A biomechanical investigation of the static stabilisers of the glenohumeral joint in the dog

The aim was to determine the relative contribution of the glenohumeral ligaments/joint capsule complex and the limited joint volume/adhesion-cohesion (LJV/AC) mechanisms to the static stability of the canine glenohumeral joint (GHJ). The GHJ of 32 complete cadaver specimens were manipulated to determine the presence of gross laxity (>2mm translation) at joint angles of 150°, 135° and 90°. Following the removal of the peri-articular muscles, laxity was measured by applying a 15N force to the scapula in a variety of directions whilst the humerus was fixed to a jig. This was repeated for the abovementioned angles in intact joints and after venting and flushing to eliminate the LJV/AC mechanisms. Results of clinical palpation and biomechanical studies were compared. Manipulation revealed a marked variation between joints although there was a tendency for progressive laxity as the joint was flexed. This finding was supported by the biomechanical study that also demonstrated no significant difference between intact and vented joints except in a cranio-caudal direction at 135° and 90°, and in a medial/lateral direction at 135°. Static stabilisers permitted a wide range of motion. Individual clinical palpations did not correlate well with biomechanical findings. Manipulation was difficult to perform and is unlikely to be a reliable method for determining subtle joint laxity. The static stabilisers do not appear to play a significant role in providing joint constraint during normal range of motion (except extension). Diagnoses of pathological laxity attributable to the static stabilisers should be made with caution and surgical treatments should take cognizance of the above-mentioned biomechanical features.

The effects of firocoxib (Previcox) in geriatric dogs over a period of 90 days

The long-term use of non-steroidal anti-inflammatory agents in geriatric dogs with osteoarthritis has not been well studied in veterinary medicine. This study evaluated the effects of firocoxib administered to dogs over 7 years of age for 90 days. Pain and lameness scores were evaluated by the owner weekly for the 1st month and then biweekly through to the end of the study, the veterinarian evaluated the dogs monthly. Serum chemistry, including urea, creatinine, alanine transferase, aspartate transaminase, bile acids and bilirubin, urine specific gravity and a urine dipstick, were performed at monthly intervals. Forty-five dogs were enrolled into the treatment group and 9 into the control group. A total of 33 dogs completed the trial in the treatment group and 8 in the control group. Lameness and pain scores were found to be significantly lower in the treated group from day 30 for most parameters evaluated. Bile acids (although not comparable to controls, with higher mean value and a high standard deviation in the control group; in addition the control group had increased bile acids at day 0) and urea (within normal reference range provided (WNL)) were significantly different in the treatment group between days 0 and 90. Urea (WNL) on days 30 and 90 and creatinine (WNL) on day 90 were significantly different between the control group and the treatment group. The most common adverse events reported were diarrhoea, vomition, dark faeces and anorexia. This study showed that firocoxib was effective in managing pain associated with osteoarthritis for 90 days. Despite the geriatric high-risk population used for this study, minimal biochemical changes were seen and adverse drug events seen were in agreement with those previously reported.

Preliminary assessment of the AAI Index during isoflurane anaesthesia in dogs undergoing clinical procedures

The auditory evoked potential (AEP) is correlated to anaesthetic depth. The AEP has been used in rats, pigs, dogs and humans to assess anaesthetic depth. This study was undertaken to determine whether the AAI Index derived from the AEP correlated with changes in end tidal isoflurane concentration in dogs. The average AAI Index was 21.8 +/- 10.5 and isoflurane concentration was 1.7 +/- 0.4%. Data were divided into 0.5% intervals of end tidal anaesthetic agent concentration (ETAA). When ETAA values were higher than 2.5% the AAI values were 2.1-2.5%, 1.6-2.0% and 1.1-1.5% higher than AAI values although not statistically different. The 2.1-2.5 % interval was statistically different from the 1.1-1.5% and <1.1% interval. The 1.6-2.0% interval was statistically different from the 1.1-1.5% and the <1.1% intervals. The 1.1-1.5% interval was statistically different from the <1.1% interval. The correlation between the AAI Index and isoflurane was -0.176 and was statistically significant (P = 0.0009). A linear regression between the AAI Index and isoflurane revealed the following relationship: AAI = 29.074 - (4.2755 x isoflurane) with a power of 0.913. The polynomial regression relationship was AAI = 53.334 - (35.715 x isoflurane) + (10.322 x isoflurane2) - (0.43646 x isoflurane3) with a power of 0.999. The AAI Index was found to correlate with changes in isoflurane concentration.

Computer simulations of propofol infusions for total intravenous anaesthesia in dogs

The volatile anaesthetic agents halothane, isoflurane and enflurane are all chlorofluorocarbons and according to international treaties, their emission into the atmosphere will be prohibited from the year 2030. The agents desflurane and sevoflurane are fluorinated hydrocarbons and act as greenhouse gases. The future of veterinary anaesthesia could be dependent on the development of total intravenous anaesthesia. Drugs utilised in total intravenous anaesthesia (TIVA) should have a short duration of action and no tendency to accumulate in the body. Propofol has been the dominant agent used. Computer technology has enabled targeted plasma concentration controlled infusions to replace manual infusion regimens. This study simulated the pharmacokinetics of various infusion regimens similar to those used in clinical practice using previously published pharmocokinetic data. Bolus doses of 0, 4, 6 and 8 mg/kg were simulated in combination with infusion rates of 0, 0.2, 0.3 and 0.4 mg/kg/min for either 240 or 1440 min. The computer was also programmed to maintain a steady state plasma concentration based on the previous simulated data. Generated data were then compared with published data. Changes in the context-sensitive half-life for propofol were also evaluated. Results showed that the generated data were similar to published data. A decrease in plasma concentration to levels associated with a light plane of anaesthesia was evident even when the highest bolus dose and infusion rate were used. There was a slow rise in plasma concentration when only an infusion was used. A lightening of anaesthetic plane may be evident early in the course of TIVA and careful monitoring of anaesthetic depth is required. As the duration of the infusion increased, plasma concentration steadily rose but achieved 95% of the steady state by 204 min. The most dramatic changes in plasma concentration occurred in the first hour of an infusion. Similarly, the infusion rates decreased most in the first 70 min. Most changes in anaesthetic depth are likely to occur early in the course of TIVA and careful observation of anaesthetic depth is required.

Canine hip extension range during gait

Assessment of canine gait is frequently used by veterinary clinicians to establish the presence of orthopaedic pain. As up to 30% of canine orthopaedic conditions affect the pelvic limb, knowledge of pelvic limb biomechanics during gait is very important. Previous studies have investigated the biomechanics at the tarsus and stifle, but little information is available regarding hip motion during gait. The aim of this study was to determine the maximum hip extension range achieved during the stance phase of gait in normal canines. In addition, this study aimed to determine the difference between maximum passive hip extension and maximum hip extension during gait. Using a sample of 30 morphologically similar normal dogs, mean maximum passive hip extension was measured using a goniometer and mean maximum hip extension range during gait was determined videographically. Inter- and intra-assessor reliability studies performed at the start of the study showed that the measurement tools and techniques used in this study were valid and reliable. The goniometric data showed that mean maximum passive hip extension range was 162.44 degrees (+/-3.94) with no significant difference between the left and the right hind limbs. The videographic data showed that mean maximum hip extension range during gait was 119.9 degrees (+/-9.26) with no significant difference between the left and right hind limbs. The results of this study provided reference values for active and passive hip extension range and showed that the degree of hip extension range required for normal gait is significantly less than maximum passive hip extension range.

Acute normovolaemic haemodilution--2 case studies

Acute normovolaemic haemodilution (ANH) is a technique used to preserve a patient's owns red blood cells and reduce the incidence of heterogeneous blood transfusion. This paper describes the use of the technique in a dog and a kitten. A significant benefit of ANH can be shown in the canine case presented. The dog lost 1800 ml of blood during surgery but the haematocrit was only reduced to 33% 6 hours after the end of surgery. The kitten, however, did not benefit from ANH. It lost a small volume of blood during surgery and developed complications. This paper also describes some of the potential complications that may occur. To the best of my knowledge, this is the 1st clinical description of ANH in a dog and a cat.

Acute normovolaemic haemodilution--is it a solution to reduce perioperative blood transfusions?

Haemodilution is a technique used to reduce perioperative homologous blood transfusions. Haemodilution is a poorly investigated technique in veterinary medicine. This article reviews haemodilution as a potential technique to reduce perioperative homologous blood transfusions. The history of haemodilution is briefly reviewed followed by the mathematical basis to haemodilution. The issue of critical oxygen delivery and its implications for haemodilution are discussed. The effects of haemodilution on the patient, including the effects on oxygen transport, blood flow and coagulation are discussed as well as the use of colloids, fluids and blood components in haemodilution. The success and failure of haemodilution in human clinical trials and experimental evidence is discussed. Some guidelines are given for the use of haemodilution in small animal patients in the perioperative setting. It appears in all likelihood that haemodilution has a limited application in cats and other small patients. Haemodilution is most beneficial when the initial haematocrit is high, a low haemodiluted haematocrit is achieved, the patients circulating volume is large and a large amount of blood was lost. It is important to avoid haemoconcentration during surgery as this increases red blood cell loss. Haemodilution is not a substitute for poor surgical technique and inadequate haemostasis intra-operatively. Intravascular volume should be maintained throughout the procedure.

Pre-anaesthetic screening of geriatric dogs

Pre-anaesthetic screening has been advocated as a valuable tool for improving anaesthetic safety and determining anaesthetic risk. This study was done determine whether pre-anaesthetic screening result in cancellation of anaesthesia and the diagnosis of new clinical conditions in geriatric dogs. One hundred and one dogs older than 7 years of age provided informed owner consent were included in the study. Each dog was weighed, and its temperature, pulse and respiration recorded. An abdominal palpation, examination of the mouth, including capillary refill time and mucous membranes, auscultation, body condition and habitus was performed and assessed. A cephalic catheter was placed and blood drawn for pre-anaesthetic testing. A micro-haematocrit tube was filled and the packed cell volume determined. The blood placed was in a test tube, centrifuged and then analysed on an in-house blood analyser. Alkaline phosphatase, alanine transferase, urea, creatinine, glucose and total protein were determined. A urine sample was then obtained by cystocentesis, catheterisation or free-flow for analysis. The urine specific gravity was determined with a refractometer. A small quantity of urine was then placed on a dip stick. Any new diagnoses made during the pre-anaesthetic screening were recorded. The average age of the dogs was 10.99+2.44 years and the weight was 19.64+15.78 kg. There were 13 dogs with pre-existing medical conditions. A total of 30 new diagnoses were made on the basis of the pre-anaesthetic screening. The most common conditions were neoplasia, chronic kidney disease and Cushing's disease. Of the 30 patients with a new diagnosis, 13 did not undergo anaesthesia as result of the new diagnosis. From this study it can be concluded that screening of geriatric patients is important and that sub-clinical disease could be present in nearly 30 % of these patients. The value of screening before anaesthesia is perhaps more questionable in terms of anaesthetic practice but it is an appropriate time to perform such an evaluation. The value of pre-anaesthetic screening in veterinary anaesthesia still needs to be evaluated in terms of appropriate outcome variables.

Anaesthesia and analgesia for dogs and cats in South Africa undergoing sterilisation and with osteoarthritis--an update from 2000

A survey was conducted in 2000 into the use of analgesic drugs by veterinarians in South Africa. This survey was repeated in 2005 to establish whether the use of analgesic drugs has increased and which analgesic drugs are being used for acute pain and osteoarthritis. The number of sterilisations performed and the number of new cases of osteoarthritis in dogs and cats was estimated. It is estimated that approximately 260000 cats are operated on each year in South Africa and that 150000 cats are sterilised. Five hundred thousand dogs undergo surgery, of which 242000 are sterilised. It appears that the number of surgical procedures performed in South Africa has decreased. The estimated death rate following anaesthesia has remained unchanged at 1:1004. Overall, the use of analgesics by South African veterinarians has increased significantly. Fifty-six per cent of cats and 74% of dogs were given peri-operative analgesics but this increased to 94% and 84% after including pre-anaesthetic medications with analgesic properties. The use of opioids (morphine and buprenorphine) and propofol has increased significantly. Approximately 253000 dogs and 33000 cats with osteoarthritis are seen by veterinarians in South Africa annually. The recognition by veterinarians of osteoarthritis in cats appears to be poor and is in need of attention. Carprofen and glucosamine/chondroitin are the most commonly used agents for the treatment of osteoarthritis. Details of the drugs used by veterinarians are given. Knowledge of analgesic drugs has increased significantly over the last 5 years. Continuing education is thought to have played an important role in the changes reported in this study.

Comparison of morphine and carprofen administered alone or in combination for analgesia in dogs undergoing ovariohysterectomy

In this study the analgesic efficacy of the pure agonistic opioid morphine and the cyclo-oxygenase type-2-selective carprofen were compared since there is no previous specific comparative study for these two common analgesics. Forty-five bitches undergoing elective ovariohysterectomy were randomly assigned to one of three groups; receiving morphine 0.4 mg/kg bodyweight pre-operatively and 0.2 mg/kg every 4-6 hours thereafter (Morphine group), receiving a once-off carprofen 4 mg/kg injection (Carprofen group) or receiving both morphine and carprofen (MorphCarp group). The dogs were premedicated with acepromazine 0.01 mg/kg and induced with either thiopentone 5-10 mg/kg or propofol 4-6 mg/kg. General anaesthesia was maintained with halothane in oxygen. The degree of pain was assessed over a 24-hour period under blinded conditions using a pain scale modified from the University of Melbourne pain scale and the Glasgow composite pain tool. Physiological parameters such as respiratory rate, pulse rate and body temperature were also assessed over the same time period. There was no significant difference in pain-scores and thus analgesia offered by the three analgesia protocols at any assessment point across the three groups, but there were differences within groups across time points. Baseline total pain-scores were lower than scores at all post-operative points within all three groups. Both morphine and carprofen provided good analgesia without any obvious adverse effects. This study indicates that at the dosages indicated above, carprofen administered on its own produces analgesia equal to that produced by morphine and that the two drugs administered together do not produce better analgesia than either drug administered on its own.

Canine renal cortical necrosis and haemorrhage following ingestion of an Amitraz-formulated insecticide dip : clinical communication

Amitraz is a formamidine compound used in veterinary medicine as a topical dip to control ticks and mites on dogs and livestock. A 10-year-old female Scottish terrier was presented following the accidental oral administration of a dip containing amitraz. This case report describes the clinical signs, treatment and pathology of this dog. Clinical signs of toxicity from amitraz result from stimulation of alpha2-adrenergic receptors. Amitraz is seldom fatal because the effects can be reversed by alpha2-adrenergic antagonists. The dog recovered from the amitraz toxicity but died 5 days later from acute renal failure.

Symmetrical double aortic arch in a beagle puppy

Double aortic arch denotes the persistence of both fourth aortic arches and has been reported as 'very rare' in the dog. Most reported cases have been seen in German shepherd dogs. An eight-week-old, male, 1.5-kg beagle presented with a three-week history of regurgitation and dyspnoea. A barium oesophagram showed severe oesophageal constriction cranial to the base of the heart, and a provisional diagnosis of a persistent right aortic arch was made. A left-sided fourth intercostal thoracotomy was performed. The ligamentum arteriosum was ligated and divided. The oesophagus was seen lying on the right-hand side of the aorta. Postoperatively, the puppy deteriorated and was euthanized. Postmortem revealed a double aortic arch entrapping both the oesophagus and trachea. The inexperienced surgeon could consider computed tomography or angiography to determine the exact vascular ring, and other possible concurrent vascular anomalies present, before surgery.

Acute aortic rupture in a dog with spirocercosis following the administration of medetomidine : clinical communication

Spirocercosis is an emerging disease in veterinary medicine. A strong suspicion of spirocercosis is usually evident after a thorough clinical examination and radiography of the chest has been performed. Lesions seen on radiography include an oesophageal mass, spondylitis and oesophageal air. Unfortunately, radiography is not diagnostic and additional diagnostic procedures are required to confirm the diagnosis. Endoscopy is commonly performed to diagnose the condition. The dog presented in this study had radiographic and clinical signs consistent with spirocercosis and definitive diagnosis was required. Shortly after sedation with medetomidine, the dog went into cardiac arrest and failed to respond to resuscitative measures. On post mortem, the diagnosis of spirocercosis was confirmed and the cause of death was identified as acute aortic rupture. Aortic aneurysms are not an uncommon finding and cause of acute death in dogs with spirocercosis. The acute rupture of the aorta in this case is most probably the result of cardiovascular changes associated with the administration of medetomidine. Medetomidine causes an acute rise in systemic vascular resistance with hypertension. The increase in shear stress across the weakened aortic wall resulted in rupture. Caution with the use of medetomidine in patients with spirocercosis is advised.

Inhibition of bacterial growth by different mixtures of propofol and thiopentone

Propofol is, as a result of its formulation, an ideal bacterial and yeast culture medium. An outbreak of sepsis in humans and an increase in wound infections in dogs has been ascribed to the use of propofol. It has been previously reported that a 1:1 mixture of propofol and thiopentone has bactericidal properties. This study was undertaken to determine if further serial mixtures of propofol and thiopentone maintained the bactericidal properties. Mixtures of 1:1 (solution A), 5:1 (solution B), 10:1 (solution C), 50:1 (solution D) and 100:1 (solution E) of 1 % propofol to 2.5 % thiopentone, 2.5 % thiopentone (solution T), 1 % propofol (solution P) and saline (solution S) were prepared and inoculated with between 105 and 106 colony-forming units of Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa and Candida albicans. A sample was withdrawn from each solution at 0, 1, 6, 12, 48 and 120 hours after inoculation and a bacterial count was performed. This study showed that thiopentone and solution A behaved in similar fashion by inhibiting bacterial growth and was bactericidal after 48 hours. Solution B was not bactericidal against S. aureus and C. albicans. Propofol and solutions D and E all supported growth of all the organisms tested. These data indicate that mixtures of propofol and thiopentone at a ratio less than 1:1 do not maintain the bactericidal properties.

Does the A-line ARX-lndex provide a reasonable assessment of anaesthetic depth in dogs undergoing routine surgery?

The monitoring of anaesthetic depth is usually based on the subjective assessment of the patient. An objective assessment of anaesthesia has only recently become possible. The auditory-evoked response has predictable changes in response to increasing doses of anaesthetic agents. Recent advances have brought about a regression model with exogenous input of the auditory-evoked response, the A-line ARX-Index (AAI Index). The AAI Index is a dimensionless number between 0 and 100. This technology has been incorporated into the AEP (auditory-evoked potential) monitor that is utilised to assess anaesthetic depth in humans. This study was undertaken to determine if the AEP monitor was useful in dogs. Ten dogs were enrolled in the study. After a full clinical and otoscopic examination, dogs were premedicated with acetylpromazine and morphine. Anaesthesia was induced with thiopentone and maintained with halothane. End-tidal carbon dioxide, temperature, pulse oximetry, blood pressure and the electrocardiogram were monitored and recorded every 5 minutes. Anaesthetic depth was assessed as either being adequate or inadequate by the anaesthetist during surgery. An AEP monitor was attached to the patient and automatically collected AAI Index data. The anaesthetist was blinded to the AEP monitor. Following the completion of the surgical procedure, the patient was allowed to wake up with the AEP monitor attached. The AAI Index was analysed to compare adequate with inadequate anaesthesia during the period of surgery and awake with sleep data during recovery. All AAI Index values associated with inadequate anaesthesia were greater than 31 while adequate values were less than 35. The difference between the groups was statistically significant and the power was 0.97. Statistically, the awake and sleep values were significantly different with a power of 0.99. From this study it can be concluded that the AAI Index shows good prospect for the evaluation of anaesthetic depth in dogs undergoing surgery. A larger study is needed to confirm these results.

A biomechanical investigation of the static stabilisers of the glenohumeral joint in the dog

The aim was to determine the relative contribution of the glenohumeral ligaments/joint capsule complex and the limited joint volume/adhesion-cohesion (UV/AC) mechanisms to the static stability of the canine glenohumeral joint (GHJ). The GHJ of 32 complete cadaver specimens were manipulated to determine the presence of gross laxity (> 2mm translation) at joint angles of 150 degrees, 135 degrees and 90 degrees. Following the removal of the peri-articular muscles, laxity was measured by applying a 15N force to the scapula in a variety of directions whilst the humerus was fixed to a jig. This was repeated for the abovementioned angles in intact joints and after venting and flushing to eliminate the UV/AC mechanisms. Results of clinical palpation and biomechanical studies were compared. Manipulation revealed a marked variation between joints although there was a tendency for progressive laxity as the joint was flexed. This finding was supported by the biomechanical study that also demonstrated no significant difference between intact and vented joints except in a cranio-caudal direction at 135 degrees and 90 degrees, and in a medial/lateral direction at 135 degrees. Static stabilisers permitted a wide range of motion. Individual clinical palpations did not correlate well with biomechanical findings. Manipulation was difficult to perform and is unlikely to be a reliable method for determining subtle joint laxity. The static stabilisers do not appear to play a significant role in providing joint constraint during normal range of motion (except extension). Diagnoses of pathological laxity attributable to the static stabilisers should be made with caution and surgical treatments should take cognizance of the above-mentioned biomechanical features.

A retrospective case series of computer-controlled total intravenous anaesthesia in dogs presented for neurosurgery

This article describes the anaesthetic management and use of total intravenous anaesthesia (TIVA) for neurosurgery in 4 dogs. Propofol in conjunction with morphine was used for the maintenance of anaesthesia. Anaesthesia was induced with either thiopentone or propofol. The program Stelpump (a target-controlled infusion program) was run on a laptop and connected to a syringe driver via an RS 232 cable. The program was found to be reliable and safe for the administration of TIVA in dogs. Invasive monitoring was required in order to monitor cardiovascular changes during surgery. Ventilation was controlled to maintain the end-tidal carbon dioxide below 40 mm Hg. The anaesthesia was characterised by haemodynamic stability. The haemodynamic stability was probably the result of the choice of TIVA and balanced anaesthesia. Intracranial pressure and oedema was controlled with dexamethasone, mannitol and ventilatory management either in combination or alone. Three dogs survived to hospital discharge and 1 dog was euthanased 2 weeks later due to tumour metastasis. The development and characterisation of the anaesthetic effects of TIVA needs to be elucidated in order to provide clinicians with rational guidelines for the appropriate use of TIVA in veterinary medicine.

The prevalence of subclinical gastroduodenal ulceration in Dachshunds with intervertebral disc prolapse

Endoscopy was used to determine the prevalence of subclinical gastroduodenal ulceration in 30 Dachshunds undergoing decompressive surgery for acute intervertebral disc prolapse. The endoscopy was performed on the day of admission and on the 3rd or 4th day after surgery. Three regions of the stomach (cardia, corpus and pylorus) and the proximal duodenum were visually inspected and biopsy samples were taken for histopathology. The combination of visual and microscopic changes were then used to determine the prevalence of subclinical gastroduodenal ulceration in this population. An overall prevalence of 76 % was calculated from these findings. Ulcerogenic medication administered prior to admission did not appear to influence the prevalence. This result identifies a need for veterinarians to be aware of this potentially severe complication and warrants the use of prophylactic anti-ulcer medication in spinal surgery patients.

The effects of diminazene aceturate on systemic blood pressure in clinically healthy adult dogs

Diminazene aceturate is a commonly used antibabesial agent. It has been postulated that diminazine may induce a decrease in blood pressure and exacerbate the hypotension presented in dogs with babesiosis. This study was undertaken to assess the effect of diminazine aceturate on the blood pressure of healthy dogs. Six healthy German shepherd dogs between 18 and 24 months of age with a mean weight of 30.4 ± 2.75 kg were used. Blood pressure was directly measured at the following time intervals: –5, 0, 5, 10, 15, 20, 25, 30, 35, 40, 50, 60, 90 and 120 minutes after treatment with diminazine aceturate (4.2 mg/kg) intramuscularly. No statistical difference (P 0.05) was found in blood pressure between any of the time intervals. An increase in heart rate was seen 5 minutes after the administration of diminazine aceturate but no change in blood pressure was evident. This study concluded that diminazene aceturate in its current formulation with antipyrine does not alter blood pressure in healthy adult dogs.

Electrical nerve stimulation as an aid to the placement of a brachial plexus block

Most local anaesthetic blocks are placed blindly, based on a sound knowledge of anatomy. Very often the relationship between the site of deposition of local anaesthetic and the nerve to be blocked is unknown. Large motor neurons may be stimulated with the aid of an electrical current. By observing for muscle twitches, through electrical stimulation of the nerve, a needle can be positioned extremely close to the nerve. The accuracy of local anaesthetic blocks can be improved by this technique. By using the lowest possible current a needle could be positioned with in 2-5 mm of a nerve. The correct duration of stimulation ensures that stimulation of sensory nerves does not occur The use of electrical nerve stimulation in veterinary medicine is a novel technique that requires further evaluation.

The cardiovascular and respiratory effects of medetomidine and thiopentone anaesthesia in dogs breathing at an altitude of 1486 m

The purpose of this study was to evaluate the cardio-respiratory effects of the combination of medetomidine and thiopentone followed by reversal with atipamezole as a combination for anaesthesia in 10 healthy German Shepherd dogs breathing spontaneously in a room at an altitude of 1486 m above sea level with an ambient air pressure of 651 mmHg. After the placement of intravenous and intra-arterial catheters, baseline samples were collected. Medetomidine (0.010 mg/kg) was administered intravenously and blood pressure and heart rate were recorded every minute for 5 minutes. Thiopentone was then slowly administered until intubation conditions were ideal. An endotracheal tube was placed and the dogs breathed room air spontaneously. Blood pressure, pulse oximetry, respiratory and heart rate, capnography, blood gas analysis and arterial lactate were performed or recorded every 10 minutes for the duration of the trial. Thiopentone was administered to maintain anaesthesia. After 60 minutes, atipamezole (0.025 mg/kg) was given intramuscularly. Data were recorded for the next 30 minutes. A dose of 8.7 mg/kg of thiopentone was required to anaesthetise the dogs after the administration of 0.010 mg/kg of medetomidine. Heart rate decreased from 96.7 at baseline to 38.5 5 minutes after the administration of medetomidine (P < 0.05). Heart rate then increased with the administration of thiopentone to 103.2 (P < 0.05). Blood pressure increased from 169.4/86.2 mmHg to 253.2/143.0 mmHg 5 minutes after the administration of medetomidine (P < 0.05). Blood pressure then slowly returned towards normal. Heart rate and blood pressure returned to baseline values after the administration of atipamezole. Arterial oxygen tension decreased from baseline levels (84.1 mmHg) to 57.8 mmHg after the administration of medetomidine and thiopentone (P < 0.05). This was accompanied by arterial desaturation from 94.7 to 79.7% (P < 0.05). A decrease in respiratory rate from 71.8 bpm to 12.2 bpm was seen during the same period. Respiratory rates slowly increased over the next hour to 27.0 bpm and a further increases 51.4 bpm after the administration of atipamezole was seen (P < 0.05). This was maintained until the end of the observation period. Arterial oxygen tension slowly returned towards normal over the observation period. No significant changes in blood lactate were seen. No correlation was found between arterial saturation as determined by blood gas analysis and pulse oximetry. Recovery after the administration of atipamezole was rapid (5.9 minutes). In healthy dogs, anaesthesia can be maintained with a combination of medetomidine and thiopentone, significant anaesthetic sparing effects have been noted and recovery from anaesthesia is not unduly delayed. Hypoxaemia may be problematic. Appropriate monitoring should be done and oxygen supplementation and ventilatory support should be available. A poor correlation between SpO2 and SaO2 and ETCO2 and PaCO2 was found.

The use of analgesic drugs by South African veterinarians

According to a survey, non-steroidal anti-inflammatory agents were the most popular analgesic used in South Africa for management of peri-operative pain, acute post-operative pain and chronic pain. The most popular non-steroidal anti-inflammatory agents are flunixin meglumine and phenylbutazone. The most popular opioid type drug is buprenorphine, followed by morphine. In the peri-operative setting, analgesic agents were not actively administered to 86.3% of cats and 80.7% of dogs. Analgesic premedications were frequently administered, e.g. xylazine or ketamine, but no specific drug was administered for post-operative pain. Veterinarians need to critically review their anaesthetic and analgesic practices in order to achieve balanced anaesthesia.

Effect of administration of nonsteroidal anti-inflammatory drugs before surgery on renal function in clinically normal dogs

OBJECTIVES

To investigate renal function in clinically normal dogs undergoing general anesthesia for ovariohysterectomies that received nonsteriodal antiinflammatory drugs (NSAID) before surgery.

ANIMALS

40 clinically normal dogs.

PROCEDURE

After induction of anesthesia, dogs were given an analgesic. Renal function was assessed before surgery and 24 and 48 hours after surgery by means of serum urea and creatinine concentrations, fractional clearance of sodium (FC(Na)), urine gamma-glutamyltransferase (GGT) and alkaline phosphatase (ALP) activities, and urine analysis. Ten dogs in each of 4 groups received ketorolac tromethamine (0.5 mg/kg of body weight), ketoprofen (1 mg/kg), carprofen (4 mg/kg), or morphine (0.1 mg/kg; control group).

RESULTS

Duration of general anesthesia ranged from 1.75 to 5 hours, with a mean of 3 hours. Two ketorolac- and 2 ketoprofen-treated dogs had transient azotemia. A significant decrease in the FC(Na) between before surgery and 24 hours after surgery, and between before surgery and 48 hours after surgery, was found in ketoprofen- and carprofen-treated dogs. Ketorolac-, ketoprofen-, and morphine-treated dogs had a decrease in urine specific gravity. Two ketorolac, 1 ketoprofen-, 1 carprofen-, and 4 morphine-treated dogs had increases in renal tubular epithelial cells on urine sediment examination 24 hours after surgery.

CONCLUSIONS AND CLINICAL RELEVANCE

In clinically normal dogs undergoing general anesthesia and elective surgery, the use of NSAID as analgesics is not contraindicated. Compared with ketorolac or ketoprofen, carprofen had the least effect on renal function and integrity.

Routine veterinary anaesthetic management practices in South Africa

A survey of the routine anaesthetic management of dogs and cats during sterilisation by veterinarians in South Africa was conducted. This report describes the premedication, induction and maintenance agents most commonly used in dogs and cats. Information about monitoring of patients during the procedure and who is responsible for induction of anaesthesia and monitoring was obtained. Questionnaires were analysed with regard to demographic data, practice size, continuing education, the number of surgical procedures and sterilisations performed per week and an estimate of yearly mortality. Acetylpromazine is the most commonly used premedication in dogs and xylazine in cats. Thiopentone in dogs and alphaxalone/alphadolone in cats were the induction agents most commonly used. Alphaxalone/alphadolone in cats and halothane in dogs are the most commonly used maintenance agents. Records of anaesthesia are poorly kept and monitoring of patients is poorly performed. Respiratory rate is the parameter most commonly monitored (90.7%), and in most cases is the sole parameter. On average 10.34 +/- 8.25 cats were operated per week, of which 5.45 +/- 5.60 were sterilised; 17.79 +/- 11.61 dogs were operated per week, of which 8.65 +/- 7.10 were sterilised. In total, 190 patients died under anaesthesia, a mortality rate of 1:1,243. Just over 50% of practitioners had attended continuing education courses during their careers.

The sedative and analgesic effects of detomidine-butorphanol and detomidine alone in donkeys

Butorphanol and detomidine constitute an effective combination for sedation and analgesia in horses. This trial was undertaken to assess the effectiveness of this combination in donkeys. The detomidine and butorphanol were given intravenously one after the other. A dose of 10 microg/kg of detomidine and 25 microg/kg of butorphanol was used. Sedation is easily extended by additional doses of butorphanol. The average dose of detomidine was 11.24 microg/kg and that of butorphanol was 28.0 microg/kg. Four donkeys in the detomidine group required additional sedation and analgesia. Detomidine alone did not totally eliminate coronary band pain. Heart rates dropped significantly in the first minute after the injection of the combination. One donkey developed an atrioventricular block, while another developed a sino-atrial block. Four donkeys developed a Cheyne-Stokes respiratory pattern. The combination of detomidine and butorphanol is an effective combination for sedation and analgesia of donkeys for standing procedures.