The effect of recumbency and hindlimb position on the lumbosacral interlaminar distance in dogs: a cadaveric computed tomography study.

OBJECTIVE: To examine the effect of sternal or lateral recumbency, with or without cranial extension of the hindlimbs, on the distance between the dorsal lumbosacral laminae in dogs. STUDY DESIGN: Blinded, randomized, crossover, experimental study. ANIMALS: A total of 19 canine cadavers. METHODS: Computed tomography of the lumbosacral junction was performed in four positions: sternal and right lateral recumbency, with hindlimbs extended cranially or not. Order of positioning was randomized. The lumbosacral interlaminar (LSI) distance, defined as the distance between the dorsal laminae of the seventh lumbar vertebra (caudal margin) and sacrum (cranial margin), was measured for each position by two independent assessors who were unaware of positioning. Mean distances in each position were compared using a paired t-test, corrected for multiple comparisons. RESULTS: For n = 19 cadavers [6 female; median (range) age 9 (0.3-16) years; weight, 20.4 (1.0-34.0) kg], cranial extension of the hindlimbs increased the LSI distance, compared with control, in both sternal (9.2 ± 2.2 mm versus 3.1 ± 1.3 mm, p < 0.001) and right lateral recumbency (8.2 ± 1.9 mm versus 4.9 ± 1.5 mm, p < 0.001). With the hindlimbs extended cranially, sternal recumbency increased LSI distance when compared with right lateral recumbency (p < 0.001). CONCLUSIONS AND CLINICAL RELEVANCE: Cranial extension of the hindlimbs in both sternal and lateral recumbency increases the LSI distance to an extent that is both statistically significant and of potential clinical relevance. Although ease of epidural access or injection was not assessed, the small (1 mm) difference in LSI distance between cranial hindlimb extension in sternal and right lateral recumbency is unlikely to be of clinical relevance. Conversely, cranial extension of the hindlimbs in either sternal or lateral recumbency would be expected to facilitate epidural injection.

Effect of intravenous lidocaine on cough response to endotracheal intubation in propofol-anaesthetized dogs.

OBJECTIVE: To determine whether the administration of intravenous (IV) lidocaine before the induction of anaesthesia in premedicated dogs reduces the cough response associated with endotracheal intubation and the propofol dose required. STUDY DESIGN: Prospective, randomized, blinded clinical study. ANIMALS: A total of 84 client-owned dogs, with American Society of Anesthesiology physical status I and II. METHODS: Dogs received intramuscular (IM) acepromazine 0.02 mg kg(-1) and methadone 0.3 mg kg(-1) and were randomly allocated to one of two groups: saline (group S) and lidocaine (group L). Five minutes before the induction of anaesthesia and 40-50 minutes after premedication, group L received lidocaine (1.5 mg kg(-1) ) and group S received an equal volume of saline solution, each administered slowly IV. Anaesthesia was induced with propofol, initially 2 mg kg(-1) IV over 40 seconds, and then in increments of 0.5 mg kg(-1) every 15 seconds to effect. The same investigator anaesthetized all cases, unaware of group allocation. The following parameters were recorded: pulse rate (PR), mean arterial pressure (MAP, oscillometry), respiratory rate (fR ), sedation score immediately before and 5 minutes after treatment, and total dose of propofol required. Differences in pulse rate, MAP and propofol dose were analysed using the two-sample t-test, coughing incidence was analysed with the chi-square test, and differences in sedation score were analysed with the Mann-Whitney test. RESULTS: After treatment, the incidence of coughing at endotracheal intubation was significantly reduced in group L compared with group S (21% versus 45%; p = 0.022). There was no significant difference between the groups with regard to propofol dose required for endotracheal intubation (p = 0.122), PR (p = 0.611), MAP (p = 0.508) or sedation score (p = 0.051). CONCLUSIONS AND CLINICAL RELEVANCE: IV lidocaine can decrease the incidence of cough during endotracheal intubation in dogs premedicated with acepromazine and methadone, but does not appear to have a sparing effect on the dose of propofol required for endotracheal intubation. Use of IV lidocaine, prior to induction of anaesthesia with propofol may be beneficial in dogs where coughing at intubation would be detrimental.

Branham sign in dogs undergoing interventional patent ductus arteriosus occlusion or surgical ligation: A retrospective study.

BACKGROUND: The Branham sign is a baroreceptor response that follows patent ductus arteriosus (PDA) closure. Although described in dogs following both interventional and surgical ductal closure, a direct comparison of the Branham sign elicited by these two techniques has not been made. AIM: Since closure with an Amplatz canine ductal occluder (ACDO) occurs over 10 minutes and surgical ligation (SL) is more rapid, we hypothesized that the Branham sign following occlusion of a PDA with an ACDO would be less severe than following SL. METHODS: Clinical records of dogs diagnosed with left-to-right shunting PDA between 2008 and 2018 were retrospectively reviewed. Of 139 dogs undergoing PDA occlusion, only 41 dogs (ACDO n = 32, SL n = 9) were included after applying exclusion criteria. Heart rate (HR) and blood pressure (BP) from occlusion time (T 0) until 30 minutes post occlusion (T 30) were recorded. Signalment and anesthetic protocol were also recorded. The influence of age and weight on the hemodynamic variations was assessed. Hemodynamic variables and calculations were compared between and within groups using a repeated measures general linear model, and post hoc tests were applied if significance was identified. RESULTS: A mild Branham sign was present in both groups, and hemodynamic changes were not significantly different between groups. In both groups, there was a significant decrease in HR (11 bpm, 5.3-16.3; p < 0.001) (10.4%, 5.4-15.5; p < 0.001) and increase in diastolic BP (9.5 mmHg, 3-16; p = 0.002) (23.5%, 7.1-39.9; p = 0.002), but systolic BP did not change significantly (p = 0.824). Age and weight did not influence Branham sign. CONCLUSION: The Branham sign in dogs is mild in both groups, lasts for at least 30 minutes, and is independent of the method of PDA closure.

Randomised trial of perioperative tramadol for canine sterilisation pain management.

Surgical sterilisation to manage free-roaming dog populations is widely used in many countries. However, few studies have examined optimal postoperative pain management regimens at low-resource, high-throughput veterinary clinics. The aim of this study was to examine the efficacy of two intravenous analgesic regimens, preoperative administration of meloxicam and tramadol, or meloxicam alone, in free-roaming dogs undergoing sterilisation. A total of 125 dogs were included, with 64 dogs in the meloxicam-tramadol arm and 61 dogs in the meloxicam-only arm in a non-inferiority study design. Pain levels in sterilisation surgery patients were assessed at four time points after surgery using the Colorado State University Canine Acute Pain Scale, a Visual Analogue Scale and a modified version of the Glasgow Composite Measure Pain Scale - Short Form. Non-inferiority was supported for each of the main scoring outcomes using non-inferiority margins of 0.5, 5 and 0.8, respectively. One dog from the meloxicam-tramadol group and four dogs in the meloxicam-only arm required rescue analgesia, with no difference between groups (P=0.21).The study demonstrated that meloxicam was effective in controlling postoperative pain in a high proportion of dogs. The addition of tramadol alongside meloxicam treatment was not found to be of clinical benefit.

Effect of methadone and acepromazine premedication on tear production in dogs.

OBJECTIVES: To evaluate the combined effect of intramuscular acepromazine and methadone on tear production in dogs undergoing general anaesthesia for elective, non-ocular procedures. DESIGN: Prospective, non-randomised, pre-post treatment study. SETTING: Patients were recruited from a referral practice in the UK. METHODS: Thirty client-owned dogs were enrolled in this study and received a combined intramuscular premedication of methadone (0.3 mg/kg) and acepromazine (0.02 mg/kg) before general anaesthesia for elective, non-ocular procedures. Full ophthalmic examination was performed and tear production was quantified using the Schirmer tear test-1 (STT-1). On the day of general anaesthesia, an STT-1 was performed before (STT-1a) and after (STT-1b) intramuscular premedication with methadone/acepromazine. RESULTS: Using a general linear model, a significant effect on STT-1 results was found for premedication with methadone/acepromazine (P=0.013), but not eye laterality (P=0.527). Following premedication, there was a significant reduction observed in the mean STT-1 readings of left and right eyes between STT-1a (20.4±2.8 mm/min) and STT-1b (16.9±4.1 mm/min; P<0.001). Significantly more dogs had an STT-1 reading less than 15 mm/min in one or both eyes after premedication (30 per cent; 9/30 dogs) compared with before premedication (6.7 per cent; 2/30 dogs; P=0.042). CONCLUSIONS: An intramuscular premedication of methadone and acepromazine results in a decrease in tear production in dogs before elective general anaesthesia. This may contribute to the risk of ocular morbidities, such as corneal ulceration, particularly in patients with lower baseline tear production.