Vergleichende Untersuchungen zur Belastung von Lawinen- und Rettungshunden bei der Lauf- und der Sucharbeit

Comparative studies on strain in avalanche- and rescue-dogs during
running and searching 22 dogs of the “Lawinenhundestaffel Bergwacht
Bayern” (avalanche rescue dog unit of Bavarian Mountain Rescue)
were subjected to a series of tests on the strain exerted upon
rescue dogs. In total, every dog underwent four different types of
strain with a duration of 2 x 20 minutes each and a 20-minute break
in between the two cycles. In the summer, the strain of running
beside a bicycle was analyzed at a height of 700 metres above
sea-level, and a combined area and alpine rubble search was carried
out. Ambient temperature was between 9°C and 26°C in summer. In the
winter, the strains of running beside skis and of an avalanche
search were analyzed at a height of 2600 metres above sea-level and
ambient temperatures between –3°C and –17°C. In order to be able to
capture the influence of the nose´s activity as a strain factor,
physiological values during and up to 2 hours after search strain
were compared to those of pure running strain. In particular the
clinical parameters yielded significant variations during the four
types of strain. The heart rate reacted to all four types of strain
with a marked increase. The continuously recorded heart rate
increased to mean values of up to 164-176 beats per minute (bpm)
(physiological: 70-160 bpm) during the four types of strain and
returned to normal within 20-30 minutes after the end of strain.
The body temperature was measured at six points in time prior to
and after strain. After strain the body temperature rose to means
between 39.0 and 39.7°C (physiological: 37.5-39.0°C) and returned
to the initial values within 20-60 minutes after the end of strain.
The venous blood parameters hardly showed any significant changes
upon strain. All blood values were determined prior to and
immediately after the second strain cycle as well as 2 hours after
the end of strain. Blood gas pH increased after strain, reaching
means of 7.40-7.43 (physiological: 7.30-7.40). In addition, there
was a decrease in means of pCO2 to 30-31 mm Hg (physiological:
36-40 mm Hg) and in bikarbonate to 19-20 mmol/l (physiological: up
to 24.2 mmol/l), whereas pO2 increased to up to 58 mm Hg
(physiological: 34-54 mm Hg). In the muscle metabolism there was a
continuous increase in creatine kinase activity after strain, with
means up to 105 IU/l (physiological: up to 90 IU/l) after 2 hours
in recovery. The plasma lactate concentration of the rescue dogs
underwent no major changes in any of the four types of strain and
never exceeded 2.3 mmol/l (physiological: 0.22-4.40 mmol/l). The
renal (bounded urea nitrogen, creatinine), the hematological
(hematocrit, hemoglobin) and the hepatic parameters (alkaline
phosphatase, alanine transaminase, total bilirubin, cholesterol) as
well as the proteins measured (total protein, albumin, globulin)
did not change significantly under any of the four types of strain.
In all strain types, blood glucose varied to a relatively small
degree ranging between 5.4 mmol/l and 5.8 mmol/l (physiological:
3.9-6.7 mmol/l). As regards salivary cortisol, there was a delayed
increase in the cortisol concentration during recovery. Means of
salivary cortisol values reached 5.5 nmol/l in maximum (resting
value: 1.5-2.3 nmol/l). Observation of behaviour yielded signs of
fatigue during avalanche search in winter and in the rubble search
in summer during the second strain phase in the form of a reduced
activity index. Area search in the summer was generally associated
with the highest activity level, and only in this type of search
there was no decrease in the activity index during the second
strain phase. Dividing the participating rescue dogs in three
age-classes (up to 4 years, 4-7 years, over 7 years) age dependent
differences could be seen. During the whole observation the older
dogs showed significant higher heart rates and significant lower
body temperatures. Compared to the other two age-classes the older
dogs also had significant higher lactate concentrations and a
obvious higher creatinkinase activity after strain. Dogs under 4
years of age showed constantly higher body temperatures and
activity indices in comparison to the two older age-classes. After
strain highest blood glucose levels could be found in the young
dogs up to 4 years. The salivary cortisol concentration was
significant lower in the dogs from 4-7 years of age. In summary,
the parameters investigated did not indicate any differences in the
strain physiology between the strain during search and the mere
strain due to running. However, based on heart rate, body
temperature, blood gas parameters, blood glucose and salivary
cortisol values significant differences were found between the
strain of search in summer and the strain of search in winter.