Blood parameters and hormonal status of sled dogs Siberian husky breed before and after racing

. The investigation of the physiological characteristics of sled dogs of Siberian husky breed seems relevant, since dogs of this breed recently play an important role for animal husbandry in the Far North in Russia. Blood samples have been taken before the racing and immediately after it. The study of hormones in the blood of Siberian husky sled dogs before and after the racing showed that the testosterone level dropped sharply after the racing by 7.6 times, which can be explained by the significant energy consumption of the dog's body during the racing. At the same time, cortisol as a hormone that protects the body from stress, regulates blood pressure, participates in the metabolism of proteins, fats and carbohydrates, has significantly increased by 3.6 times (P<0.05), which indicated the activation of the body's protective systems during the period of exposure to stress. The content of estradiol had not undergone significant changes. The exertion affected the content of red blood cells their decrease occurred (by 7.3%), a similar dynamics in hemoglobin level was observed. It was found as the result of biochemical blood tests that the creatinine level after racing increased by 4.6 mmol/l. The levels of aspartate aminotransferase and alanine aminotransferase decreased by 31.5 and 30.8 units/l, respectively. The content of lactate dehydrogenase increased by 31.3 units/l. The level glucose in the blood of sled dogs after racing decreased


Introduction
One of the main traits of animal organism is the ability to constantly adapt to changing environmental conditions.Under physiological adaptation (from Lat.adaptatio) understand the totality of morphological and physiological processes in the body that underlie its adaptation to specific conditions of existence in the external environment [1].All observed evolutionary changes are explained by the continuous adaptation of species and individual selection.
The study of the physiological characteristics of sled dogs of Siberian husky breed seems relevant, since dogs of this breed play an important role for animal husbandry in Russian Far North at the present time [2].
According to opinion of same scientists as T V Konovalova et al. [3], T Imbabi et al. [4], physiological adaptation is divided into species such as inherited, individual, characterizing an individual, and population, which characterizes a group of organisms of a given species (breed) developing under certain environmental conditions.
However, there is still a little information in the scientific literature about the patterns of manifestation of physiological reactions of the body of dogs depending on various natural conditions.There is no information about the degree of stress of adaptive reactions of the organism, taking into account the climatic heterogeneity of the terrain [5].
The adaptation of the animals based on its ability to "directional variability" is one of its most important properties that ensure their normal development.It makes it possible to ensure the survival of the species in a specific habitat, resistance to the effects of abiotic and biological factors [6].
The ability of organism to adapt is realized within the framework of the close interaction of the genotype and environmental conditions.The term "adaptation" and its derivatives are often used by various researchers.Adaptive possibility is especially expressed when the study of hematological and biochemical parameters of animal blood [7].This is confirmed by many scientific works in which the typology of dog behavior, characteristics of the types of their nervous system, as well as the hormonal and hematological status of dogs are presented in detail.The innate constitutional type of nervous activity of dogs, their side-by-side reactions to the external environment is due to the genotype.At the same time, the animal is constantly exposed to environmental stimuli, and it must react to them then these reactions are fixed during life.Thus, the finally formed higher nervous activity of the individual, his resistance to adverse environmental factors, is a combination of innate and acquired traits [8].
Since stress is a non-specific response of the organism to any demand presented to it, from these positions it is considered as the initial stage for launching adaptation mechanisms [9].
In the process of adaptation, animals are influenced by stress factors, under the action of which reactions occur in the body that ensure its homeostatic balance and allow the body to lead a "free and independent life" in changed environmental conditions.These reactions of the organism are called adaptive.The great special interest for cynology is the investigation of stress factors that have the strongest effect on the organism of dog.
It should be noted that only extreme one-time effects or long-acting stimuli can act as factors that violate the mechanisms of self-regulation of the body, and thereby significantly reduce the ability of living beings to maintain the constancy of their internal environment.Under stress almost all types of metabolism occurring in the body are disrupted.Therefore, the evaluation of their adaptive capabilities deserves a comprehensive investigation [10,11].
The study of adaptation gas of great importance for understanding the processes of selfregulation of the organism, its interaction with the environment.Reactions by which the body responds to stimuli of considerable intensity have common non-specific features and are called the general adaptation syndrome.
Heat resistance is the preservation of temperature homeostasis by animals in response to the influence of high ambient temperatures.It is established that this stability is primarily determined by the regulation of heat exchange.Heat-resistant animals are characterized by a greater number of sweat glands, rarer, smoother, glossy hair and more intense skin pigmentation.
The main physical irritant for warm-blooded animals is the temperature of the surrounding air and indoor surfaces, since it has a direct effect on the heat regulation by organism of animal.Dogs as animals mainly housed outdoors are most susceptible to the influence of climatic factors.The problem of seasonal effects of extreme temperatures on the body of farm animals and dogs under natural conditions is of great interest, but has not yet been sufficiently studied [12].
For warm-blooded animals, which include dogs, there is the temperature homeostasis that maintains a relatively constant body temperature.The circulatory system is the most striking example of a rapid response to the effects of temperature stimuli, providing among other things the maintenance of thermal balance.
The dogs as the warm-blooded animals have a high level of metabolic processes.Heat is released during biochemical reactions inside the body.The lower the temperature of the medium, the greater the heat loss and the more intense the processes are, the same happens when the air temperature rises.The reserves of the cardiovascular system of dogs are very large and if necessary can increase several times, but this process is not infinite.
The respiratory tract gives off heat mainly by evaporation of moisture and in part as the result of heating the inhaled air.The size of the heat transfer in this case depends on the temperature and humidity of the inhaled air and the volume of lung ventilation.In dogs this kind of heat transfer comes to the fore.As it was noted earlier, dogs deprived of sweat glands evaporate moisture as a result of rapid breathing from the surface of the protruding tongue.
Active physical exercises on the body are the strongest stress factor, the study of the influence of which on hematological, behavioral and hormonal blood parameters is an extremely relevant direction in cynology and especially in the study of the characteristics of sled dogs [13].
The purpose of research was to study hormonal status, hematological and biochemical blood parameters of sled dogs Siberian husky breed before and after racing.
Purpose of research was to study blood parameters and hormonal status of sled dogs Siberian husky breed before and after racing.

Materials and methods
The research has been carried out at the Institute of Animal Science and Biology of Russian State Agrarian University -Moscow Timiryazev Agricultural Academy and on the basis of the Racing Sports Center "Severnaya Nadezhda" in the Neysky district in the Kostroma region.
The sled dogs of Siberian husky breed that participated in the All-Russian racings "Severnaya Nadezhda" were as the object for our research.All experimental animals had an aviary type of housing and the same type of feeding according to generally accepted norms in dog breeding.
The investigations were carried out according to the developed research methodology using modern research methods.Blood samples for research were taken from the animals before and after the racing, which allowed us to reveal their hematological, biochemical and hormonal status.The length of the distance was 25 km, which was covered by animals with the average speed of 15 km/h.
The hematological status of dogs was studied by the content of shaped blood elements (erythrocytes, leukocytes, platelets), as well as by the level of hemoglobin before and after racing by taking blood from 6 heads of Siberian husky sled dogs.At the same time in the venous blood the biochemical profile of the blood in sled dogs was studied according to the following indicators: creatinine, enzymes aspartate aminotransferase and alanine aminotransferase, lactate dehydrogenase, creatine phosphokinase, glucose, total protein and albumin content, and triglycerides, as well as the level of hormones such as testosterone, estradiol and cortisol.The blood samples were taken for 30 minutes before the start and immediately after the finish of the relay with a volume of 5 ml in glass conical tubes then the tubes with blood were placed in a refrigerator bag and transported to the veterinary laboratory.
The obtained research results were subjected to biometric processing using generally accepted methods, the arithmetic mean with its error ( x S X  ) and the coefficient of variability (Cv, %) were calculated.
As additional indicators of the general condition of the animals, their body temperature, pulse, respiratory rate were monitored, which were determined by generally accepted in animal science methods.

Results and discussion
During the research we have evaluated some hematological parameters in dogs before and after the racing.There were 6 dogs race in each of the relay.Each of the dogs participating in the experiment was individual and had its own hematological parameters, which were within the physiological norm.
The main physiological significance of red blood cells lies in their ability to carry oxygen and carbon dioxide, but this is not the only important thing.It is important that 100 ml of erythrocyte mass contains about 30 g of protein (26-28 g of globin and only 2 to 4 g of other plasma proteins).Having a huge common surface, erythrocytes in homoiothermic organisms are able to perform the function of protecting the body during high exertions as in our case.Dogs in the relay have covered the distance of 15 km.In such tests the study of the content of red blood cells is necessary and important.
It has been found by us that at permissible minimum and maximum values of the concentration of erythrocytes from 3.5×10 12 /l to 9.6×10 12 /l.In sled dogs of Siberian husky breed these values before the racing were 7.10×10 12 /l, and after the racing it was 6.62×10 12 /l, which corresponded to the physiological norm (table 1).The decrease of erythrocytes in the blood of Siberian husky dogs was 0.48×10 12 /l or 7.3%.The decrease in the content of red blood cells in sled dogs of Siberian husky breed was associated with loss of energy and some dehydration.Hence, we can assume general changes in metabolic processes in the body, which were reflected in the level of red blood cells.At the same time we also have noted that the indicators were within the reference values.
There were no significant differences in the content of leukocytes in the group of dogs compared before and after racing in our research.So, the number of leukocytes before the racing was 10.20×10 9 /l, and after it was 11.17×10 9 /l.We can see the reverse picture of changes in the content of leukocytes in contrast to the dynamics of erythrocytes.There was the increase of leukocytes, but it also was also not statistically significant.
In general, hemoglobin is the indicator reflecting the general condition of the body.For adult dogs in a normal state of the body the hemoglobin content is 120-180 g/l.Deviations from the average values of indicators in the hemoglobin content indicate progressive oxygen starvation of cells due to the death of red blood cells.We have not observed any sharp deviations from the norm in our studies.
Dogs regularly participating in middle-distance races had slightly different hemoglobin levels.The average values of the hemoglobin content after racing were at the average level, which was obviously due to the heavy exertion on dogs.The concentration of hemoglobin has decreased insignificantly during the racing in our experimental dogs.If before the racing the average figures were 151.68 g/l, then after it was 142.87 g/l.
It is known that the individual traits of animals have the greatest influence on the indicators of red blood cells.At the same time, we have noted a similar dynamics of hemoglobin during the racing with that of red blood cells before and after exertion.
Platelets are necessary for the implementation of such protective functions in the body as blood clotting and ensuring the integrity of blood vessels.Exertions during the racing led to a slight change in the concentration of platelets in the blood of sled dogs.For example, in dogs of Siberian husky breed their content has been decreased from 209.00×10 9 /l before the racing and ranged 182.00×10 9 /l after the racing.Thus, the dynamics of platelet levels was comparable to the dynamics of the content of erythrocytes and hemoglobin in the blood and was inversely proportional to the dynamics of leukocytes.
Studies have shown that aerobic exertions led to moderate deviations in indicators in the blood.The change was probably facilitated by metabolic stresses during prolonged exertions during the racing process.
Biochemical parameters of the blood on Siberian husky breed sled dogs before and after racing are shown in table 2.
It was found during the conducted studies that the level of creatinine after racing has been increased by 4.6 mmol/l or 4.3%.The levels of aspartate aminotransferase and alanine aminotransferase have been decreased by 31.5 and 30.8 units/l, respectively, or 51.4 and 75.3%.The content of lactate dehydrogenase has been increased by 31.3 units/l or 31.3%.The level of glucose in the blood of sled dogs after racing has been decreased from 5.0 mmol/l to 4.5 mmol/l or by 11.1%, which was quite understandable by the significant energy consumption of dogs during the racing.It was found the decrease in the content of total protein and its albumin fraction during the racing by 6.0 and 2.5 g/l or 10.2 and 8.3%, respectively.Moreover, the decrease in albumin level was statistically significant at p<0.05.
As the result of the racing the level of creatine phosphokinase has been increased by 24.3 units /l or 15.1%, and the content of triglycerides has been decreased by 0.12 mmol/l or 25.0%.
The results obtained indicate the ambiguous change in biochemical parameters, which reflected changes in metabolism in the body of sled dogs before and after racing.
The level of hormones in the blood of Siberian husky breed sled dogs before and after racing is shown in table 3. It was found that the testosterone level has been dropped sharply after the racing by 7.6 times, which can also be explained by the significant energy consumption of the dog's body during the racing.We have to note the very high variability of this hormone before racing (68.2 %), but after racing variability of this hormone had come down in 2.6 times.At the same time cortisol, which is a hormone that protects the body from stress, regulates blood pressure, participates in the metabolism of proteins, fats and carbohydrates, has been significantly increased by 3.6 times (P<0.05),which indicated the activation of the body's protective systems during the period of exposure to stress.This hormone also had the high enough variability before racing (37.9 %).The content of the hormone estradiol did not have undergone significant changes and its variability was extremely low before and after racing.
Consequently, indicators of the hormonal status of the body and biochemical blood parameters in sled dogs of Siberian husky breed can serve as criteria for their evaluation during the racing in relays.

Conclusions
1.For the first time, the comprehensive analysis of the physiological state of sled dogs Siberian husky breed by hematological, biochemical and hormonal status during the dog sledding racing before and after the exertion was carried out.The investigation of hematological parameters in sled dogs before and after the racing has shown that the differences before and after the racing had no statistical significance.The exertion affected the content of red blood cells their decrease occurred (by 7.3%), a similar dynamics in hemoglobin level has been observed.The number of white blood cells on the contrary increased after the racing.Exertions during the racing led to a slight change in the number of platelets in the blood of sled dogs Siberian husky breed their content decreased.2. It was found during the studying the complex of biochemical blood parameters, that creatinine level after exercise increased by 4.6 mmol/l or 4.3%.The levels of aspartate aminotransferase and alanine aminotransferase have been decreased by 31.5 and 30.8 units/l, respectively, or 51.4 and 75.3%.The content of lactate dehydrogenase increased by 31.3 units/l or 31.3%.The level glucose in the blood of sled dogs after exercise decreased from 5.0 mmol/l to 4.5 mmol/l or by 11.1%, which was quite understandable by the significant energy consumption of sled dogs during the racing.It has been found the decrease in the content of total protein and its albumin fraction during the racing by 6.0 and 2.5 g/l or 10.2 and 8.3%, respectively.Moreover, the decrease in albumin level was statistically significant at p<0.05. 3. It was found during the studying the hormonal status, that testosterone level dropped sharply after the racing by 7.6 times, which can also be explained by the significant energy consumption of the dog's body during the racing.At the same time cortisol significantly increased 3.6 times (P<0.05),which indicated the activation of the body's defense systems during the period of exposure to stress.The content of the hormone estradiol did not have undergone significant changes.4. Thus, the results obtained can be used as reference indicators of the levels of hematological and biochemical parameters of the blood, as well as the hormonal status of sled dogs Siberian husky breed and serve as the criterion for the selection of dogs to participate in racing competitions.

Table 1 .
Hematological indicators in sled dogs of Siberian husky breed before and after racing (

Table 2 .
Biochemical blood indicators in Siberian husky sled dogs breed before and after racing Note: * p<0.05 is the difference between the indicators before and after the racing.

Table 3 .
Hormone levels in the blood of sled dogs Siberian husky breed before and after racing Note: * p<0.05 is the difference between the indicators before and after the racing.