Objective—To determine the dimensions and volume of thyroid tissue in clinically normal cats by use of computed tomography.
Procedure—Helical computed tomography images (2-mm collimation) were acquired from the cranial aspect of the second cervical vertebra through the caudal aspect of the fourth cervical vertebra. Data were acquired before contrast medium administration (n = 7 cats) and immediately after contrast medium enhancement (1 cat). Length, width, and height measurements of each thyroid lobe were made by use of transverse, dorsal, and sagittal plane images. Thyroid lobe volume was estimated by use of 3 methods.
Results—All thyroid lobes were histologically normal. Mean dimensions for a thyroid lobe were 16.5 × 2.00 × 4.31 mm (length × width × height) using only data from transverse images. Mean thyroid lobar volume was 113.75 mm3 using the sum of areas method. Mean total volume of thyroid tissue was 215.25 mm3 using the sum of areas method.
Conclusions and Clinical Relevance—Results may be useful for computed tomography evaluation of abnormal thyroid glands in cats, which warrants investigation.
Objective—To determine the effects of pretreatment
with α-linolenic acid, an omega-3 polyunsaturated
fatty acid, on equine synovial explants challenged
with lipopolysaccharide (LPS).
Animals—8 mature mixed-breed horses (4 mares
and 4 geldings).
Procedure—Synovial explants were assigned to
receive 1 of 7 concentrations of α-linolenic acid, ranging
from 0 to 300 µg/mL. At each concentration, half
of the explants were controls and half were challenged
with 0.003 µg of LPS as a model of synovial
inflammation. Cell inflammatory response was evaluated
by measurement of prostaglandin E2 production
via an ELISA. Synovial cell viability, function, histomorphologic
characteristics, and cell membrane composition
were evaluated by use of trypan blue dye
exclusion, hexuronic acid assay for hyaluronic acid,
objective microscopic scoring, and high-performance
liquid chromatography, respectively.
Results—Challenge with LPS significantly increased
production of prostaglandin E2 and decreased production
of hyaluronic acid. Treatment with α-linolenic
acid at the highest dose inhibited prostaglandin E2
production. Cell viability and histomorphologic characteristics
were not altered by treatment with
α-linolenic acid or LPS challenge. Treatment with
α-linolenic acid increased the percentage of this fatty
acid in the explant cell membranes.
Conclusions and Clinical Relevance—Results suggest
that investigation of α-linolenic acid as an anti-inflammatory
medication for equine synovitis is warranted.
(Am J Vet Res 2005;66:1503–1508)
Objective—To evaluate the effects of anti-inflammatory
drugs on lipopolysaccharide (LPS)-challenged and
-unchallenged equine synovial membrane in terms of
production of prostaglandin E2 (PGE2) and hyaluronan,
viability, and histomorphologic characteristics.
Sample Population—Synovial membranes were collected
from the carpal, tarsocrural, and femoropatellar
joints of 6 adult horses.
Procedure—Synovial membranes from each horse
were minced and pooled and explants were treated
with one of the following: no drug (control), drug, LPS
alone, or LPS and drug. Treatment drugs were
phenylbutazone (PBZ), flunixin meglumine (FNX),
ketoprofen (KET), carprofen (CRP), meloxicam (MEL),
low-concentration methylprednisolone (METH), highconcentration
METH, dimethyl sulfoxide (DMSO), or
an experimental COX-2 inhibitor (dissolved in DMSO).
Following 48 hours of culture, medium was assayed
for PGE2 and hyaluronan concentration. Synovial
explants were assessed for viability and histomorphologic
Results—For the LPS-challenged explants, PBZ, FNX,
KTP, CRP, MEL, and low-concentration METH suppressed
PGE2 production, compared with LPS challenge
alone. Only MEL suppressed PGE2 production
from LPS-challenged explants, compared with unchallenged
explants. Synovial explants maintained > 90%
viability and there was no significant difference in viability
or hyaluronan production among explants.
Histomorphologic scores were significantly
decreased for explants treated with low-concentration
METH or DMSO.
Conclusions and Clinical Relevance—PBZ, FNX,
KTP, CRP, MEL, and low-concentration METH suppressed
PGE2 production in LPS-challenged explants.
Meloxicam appeared to have more selective suppression
of COX-2 activity. Histomorphologic scores suggest
detrimental effects of METH, DMSO, and the
experimental COX-2 inhibitor. Commonly used nonsteroidal
anti-inflammatory drugs suppress induced
synovial membrane PGE2 production without detrimental
effects on synovial membrane viability and
function. ( Am J Vet Res 2001;62:54–60)
Objective—To perform polymerase chain reaction
(PCR) analysis on paraffin-embedded myocardium
from dogs with dilated cardiomyopathy (DCM) and
dogs with myocarditis to screen for canine parvovirus,
adenovirus types 1 and 2, and herpesvirus.
Sample Population—Myocardial specimens from 18
dogs with an antemortem diagnosis of DCM and 9
dogs with a histopathologic diagnosis of myocarditis
Procedure—Paraffin-embedded myocardial specimens
were screened for viral genome by PCR analysis.
Positive-control specimens were developed from
cell cultures as well as paraffin-embedded tissue
specimens from dogs with clinical and histopathologic
diagnoses of viral infection with canine parvovirus,
adenovirus types 1 and 2, and herpesvirus. The histologic
characteristics of all myocardial specimens were
classified regarding extent, location, and type of
inflammation and fibrosis.
Results—Canine adenovirus type 1 was amplified
from 1 specimen from a dog with DCM. Canine parvovirus,
adenovirus type 2, and herpesvirus were not
amplified from any myocardial specimens. Histologic
analysis of specimens from dogs with DCM revealed
variable amounts of fibrosis; myocardial inflammation
was observed in 1 affected dog. Histopathologic analysis
of specimens from dogs with myocarditis disclosed
variable degrees of inflammation and fibrosis.
Conclusions and Clinical Relevance—Viral agents
canine parvovirus, adenovirus types 1 and 2, and herpesvirus
are not commonly associated with DCM or
active myocarditis in dogs. Additional studies evaluating
for nucleic acid from viruses that less commonly
affect dogs or different types of infectious agents may
be warranted to gain insight into the cause of DCM
and myocarditis in dogs. ( Am J Vet Res 2001;62:
Objective—To evaluate and compare bone modeling and remodeling in fractured and non-fractured central tarsal bones (CTBs) of racing Greyhounds.
Sample—Paired cadaveric tarsi from 6 euthanized racing Greyhounds with right CTB fractures and 6 racing Greyhounds with other nontarsal injuries.
Procedures—CTBs were dissected and fractured CTBs were reconstructed. Central tarsal bones were evaluated through standard and nonscreen high-detail radiography, computed tomography, and histologic examination. The bone mineral density (BMD) was calculated adjacent to fracture planes and as a gradient on sagittal computed tomographic images. Sagittal and transverse plane sections of bone were obtained and submitted for subjective histologic assessment. Linear mixed-effects models were used to compare findings.
Results—Fractured right CTBs had greater BMD in the dorsal and midbody regions of the sagittal plane sections than did nonfractured CTBs. The BMD ratios from bone adjacent to the dorsal slab fracture planes were not different between fractured and nonfractured right CTBs.
Conclusions and Clinical Relevance—Findings supported the existence of site-specific bone adaptation in CTBs of Greyhounds, with modeling and remodeling patterns that were unique to fractured right CTBs. The dorsal and midbody regions of fractured bones had greater BMD, and fractures occurred through these zones of increased BMD.
Objective—To evaluate and correlate patterns of subchondral bone density and articular cartilage degeneration (derived by use of gross, histologic, and computed tomographic [CT] examinations) in equine third metacarpal condyles with and without osteoarthritis.
Sample Population—8 metacarpophalangeal (MCP) joints (n = 4 horses) without osteoarthritis and 6 osteoarthritis-affected MCP joints (4).
Procedures—Horses were euthanized. The third metacarpal condyles of the joints were examined grossly and via CT (3 slice images/condyle). For 6 condylar zones, mean bone density and pattern of density distribution were determined. Data for osteoarthritis-affected and control joints were compared. Histomorphometric point count analyses identified areas of bone density for comparison with CT density measurements.
Results—Osteoarthritis-affected condyles had heterogeneous subchondral bone with focal resorptive lesions and patterned sclerosis, whereas control condyles had symmetric bone density distribution. In osteoarthritis-affected condyles, bone density determined via gray scale image density analysis was greater (dorsal and medial pattern), compared with control condyles, and differed among zones because of resorption and sclerosis. With regard to bone density in osteoarthritis-affected condyles, histologic findings correlated with CT images, and bone lesions were significantly correlated with cartilage lesions.
Conclusions and Clinical Relevance—In horses, heterogeneous distribution and greater subchondral bone density were characteristic of osteoarthritis-affected condyles, compared with control condyles. Subchondral bone lesions correlated with overlying cartilage lesions in osteoarthritis-affected MCP joints. Identification of CT image characteristics appears to predict the presence of a cartilage lesion in MCP joints of horses with osteoarthritis.
Objective—To compare biodegradable magnesium phosphate cement (Mg-cement), calcium phosphate cement (Ca-cement), and no cement on bone repair, biocompatibility, and bone adhesive characteristics in vivo in horses.
Animals—8 clinically normal adulthorses.
Procedures—Triangular fragments (1-cm-long arms) were created by Y-shaped osteotomy of the second and fourth metatarsal bones (MTII and MTIV, respectively). Fragments were replaced in pairs to compare Mg-cement (MTII, n = 8; MTIV, 8) with Ca-cement (MTIV, 8) or with no cement (MTII, 8). Clinical and radiographic evaluations were performed for 7 weeks, at which time osteotomy sites were harvested for computed tomographic measurement of bone density and callus amount, 3-point mechanical testing, and histologic evaluation of healing pattern and biodegradation.
Results—All horses tolerated the procedure without clinical problems. Radiographically, Mg-cement secured fragments significantly closer to parent bone, compared with Ca-cement or no treatment. Callus amount and bone remodeling and healing were significantly greater with Mg-cement, compared with Ca-cement or no cement. Biomechanical testing results and callus density among treatments were not significantly different. Significantly greater woven bone was observed adjacent to the Mg-cement without foreign body reac-tion, compared with Ca-cement or no cement. The Mg-cement was not fully degraded and was still adhered to the fragment.
Conclusions and Clinical Relevance—Both bone cements were biocompatible in horses, and Mg-cementmay assistfracture repair by osteogenesis and fragmentstabilization. Fur ther studies are warranted on other applications and to define degradation characteristics.
Objective—To compare biomechanical strength, interface quality, and effects of bone healing in bone-implant interfaces that were untreated or treated with calcium phosphate cement (Ca-cement), magnesium phosphate cement (Mg-cement), or polymethylmethacrylate (PMMA) in horses.
Animals—6 adult horses.
Procedures—4 screw holes were created (day 0) in each third metacarpal and third metatarsal bone of 6 horses. In each bone, a unicortical screw was placed in each hole following application of Ca-cement, Mg-cement, PMMA, or no treatment (24 screw holes/treatment). Screws were inserted to 2.82 N m torque. Horses were euthanized and bones were harvested at day 5 (16 screw holes/treatment) or day 182 (8 screw holes/treatment). Radiography, biomechanical testing, histomorphometry, and micro–computed tomography were performed to characterize the bone-implant interfaces.
Results—Use of Mg-cement increased the peak torque to failure at bone-implant interfaces, compared with the effects of no treatment and Ca-cement, and increased interface toughness, compared with the effects of no treatment, Ca-cement, and PMMA. Histologically, there was 44% less Ca-cement and 69% less Mg-cement at the interfaces at day 182, compared with amounts present at day 5. Within screw threads, Ca-cement increased mineral density, compared with PMMA or no treatment. In the bone adjacent to the screw, Mg-cement increased mineral density, compared with PMMA or no treatment. One untreated and 1 Ca-cement–treated screw backed out after day 5.
Conclusions and Clinical Relevance—In horses, Mg-cement promoted bone-implant bonding and adjacent bone osteogenesis, which may reduce the risk of screw loosening.
Objective—To determine elution characteristics of bone morphogenetic protein (BMP)-2 from a polycaprolactone coating applied to orthopedic implants and determine effects of this coating on osseointegration.
Procedures—An in vitro study was conducted to determine BMP-2 elution from polycaprolactone-coated implants. An in vivo study was conducted to determine the effects on osseointegration when the polycaprolactone with BMP-2 coating was applied to bone screws. Osseointegration was assessed via radiography, measurement of peak removal torque and bone mineral density, and histomorphometric analysis. Physiologic response was assessed by measuring serum bone-specific alkaline phosphatase activity and uptake of bone markers.
Results—Mean ± SD elution on day 1 of the in vitro study was 263 ± 152 pg/d, which then maintained a plateau at 59.8 ± 29.1 pg/d. Mean peak removal torque for screws coated with polycalprolactone and BMP-2 (0.91 ± 0.65 dN·m) and screws coated with polycaprolactone alone (0.97 ± 1.30 dN·m) did not differ significantly from that for the control screws (2.34 ± 1.62 dN·m). Mean bone mineral densities were 0.535 ± 0.060 g/cm2, 0.596 ± 0.093 g/cm2, and 0.524 ± 0.142 g/cm2 for the polycaprolactone–BMP-2–coated, polycaprolactone-coated, and control screws, respectively, and did not differ significantly among groups. Histologically, bone was in closer apposition to the implant with the control screws than with either of the coated screws.
Conclusions and Clinical Relevance—BMP-2 within the polycaprolactone coating did not stimulate osteogenesis. The polycaprolactone coating appeared to cause a barrier effect that prevented formation of new bone. A longer period or use of another carrier polymer may result in increased osseointegration.
Objective—To provide long-term follow-up information for a series of dogs and cats with invasive and noninvasive thymomas treated by excision alone.
Design—Retrospective case series.
Animals—9 cats and 11 dogs with thymoma.
Procedures—Medical records were reviewed. The following factors were analyzed for their effect on prognosis: age of dog or cat, invasiveness of the tumor, percentage of lymphocytes in the mass (percentage lymphocyte composition) on histologic evaluation, and mitotic index of the mass.
Results—All patients were treated with excision of the tumor alone. Median overall survival time for the cats was 1,825 days, with a 1-year survival rate of 89% and a 3-year survival rate of 74%. Median overall survival time for the dogs was 790 days, with a 1-year survival rate of 64% and a 3-year survival rate of 42%. Recurrence of thymoma was observed in 2 cats and 1 dog, and a second surgery was performed in each, with subsequent survival times of 5, 3, and 4 years following the first surgery. Percentage lymphocyte composition of the mass was the only factor that was significantly correlated with survival time; animals with a high percentage of lymphocytes lived longer.
Conclusions and Clinical Relevance—Results of this study indicated that most cats and dogs with thymomas did well after excision. Even cats and dogs with invasive masses that survived the surgery and the few cats and dogs with recurrent thymomas or paraneoplastic syndromes had a good long-term outcome. Excision should be considered an effective treatment option for dogs and cats with thymomas.