Polychlorinated biphenyls and chlorinated pesticides in harbor seals (Phoca vitulina concolor) from the northwestern Atlantic coast.

Concentrations of polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethane (DDT) and its metabolites, chlordane-related compounds (CHLs), mirex, hexachlorocyclohexane isomers (HCHs), dieldrin, and hexachlorobenzene (HCB) were determined in blubber of harbor seals (Phoca vitulina concolor) from the northwestern Atlantic coast. PCBs, DDTs, and CHLs were the major persistent organochlorines in harbor seal blubber, while mirex, HCHs, dieldrin, and HCB were minor contaminants. Highest concentrations were found in the adult males, followed by the pups, yearlings, adult females, and fetuses. DDT and PCB concentrations have declined from the high levels reported in the early 1970s, but no declines were observed in our samples over the ten-year period 1991-2001. DDT/PCB ratios were indicative of a more rapid decline of DDTs than PCBs, while ratios of p,p'-DDE/DDT were indicative of a metabolic "weathering" of DDT. The population appears to be susceptible to disease outbreaks, as evidenced by a recurrence of viral epizootics since the late 1970s. The PCB burdens in these seals are similar to levels reported in seals from polluted regions of Europe and Asia, and exceed the estimated threshold levels for adverse reproductive and immune system effects in the species.

Use of an inertial measurement unit to assess the effect of forelimb lameness on three-dimensional hoof orientation in horses at a walk and trot.

OBJECTIVE: To determine intralimb orientation changes with an inertial measurement unit (IMU) in hooves of horses at a walk and trot after induction of weight-bearing single forelimb lameness and to determine whether hoof orientations are similar to baseline values following perineural anesthesia. ANIMALS: 6 clinically normal horses. PROCEDURES: 3-D hoof orientations were determined with an IMU mounted on the right forelimb hoof during baseline conditions, during 3 grades of lameness (induced by application of pressure to the sole), and after perineural anesthesia. Linear acceleration profiles were used to segment the stride into hoof breakover, stance, initial swing, terminal swing, and total swing phases. Intralimb data comparisons were made for each stride segment. A repeated-measures mixed-model ANOVA was used for data analysis. RESULTS: Lameness resulted in significant changes in hoof orientation in all planes of rotation. A significant increase in external rotation and abduction and a significant decrease in sagittal plane rotation of the hoof were detected at hoof breakover during lameness conditions. For sagittal plane orientation data, the SDs determined following perineural anesthesia were higher than the SDs for baseline and lameness conditions. CONCLUSIONS AND CLINICAL RELEVANCE: Results of this study indicated the IMU could be used to detect 3-D hoof orientation changes following induction of mild lameness at a walk and trot. An increase in data variability for a sagittal orientation may be useful for assessment of local anesthesia for hooves. The IMU should be further evaluated for use in clinical evaluation of forelimb lameness in horses.

Hoof accelerations at hoof-surface impact for stride types and functional limb types relevant to show jumping horses.

Increased knowledge of the influence of stride type on hoof impact accelerations for fore and hind limbs could lead to a more complete picture of hoof-ground interactions in equine athletes. Hoof accelerations were quantified for each hoof of five show jumping horses using two orthogonal single axis ± 250 g accelerometers. Accelerations were recorded when cantering horses jumped fences of varying types (upright and oxer) and heights (90-130 cm) on three different surface conditions. Strides were identified as normal canter strides, take-off strides and landing strides. Descriptive hoof impact parameters were maximal vertical deceleration (MaZ), range of maximum fore-aft acceleration and deceleration (RaX), quotient of acceleration vectors (arctangent for RaX/MaZ) and hoof breaking duration (time from MaZ to first level of <0.042 g absolute fore-aft acceleration). The highest hoof impact accelerations occurred during the take-off stride (mean MaZ over limbs 52.6-91.6 g vs. all-stride mean 39.8 g; mean RaX 63.9-80.5 g vs. all-stride mean 50.7 g). At the jump landing, the forelimbs also experienced high MaZ (46.8 and 49.0 g) of the same order of magnitude as the forelimbs at the take-off. Non-lead limbs had higher MaZ in the normal canter stride, comparing within forelimb and hind limb pairs, and the reverse relationship occurred for RaX and for the quotient of acceleration vectors. The systematic variation introduced by limb and stride type suggests that these gait parameters are important to understand in a sport-specific context for horse surfaces, especially in the development of standardised testing equipment that simulates horse-surface interactions.