Spinal meningeal cyst in a dog: a case report and literature review.

A two-year-old, female Chinese shar pei was presented with a one-year history of ataxia involving the pelvic limbs. The neurological lesion was localized to the thoracolumbar region of the spinal cord. A cyst involving the dorsal subarachnoid space at the level of the 12th thoracic vertebral body was identified with myelography. The diagnosis of a meningeal cyst was made, and surgical treatment consisting of a dorsal laminectomy and cyst fenestration was performed. The pelvic-limb ataxia improved, and the owners considered the dog to be normal three months after surgery. The classification, etiology, clinical signs, diagnostic techniques, treatment, and histology of meningeal cysts are reviewed.

Surgical treatment of septic pedal osteitis in horses: nine cases (1980-1987).

Over an 8-year period, 9 horses with septic pedal osteitis were admitted to the New York State College of Veterinary Medicine. Septic pedal osteitis was defined by the presence of purulent exudate combined with radiographic evidence of lysis of the distal phalanx. The condition described involved only the distal phalanx, the laminae and hoofwall, and the soft tissues of the sole. Treatment included curettage and removal of the affected portion of the distal phalanx through a ventral approach to the foot, combined with systemic administration of antibodies. Of the 9 horses, 7 returned to soundness and original function within 12 weeks after surgery. During the early postoperative period, 2 horses died from causes unrelated to the surgery or to septic pedal osteitis.

Portosystemic shunts in cats: seven cases (1976-1984).

Congenital portosystemic venous shunt causing signs of hepatic encephalopathy was diagnosed in 7 cats. The left gastric vein served as the shunt in four of these. Increases in blood ammonia and postprandial serum bile acids were the most consistent serum biochemical abnormalities. Excessive variation in red blood cell shape was a common but nonspecific hematologic finding. The jejunal-mesenteric venous injection of contrast material was the preferred method of portography to diagnose portosystemic shunts. Two cats were treated successfully by partial surgical occlusion of their shunts.

Repair of a delayed-union stress fracture of the dorsal cortex of a metacarpal bone in a horse.

A delayed union metacarpal stress fracture was repaired in a horse, using lag-screw fixation in conjunction with dc electrical stimulation. Twelve weeks after surgery, radiographic and scintigraphic evaluations revealed that the fracture line was not discernible and that there was a decrease in radiopharmaceutic uptake, as compared with that in previous bone imaging studies. In this horse, DC stimulation of a delayed union stress fracture in a bone resulted in a healing pattern similar to that in human beings with delayed union fractures when treated with electrical stimulation.

Direct current stimulation of bone production in the pony: observations with a diaphyseal osteotomy model.

Electrically induced osteogenesis exhibits a dose response curve and can induce bone formation in the absence of trauma and in nonunions. Electrically induced osteogenesis, using direct electric current (DC) in a third metacarpal diaphyseal osteotomy model, in conjunction with internal fixation and postoperative loading, was investigated. Twelve young adult ponies of mixed sex were divided into 2 treatment groups (A and B) of 3 stimulated and 3 controls each and evaluated, using a specifically designed procedure. Stimulated ponies in both groups were given 20 microA of DC via an implanted bone growth stimulator (BGS); group A ponies were stimulated for 60 days and group B ponies for 120 days. Biocompatibility of the BGS was excellent in all ponies. Radiographically, there was more advanced healing with better vascular development in the ponies stimulated for 60 days compared with controls, but no discernible difference was seen at 120 days. Nuclear medical bone imaging revealed a peak uptake at 4 weeks in stimulated groups and the uptake decreased after 8 weeks. Radiopharmaceutical uptake in stimulated ponies was consistently below control uptake throughout the study. Mean specific gravity (SG) of specimens prepared for testing materials properties for group A and B controls were 2.044 +/- 0.119 and 1.939 +/- 0.065, respectively. The SG for group A and group B stimulated were 1.992 +/- 0.049 and 1.876 +/- 0.031, respectively. The SG of specimens obtained from metacarpi of age-matched control ponies was 2.194 +/- 0.166. The ultimate bending strengths and the flexural moduli of elasticity in 60-day control ponies and stimulated ponies were 57 +/- 8.4, 59 +/- 23.9 MN/m2 and 89 +/- 3.5, 106 +/- 6.5 MN/m2 and in 120-day control ponies and stimulated ponies were 13 +/- 1.0, 13 +/- 3.2 GN/m2 and 13 +/- 2.89, 15 +/- 0.577 GN/m2, respectively. Sixty-day samples and 120-day samples had pending strengths (SU) of 25% and 50% that of unfractured cortex, respectively. These findings indicate that 20 microA of DC stimulation on a diaphyseal osteotomy model may not stimulate sufficient bone production to affect the mechanical properties of the bone. Therefore, based on our research, clinical use of BGS in fresh fracture management cannot be recommended.

Direct current stimulation of bone production in the horse: preliminary study with a "gap healing" model.

The effect of a 20-microA direct-current implantable bone growth stimulator (BGS) on bone production with a "gap healing" model in the horse was evaluated. The right and left 4th metatarsal bones (Mt-4) were used in 7 adult horses to create the "gap healing" model. A 4-mm section of the Mt-4 bone was resected bilaterally in each horse. The BGS was surgically placed into the 7 left Mt-4 defects. The 7 right Mt-4 defects served as controls. Six horses survived the 16-week experimental period. Signs of pain, decreased range of limb motion, or lameness was not observed in any animal during the 16 weeks. None of the animals showed complete healing radiographically. Four stimulated sites showed less periosteal reaction and 2 showed greater reaction than the 6 controls. The greatest amount of periosteal reaction or bone resorption was seen around the screws and plates in both groups. Uptakes of 99mTc-MDP in counts/pixel for control sites and stimulated sites were 7.90 and 8.25 in the "gap defect" and 5.19 and 5.06 in the areas adjacent to the gap defect. The ratio of uptake between the gap defect and adjacent area was 1.5 and 1.58 respectively. Biocompatability of the BGS was excellent; however, 1 horse had a broken cathode wire 5 cm from the generator capsule at 6 weeks. All polyethylene cathode sheaths were fluid filled at 16 weeks. The average mineralization rates were 1.57 +/- 0.34, 1.71 +/- 0.28 mm/day and bone formation activity was 0.0182 +/- 0.171, and 0.0168 +/- 0.0149 mm2/day for control limbs and stimulated limbs, respectively. There was no significant difference between groups in any of the histomorphometric values measured. Direct current (20 microA) did not increase bone production in this experiment. Methods to objectively evaluate electrically induced osteogenesis and a "gap defect" model for BGS research on the horse are discussed. The results provide a basis for additional research on electrical stimulation of fractures in the horse and for dose-response studies.

Capacitively coupled electrical stimulation of bone healing in the horse: in vivo study with a Salter type IV osteotomy model with stainless steel surface electrodes.

The use of capacitively coupled low-voltage signals for stimulation of osteogenesis has been reported in a variety of animal models. Electrically induced osteogenesis was investigated with a capacitively coupled electric field on a radius (distal-lateral orientation) osteotomy model, in conjunction with internal fixation and postoperative loading. Twelve adult horses of either sex were allotted to 2 groups of 6; 1 group was given electrical stimulation and the other served as controls. A low-voltage high-frequency capacitively coupled electrical signal was locally and continuously applied to the electrically stimulated group for 60 days through external, bare stainless steel surface electrodes which were placed on the skin in circuit with a small, portable power source. Harness compatibility and stimulator and battery durability were excellent. However, stainless steel electrodes required a rigid maintenance schedule to maintain consistent current levels. Synovial fluid evaluation demonstrated intra-articular inflammation (decreased viscosity, hyaluronic acid, and increased protein concentration) 1 week postoperatively that generally improved during subsequent weeks and no distinction between groups was observed at 60 days. Radiographically, there was no difference in the appearance of the healing process of control and that of stimulated horses during the 60 days. Angiography showed bridging blood vessels in both groups. Uptake of a bone seeking radiopharmaceutical peaked at 3 weeks in both groups and was 1.92 +/- 0.6 cps/pixel/mCi and 1.26 +/- 0.40 csp/pixel/mCi for control and stimulated horses, respectively. At any given observation period, uptake in the lesion area was greater in the control group. Ultimate strengths of trabecular bone in 60-day control radii and stimulated radii were 12.64 +/- 3.013 and 9.60 +/- 3.95 MN/m2, and the flexural moduli of elasticity were 698.0 +/- 423 and 402.0 +/- 523 MN/m2, respectively. Porosity index was similar for all specimens. Gross, histologic, and microradiographic evaluations indicated that controls healed more efficiently than stimulated horses. A capacitively coupled applied voltage of 2.2 V RMS (mean) producing a current of 17.32 mA (mean) did not stimulate sufficient bone production in a metaphyseal osteotomy model to affect the mechanical properties of the bone or accelerate the healing process.

Fatigue characteristics and biocompatability of a totally implantable bone growth stimulator in ponies.

Materials fatigue and gross biocompatability of an implantable bone growth stimulator (BGS) were assessed in a 6-month trial using 6 ponies. The forelegs of each pony were implanted with a BGS; the right leg implant had the cathode and cathode lead preconnected by the manufacturer, and the left leg implant was connected at surgery. Evaluation was by radiographic and clinical examination at the beginning and end of the experimental period. Six of the 12 cathode leads (50%) and 7 of the 12 cathodes (58%) were broken at 6 months. All of the implanted preconnected cathode and insulated cathode leads and 33.3% of the surgically connected cathodes and insulated cathode leads were connected at the titanium connector socket at 6 months. This BGS may exhibit wire fatigue greater than 50% of the time when used in the distal extremity of the horse.

Effects of castration, with and without testosterone replacement, on leg bone integrity in the domestic fowl.

Studies were conducted to assess the effects of castration on leg bone integrity of male White Leghorn chickens. Eighteen 5-week-old males were randomly allocated to 3 groups: group 1--intact controls, group 2--castrated, and group 3--castrated and subsequently treated with testosterone (T)-filled Silastic capsule implants. Body weight and plasma concentrations of luteinizing hormone, androgens, and total calcium were measured in each bird at intervals throughout the experiment. Subsequently, radiographs were performed upon the tibiotarsus-tarsometatarsus region of the left limb of birds from the 3 treatment groups at 7, 35, and 47 weeks of age and assigned a score of 1 to 3 (1 = normal; 3 = greatest pathologic change). Analysis of radiologic scores indicated that at 35 and 47 weeks, castrated birds (group 2) had a mean score significantly greater than that of control birds (group 1). The abnormality was typified by hyperossification with exostoses in the ossified tibial cartilage and lateral calcaneal ridge. In contrast, radiologic scores from individual T-implanted castrated birds (group 3) at 35 and 47 weeks were more variable, but the mean score was not statistically different from that of the control group. We conclude that the depression of circulating concentrations of sex steroids, by castration, in young male chickens results in hypercalcification of the tibiotarsus-tarsometatarsus region of the limb. This effect appears to be mediated directly or indirectly by T or a metabolite of T.

Equine colonic motility: interactions among wall motion, propulsion, and fluid flow.

Transmission of intestinal content with respect to wall position and intraluminal pressure was studied using implanted catheters in portions of the haustrated left ventral colon and nonhaustrated pelvic flexure and left dorsal colon in 3 conscious, standing, and feeding ponies. Wall position and content movement was studied in 1 noncatheterized conscious pony that was standing and eating. When coordinated wall movements involving greater than or equal to 30 cm of adjacent colon were seen, point-to-point content movement accompanied intraluminal pressure peaks occurring in the same direction. Near the pelvic flexure, intraluminal pressure peak maximums coincided and reduced colonic diameters and reduced intercatheter distances. Qualitative observation of 3 related aspects of intestinal motility: wall motion, propulsion, and fluid movement can be studied in the conscious feeding pony.

Degenerative joint disease: multiple joint involvement in young and mature dogs.

Radiologic, pathologic, and ancillary methods were used to determine the occurrence of degenerative joint disease involving multiple joints of immature and adult dogs. Animals were selected for the development of hip joint dysplasia and chronic degenerative joint disease. Of disease-prone dogs, 82% (45 of 55 dogs) had radiologic changes, indicative of hip dysplasia, by 1 year of age. At necropsy, more abnormal joints were identified than by radiographic examination. Among 92 dogs between 3 to 11 months of age that had joint abnormalities, 71% had hip joint involvement; 38%, shoulder joint involvement; 22%, stifle joint involvement; and 40% had multiple joint involvement. Polyarthritis was asymptomatic and unexpected. Radiographic examination of older dogs also revealed evidence of degenerative joint disease in many joints. Multiple joint involvement was substantiated at necropsy of young and mature dogs. A similar pattern of polyarticular osteoarthritis was revealed in a survey (computer search) of necropsy reports from medical case records of 100 adult and elderly dogs. Usually, the joint disease was an incidental observation, unrelated to the clinical disease or to the cause of death. The frequent occurrence of degenerative changes in several joints of dogs aged 6 months to 17 years indicated that osteoarthritis may be progressive in these joints and raises the possibility that systemic factors are involved in the disease process.

Reticulography of the cow in dorsal recumbency: an aid in the diagnosis and treatment of traumatic reticuloperitonitis.

The accuracy of radiographic evaluation of the reticulum for traumatic reticuloperitonitis was evaluated. In a retrospective study involving 30 cows that had been radiographed in standing position, the diagnosis of penetrating foreign body was made with certainty in only 3 of 19 cases in which foreign bodies were identified. In 8 cases, no foreign body was identified radiographically, but a foreign body was found at surgery. In a prospective study, 19 cows were radiographed in both the standing and dorsal recumbent (dorsal reticulography) positions; in 10 cases, the diagnosis made on the basis of the standing radiograph was changed because of the dorsal reticulographic findings. When compared with surgical or necropsy findings in 9 cases, dorsal reticulography was accurate in determining whether a radiopaque foreign body was embedded in the reticulum wall. Thus, dorsal reticulography was shown to be an accurate diagnostic method for evaluating cows with suspected traumatic reticulitis, whereas radiographs obtained in the standing position were relatively inaccurate.

Retropulsion-propulsion in equine large colon.

The circular and longitudinal muscle coats of equine "midcolon" were found to be directly electrically coupled. They appear to act in concert, in healthy animals, as a pacemaker in the area of the large colon pelvic flexure, for retropulsive-propulsive myoelectrical events. The retropulsive events keep the cecum and right ventral and left ventral divisions of the colon filled, imposing a delay time for fermentation of cellulose and for bacterial protein synthesis. Point-to-point involvement of adjacent colon sections was slowed by cooling the intestinal contents with no adverse clinical signs. Diminution of the blood flow to this regulatory area was achieved in 12 weanling foals (raised parasite-free) by parasitic cranial mesenteric arteritis, using Strongylus vulgaris larvae. Four of the 12 developed clinical signs of abdominal pain, but on necropsy 3 of these 4 had no gross lesions in the gastrointestinal tract. Dissociation of the left ventral and left dorsal colon divisions, as regards intraluminal pressure events and their antecedent myoelectrical action potentials, was induced in 7 of 8 adult animals given an acaricide which under field conditions is associated with progressive large colon obstruction and colic.

Fibrinous pericarditis in the horse.

During a period of 18 months, between July 1978 and January 1980, 4 adult horses were referred to the New York State College of Veterinary Medicine with evidence of congestive heart failure. Characteristic clinical abnormalities included marked muffling of heart sounds, tachycardia, jugular vein distention, and peripheral edema. Treatment with antibiotics, diuretics, and anti-inflammatory drugs was unsuccessful, and all four died or were euthanatized and necropsied. At necropsy, there was marked distention of the pericardial sac with fluid, and thick layers of fibrin were deposited uniformly over the epicardium. In 3 cases, attempts to isolate bacteria and viruses from pericardial fluid were unsuccessful; in the 4th case, Actinobacillus equuli was isolated on culture of the pericardial fluid.

Aneurysmal bone cyst in the horse.

An aneurysmal bone cyst was diagnosed in the distal metaphysis of Mt3 in a 9-month-old-Quarter Horse colt. The lesion developed between the fifth and ninth month of life and clinically appeared as a non-painful swelling which did not cause a lameness. Radiographs of the lesion showed expansion of the cortex and incomplete septa of new bone extending from the cortex into surrounding soft tissue. Surgical intervention revealed a blood filled cavity. The animal died during the immediate post-surgical period. Histopathologic evaluation of the lesion was performed.