMVD), the most common cardiovascular disease in dogs. Due to the presence of clinical signs of heart failure, Josie would be classified as Stage C heart failure based on the American College of Veterinary Internal Medicine (ACIVM) system.

Pathophysiology of MMVD

Insufficiency of the mitral valve (valve fails to fully close)→
Mitral regurgitation (blood from left ventricle flows back into left atrium)→ Compensatory changes to heart structure (left atrium and ventricle dilation/hypertrophy)→ Eventual failure of left atrium to accommodate load→
Backup of blood into the lungs→Increased hydrostatic pressure→
Pulmonary edema (congestive heart failure)

To stabilize the patient, Josie was given an injection of furosemide and butorphanol. Furosemide is a loop diuretic used to remove any fluid accumulation in the lungs (treats pulmonary edema due to congestive heart failure). Butorphanol is an opiate used as an analgesic (to relieve pain). After these injections, Josies SpO2 rose to 96% while on oxygen therapy. SpO2 assesses the oxygen saturation of the blood. A SpO2 minimum of 95% is acceptable, with 98% minimum being preferred.

Once Josie was stable, the doctor discussed Josie’s condition with the owner. The doctor strongly suspected Josie had left-sided heart failure due to MMVD. The median survival time with treatment is approximately one year for a dog in Josie’s current condition. The doctor’s recommendations were for radiographs and transfer to the ISU cardiology department for further workup, including an echocardiograph (the gold standard for diagnosis of heart disorders) or humane euthanasia. The owners elected for radiographs and to take their dog home against medical advice (AMA) with some medication (Pimobendan and Furosemide). Pimobendan is a heart medication used to treat congestive heart failure. It opens up the blood vessels leaving the heart (decreasing resistance) and increases the strength of contractions of the heart muscle.

Two days later, Josie was brought back into IVS for humane euthanasia. She died prior to the setting of a catheter.

All radiographs taken at IVS are sent to a board-certified radiologist for further assessment. The following report was written by Dr. Wall, a radiologist who works as an IDEXX telemedicine consultant.

Radiologist Report Findings

The cardiac silhouette is increased in the apicobasilar, craniocaudal, and mediolateral dimensions. There is a loss of the cranial and caudal cardiac waist. Left atrial enlargement is present. There is dorsal deviation of the trachea secondary to the cardiomegaly. There is mild narrowing and compression of the caudal mainstem bronchi. The cardiac silhouette as a rounded appearance on the ventral dorsal view. The pulmonary veins are enlarged. A diffuse unstructured interstitial pattern is present throughout the pulmonary parenchyma. A small amount of pleural effusion is suspected to be present, as there is a slight scalloped appearance to the ventral lung lobe margins on the lateral images.

Conclusions: Cardiogenic pulmonary edema is present. Left-sided heart failure is present. Concurrent right-sided heart failure cannot be ruled out. With the patient's young age, a congenital anomaly may be the underlying etiology for the cardiomegaly. Mitral valve insufficiency is considered to be present; concurrent pericardial effusion may be present.


  • Boswood, A., Haggstrom, J., Gordon, S. G., & G. Wess. (2016). Effect of Pimobendan in Dogs with Preclinical Myxomatous Mitral Valve Disease and Cardiomegaly: The EPIC Study—A Randomized Clinical Trial. Journal of Veterinary Internal Medicine, 30(6), 1765–1779.
  • Brooks, W. (2001, January 1). Furosemide (Lasix, Salix, Disal). Veterinary Partner. Brooks, W. (2006, July 24). Butorphanol Tartrate (Stadol, Torbutrol, Torbugesic, Dolores,
  • Butorphic, Dolo)rex. Veterinary Partner.
  • Campbell, F. (2013). Cardiac Disease and Examination. VIN.
  • Rishniw, M. (2008, January 7). Pimobendan (Vetmedin). Veterinary Partner.
  • Rishniw, M. (2018, April 6). Congestive Heart Failure in Dogs and Cats. Veterinary Partner. Rishniw, M., Swift, S., & Martinez Pereira, Y. (n.d.). Heart: congestive heart failure. Vetlexicon. Troph, M. (2021, November). Histology Unit 4 Notes. BMS 333 Biomedical Science 1.
  • Wall, C. (2022). (rep.). Radiology Services Report. IDEXX Laboratories.

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