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CLINICAL PERSPECTIVE
This Week’s Sticky Case (September 21-27)
Patient
“Ranger” – 7-year-old neutered male mixed-breed dog
Presenting Complaint
Progressive exercise intolerance, intermittent coughing, and a recent episode of collapse.
History
Ranger was adopted from a rescue organization approximately six months ago after being transported from the southeastern United States. At the time of adoption, he tested positive for Dirofilaria immitis antigen.
Because Ranger appeared clinically stable, his owners planned to pursue heartworm treatment through their primary veterinarian. Over the past several weeks, however, they have noticed that he tires more quickly on walks and occasionally coughs after activity.
Yesterday, Ranger became excited when visitors arrived at the house. After running across the yard, he suddenly stopped, appeared weak, and collapsed for approximately 15 seconds. He recovered without intervention but remained quiet afterward.
There has been no vomiting, seizure activity, or known toxin exposure.
Physical Examination
- Temperature: 101.3°F
- Heart rate: 126 bpm
- Respiratory rate: 36 breaths/min
- Mucous membranes: Pink
- Capillary refill time: <2 seconds
- Mildly increased respiratory effort
- Grade II/VI right-sided systolic murmur
- Femoral pulses adequate
- No jugular distention
- No ascites
- No obvious neurologic abnormalities
Initial Diagnostics
Heartworm testing
- Heartworm antigen: Positive
- Modified Knott test: Microfilariae detected
CBC/Chemistry
- Mild eosinophilia
- Mild thrombocytopenia
- No significant anemia
- Renal and hepatic values within reference intervals
Thoracic Radiographs
- Enlarged and tortuous pulmonary arteries
- Right-sided cardiac enlargement
- Mild diffuse pulmonary interstitial changes
Given the collapse and radiographic findings, echocardiography is performed.
Echocardiogram
- Moderate right ventricular enlargement
- Right atrial enlargement
- Flattening of the interventricular septum
- Tricuspid regurgitation with elevated velocity
- Pulmonary artery enlargement
- Findings collectively support a high probability of clinically significant pulmonary hypertension
- No heartworms visualized within the right atrium or across the tricuspid valve
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