The effects of femoral stem and neck length on cement strains in a canine total hip replacement model

OBJECTIVE: To determine the effects of femoral prosthesis stem length and head size on cement strains in a canine hip replacement system. STUDY DESIGN: An in vitro experimental model. SAMPLE POPULATION: (1) Three standard and 3 1-cm shortened femoral implants with +3 femoral heads. (2) Two standard implants with +0, +3, and +6 femoral heads. METHODS: Femoral stems were embedded in polymethylmethacrylate cement. A uniaxial proximodistal-oriented strain gauge was applied to the cement on the medial and lateral aspects of the construct 1.5 cm, 6.0 cm and 7.0 cm distal to the collar. Each construct with a +3 femoral head was mounted in a materials testing system. An axial compressive load (0-200 N) was applied to the femoral head and cement strains were recorded. Additionally, 2 standard length constructs were also tested with +0 and +6 femoral heads. The effects of stem length and neck length on cement strains were assessed with analysis of variance. RESULTS: Strains increased at all locations with increasing loads for all constructs. Shorter implants had higher strains by 152% and 171%, lateral (P =.003) and medial (P =.0025) to the stem tip. No significant strain differences were noted, at any strain gauge location, between different neck lengths (P values ranged from.20 to.67). CONCLUSIONS: Although a shorter implant stem has a potential to improve implant fit, it led to significantly higher cement strains that may increase the risk for aseptic loosening. Changes in femoral neck length did not significantly affect cement strains under the conditions tested. CLINICAL RELEVANCE: Shortening of the femoral stem currently cannot be recommended in canine total hip replacement. The existing use of variable neck lengths likely does not increase the risk of failure of the femoral stem.     

In vitro biomechanical study of rotational stabilizers of the canine elbow joint

OBJECTIVE: To develop a model for measuring rotary stability of the canine elbow joint and to evaluate the relative contribution of the anconeal process (AN), lateral collateral ligament (LCL), and medial collateral ligament (MCL). SAMPLE POPULATION: 18 forelimbs from 12 canine cadavers. PROCEDURE: Forelimbs were allocated to 3 experimental groups (6 forelimbs/group). Each intact forelimb was placed in extension at an angle of 135 degrees and cycled 50 times from -16 degrees (pronation) to +28 degrees (supination) in a continuous manner at 2.0 Hz. Cycling was repeated following sectioning of the structure of interest (group 1, AN; group 2, LCL; and group 3, MCL). Torque at -12 degrees (pronation) and +18 degrees (supination) was measured for each intact and experimentally sectioned limb. A Student t test was performed to compare torque values obtained from intact verses experimentally sectioned limbs and for comparison with established criteria for differentiation of primary (> or = 33%), secondary (10 to 33%), and tertiary rotational stabilizers (< 10%). RESULTS: In pronation, the AN was the only primary stabilizer (65%). For supination, the LCL was a primary stabilizer (48%), AN was a secondary stabilizer (24%), and MCL was a tertiary stabilizer (7%). CONCLUSIONS AND CLINICAL RELEVANCE: With the elbow joint in extension at an angle of 135 degrees, the AN is a primary rotational stabilizer in pronation, and the LCL is a primary stabilizer in supination. Disruption of the AN or LCL may affect rotary range of motion or compromise stability of the elbow joint in dogs.     

Pyrogallol concentrations in rumen content, liver and kidney of cows at pasture

Pyrogallol (1, 2, 3-trihydroxybenzene), the decomposition product of hydrolysable tannins in oak bark, leaves and acorns, is suspected to be poisonous to animals. The aim of our investigations was to correlate clinical signs and pathological findings with pyrogallol concentrations in organs of poisoned and healthy animals. In a field study, pyrogallol concentrations were determined in liver, kidney, and rumen from seven cattle. In a herd of twelve cows, five animals suffered from hemorrhagic diarrhea, anorexia, weakness, rumen stasis, dyspnoea, and colic symptoms. Death was observed in five cows within five weeks after repeated intake of green acorns and oak leaves. Toxicological analyses of rumen content, liver, and kidney specimens of one cattle confirmed the suspicion of pyrogallol contamination. In this animal, values ranged from 6 to 13 ng pyrogallol per gram specimen. In control cattle, concentrations were clearly lower than in perished cattle. Under antioxidative work-up conditions, detection limit was 0.6 ng/g in rumen content and 1.0 ng/g in liver and kidney, respectively.     

Application of arthroplasty principles to canine cemented total hip replacement

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Determination of the Inflammatory Potential of Bioaerosols from a Duck‐Fattening Unit by Using a Limulus Amebocyte Lysate Assay and Human Whole Blood Cytokine Response

Inhalation of bioaerosols from animal houses can induce acute inflammatory reactions in the respiratory tract. Determination of the concentration of airborne endotoxins is widely used to characterize this risk. In this study, the activity of bioaerosol samples from a duck‐fattening unit to induce interleukin‐1β (IL‐1β) in human blood and to react with Limulus Amebocyte Lysate (LAL) was investigated. The activity detected in the whole blood assay correlated well with the endotoxic activity found in the LAL assay (Spearmen's ρ = 0.902). However in all samples, the inflammation‐inducing potential was overestimated by the LAL assay. It is assumed that this overestimation could be, in part, a result of an overestimation of the inflammatory potential of endotoxins originating from Pseudomonadaceae by the LAL assay. Pseudomonadaceae were regularly isolated from the air of the duck‐fattening unit. The results presented here indicate that the whole blood assay can be used besides the LAL assay as an additional method to characterize the inflammation‐inducing potential of bioaerosols.     

Immunization of Sows in an Integrated Pig‐breeding Herd using a Homologous Inactivated Salmonella Vaccine Decreases the Prevalence of Salmonella typhimurium Infection in the Offspring

The efficacy of a homologous vaccination in preventing infection of suckling piglets with Salmonella (S.) Typhimurium was evaluated after an immunization of pregnant sows using an inactivated herd‐specific S. Typhimurium vaccine. Twenty‐five pregnant sows were vaccinated three times antepartum. The efficiency of this vaccine regime was assessed by comparison with a control group of 37 sows and their suckling piglets, which were daily treated with enrofloxacin from day 14 antepartum until the day of weaning. From the first day of life until day 142 post‐partum, faecal samples of the piglets were collected and analysed for Salmonella shedding. In parallel, systemic antibody responses were monitored using a whole cell‐based isotype‐specific enzyme‐linked immunosorbent assay (ELISA). The bacteriological investigation showed marked effects of vaccination. Salmonella Typhimurium could not be detected in any of the faecal samples of the piglets from the vaccinated sows. In contrast, the piglets of the group with long‐time antibiotic treatment shed salmonellae rating to 47.4% of the animals. Furthermore, the offspring from vaccinated sows showed significantly decreased antibody activities of immunoglobulin (Ig)A and IgG. These bacteriological and serological results indicate a significantly lower Salmonella prevalence in piglets of the vaccinated group. As this study shows, the presented strategy of vaccination of pregnant sows with an inactivated Salmonella vaccine seems to be a suitable measure in decreasing Salmonella prevalence in offspring of infected sows.     

Pulmonary pharmacokinetics of tulathromycin in swine. Part I: Lung homogenate in healthy pigs and pigs challenged intratracheally with lipopolysaccharide of Escherichia coli

The objective of the study was to assess the pharmacokinetics of tulathromycin in lung tissue homogenate (LT) and plasma from healthy and lipopolysaccharide (LPS)‐challenged pigs. Clinically healthy pigs were allocated to two dosing groups of 36 animals each (group 1 and 2). All animals were treated with tulathromycin (2.5 mg/kg). Animals in group 2 were also challenged intratracheally with LPS from Escherichia coli (LPS‐Ec) 3 h prior to tulathromycin administration. Blood and LT samples were collected from all animals during 17‐day post‐tulathromycin administration. For LT, one sample from the middle (ML) and caudal lobes (CL) was taken. The concentration of tulathromycin was significantly lower in the ML after the intratracheal administration of LPS‐E. coli (P < 0.02). In healthy pigs and LPS‐challenged animals, the distribution of the drug into the lungs was rapid and persisted at high levels for 17‐day postadministration. The distribution of the drug within the lung seems to be homogenous, at least between the middle and caudal lobes within dosing groups. The concentration versus time profile of the drug and pharmacokinetic parameters in two different lung areas (middle and caudal lobe) were consistent within the groups. The clinical significance of these findings is unknown.     

Anti‐microbial Susceptibility for east1+Escherichia coli Isolated from Diarrheic Pigs in Korea

The in vitro susceptibilities of 128 isolates of east1⁺Escherichia coli from pre‐weaned and post‐weaned pigs with diarrhoea were tested with nine commonly used anti‐microbial agents by an agar dilution minimal inhibitory concentration (MIC) procedure according to National Committee for Clinical Laboratory Standards guidelines. For the isolates from pre‐weaned and post‐weaned pigs, most of them were susceptible to low concentrations (MIC₉₀) of tetracycline (4 and 2 μg/ml), ceftiofur (2 and 2 μg/ml), and colistin (4 and 2 μg/ml). Marked resistance was found in others.     

The intra‐ and intertester repeatability of radiographic elbow incongruity grading is high in chondrodystrophic dog breeds

Elbow incongruity is a form of elbow dysplasia that causes osteoarthritis, pain, and lameness, and it is common in chondrodystrophic dog breeds. The objective of this retrospective secondary analysis study was to evaluate the intra‐ and interobserver repeatability of a novel radiographic incongruity grading system for assessing elbow incongruity in three chondrodystrophic dog breeds—the dachshund, Skye Terrier, and Glen of Imaal Terrier. We conducted an observer agreement study that included 220 mediolateral antebrachial radiographs from 110 dogs with the elbow in 90° flexion. The radiographs were independently assessed by three observers at three time points, using a four‐stepped grading scale. The proportion of agreement and Kappa coefficient were calculated. Both the intra‐ and interobserver proportions of agreement were substantial when three grades were required to be identical (.705‐.777 and .609, respectively), and almost perfect for two identical grades (.991‐1.000 and .991, respectively). Some differences in repeatability between breeds were noted; specifically, the intraobserver repeatability was higher in the dachshund, and the interobserver repeatability was lower in the Glen of Imaal Terrier. Our study showed that the radiographic imaging protocol and incongruity grading system have high repeatability when assessing elbow incongruity in chondrodystrophic dog breeds.