Objective—To conduct an in vitro investigation of the
biomechanical characteristics of the canine lumbar
spinal column in flexion and extension and measure
the destabilizing effects of multiple consecutive unilateral
and bilateral hemilaminectomies.
Sample Population—30 isolated multisegmental
spinal units (L1-L4) from nonhypochondroplastic dogs
weighing 15 to 30 kg.
Procedure—Physically normal and surgically altered
spinal specimens were subjected to 4-point bending
in flexion and extension to determine effects of multiple
consecutive hemilaminectomies on the basis of
analysis of test system load-displacement data. Six
groups with 5 spinal columns in each were defined on
the basis of the following procedures: hemilaminectomy
at L2-L3, 2 adjacent hemilaminectomies at L1-
L3, 3 adjacent hemilaminectomies at L1-L4, bilateral
hemilaminectomies at L2-L3, 2 bilateral hemilaminectomies
at L1-L3, and no hemilaminectomy (intact).
Spinal stability before and after surgery was determined
in all groups. Each group served as its own
control for nondestructive testing. Spinal strength
was evaluated through destructive testing to determine
deformation at failure, strength to failure, and
mode of catastrophic failure. The intact group served
as the control for destructive testing.
Results—Stability in extreme flexion and extreme
extension did not change significantly following any
hemilaminectomy procedure. Postoperative stability
within the neutral zone was significantly decreased in
all groups. Range of motion within the neutral zone
was not significantly different from the intact condition
in any group.
Conclusions and Clinical Relevance—Multiple
hemilaminectomies did not decrease stiffness of the
lumbar spinal column during flexion and extension.
These results support clinical recommendations
regarding multiple consecutive hemilaminectomies in
dogs. (Am J Vet Res 2003;64:1139–1145)
Objective—To evaluate the local and systemic effects of IM implantation of lead shot alternatives in rats.
Animals—22 laboratory rats.
Procedures—Sterile IM implantation of shot metals was performed, with euthanasia and necropsy at 2, 8, 16, and 26 weeks after implantation. Skeletal muscle specimens were examined histologically and kidney specimens were tested for heavy metals. In vivo and in vitro evaluation of corrosion of metals was performed.
Results—Corrosion of susceptible metals was greatest at 2 weeks in vivo and in vitro. Inflammation associated with all pellet types was greatest 2 weeks after implantation. Nickel-plated steel incited significantly greater inflammation at 2 weeks, compared with bismuth alloy. Kidney iron concentration was significantly greater at 26 weeks, compared with other test periods. Local tissue deposition of iron was verified by use of Prussian blue staining for all iron-containing metals. Concentration of arsenic in kidneys was significantly greater at 8, 16, and 26 weeks after implantation, compared with 2 weeks.
Clinical Relevance and Impact for Human Medicine—Humans or dogs wounded with nickel-plated steel may require more aggressive initial monitoring than those wounded with other shot types. Monitoring of systemic arsenic concentrations may be indicated in patients wounded with shotgun pellets.
To assess single-day and multiday repeatability of weight distribution (stance) data obtained with a commercial analyzer for dogs with naturally occurring hind limb lameness.
46 dogs (15 and 31 for single-day and multiday trials, respectively).
For single-day trials, 5 to 10 measurements/trial were collected to determine body weight (BW), weight distribution on each limb, and forelimb and hind limb symmetry indices (SIs). The dog was removed from the room and returned immediately; 5 trials were performed. For multiday trials, measurements were performed in the same manner on 2 sequential days. Data were compared among trials (single-day measurements) and between days (multiday measurements). Repeatability (correlation coefficients and Lin concordance correlation coefficients [LCCCs]) and variability (coefficients of variation [CVs]) were assessed.
In single-day trials, BW (r = 0.999), weight distribution on the lame hind limb (r = 0.915) and contralateral hind limb (r = 0.948), and hind limb SI (r = 0.964) were each significantly correlated among trials. In multiday trials, BW results were similar; weight distribution on the lame hind limb and contralateral hind limb and hind limb SI were each less closely but still significantly correlated between days. The LCCCs were highest for BW, weight distribution on the contralateral hind limb, and hind limb SI in single-day trials and for BW and weight bearing on the contralateral and lame hind limbs in multiday trials. The CVs were lowest for BW and highest for forelimb SI in both trial types.
CONCLUSIONS AND CLINICAL RELEVANCE
The analyzer used allowed repeatable measurement of BW and weight distribution on the hind limbs of dogs with hind limb lameness. Measurement of forelimb stance variables was not repeatable in this group of dogs.
Objective—To measure strain in the common calcaneal tendon during trotting in dogs and to compare strain before and after immobilization of the tarsal joint.
Procedures—A microminiature strain gauge was surgically implanted on the tendinous portion of the gastrocnemius muscle. Surface electromyography (EMG) values, percentage strain, and ground reaction forces were measured before and after immobilization. Peak vertical force; vertical impulse; initial, maximum, and final strain; and peak-to-peak EMG amplitude were recorded. Data were analyzed by use of a repeated-measures ANOVA and paired t tests.
Results—Timing of strain data correlated closely with foot strike of the hind limb and EMG activity in all dogs. Maximum tendon strain was simultaneous with peak vertical force. Continued muscle contraction was evident after immobilization. There was no significant difference in maximum strain after immobilization, compared with maximum strain during normal motion. Minimum strain, both at the beginning and end of the strain curve, was sig-nificantly decreased for the immobilized state, compared with results for nonimmobilized joints.
Conclusions and Clinical Relevance—Immobilization of the tarsal joint did not eliminate calcaneal tendon strain during weight bearing in dogs. Decreased isometric muscle contraction during the swing phase of the gait could account for smaller minimum strain in immobilized joints. Immobilization is frequently applied after Achilles tendon rupture to alleviate strain and force on the sutured repair, with possible complications because of the immobilization method. Consideration of these findings could be important in adjusting current treatment recommendations.
Objective—To evaluate a method for experimental
induction of osteoarthritis in the hip joints of dogs.
Animals—12 mixed-breed dogs.
Procedure—A unilateral triple pelvic osteotomy was
performed. In 6 dogs, the iliac osteotomy was
repaired with 45° of internal rotation, reducing coverage
of the femoral head by the acetabulum. In the
other 6 dogs, the fragments were repaired in anatomic
alignment. Radiography, force plate evaluations, and
subjective lameness evaluations were performed
before and after surgery. Dogs were euthanatized 7
months after surgery, and samples of cartilage and
joint capsule were examined histologically.
Results—Subjective lameness scores, radiographic
appearance of the hip joints, and Norberg angles
were not significantly different between groups; however,
force plate evaluations did reveal significant differences
in vertical ground reaction forces. Femoral
head coverage was significantly decreased with rotation
of the acetabulum. Mild inflammatory changes
were discernible in the joint capsule and articular cartilage
of some dogs in both groups.
Conclusions and Clinical Relevance—Results suggest
that 45° internal rotation of the acetabulum does
not consistently induce biologically important
osteoarthritic changes in the hip joints of dogs.
(Am J Vet Res 2000;61:484–491)
OBJECTIVE To evaluate effects of simultaneous intra-articular and IV injection of autologous adipose-derived stromal vascular fraction (SVF) and platelet-rich plasma (PRP) to dogs with osteoarthritis of the hip joints.
PROCEDURES Dogs with osteoarthritis of the hip joints that caused signs of lameness or discomfort were characterized on the basis of results of orthopedic examination, goniometry, lameness score, the Canine Brief Pain Inventory (CBPI), a visual analogue scale, and results obtained by use of a pressure-sensing walkway at week 0 (baseline). Dogs received a simultaneous intraarticular and IV injection of SVF and PRP or a placebo. Dogs were examined again 4, 8, 12, and 24 weeks after injection.
RESULTS CBPI scores were significantly lower for the treatment group at week 24, compared with scores for the control group. Mean visual analogue scale score for the treatment group was significantly higher at week 0 than at weeks 4, 8, or 24. Dogs with baseline peak vertical force (PVF) in the lowest 25th percentile were compared, and the treatment group had a significantly higher PVF than did the control group. After the SVF-PRP injection, fewer dogs in the treated group than in the control group had lameness confirmed during examination.
CONCLUSIONS AND CLINICAL RELEVANCE For dogs with osteoarthritis of the hip joints treated with SVF and PRP, improvements in CBPI and PVF were evident at some time points, compared with results for the control group.
OBJECTIVE To evaluate pharmacokinetics of cefazolin after IV injection of cefazolin (22 mg/kg) and after simultaneous IV and IM injections of cefazolin (total dose, 44 mg/kg) to dogs.
ANIMALS 12 adult Beagles.
PROCEDURES Dogs (6/group) were assigned to receive a single injection of cefazolin (IV group; 22 mg/kg, IV) or simultaneous injections (IV + IM group; 22 mg/kg, IV, and 22 mg/kg, IM). Interstitial fluid was collected over a 5-hour period by use of ultrafiltration probes for pharmacokinetic analysis.
RESULTS Mean cefazolin concentration in the interstitial fluid at 1, 1.5, 2, 3, 4, and 5 hours after injection was 39.6, 29.1, 21.2, 10.3, 6.4, and 2.7 μg/mL, respectively, for the IV group and 38.3, 53.3, 46.4, 31.7, 19.1, and 8.9 μg/mL, respectively, for the IV + IM group. Mean area under the concentration-time curve extrapolated to infinity, maximum concentration, half-life, and time to maximum concentration was 74.99 and 154.16 h·μg/mL, 37.3 and 51.5 μg/mL, 0.96 and 1.11 hours, and 1.28 and 1.65 hours, respectively, for the IV and IV + IM groups.
CONCLUSIONS AND CLINICAL RELEVANCE Cefazolin concentrations in interstitial fluid of dogs were maintained at > 4 μg/mL for 4 hours after a single IV injection and for 5 hours after simultaneous IV and IM injections. Therefore, simultaneous IV and IM administration of cefazolin 30 to 60 minutes before surgery should provide interstitial fluid concentrations effective against the most common commensal organisms (Staphylococcus spp and Streptococcus spp) on the skin of dogs for surgical procedures lasting ≤ 4 hours.
Animals—38 client-owned dogs with osteoarthritis examined at 2 university veterinary clinics.
Procedures—Dogs were randomly assigned to receive a typical commercial food (n = 16) or a test food (22) containing 3.5% fish oil omega-3 fatty acids. On day 0 (before the trial began) and days 45 and 90 after the trial began, investigators conducted orthopedic evaluations and force-plate analyses of the most severely affected limb of each dog, and owners completed questionnaires to characterize their dogs' arthritis signs.
Results—The change in mean peak vertical force between days 90 and 0 was significant for the test-food group (5.6%) but not for the control-food group (0.4%). Improvement in peak vertical force values was evident in 82% of the dogs in the test-food group, compared with 38% of the dogs in the control-food group. In addition, according to investigators' subjective evaluations, dogs fed the test food had significant improvements in lameness and weight bearing on day 90, compared with measurements obtained on day 0.
Conclusions and Clinical Relevance—At least in the short term, dietary supplementation with fish oil omega-3 fatty acids resulted in an improvement in weight bearing in dogs with osteoarthritis.