Vertical position of the patella in the stifle joint of clinically normal large-breed dogs

OBJECTIVE: To define the vertical position of the patella in clinically normal large-breed dogs. SAMPLE POPULATION: Cadavers of 13 clinically normal large-breed dog. PROCEDURE: Both hind limbs were harvested with intact stifle joints and mounted on a positioning device that allowed full range of motion of the stifle joint. Lateral radiographic views were obtained with the stifle joints positioned at each of 5 angles (148 degrees, 130 degrees, 113 degrees, 96 degrees, and 75 degrees). Vertical position of the patella through a range of motion was depicted on a graph of mean stifle angle versus corresponding mean proximal patellar position (PPP) and distal patellar position (DPP) relative to the femoral trochlea for each dog. Ratio of length of the patellar ligament to length of the patella (L:P) was determined for each dog. Overall mean, SD, and 95% confidence intervals for L:P were calculated for all dogs. RESULTS: Evaluation of vertical position of the patella through a range of motion revealed a nearly linear relationship between joint angle and PPP and joint angle and DPPF Evaluation of L:P results did not reveal significant differences between limbs (left or right) or among joint angles. Overall mean +/- SD L:P for all dogs was 1.68 +/- 0.18 (95% confidence interval, 1.33 to 2.03). CONCLUSIONS AND CLINICAL RELEVANCE: The L:P proved to be a repeatable measurement of vertical patellar position, which is independent of stifle angles from 75 degrees to 148 degrees.This measurement could be used as a quantitative method for diagnosing patella alta and patella baja in large-breed dogs.     

Evaluation of the importance of centrifugation as a component of zinc sulfate fecal flotation examinations

Fifty canine fecal samples were evaluated by five flotation procedures to compare the sensitivity of the zinc sulfate (ZnSO4) centrifugation flotation test with ZnSO4 flotation tests using benchtop incubation during the flotation period. One or more parasite species were detected in 40 samples. Results showed that centrifugation with ZnSO4 solution was significantly more likely to detect a positive sample than benchtop procedures. The difference in procedures was due primarily to increased detection of Trichuris eggs and Giardia cysts by centrifugal flotation. No significant difference was seen in the ability of benchtop procedures to detect positive samples when tests sat either for 5 or 10 minutes before examination.     

Ultrastructure of feline mammary hypertrophy

The ultrastructure of feline mammary hypertrophy was studied in a five-month-old female which had aborted recently, a ten-year-old female which was one month postestrus, and a four-year-old progestin-treated neutered male. Morphologic comparisons were made to normal mammary tissue from a one-year-old female cat. Hypertrophied mammary tissue had the same cell types and spatial relationships as did the normal gland. Major differences included a more highly developed duct system composed of metabolically active cells which often were arranged in multiple cell layers, and periductular stroma with increased fibroblasts and vascularization. Hypertrophied epithelial cells were characterized generally by smooth-contoured nuclear membranes, more evenly dispersed heterochromatin, prominent nucleoli, increased polyribosomes, and elongated mitochondria. Secretory activity was developed significantly only in the cat that had aborted recently. Modifications in myoepithelial cells included: more evenly dispersed nuclear heterochromatin, thicker bundles of cytoplasmic filaments, more straight plasma membranes along the basal lamina, and elongated hemidesmosomes. Multilayering of the basal lamina was accentuated. Stromal fibroblasts had nuclear heterochromatin distributed similarly to that of epithelial and myoepithelial cells, and increased rough endoplasmic reticulum. Myoepithelial cells did not contribute to the increased stromal cellularity. No significant ultrastructural differences were noted between mammary hypertrophy in young, old, and progestin-treated cats.     

VERTEBRAL HEART SCORES IN EIGHT DOG BREEDS

The vertebral heart score (VHS) measurement is commonly used to provide a more objective measurement of cardiomegaly in canines. However, several studies have shown significant breed variations from the value previously established by Buchanan and Bücheler (9.7 ± 0.5). This study describes VHS measurements in Pug, Pomeranian, Yorkshire Terrier, Dachshund, Bulldog, Shih Tzu, Lhasa Apso, and Boston Terrier dog breeds. Dogs with two or three view thoracic radiographs, no subjective radiographic evidence of cardiomegaly, and no physical examination findings of heart murmurs or gallop rhythms were included in the study. The Pug, Pomeranian, Bulldog, and Boston Terrier groups were found to have a VHS significantly greater than 9.7 ± 0.5 (P < 0.00001, P = 0.0014, P < 0.0001, P < 0.00001, respectively). Body condition score (BCS) was found to have a significant effect on the VHS of Lhasa Apso group. Anomalous vertebrae in the thoracic column were associated with a significant increase in VHS of the Bulldog (P = 0.028) and Boston Terrier (P = 0.0004) groups. Thoracic depth to width ratio did not have a significant effect on VHS.     

Persistence of cellulitis-associated Escherichia coli DNA fingerprints in successive broiler chicken flocks

Avian cellulitis in broiler chickens is primarily caused by Escherichia coli. Previous research found that the E. coli isolates of cellulitis origin were unique to each ranch, suggesting that these E. coli were endemic within the ranch environment. To test the hypothesis that the E. coli associated with cellulitis are endemic in the litter of the broiler house, we designed a study to determine whether E. coli DNA fingerprints associated with cellulitis persist over successive flocks that are grown in the same house. In addition, we assessed the impact of different cleaning and disinfection strategies on this persistence. Two broiler houses were followed on each of five farms over 3-4 flocks. A total of 353 E. coli isolates from cellulitis lesions were analyzed in this study, and 314 of these isolates (89%) were DNA fingerprinted by PFGE. In each ranch, there were several DNA fingerprint patterns that were present over successive flocks, regardless of the cleaning and disinfection strategy utilized. Isolates persisted as long as 191 days, implying that these E. coli are capable of persisting in the broiler house environment for long periods of time. In addition, these E. coli isolates were associated with cellulitis lesions in successive flocks. Thus, the isolates of E. coli that are associated with cellulitis in broiler chickens appear to be endemic in the litter environment of the broiler house.     

Use of an aiming device for application of a type-II (bilateral) external fixator to a fractured tibia of a dog

An aiming device was used to guide insertion of fixation pins in a type-II (bilateral) external fixator stabilizing an open canine tibial fracture. This device, designed by the Swiss AO group, has multiple applications in orthopedic surgery, because it accurately locates the exit point of a pin or drill hole on the far side of a bone or fractured bone fragment. When used with the type-II external fixator, it greatly facilitates pin placement by ensuring that, as a pin emerges from the bone, it is in line with the second clamp on the opposite connecting bar.     

Idiopathic gastroesophageal reflux disease in an adult horse

Chronic gastroesophageal reflux disease was diagnosed in a 22-year-old female Tennessee Walking Horse that had signs of bruxism and ptyalism. Esophageal ulceration was detected via endoscopy. Compared with the damage to the proximal portions of the esophagus, the severity of the ulceration increased toward the gastroesophageal junction. Esophageal ulceration attributable to chronic gastric acid reflux is usually secondary to pyloric outflow obstruction in horses. In the horse of this report, there was no evidence of either a chronic pyloric or duodenal obstruction that could have resulted in esophageal ulceration. Esophageal ulceration in this horse was attributed to gastroesophageal reflux disease, a common condition in humans in which the underlying abnormality is functional incompetence of the gastroesophageal junction. Treatment is directed at decreasing gastric acidity and protecting the ulcerated mucosa. In the horse of this report, treatment was unsuccessful and the horse was euthanatized; a physical cause of gastroesophageal reflux disease was not identified during an extensive postmortem examination.     

An animal model for interface tissue formation in cemented hip replacements

OBJECTIVE: To create a model in sheep for investigation of early changes related to the formation of an interface membrane in hip prosthesis. STUDY DESIGN: Experimental study. ANIMALS: Twenty-four female adult Swiss Alpine sheep. METHODS: Sheep were divided into 2 groups of 12 for unilateral cemented total hip arthroplasty. In Group I, the prosthesis was fixed with retrograde cement gun injection to achieve a complete cement mantle, whereas in Group II a primary cement mantle defect was produced. Groups I and II were further divided into 2 sub-groups with study end points of 2 and 8.5 months after surgery. Radiographs were evaluated postoperatively and at euthanasia for migration of the femoral component and bone resorption. Histologic sections were evaluated semiquantitatively for changes in cell types and numbers, and bone reactions; and quantitatively for size of interface membrane and new bone formation. RESULTS: Radiographically, there tended to be an increase in bone resorption and periosteal bone formation throughout the femoral shaft in Group II compared with Group I, but this was only statistically significant at the region of the femoral neck (R5) at both time periods (P<.05). Semiquantitative histologic evaluation revealed significant increases (P<.05) in cellularity, numbers of fibroblasts, giant cells, macrophages, and mononuclear cells, in Group II primarily at 2 months after surgery. This was also true for interface membrane formation and bone remodeling. Quantitative data showed an increased in the size of the interface membrane and area of bone formation at 8.5 months in Group II. CONCLUSIONS: The cement defect model offered controlled and repeatable production of an interface membrane. The results suggest that a primary cement mantle defect could be a possible trigger for implant instability, eliciting a cascade of biomechanical and molecular events in bone tissue leading to aseptic loosening. CLINICAL RELEVANCE: The results show the effect of defects in the cement mantle in promoting interface membrane formation. Long-term and biochemical studies are required to evaluate the relevance of this interface membrane formation.