Andrea M. Nolan

Acute phase proteins in serum and milk from dairy cows with clinical mastitis

The serum concentrations of haptoglobin, serum amyloid A and α acid glycoprotein were determined in serum collected from healthy dairy cows and cows with clinical mastitis, graded as mild (clots in milk) or moderate (clots in milk and visible signs of inflammation in the mammary gland/s) to assess their relative diagnostic value in detecting the disease. The concentrations of haptoglobin and serum amyloid A were also measured in milk collected from infected and uninfected quarters. The concentrations of haptoglobin and serum amyloid A were higher in the serum and milk from the cows with mild or moderate mastitis. The diagnostic value of haptoglobin in differentiating between healthy animals and those with mastitis gave sensitivities and specificities of 82 per cent and 94 per cent respectively with serum and 86 per cent and 100 per cent with milk. The diagnostic value of serum amyloid A in differentiating between healthy animals and those with mastitis gave sensitivities and specificities of 83 per cent and 90 per cent with serum and 93 per cent and 100 per cent with milk. The diagnostic value of serum α acid glycoprotein in differentiating between healthy animals and those with mastitis gave sensitivities and specificities of 62 per cent and 91 per cent.

Development of a behaviour-based scale to measure acute pain in dogs

A composite scale for assessing pain in dogs in a hospital setting has been developed on the basis of observations of their behaviour. Initially, 279 words and expressions suggested by 69 veterinary surgeons were reduced into 47 words and expressions which were allocated into seven behaviour categories: demeanour and response to people, posture, mobility, activity, response to touch, attention to painful area and vocalisation. Three statistical methods, hierarchical agglomerative cluster analysis, Cronbachs alpha coefficient, and analysis of variance with multiple comparisons and empirical cumulative distributions, were used to validate these procedures, and a questionnaire accompanied by a list of definitions was designed around the expressions. The new composite scale is more detailed than previously reported scales for assessing pain in dogs on the basis of their behaviour, and the methods used in its development are based on sound scientific principles.

Dynamic changes in NADPH-diaphorase staining reflect activity of nitric oxide synthase: evidence for a dopaminergic regulation of striatal nitric oxide release.

In fixed tissue, neuronal NADPH-diaphorase staining results from nitric oxide synthase (NOS) activity. Neuronal NOS only synthesizes nitric oxide once activated by the binding of Ca2+/calmodulin. We show here that neuronal NADPH-diaphorase staining is also dependent on Ca2+/calmodulin, implying that only activated NOS is detected. In addition, in bovine pulmonary endothelial cells, carbachol and bradykinin dramatically and rapidly increase the intensity of NADPH-diaphorase staining. Furthermore, administration of MK801, an NMDA antagonist, decreases neuronal NADPH-diaphorase staining. This suggests that the intensity of the NADPH-diaphorase staining is related to the level of enzyme activation at the moment of tissue fixation. The potential of exploiting this observation to detect cellular activation of NOS is illustrated by the observations that the intensity of NADPH-diaphorase staining in rat striatal neurones is decreased following systemic treatment with the D1-like dopamine receptor antagonist SCH23390, and increased by the D2-like antagonist eticlopride. These results therefore provide strong evidence that the NADPH-diaphorase reaction can be used to monitor NOS activity at a cellular level of resolution, and reveal a dopaminergic regulation of NOS activity in the striatum mediated by D1-like and D2-like dopamine receptors.

Up-regulation of metabotropic glutamate receptor subtypes 3 and 5 in spinal cord in a clinical model of persistent inflammation and hyperalgesia

&NA; Evidence from experimental pain research has revealed that metabotropic glutamate receptors (mGluRs) play a pivotal role in nociceptive processing, inflammatory pain and hyperalgesia. The aim of this study was to characterise expression of group I and II mGluRs in spinal cord in a model of naturally occurring persistent inflammation (sheep with unilateral lameness due to inflammation of the digital tissues of the feet, estimated to have been affected by the condition for >2 weeks) and an experimental model of acute inflammation (injection of intradermal carrageenan into lower forelimb in sheep). Animals with unilateral clinical inflammation displayed significant mechanical hyperalgesia on the affected limb. Carrageenan treatment produced significant bilateral limb mechanical hyperalgesia 3 h post‐injection. Up‐regulation of mGluR3 and mGluR5 mRNA was observed in ipsilateral spinal cord recovered from clinically lame animals, restricted to laminae II–V and I–II, respectively. Western blot analyses of protein extracts revealed a bilateral increase in mGluR2/3 and mGluR5. No change was detected in spinal cord mGluR1 or mGluR2 mRNA. There was no change in mGluR1,2,3,5 subtype mRNA or proteins in spinal cord recovered from animals 3 h post‐carrageenan. These results demonstrate for the first time that mGluR subtypes are differentially expressed in spinal cord dorsal horn in response to persistent inflammation, and suggest that mGluR activity may be involved in mediating altered behaviours associated with clinical inflammatory pain.

Simultaneous infusions of propofol and ketamine in ponies premedicated with detomidine: a pharmacokinetic study

The pharmacokinetics of propofol and ketamine administered together by infusion were investigated in four ponies. Blood propofol and plasma ketamine and norketamine concentrations were measured by high performance liquid chromatography. After premedication with detomidine (20 micrograms kg-1) anaesthesia was induced with ketamine (2.2 mg kg-1 intravenously). The trachea was intubated and the ponies were allowed to breathe 100 per cent oxygen. A bolus dose of propofol (0.5 mg kg-1) was then administered intravenously and propofol and ketamine were infused for 60 and 45 minutes, respectively. The average mean infusion rate of propofol was 0.136 mg kg-1 min-1, and the ketamine infusion rate was maintained at 50 micrograms kg-1 min-1. The mean (SD) elimination half-lives of propofol and ketamine were 69.0 (8.0) and 89.8 (26.7) minutes, the mean volumes of distribution at steady state were 0.894 (0.161) litre kg-1 and 1.432 (0.324) litre kg-1; the mean body clearances were 33.1 (4.5) and 23.9 (3.8) ml kg-1 min-1 and the mean residence times for the infusion were 87.1 (4.1) and 110.7 (8.2) minutes, respectively. Norketamine, the main metabolite of ketamine, was detected throughout the sampling period. The mean residence time for norketamine was 144 (16) minutes. All the ponies recovered quickly from the anaesthesia; the mean times to sternal recumbency and standing were 11.1 (5.3) and 30.0 (20.8) minutes, respectively, from the end of the infusion.

A pharmacodynamic study of propofol or propofol and ketamine infusions in ponies undergoing surgery

The pharmacodynamics of infusions of propofol alone (group 1) were compared with the pharmacodynamics of infusions of propofol and ketamine together (group 2) in eight ponies undergoing castration. Anaesthesia was induced with detomidine, 20 micrograms kg-1, followed by ketamine, 2.2 mg kg-1. Subsequently, a bolus dose of propofol, 0.5 mg kg-1, was administered intravenously to both groups, and an infusion of propofol was given for an average of 74 minutes to group 1, and an infusion of propofol and ketamine was given for 60 minutes to group 2. The mean (SD) infusion rates of propofol were 0.330 (0.050) mg kg-1 min-1 in group 1, and 0.124 (0.009) mg kg-1 in group 2, and the ketamine infusion rate was maintained constant at 40 micrograms kg-1 min-1. Arterial hypotension and marked respiratory depression were evident in some of the ponies receiving propofol alone, whereas in the ponies anaesthetised with propofol and ketamine, respiratory and cardiovascular parameters were well maintained. All the ponies in both groups recovered quickly from anaesthesia, with mean times to sternal recumbency and standing of 19.8 (8.0) minutes and 27.2 (7.4) minutes respectively for group 1 and 8.4 (3.2) min and 14.9 (10.1) minutes for group 2.

Evaluation and optimisation of a target-controlled infusion system for administering propofol to dogs as part of a total intravenous anaesthetic technique during dental surgery

The performance of a modified target-controlled infusion system was investigated in 16 dogs undergoing routine dental work, by comparing the predicted concentrations of propofol in venous blood samples with direct measurements; the optimum targets for the induction and maintenance of anaesthesia were also identified. The performance of a target-controlled infusion system is considered clinically acceptable when the median prediction error, a measure of bias, is not greater than ±10 to 20 per cent, and the median absolute performance error, a measure of the accuracy, is not greater than 20 to 30 per cent. The results fell within these limits indicating that the system performed adequately. The optimal induction target was 3 μg/ml, and anaesthesia of adequate depth and satisfactory quality was achieved with maintenance targets of between 2.5 and 4.7 μg/ml propofol. The system was easy to use and the quality of anaesthesia was adequate for dental work.

Quality of life is reduced in obese dogs but improves after successful weight loss

Obesity is thought to affect quality of life, but limited objective data exist to support this supposition. The current study aim was to use a questionnaire to determine health-related quality of life (HRQOL) both before and after weight loss, in obese client-owned dogs. Fifty obese dogs were included, and represented a variety of breeds and genders. Prior to weight loss, owners were asked to complete a validated standardised questionnaire to determine HRQOL. Thirty of the dogs successfully completed their weight loss programme and reached target, and owners then completed a follow-up questionnaire. The completed questionnaire responses were transformed to scores corresponding to each of four factors (vitality, emotional disturbance, anxiety and pain), and scored on a scale of 0-6. Changes in the scores were used to explore the sensitivity of the questionnaire, and scores were correlated with responses to direct questions about quality of life and pain, as well as weight loss. Dogs that failed to complete their weight loss programme had lower vitality and higher emotional disturbance scores than those successfully losing weight (P=0.03 for both). In the 30 dogs that completed, weight loss led to an increased vitality score (P<0.001), and decreased scores for both emotional disturbance (P<0.001) and pain (P<0.001). However, there was no change in anxiety (P=0.09). The change in vitality score was positively associated with percentage weight loss (r(P)=0.43, P=0.02) and percentage body fat loss (r(P)=0.39, P=0.03). These results indicate demonstrable improvement in HRQOL for obese dogs that successfully lose weight.

Behavioural evidence supporting a differential role for group I and II metabotropic glutamate receptors in spinal nociceptive transmission.

Metabotropic glutamate receptors (mGluRs) have been shown to contribute to nociceptive processing in spinal cord. This study examined the effects of intrathecal treatment with group I and II mGluR compounds on withdrawal thresholds to noxious mechanical stimuli, in the absence of tissue damage or inflammation, in adult female sheep. Both the group I/II mGluR agonist (+/-)-1-aminocyclopentane-trans-1,3-dicarboxylic acid (trans-ACPD; 5.2-520 nmol) and the group II agonist (2S,1S, 2S)-2-(carboxycyclopropyl)glycine (L-CCG-I; 620 nmol) significantly increased mechanical withdrawal thresholds between 5-15 min post-injection. These anti-nociceptive effects were blocked by co-administration of the mGluR antagonist (2S)-alpha-ethylglutamate (EGLU; 570 nmol; group II), but not (RS)-1-aminoindan-1,5-dicarboxylic acid (AIDA; 450 nmol; group I). Intrathecal administration of the group I-specific agonist (S)-3,5-dihydroxyphenylglycine ((S)-3,5-DHPG; 50 nmol) produced a significant reduction in mechanical thresholds, which was blocked by co-administration of the group I antagonist AIDA. In contrast, the highest dose of (S)-3,5-DHPG tested, 5 micromol, significantly elevated response thresholds. These results demonstrate that both group I and II mGluRs play crucial, but contrasting roles in mediating acute mechanical nociceptive events in spinal cord.

Effect of flunixin meglumine on the thresholds to mechanical stimulation in healthy and lame sheep.

The antinociceptive effect of flunixin meglumine was assessed in healthy and lame sheep by using a noxious mechanical stimulus. Sheep suffering from the chronically painful condition, footrot, have previously been shown to have lower thresholds to noxious mechanical stimuli than healthy animals. In the present study, 22 sheep suffering from footrot did not have a lower mean mechanical threshold than 25 matched healthy animals, but it was significantly greater than that recorded from eight experimental sheep (5.0 [2.5], 4.9 [2.1] and 3.0 [1.0] Newtons, respectively). Doses of 1.0 or 2.0 mg kg-1 of flunixin meglumine had no effect on the thresholds to noxious mechanical stimulation in either experimental sheep tested over six hours, or in lame sheep tested over a period of 30 minutes. The repeated administration of flunixin to sheep suffering from footrot over a period of three days reduced their thresholds to noxious mechanical stimulation.