Relationship between physiological factors and clinical pain in dogs scored using a numerical rating scale

A study was designed to investigate the association between heart rate, respiratory rate and pupil dilation and a subjective pain score allocated using a numerical rating scale (NRS). Four groups of dogs (n = 17 to 20 per group) were included: orthopaedic surgery cases, soft tissue surgery cases, dogs with medical conditions and healthy dogs. Each dog was examined by five veterinary surgeons within a four-hour period. When examining each dog, the observers recorded heart rate, respiratory rate, pupil dilation (present or absent) and a pain score using a NRS (range 0 to 10). For surgical cases, all study assessments were carried out between 21 and 27 hours following the end of surgery. The correlation coefficients between physiological parameters and NRS score were small but, depending on the analysis, were significant for heart rate and NRS score (P < 0·05). However, the size of the coefficient, 0·168, indicated that the relationship was not biologically significant. There was no association between respiratory rate and NRS score. Analysis of the relationship between NRS score and pupil dilation indicated that there was an association between this factor and pain, depending on the analysis. This was significant for the surgical groups (P < 0·05) but not for the other groups.
These findings indicate that heart rate and respiratory rate are not useful indicators of pain in hospitalised dogs. It is also unlikely that pupil dilation will be a useful tool in the assessment of pain.     

Water stress effects on root exudation by lodgepole pine

Individual roots of a 7-year-old lodgepole pine (Pinus contorta Dougl. ex Loud) were subjected to water potentials of 0, ?200 or ?400 kPa using PEG 4000 as the osmotic agent. Root exudation of photoassimilated ¹⁴CO₂ was followed over time. Although roots subjected to a water potential of ?400 kPa exuded more ¹⁴C-labeled material than roots at either 0 or ?200 kPa, more labeled material was also translocated to these roots, suggesting an attempt to alleviate the water stress. Some roots exuded over 80% of the total ¹⁴C-activity which moved to the roots in 10 days. Although exudation did not appear to be influenced by mycorrhizal infection, mother roots exuded a greater proportion of ¹⁴C-labeled assimilates than lateral roots.     

The effects of hypoxia,in vivo,on red blood cell β-adrenoceptors in the rainbow trout,Oncorhynchus mykiss

Rainbow trout, Oncorhynchus mykiss, were exposed to 48h of environmental hypoxia (water partial pressure of oxygen = 8.0 kPa) at either 5 or 15°C. Blood was sampled during hypoxia via a dorsal aorta cannula to measure arterial blood partial pressure of oxygen and plasma catecholamine concentrations. After 48h, the number (B_max) and dissociation constant (K_d) of red blood cell surface -adrenoceptors were determined using a radioligand-displacement binding assay. At 5°C, plasma catecholamine levels were elevated at 24h whereas at 15°C, levels were elevated at 48h. At either temperature, following 48h of hypoxia, there was no change in B_max or K_d of red blood cell surface -adrenoceptors, compared to normoxic control fish. This study demonstrates that chronic exposure to moderate hypoxia does not affect the number or affinity of cell surface -adrenoceptors on trout red blood cells.