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Updated: Feb 4, 2026
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Non-aversive Animal Restraint Enabling Recording of Optomotor Reflex in Ground Squirrels
Published on: July 25, 2025
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Cardiovascular resistance to thrombosis in 13-lined ground squirrels
Alison Bonis1, Leah Anderson1, Gaëlle Talhouarne1
1Biology Department, University of Wisconsin-La Crosse, 1725 State St. La Crosse, La Crosse, WI, 54601, USA.
Summary
13-lined ground squirrels exhibit remarkable resistance to blood clots and heart damage during hibernation. Their unique physiological adaptations, including suppressed coagulation and enhanced fibrinolysis, prevent thrombosis and myocardial ischemia.
Area of Science:
- Physiology
- Hibernation Biology
- Cardiovascular Research
Background:
- Hibernation involves prolonged torpor with reduced physiological functions, interrupted by brief arousals.
- These extreme physiological shifts in ground squirrels should theoretically increase risks of blood clots and myocardial ischemia.
- However, 13-lined ground squirrels survive hibernation without lethal thrombotic or ischemic events.
Purpose of the Study:
- To investigate the resistance of 13-lined ground squirrels to thrombosis and myocardial ischemia during hibernation.
- To identify the physiological mechanisms underlying this resistance.
Main Methods:
- Measured blood markers of coagulation, fibrinolysis, thrombosis, and ischemia throughout the hibernation cycle.
- Assessed histological markers of myocardial ischemia.
- Induced myocardial ischemia using isoprenaline in hibernating squirrels.
Main Results:
- Significantly reduced thrombin-antithrombin complex levels indicated an antithrombotic state during hibernation.
- An elevated ratio of tPA:PAI-1 complex to total PAI indicated a hyperfibrinolytic state during torpor.
- Histological markers of myocardial ischemia were elevated but reversible, with no increase in blood markers of cell death.
Conclusions:
- Ground squirrels prevent major blood clot formation during hibernation via suppressed coagulation and a hyperfibrinolytic state.
- These animals possess significant myocardial resistance to ischemia during hibernation.
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