Characteristics of cerebrospinal fluid flow in Cavalier King Charles Spaniels analyzed using phase velocity cine magnetic resonance imaging.

Syringomyelia is an important morbidity source in Cavalier King Charles Spaniels. Although abnormal cerebrospinal fluid (CSF) flow secondary to Chiari malformations is thought to cause syringomyelia in humans, this relationship is unknown in dogs. We used phase-contrast magnetic resonance (MR) imaging to evaluate CSF flow in dogs. Fifty-nine Cavalier King Charles Spaniels were assigned a neurologic grade reflecting their neurologic status. Five normal control dogs of other breeding were imaged for comparison. The presence of syringomyelia was noted from sagittal MR images. The pattern and velocity of CSF flow were assessed using phase-contrast cine MRI at the foramen magnum, C2-C3 disc space, and within syrinxes. Flow was measured most easily with the neck flexed to mimic standing. CSF flow velocity in the dorsal aspect of the subarachnoid space at the foramen magnum was significantly higher in control dogs than Cavalier King Charles Spaniels (P = 0.035). Flow was obstructed at the foramen magnum in 41 of 59 Cavalier King Charles Spaniels. Turbulent flow and jets were associated with syringomyelia presence and severity, and CSF flow velocity at C2/3 dorsally was inversely related to the presence of syringomyelia (P = 0.0197). Peak dorsal subarachnoid space CSF flow velocity at the foramen magnum and C2-C3 were together highly predictive of syringomyelia. CSF flow can be assessed in dogs using phase-contrast cine MRI. Obstruction to flow at the foramen magnum is common in Cavalier King Charles Spaniels and CSF flow pattern and velocity are related to the presence of syringomyelia.

Morphology of the caudal fossa in Cavalier King Charles Spaniels.

Chiari malformations and syringohydromyelia are an important disease complex in Cavalier King Charles Spaniels. Although abnormalities in caudal fossa morphology are considered major contributors to the development of this disease, limited information exists on the range of morphologies in Cavalier King Charles Spaniels and on the relationship of these to clinically evident disease. Sixty-four Cavalier King Charles Spaniels were studied. Each underwent a neurologic examination and magnetic resonance imaging of the cervical spine and brain. T2-weighted sagittal images were used to determine both the morphologic characteristics and volume of the caudal fossa in each dog. This volume was also analyzed as a percentage of total cranial cavity volume. Each attribute was correlated with neurological grade and presence of syringohydromyelia. Fifteen dogs had neurologic signs, and 59 had morphologic abnormalities of the craniocervical junction. While 27 dogs had syringohydromyelia, 13 of these were clinically normal. Cerebellar herniation and occipital dysplasia were common findings but were not associated with syringohydromyelia. Dorsal compressive lesions were noted at the first and second cervical vertebral junction. Factors associated with the presence of neurologic signs included syringohydromyelia and the ratio of caudal fossa/total cranial cavity volume; dogs with signs had significantly larger syringohydromyelia than asymptomatic dogs. Caudal fossa size was not associated with syringohydromyelia. A positive association was identified between foramen magnum size and length of cerebellar herniation. The prevalence of craniocervical junction abnormalities is high in Cavalier King Charles Spaniels. While several factors are associated with neurologic signs, occipital hypoplasia appears to be the most important factor.

The effects of epidural deracoxib on the ground reaction forces in an acute stifle synovitis model.

OBJECTIVE: To evaluate the efficacy of epidurally administered deracoxib to mediate the signs of a sodium urate crystal-induced stifle synovitis in dogs, and to compare the efficacy of epidural versus subcutaneously administered deracoxib. STUDY DESIGN: Experimental, randomized, blinded, placebo-controlled modified cross-over design. ANIMALS: Random source, adult, mixed breed dogs (n = 24; 14 males, 10 females). METHODS: Sodium urate crystals were used to create a stifle synovitis model to evaluate the efficacy of deracoxib. Dogs were divided into 4 groups: 3 mg/kg epidural deracoxib, 1.5 mg/kg epidural deracoxib, 3 mg/kg subcutaneous deracoxib, and a placebo (vehicle for deracoxib). Force plate and subjective evaluations were made at time 0, 2, 4, 8, 12, and 24 hours post-treatment. Repeated measures ANOVA with Bonferroni-corrected post hoc comparisons was used to determine significant treatment effects. RESULTS: Peak vertical force (PVF) and vertical impulse (VI) were both significantly higher in deracoxib treated dogs compared with placebo. For 3 mg/kg epidural and subcutaneous deracoxib, PVF and VI were significantly greater than for 1.5 mg/kg epidural deracoxib. Overall pain score for all deracoxib-treated dogs was significantly lower than for placebo dogs. CONCLUSIONS: Epidural administration of deracoxib is effective at providing analgesia in an acute joint pain model; however, it does not appear to be more effective than systemic administration. CLINICAL RELEVANCE: Injectable deracoxib is effective in providing analgesia in acute inflammatory conditions of synovial joints.

Evaluation of the internal vertebral venous plexus, vertebral canal, dural sac, and vertebral body via nonselective computed tomographic venography in the cervical vertebral column in healthy dogs.

OBJECTIVE: To evaluate nonselective computed tomographic (CT) venography for evaluating the cervical internal vertebral venous plexus (IVVP), define the diameter and area dimensions of the IVVP, and determine the relationship between dimensions of the cervical IVVP and other vertebral components in medium-sized dogs. Animals-6 healthy dogs that weighed 18 to 27 kg. Procedure-Helical CT scans were performed from C1 to C7 before and after IV injection of contrast medium (480 mg of iodine/kg) and a continuous infusion (240 mg of iodine/kg). Image data were transferred to a CT workstation, and measurements were performed on displayed transverse images. Diameter and area measurements of the vertebral canal, dural sac, IVVP, and vertebral body were obtained at C3 to C7. RESULTS: Opacification of vertebral venous structures was achieved in all dogs with no adverse reactions. Sagittal diameters of the IVVP for C3 to C7 ranged from 0.6 to 3.2 mm. Transverse diameters ranged from 2.32 to 5.74 mm. The IVVP area represented 12.4% of the mean vertebral canal transverse area and 30.61% of the mean vertebral epidural space area. Area measurements of the IVVP were significantly correlated with vertebral canal area and dural sac area. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that nonselective CT venography is a safe, sensitive method for performing morphometric assessments of the cervical IVVP in dogs. Findings support the theory that there may be a physiologic or developmental relationship between cervical vertebral canal components.

Comparison of postoperative pain after ovariohysterectomy by harmonic scalpel-assisted laparoscopy compared with median celiotomy and ligation in dogs.

OBJECTIVE: To compare the effects of postoperative pain after ovariohysterectomy by harmonic scalpel-assisted laparoscopy (HALO) and traditional ovariohysterectomy (OVH) in dogs. STUDY DESIGN: A randomized, blinded, prospective study. SAMPLE POPULATION: Sixteen, purpose-bred, intact female, Beagle dogs. METHODS: Dogs were divided into 2 groups: Group 1 (8 dogs), which had OVH by HALO, and Group 2 (8 dogs), which had traditional OVH. Physiologic data, abdominal nociceptive threshold scores, and University of Melbourne pain scores (UMPS) were recorded at 2, 6, 12, 24, 48, and 72 hours after surgery. Blood samples for measurement of plasma cortisol, glucose, and creatine phosphokinase (CPK) concentrations were collected at the time of the incision, and 2, 6, 12, 24, 48, and 72 hours after surgery. RESULTS: No significant surgical complications occurred. The HALO mean surgical time was significantly longer (55.7 minutes) than traditional OVH (31.7 minutes). No significant differences were observed between groups for the pain measures of heart rate, respiratory rate, temperature, CPK, and glucose concentrations. The OVH group had significantly higher mean plasma cortisol levels at hour 2 after surgery than the HALO group (P=.0001). The mean UMPS were significantly higher in OVH than the HALO group at all postoperative times (P=.0001). The mean nociceptive threshold measurements revealed significantly higher tolerated palpation pressures in HALO than OVH at all postoperative times, except hour 72 (P=.0002). CONCLUSIONS: Dogs appeared to be in less pain with HALO than OVH. The harmonic scalpel coagulated ovarian and uterine vessels completely with minimal collateral damage to surrounding tissues. CLINICAL RELEVANCE: HALO is a safe alternative to OVH and offers a minimally invasive and less painful method of surgery.

Hemodynamic effects of orally administered carvedilol in healthy conscious dogs.

OBJECTIVE: To evaluate the hemodynamic effects of orally administered carvedilol in healthy dogs with doses that might be used to initiate treatment in dogs with congestive heart failure. ANIMALS: 24 healthy dogs. PROCEDURE: Dogs were randomly allocated to receive carvedilol PO at a dose of 1.56, 3.125, or 12.5 mg, twice daily for 7 to 10 days; 6 dogs served as controls. Investigators were blinded to group assignment. Hemodynamic variables were recorded prior to administration of the drug on day 1 and then 2, 4, and 6 hours after the morning dose on day 1 and days 7 to 10. Change in heart rate after IV administration of 1microg of isoproterenol/kg and change in systemic arterial blood pressure after IV administration of 8 microg of phenylephrine/kg were recorded 2 and 6 hours after administration of carvedilol. RESULTS: Administration of carvedilol did not significantly affect resting hemodynamic variables or response to phenylephrine. The interaction of day and carvedilol dose had a significant effect on resting heart rate, but a significant main effect of carvedilol dose on resting heart rate was not detected. Increasing carvedilol dose resulted in a significant linear decrease in heart rate response to isoproterenol. CONCLUSIONS AND CLINICAL RELEVANCE: In healthy conscious dogs, orally administered carvedilol at mean doses from 0.08 to 0.54 mg/kg given twice daily did not affect resting hemodynamics. Over the dose range evaluated, there was a dose-dependent attenuation of the response to isoproterenol, which provided evidence of beta-adrenergic receptor antagonism.

Evaluation of analgesia provided by the administration of epidural ketamine in dogs with a chemically induced synovitis.

OBJECTIVE: To determine if epidural ketamine provides analgesia in dogs with a chemically induced synovitis. STUDY DESIGN: Prospective randomized experimental trial. ANIMALS: Thirty-two healthy, adult mongrel dogs (13-30 kg). METHODS: (Part I) Synovitis was induced in the right stifle of 16 dogs and allowed to develop for 12 hours. Epidural injection at the lumbosacral space of either ketamine (2 mg kg(-1); n = 8) or placebo (n = 8) was performed. Limb use and pain were measured using a force platform and numerical rating scale (NRS). Assessments were performed before and at 12, 14, 16, 18, 20, and 24 hours after the induction of synovitis. (Part II) Epidural injection of either ketamine (n = 8) or placebo (n = 8) was performed immediately before the induction of synovitis. Analgesia was assessed as in Part I. Assessments occurred before and at 2, 4, 6, 8, and 12 hours after the induction of synovitis. RESULTS: (Part I) Vertical ground reaction forces (VGRF) significantly decreased and NRS scores of total pain significantly increased after the induction of synovitis in all dogs (p < 0.05). No significant differences in VGRF or NRS scores were measured between treatment groups at any assessment period. (Part II) Dogs that received ketamine had significantly lower NRS scores 2 hours after treatment (p < 0.05). NRS scores did not differ between groups at any other evaluation. VGRF did not differ significantly between treatment groups at any assessment period. CONCLUSION: Epidural ketamine at a dose of 2 mg kg(-1) administered after the development of synovitis does not provide significant levels of analgesia. Administration of ketamine before the induction of synovitis significantly decreased the NRS score 2 hours post-induction. CLINICAL RELEVANCE: Administration of epidural ketamine before tissue injury may provide analgesia of short duration in dogs.

Laparoscopic ovariohysterectomy in nine dogs.

Minimally invasive surgery has been found in humans to reduce pain, incidence of infections, and duration of hospitalization. Minimally invasive procedures are also being described in veterinary medicine. Laparoscopic ovariohysterectomy (OHE) was performed on nine, healthy, intact female dogs using a Harmonic scalpel. Creatine kinase values were determined both before and 12 hours following the laparoscopic OHE; the magnitude of the difference between preoperative and postoperative creatine kinase values did not correlate with length of operative time, length of incisions, or amount of hemorrhage. Complications included one dog that had an omental herniation that was primarily repaired and one dog with seroma formation. Median surgical time for all dogs was 60 minutes (range, 35 to 100 minutes).

Microvascular free tissue transfer of the rectus abdominis muscle in dogs.

OBJECTIVE: To assess donor-site morbidity and survival of the rectus abdominis muscle with an overlying skin graft after free tissue transfer to a medial femorotibial defect in dogs. STUDY DESIGN: Experimental study. SAMPLE POPULATION: Phase 1: 6 canine cadavers; phase 2: 7 adult mixed-breed dogs. METHODS: Phase 1: The rectus abdominis muscle was removed from canine cadavers, muscular and vascular dimensions were recorded, and angiography was performed. Phase 2: Muscular transfer was performed through anastomosis of the caudal epigastric artery and vein to the saphenous artery and medial saphenous vein. Transferred tissues were evaluated on postoperative days 3, 6, 10, and 13. Animals were examined daily until euthanasia between postoperative days 31 and 42. Postmortem angiograms were performed and tissues collected for histopathologic evaluation. RESULTS: Phase 1: Appropriate vascular dimensions for microvascular anastomosis were confirmed and surgical technique perfected. Phase 2: Muscular excision produced minimal donor-site morbidity. All muscles survived after microvascular transfer and angiography confirmed vascular patency. All of the skin grafts survived, with one graft undergoing partial necrosis. CONCLUSIONS: The rectus abdominis muscle can be successfully transferred to a medial femorotibial defect and can serve as a bed for acute skin grafting. No significant donor-site morbidity is associated with its removal. CLINICAL RELEVANCE: Microvascular free tissue transfer of the canine rectus abdominis muscle has not been previously described. This technique provides a new alternative for repair of appropriate wounds. Additional studies are needed to define its utility in clinical patients.

Evaluation of lameness associated with arthroscopy and arthrotomy of the normal canine cubital joint.

OBJECTIVE: To evaluate gait, range of motion (ROM), and lameness in normal dogs after arthroscopy or arthrotomy of the cubital joint. STUDY DESIGN: Experimental study. ANIMALS: Fourteen mature, healthy dogs. METHODS: Dogs were randomly assigned to treatment groups. Seven underwent arthrotomy and 7 underwent arthroscopy of the left cubital joint. Dogs were evaluated using kinetic gait assessment, subjective evaluation scores, and cubital joint ROM. Evaluations were performed before and on days 2, 4, 7, 15, 22, and 29 after surgery. Radiographs made before and after the surgical procedures were evaluated. RESULTS: Significant differences in peak vertical force and vertical impulse force were not observed between surgery groups (P =.88 and.49, respectively). Joint ROM was not significantly different between groups (P =.09 for flexion and.91 for extension). For all dogs, joint ROM and radiographic evaluations remained normal throughout the study period. Significant differences in subjective lameness scores, weight bearing, or pain were not observed between groups (P >/ or =.19 for all variables). CONCLUSIONS: In this study population, significant differences between dogs undergoing arthroscopy or arthrotomy of the cubital joint with respect to postoperative pain, weight bearing, joint ROM, or temporal improvement of ground reaction forces were not observed. CLINICAL RELEVANCE: The results of this study suggest that postoperative morbidity should not be a factor when making a decision to perform either arthroscopy or arthrotomy for exploration of the medial compartment of the canine cubital joint.