Brightness of venous blood in South American camelids: implications for jugular catheterization

Objective  To compare the brightness of South American camelid venous blood to that of Equidae.
Study design  Prospective clinical evaluation.
Animals  Twelve South American camelids (eight llamas, four alpacas), eight horses and ponies (control group).
Methods  Appropriately sized catheters were placed in the jugular vein of each animal under local anaesthesia. The blood spilt before the catheter was capped was caught on a white tile. A sample of blood was drawn for blood-gas analysis. The brightness of the blood (both on the tile and in the syringe) was matched to a colour chart (1 = darkest red, 8 = brightest red) by a single observer under bright light conditions. Packed cell volume (PCV) and partial pressure of oxygen (PvO₂) in the blood were also measured on the syringe blood. Normally distributed data were compared using a two tailed t -test, and non-normally distributed data were compared using a Mann–Whitney U -test. Significance was set at p  < 0.05.
Results  Camelid venous blood was significantly brighter red than that of horses and ponies both on the white tile ( p  = 0.0003) and in the syringe ( p  = 0.0001). PCV was significantly lower in camelids (32 ± 4%) compared with horses (37 ± 5%). Partial pressure of oxygen values were similar between groups.
Conclusions and clinical relevance  Jugular venous blood in alpacas and llamas is significantly brighter red than that of horses. Colour should not be used as a sole determinant of venous or arterial catheterization in this species.     

The effect of volatile anaesthetics on the relative sensitivity of facial and distal thoracic limb muscles to vecuronium in dogs

ObjectiveTo compare n. facialis-m. nasolabialis (nF-mNL) and n. ulnar-mm. carpi flexorii (nU-mCF) sensitivity to vecuronium during halothane or isoflurane anaesthesia.Study designRandomized, prospective, experimental study.AnimalsForty-four client-owned dogs (19 male, 25 female) undergoing surgery; mean age: 5.0 years; mean body mass: 24.7 kg.MethodsThirty minutes after acepromazine (0.05 mg kg^?1) and morphine (0.5 mg kg^?1), anaesthesia was induced with intravenous (IV) thiopental and maintained with either halothane (n = 22) or isoflurane (randomly allocated) in oxygen. The lungs were mechanically ventilated and end-tidal inhaled anaesthetic (Fe’_IAA) maintained at 1.2 × MAC values. Neuromuscular transmission at nF-uNL and nU-mCF was monitored using the train of four count. Vecuronium (50 μg kg^?1 IV) was injected (t = 0) after 15 trains, 50-60 minutes after inhalational anaesthesia began, when Fe’_IAA had been constant for >15 minutes. Times of the disappearance (-) and reappearance (+) of the fourth (T4) and first twitch (T1) were recorded allowing the calculation of: latent (t = 0 to T4-) and manifest onset times (t = 0 to T1-) duration of blockade (T1- to T1+) and drug effect (T4- to T4+) and recovery time (T1+-T4+). Student’s paired t-test was used to compare simultaneous responses at nF-uNL and nU-mCF. An unpaired t-test was used to compare anaesthetic effects.ResultsLatent and manifest onset times were significantly (p < 0.05) briefer, blockade and drug effects were significantly longer and recovery from blockade were significantly slower in the nF-mNL unit in both halothane and isoflurane recipients. Profound block duration and drug action were significantly longer and recovery from blockade were significantly slower in halothane recipients at both nerve-muscle units.Conclusion and clinical relevanceThe nF-mNL was more sensitive than nU-mCF to vecuronium, particularly in halothane-anaesthetized dogs.     

The extradural pressure profile in goats following extradural injection

ObjectiveTo measure the extradural pressures in goats before and after extradural injection, and to investigate the occurrence of extradural pressure waves.Study designProspective experimental trial.AnimalsNine healthy adult goats weighing 59.4 ± 6.4 kg, scheduled for stifle arthroscopy.MethodsThe goats were pre–medicated with midazolam and anaesthesia was induced with propofol and maintained with sevoflurane. The goats were placed in lateral recumbency and extradural puncture was performed via the lumbosacral space. Correct placement of the needle was assessed by lack of resistance to the injection of saline. The needle was connected to an electronic pressure transducer to record extradural pressure. Measurements were taken before and after extradural injection of methadone (0.1 mg kg^?1, diluted to a total volume of 0.2 mL kg^?1) and 10 minutes later. Contrast medium was injected and correct extradural needle placement confirmed by radiography.ResultsLack of resistance to injection of saline occurred in all goats, but there were no pressure waves observed before injection in any animal. Radiography indicated incorrect needle placement in four animals and one had pressure waves synchronous with the arterial pulse after methadone injection. Correct needle placement was confirmed in the remaining five animals which exhibited pressure waves after extradural methadone injection. In the five goats with successful needle placement the baseline extradural pressure ranged from 0.4 to 2.5 kPa (3–19 mmHg), increasing to 4.4–39.9 kPa (33–300 mmHg) after injection. Ten minutes after injection, extradural pressure remained elevated and ranged from 2.5 to 17.3 kPa (19–130 mmHg).Conclusions and clinical relevanceExtradural pressure waves were not useful to confirm correct extradural needle placement in laterally recumbent goats. The presence of such waves after injection of 0.2 mL kg^?1 may be indicative of correct placement but even here we saw one of nine animals with extradural pressure waves where we failed to confirm correct needle placement. Extradural pressure increases after extradural injection.     

A Novel Pin Distraction Device for Arthroscopic Assessment of the Medial Meniscus in Dogs

Objective— To describe an extra-articular joint distractor for meniscal examination and treatment during canine stifle arthroscopy.
Study Design— Case series.
Animals— Dogs ≥20 kg with suspected cranial cruciate ligament (CrCL) deficiency.
Methods— A custom designed linear side bar was constructed to allow invasive pin distraction of the stifle joint. Its design efficacy for distraction of the medial joint compartment, observation and probing of the medial meniscus, and value during meniscal surgery was evaluated by clinical use.
Results— Application of the stifle distractor medial to the stifle joint using 2 negative threaded pins was easily performed percutaneously without the need of power equipment; however, unintended intra-articular placement of 1 threaded pin occurred in 2 stifles, without appreciable consequence to joint function. Observation as well as thorough probing of the caudal horn of the medial meniscus, even in the presence of a prominent remnant of the CrCL or severe periarticular fibrosis, was possible. Partial meniscectomy was effectively performed as needed without apparent damage to the associated articular surfaces.
Conclusions— Distraction and translation of the medial compartment of the stifle joint using invasive pin distraction allowed observation and palpation of the caudal horn of the medial meniscus so that assessment and treatment were readily accomplished without apparent morbidity.
Clinical Relevance— With careful attention to accurate pin placement, invasive pin distraction of the medial compartment of the canine stifle joint may improve arthroscopic evaluation and treatment of meniscal pathology.     

Mapping of Split-Line Pattern and Cartilage Thickness of Selected Donor and Recipient Sites for Autologous Osteochondral Transplantation in the Canine Stifle Joint

Objective— To characterize donor and recipient sites for autologous osteochondral transplantation in the canine stifle joint with respect to split-line pattern and cartilage thickness.
Study Design— In vitro study.
Sample Population— Stifle joints (n=30) of dogs >20 kg.
Methods— Collagen network orientation of the hyaline cartilage coverage of the distal femur was assessed using split-line technique (n=10). Cartilage thickness was measured radiographically on osteochondral plugs harvested at the abaxial and axial surfaces of the femoropatellar joint (n=15), the most proximal abaxial aspect of the medial condyle (CO; n=5) and at both femoral condyles (n=15).
Results— Cartilage within the femoropatellar joint and both femoral condyles had mostly transversely orientated pattern of split-lines. Abaxial to the femoropatellar joint split-lines were absent. All donor sites had significantly thinner cartilage than the medial condyle (CM). Only the distal trochlea had cartilage thickness comparable to the lateral condyle (CL). The thinnest cartilage was found abaxial to the femoropatellar joint followed by CO, which was ∼2–3 times thinner than the cartilage at both condyles.
Conclusions— None of the investigated donor sites provided transplants of comparable cartilage thickness to CM. Transplants from within the femoropatellar joint should be harvested in priority as they reach cartilage morphology comparable to CL.
Clinical Relevance— Adjusting for cartilage thickness and split-line pattern may improve long-term outcome after autologous osteochondral transplantation. But surface curvature and donor-site morbidity have to be considered as well when choosing the most suitable donor site.     

Percutaneous Cementoplasty in the Palliative, Multimodal Treatment of Primary Bone Tumors of the Distal Aspect of the Radius in Four Dogs

Objective— To (1) evaluate the analgesic effect of percutaneous cementoplasty (PC) in dogs with primary bone tumor (PBT) of the distal aspect of the radius and (2) evaluate the impact on the course of disease by adding PC to a palliative, multimodal treatment protocol in these dogs.
Study Design— Prospective pilot study.
Animals— Dogs (n=4) with PBT of the distal aspect of the radius.
Methods— Tumor lesions were filled percutaneously with polymethylmethacrylate under fluoroscopic guidance. Pamidronate was administered once in a week before PC. Radiotherapy and chemotherapy were initiated 2 and 6 weeks after PC, respectively. Force plate analysis was performed immediately before 2, and 6 weeks after PC. Survival time was defined from PC to euthanasia.
Results— Two dogs had a significant increase in peak vertical force 2 weeks after PC ( P =.043) and remained free of lameness for 18 and 20 weeks, respectively. One dog had an acute relapse after an initially lame-free period of 10 days. The remaining dog failed to improve ( P =.686). Three dogs developed at least 2 complications including transient worsening of the lameness after PC, cement leakage, wound infection and suspected thromboembolism in combination with cough and anemia. Median survival was 4.8 months (range, 1–5.7 months).
Conclusions— PC in combination with pamidronate significantly improved lameness in 2 dogs; however, PC is not risk-free. Deep wound infection, intraarticular cement leakage, and venous thrombosis were the main complications.
Clinical Relevance— PC might be a useful addition to established palliative, multimodal treatment protocols in dogs with PBT; however, because of the complications encountered PC warrants further study before routine use can be considered.