Accuracy and optimization of force platform gait analysis in Labradors with cranial cruciate disease evaluated at a walking gait

OBJECTIVE: To determine the combination of ground reaction forces (GRFs) that best discriminates between lame and non-lame dogs. To compare the sensitivity of force platform gait analysis and visual observation at detecting gait abnormalities in Labradors after surgery for rupture of the cranial cruciate ligament (CCL). ANIMALS: All dogs were adult Labrador Retrievers: 17 free of orthopedic and neurologic abnormalities, 100 with unilateral CCL rupture, and 131 studied 6 months after surgery for unilateral CCL injury, 15 with observable lameness. PROCEDURE: Dogs were walked over a force platform with GRF recorded during the stance phase. Analytic properties of force platform gait analysis were calculated for several combinations of forces. The probability of visual observation detecting a gait abnormality was compared with that of force platform gait analysis. RESULTS: We determined that a combination of peak vertical force (PVF) and falling slope were optimal for discriminating sound and lame Labradors. After surgery, many dogs (75%) with no observable lameness failed to achieve GRFs consistent with sound Labradors. CONCLUSION: A force platform is an accurate method of assessing lameness in Labradors with CCL rupture and is more sensitive than visual observation. Assessing lameness with a combination of GRFs is better than using univariate GRFs. CLINICAL RELEVANCE: Therapies for stifle lameness can be accurately and objectively evaluated using 2 vertical ground reaction forces obtained from a force platform.     

Immunogenic properties of soluble antigens or whole cells of Brucella abortus strain 45/20 associated with immunoadjuvants. I. Soluble antigens.

A purified protein derivative-live preparation of Brucella abortus strain 45/20 was tested for immunogenic properties either alone, after lipid conjugation, or in association with defined adjuvants. The adjuvants were trehalose dimycolate (cord factor), isolated from wax D of mycobacteria and murmyl dipeptide (N-acetyl-muramyl-L-alamyl-D-isoglutamine), a synthetic glycopeptide analog of peptidoglycan subunits found in many bacterial cell walls and wax D of mycobacteria. Guinea pigs were intradermally inoculated with a single injection of the vaccine preparations eight weeks before intramuscular challenge with B. abortus, strain 2308. None of the purified protein derivative-like preparations were as effective in the prevention of splenic infections with B. abortus as were killed whole cells of strain 45/20 in Freund's complete adjuvant. Whole cells in Freund's complete adjuvant were able to reduce mean colony counts by 97% (P = 0.02), while purified protein derivative-like vaccines were able to reduce mean colony counts by only 32 to 61% as compared to control animals. Results suggest that purified protein derivative-like preparations have limited immunogenic properties under present test conditions.     

Urethral obstruction in a male llama

An 8-year-old sexually intact male llama was euthanatized because of obstruction of the penile portion of the urethra and rupture of the urinary bladder. Clinical signs of obstruction included anorexia, lethargy, teeth grinding, straining to defecate, inability to urinate, and tense abdomen. Laboratory findings included anemia, leukocytosis with left shift, high serum urea nitrogen, creatinine, and phosphorus concentrations, and low serum chloride concentration. Necropsy revealed ruptured urinary bladder and acute fibrinous peritonitis. A firm, gray, nonmineralized urethral plug occluded the penile portion of the urethra for a distance of 14 cm in the midpenile region, distal to the sigmoid flexure of the penis. The urinary bladder mucosa and the urethra had microscopic evidence of chronic inflammation. Escherichia coli, Klebsiella sp, and alpha-streptococci were isolated from the urethral plug.     

Role of the tendons of the biceps brachii and infraspinatus muscles and the medial glenohumeral ligament in the maintenance of passive shoulder joint stability in dogs

OBJECTIVE: To objectively evaluate the effect of transecting the tendon of the biceps brachii muscle (BBT), tendon of the infraspinatus muscle (IFS), or medial glenohumeral ligament (MGHL) on shoulder joint stability in canine cadavers. SAMPLE POPULATION: 81 forelimbs from mature dogs. PROCEDURE: Cadaver forelimbs were placed in a testing frame and axially preloaded with 4 kg of weight. Shoulder joint stability was tested in neutral joint position, flexion, and extension before and after transection of the BBT (n = 37), IFS (37), or MGHL (7). Humeral translation relative to the glenoid was induced by applying a 3-kg load in each of 3 directions (cranial, lateral, and medial) and quantitatively measured by use of an electromagnetic motion tracking system. Peak translational data were compared in each joint position before and after transection of the BBT, IFS, or MGHL. RESULTS: When tested in neutral position, the cranial, lateral, and medial translation of the humerus was significantly increased after BBT transection. In the flexed position, translation of the humerus in the cranial and lateral directions was significantly increased after BBT transection. In the extended position, the medial translation of the humerus was significantly increased after BBT transection. Complete medial luxation of all humeral heads occurred following transection of the MGHL. CONCLUSIONS AND CLINICAL RELEVANCE: The BBT contributes to passive shoulder joint stability in dogs, particularly in the neutral and flexed positions. It also provides medial stability during shoulder joint extension. Complete luxation of the joint occurs when the MGHL is transected.     

Infrared spectroscopy of comet 81P/Wild 2 samples returned by Stardust

Infrared spectra of material captured from comet 81P/Wild 2 by the Stardust spacecraft reveal indigenous aliphatic hydrocarbons similar to those in interplanetary dust particles thought to be derived from comets, but with longer chain lengths than those observed in the diffuse interstellar medium. Similarly, the Stardust samples contain abundant amorphous silicates in addition to crystalline silicates such as olivine and pyroxene. The presence of crystalline silicates in Wild 2 is consistent with mixing of solar system and interstellar matter. No hydrous silicates or carbonate minerals were detected, which suggests a lack of aqueous processing of Wild 2 dust.