Background: Circadian rhythms are biological rhythms generated by an organism or group of organisms that have an intrinsic period of 24 h. Among the many variables that exhibit circadian rhythmicity, body temperature has received considerable attention. The circadian rhythm of body temperature is a well-documented physiological phenomen. Also, it has been shown that changes in heat loss via convection and radiation are primarily caused by variations in skin blood flow, with consequent changes in skin temperature. For this reason, foot temperature assumes a great importance both as indicator of equine laminitis and foot-and-mouth disease in sheep. Particularly, the foot rot, term loosely used to describe lameness associated with the bovine foot, is characterized by acute inflammation of the skin and adjacent soft tissue of the interdigital cleft or space in which the modifications of temperature assume a great importance. In fact, the regulation of body temperature is an essential component of the process of fever, which plays an important role in an organism’s response to infection and disease, and its manipulation is a standard procedure in various surgical and therapeutic procedures. In this regards, the aim of this study was to evaluate the pattern of rectal temperature (RT) both in healthy Comisana sheep and in Comisana sheep affected by foot rot. Materials, Methods & Results: This experiment was carried out on 10 clinically healthy and not pregnant female sheep, and 10 not pregnant female sheep affected by foot rot. During the experimental period, all animals were kept under a natural photoperiod (sunrise 06:30, sunset 19:00). RT was measured every 3 h intervals for 24 consecutive hours starting at 11:00 on day 1 and ending at 11:00 on day 2. A trigonometric statistical model was applied to the average values of each time series, so as to describe the periodic phenomenon analytically, by characterizing the main rhythmic parameters according N to the single cosinor procedure. Four rhythmic parameters were determined: mean level, amplitude (the difference between the peak, or trough, and the mean value of a wave), acrophase (the time at which the peak of a rhythm occurs), and robust- ness (strength of rhythmicity). The application of the periodic model showed a circadian rhythm of RT in healthy subjects and no circadian rhytmicity of RT was observed in ill sheep. Discussion: The analysis of the results obtained under experimental conditions used in the present study indicated the existence of a circadian periodicity of rectal temperature in healthy sheep whereas no circadian oscillations of rectal tem- perature were revealed in sheep affected by foot rot. A simple and coherent explanation for these pathological alterations is that the set point is elevated during the rising phase and returned to normal during the later phase. Taking together, the findings of the present study, along with those of others, emphasize the concept that RT exhibits a circadian rhythm that reflect the familiar circadian patterns of endogenous source and the existence of circadian oscillations around a set point with changes in mean body temperature and an absent rhythm when temperature is modified to a new set point, as observed in sheep affected by foot rot.

Pattern of Rectal Temperature in Sheep Affected by Foot Rot

GIANESELLA, MATTEO;MORGANTE, MASSIMO;
2012

Abstract

Background: Circadian rhythms are biological rhythms generated by an organism or group of organisms that have an intrinsic period of 24 h. Among the many variables that exhibit circadian rhythmicity, body temperature has received considerable attention. The circadian rhythm of body temperature is a well-documented physiological phenomen. Also, it has been shown that changes in heat loss via convection and radiation are primarily caused by variations in skin blood flow, with consequent changes in skin temperature. For this reason, foot temperature assumes a great importance both as indicator of equine laminitis and foot-and-mouth disease in sheep. Particularly, the foot rot, term loosely used to describe lameness associated with the bovine foot, is characterized by acute inflammation of the skin and adjacent soft tissue of the interdigital cleft or space in which the modifications of temperature assume a great importance. In fact, the regulation of body temperature is an essential component of the process of fever, which plays an important role in an organism’s response to infection and disease, and its manipulation is a standard procedure in various surgical and therapeutic procedures. In this regards, the aim of this study was to evaluate the pattern of rectal temperature (RT) both in healthy Comisana sheep and in Comisana sheep affected by foot rot. Materials, Methods & Results: This experiment was carried out on 10 clinically healthy and not pregnant female sheep, and 10 not pregnant female sheep affected by foot rot. During the experimental period, all animals were kept under a natural photoperiod (sunrise 06:30, sunset 19:00). RT was measured every 3 h intervals for 24 consecutive hours starting at 11:00 on day 1 and ending at 11:00 on day 2. A trigonometric statistical model was applied to the average values of each time series, so as to describe the periodic phenomenon analytically, by characterizing the main rhythmic parameters according N to the single cosinor procedure. Four rhythmic parameters were determined: mean level, amplitude (the difference between the peak, or trough, and the mean value of a wave), acrophase (the time at which the peak of a rhythm occurs), and robust- ness (strength of rhythmicity). The application of the periodic model showed a circadian rhythm of RT in healthy subjects and no circadian rhytmicity of RT was observed in ill sheep. Discussion: The analysis of the results obtained under experimental conditions used in the present study indicated the existence of a circadian periodicity of rectal temperature in healthy sheep whereas no circadian oscillations of rectal tem- perature were revealed in sheep affected by foot rot. A simple and coherent explanation for these pathological alterations is that the set point is elevated during the rising phase and returned to normal during the later phase. Taking together, the findings of the present study, along with those of others, emphasize the concept that RT exhibits a circadian rhythm that reflect the familiar circadian patterns of endogenous source and the existence of circadian oscillations around a set point with changes in mean body temperature and an absent rhythm when temperature is modified to a new set point, as observed in sheep affected by foot rot.
2012
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11577/2496295
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