Peripheral Thermoregulation: Foot Temperature in Two Arctic Canines

Henshaw, Robert E.; Underwood, Larry S.; Casey, Timothy M.

doi:10.1126/science.175.4025.988

Cited by 38 publications

(16 citation statements)

References 11 publications

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“…1B). In Arctic wolves and foxes, foot temperature is maintained near 0°C by a cutaneous vascular plexus in their paw and toe pads, which allows the foot skin temperature to be regulated to within a degree of freezing, even when animals are standing on substrates of −50°C (Henshaw et al, 1972). A similar vascular arrangement is also found in sea birds (e.g.…”

Section: Physiological Defencesmentioning

confidence: 69%

Adaptations to polar life in mammals and birds

Blix

2016

Journal of Experimental Biology

141

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This Review presents a broad overview of adaptations of truly Arctic and Antarctic mammals and birds to the challenges of polar life. The polar environment may be characterized by grisly cold, scarcity of food and darkness in winter, and lush conditions and continuous light in summer. Resident animals cope with these changes by behavioural, physical and physiological means. These include responses aimed at reducing exposure, such as 'balling up', huddling and shelter building; seasonal changes in insulation by fur, plumage and blubber; and circulatory adjustments aimed at preservation of core temperature, to which end the periphery and extremities are cooled to increase insulation. Newborn altricial animals have profound tolerance to hypothermia, but depend on parental care for warmth, whereas precocial mammals are well insulated and respond to cold with non-shivering thermogenesis in brown adipose tissue, and precocial birds shiver to produce heat. Most polar animals prepare themselves for shortness of food during winter by the deposition of large amounts of fat in times of plenty during autumn. These deposits are governed by a sliding set-point for body fatness throughout winter so that they last until the sun reappears in spring. Polar animals are, like most others, primarily active during the light part of the day, but when the sun never sets in summer and darkness prevails during winter, high-latitude animals become intermittently active around the clock, allowing opportunistic feeding at all times. The importance of understanding the needs of the individuals of a species to understand the responses of populations in times of climate change is emphasized.

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Section: Physiological Defencesmentioning

confidence: 69%

Adaptations to polar life in mammals and birds

Blix

2016

Journal of Experimental Biology

141

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“…If a footpad with a counter‐current heat exchanger is in a warm environment, the blood in that pad will be warm, and the counter‐current heat exchanger will have little effect. When the footpad is exposed to a cold environment, blood flow increases in the legs through regulated vasodilatation in the footpad 1,15,16 . Initially, vasodilatation will accelerate heat loss due to increased blood flow to the cutaneous circulation, and the counter‐current heat exchanger cannot retain the heat already in the paw, 1 but continual heat loss is prevented by the counter‐current heat exchanger.…”

Section: Discussionmentioning

confidence: 99%

“…They travel on the snow and ice hunting for prey. Henshaw et al showed that these animals maintain their foot temperature just above the tissue freezing point (about −1°C) when the foot is immersed in a −35°C bath in a laboratory setting 1 . They suggested that increased blood flow to the footpad surface is the mechanism for maintaining foot temperature.…”

Section: Introductionmentioning

confidence: 99%

Functional anatomy of the footpad vasculature of dogs: scanning electron microscopy of vascular corrosion casts

Ninomiya

Akiyama

Simazaki

et al. 2011

Veterinary Dermatology

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Dogs are well adapted to cold climates and they can stand, walk and run on snow and ice for long periods of time. In contrast to the body trunk, which has, dense fur, the paws are more exposed to the cold due to the lack of fur insulation. The extremities have a high surface area-to-volume ratio, so they lose heat very easily. We offer anatomical evidence for a heat-conserving structure associated with dog footpad vasculature. Methylmethacrylate vascular corrosion casts for scanning electron microscopy, Indian ink-injected whole-mount and histological specimens were each prepared, in a series of 16 limbs from four adult dogs. Vascular casts and Indian ink studies showed that abundant venules were arranged around the arteries supplying the pad surface and formed a vein-artery-vein triad, with the peri-arterial venous network intimately related to the arteries. In addition, numerous arteriovenous anastomoses and well-developed venous plexuses were found throughout the dermal vasculature. The triad forms a counter-current heat exchanger. When the footpad is exposed to a cold environment, the counter-current heat exchanger serves to prevent heat loss by recirculating heat back to the body core. Furthermore, the arteriovenous anastomoses shift blood flow, draining blood to the skin surface, and the venous plexuses retain warm blood in the pad surface. Hence, the appropriate temperature for the footpad can be maintained in cold environments.

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“…In the cat, we have been unable to elicit paw pad vasodilatation by hypothalamic warming (W. Grewe, W. Janig, H. Kummel & S. Varma, unpublished observations), although we have some evidence consistent with such a response to spinal cord warming (Gregor, Janig & Riedel, 1976;Jainig & Kuimmel, 1981). Alternatively, digital vasodilator nerves could be involved in the protective increases of digital blood flow that are seen in cold-acclimatized animals, including man, during local exposure of the extremities to cold (Hampton, 1969;Henshaw, Underwood & Casey, 1972;Johansen & Millard, 1974;Bell, 1983).…”

Section: Effects Of Acetylcholine Antagonists On Responses To Nerve Smentioning

confidence: 99%

Differentiation of vasodilator and sudomotor responses in the cat paw pad to preganglionic sympathetic stimulation.

Bell¹,

Jänig²,

Kümmel³

et al. 1985

The Journal of Physiology

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SUMMARY1. We monitored sweat secretion (using skin potential) and blood flow (using skin temperature) in the hind-paw skin of chloralose-anaesthetized cats pre-treated with guanethidine, and studied the responses to electrical stimulation of the ipsilateral lumbar sympathetic trunk.2. Stimulation caused sweat secretion and an increase in skin blood flow which was almost entirely restricted to the paw pads and was completely ipsilateral. Stimulation of the tibial nerve trunk produced similar effects, except that the increase in blood flow was more prolonged.3. The vasodilator effect of sympathetic trunk stimulation was not affected by chronic deafferentation of the paw.4. Atropine methonitrate (05-1 mg/kg i.v.) abolished the sudomotor response to sympathetic stimulation, but did not attenuate the blood flow response.5. Hexamethonium (1-2 mg/kg i.v.) abolished the vasodilator response to sympathetic stimulation, but did not affect the sudomotor response. Larger doses of hexamethonium (10-20 mg/kg) abolished both responses.6. The data suggest that the lumbar post-ganglionic neurones mediating vasodilatation in the skin of the cat paw pad are distinct from those that mediate sudomotor secretion.

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Peripheral Thermoregulation: Foot Temperature in Two Arctic Canines

Cited by 38 publications

References 11 publications

Adaptations to polar life in mammals and birds

Adaptations to polar life in mammals and birds

Functional anatomy of the footpad vasculature of dogs: scanning electron microscopy of vascular corrosion casts

Differentiation of vasodilator and sudomotor responses in the cat paw pad to preganglionic sympathetic stimulation.

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