Case 35: Collapse

Case 35 — Collapse

Primary clinician: Patrizia Knafelz, DVM, DACVIM (Cardiology)
Supervising clinician: Mark D. Kittleson, DVM, PhD, DACVIM (Cardiology)

Dante is an 8-year-old MC Boxer presented to Cardiology Service with the primary complaint of episodic collapse.
The owner is a registered veterinary technician. The owner states that the episodes began a couple of weeks ago and have increased in frequency.
He had one episode 3 days ago and 4 two days ago. Most of the episodes have started while Dante is asleep on the bed or lying on the ground. He jumps up and then falls over on his side with his legs stiff. One time Dante walked through the kitchen and collapsed. He does not appear to lose consciousness and does not urinate or defecate. There is no clonic motion. The episodes last less than 1 minute and he regains normal mentation immediately afterward.
The owner has taken Dante’s heart rate and recorded it to be approximately 40 bpm every time one of the episodes occurred. After one episode, the owner gave Dante 0.5 ml atropine intramuscularly. A few minutes later she recorded a heart rate of 60 bpm.
The owner checked Dante’s heart rate yesterday and recorded 80 bpm.
The owner reports polydipsia/polyuria (PU/PD). He was also observed drinking a lot of water in the Cardiology Service exam room.
Past medical history includes hypothyroidism, anterior uveitis and a broken femur with neurological damage. Due to the neurological damage to the right hind leg, the toes required amputation and now Dante must wear a bootie on the foot.
Current medication: thyroxine 0.7 mg BID.

ECG: The ECG showed a sinus arrhythmia and periods of high grade 2:1 2nd degree AV block with an average heart rate of 80 beats per minute. Occasional supraventricular premature complexes noted.
Echocardiogram: Mild tricuspid insufficiency and mild aortic insufficiency. All measurements were within normal limits (IVSd = 0.7 cm, LVIDd = 3.9 cm, LVPWd = 1.2 cm, IVSs = 0.9 cm, LVIDs = 2.6 cm, LVPWs = 1.4 cm, Ao root diameter = 2.2 cm, LA dimension = 3.4 cm, LA:Ao = 1.5, SF = 34%, pulmonic velocity = 1.4 m/s (PG = 7.6 mmHg), tricuspid velocity = 2.3 m/s (PG = 20 mmHg), Ao velocity = 1.7 m/s (PG = 12 mmHg).
Atropine test: 2.6 ml (0.04 mg/kg) of atropine was injected SQ. 30 minutes later the ECG was repeated with no change in ventricular rate noted which is suggestive of a conduction problem; high grade 2nd degree AV block was 3:1 and 4:1 after atropine because of an increase in sinus rate. HR approximately 86 bpm prior to and after atropine. Event monitor will be placed.
Abdominal ultrasound: WNL with the exception of “thumb prints” on spleen noted.
Urinalysis: Hazy turbidity; pH 7.0; specific gravity = 1.012; 1+ bilirubinuria (Ictotest) which is within normal range for a male dog; rare RBC; few lipid droplets.

We are placing an event monitor on Dante to determine his cardiac rhythm during one of his episodes. When you see an episode of collapse, push the button on the monitor, as soon as you see Dante collapse. The event monitor records 2 events. Please contact the Cardiology Service when an event has been recorded. The ECG signal recorded on the monitor can be transmitted over the telephone line to us during our regular business hours.
Dante has been drinking a lot of water and urinating a lot (PU/PD). Therefore, an abdominal ultrasound was performed on Dante. Everything looked normal on the abdominal ultrasound. A urine sample showed that his kidneys may not be concentrating the urine normally.
Thank you for bringing Dante to Cardiology Service. He was a pleasure to work with, a very sweet and polite gentleman!