How do rats sweat? - briefly
Rats possess only a few eccrine sweat glands on their foot pads and rely mainly on panting and saliva spreading to dissipate heat. Consequently, they do not sweat profusely like many mammals.
How do rats sweat? - in detail
Rats regulate body temperature primarily through mechanisms other than extensive sweat production. Functional sweat glands are present only on the ventral surface of the paws, where eccrine glands open onto the foot pads. These glands secrete a watery fluid that evaporates from the skin, providing modest cooling during high ambient temperatures or intense activity. The density of eccrine glands on rat foot pads is low compared to mammals that rely heavily on sweating; consequently, the overall contribution to heat loss is limited.
In addition to the limited eccrine system, rats possess apocrine glands in the perianal region and around the facial whisker follicles. These glands release a viscous secretion rich in lipids and proteins, serving primarily for scent marking rather than thermoregulation. Because the secretions are not volatile, they do not aid in evaporative cooling.
When ambient temperature rises, rats increase respiratory rate and adopt panting, a rapid, shallow breathing pattern that enhances evaporative loss from the respiratory surfaces. Panting is the dominant evaporative cooling strategy in rodents. Concurrently, peripheral vasodilation occurs in the tail and skin, allowing heat to be transferred from core blood to the environment. The tail’s extensive vascular network functions as a radiative heat sink; blood flow can be modulated via sympathetic control to adjust heat dissipation.
Behavioral adaptations complement physiological responses. Rats seek cooler microhabitats, such as burrows or shaded areas, and spread saliva on the paws to augment moisture on the foot pads. Grooming behavior spreads saliva across the fur, increasing surface wetness and promoting evaporative cooling.
Key points summarizing rat thermoregulatory strategies:
- Eccrine glands confined to paw pads; low density, limited cooling effect.
- Apocrine glands present for pheromonal communication, not temperature control.
- Panting provides primary evaporative heat loss.
- Tail vasodilation acts as a thermal radiator.
- Behavioral choices (shade seeking, grooming, saliva spreading) enhance cooling.
Research using infrared thermography and microvascular imaging confirms that tail temperature rises sharply during heat stress, indicating active vasodilation. Experimental blockage of the tail’s blood flow impairs heat dissipation, reinforcing the tail’s critical role. Studies measuring sweat output from paw pads show volumes insufficient to sustain thermoregulation alone, validating reliance on respiratory and vascular mechanisms.