Survival Rates of Out-Migrating Yearling Chinook Salmon in the Lower Columbia River and Plume after Exposure to Gas-Supersaturated Water

In 2011, unusually high flows caused total dissolved gas (TDG) levels in the Columbia River, USA, to escalate well above the 120% regulatory limit that was imposed to prevent harmful impacts to aquatic organisms. After observing gas bubble trauma (GBT) in dead yearling Chinook Salmon Oncorhynchus tshawytscha (smolts) held in tanks, we compared estimated survival rates of acoustic-tagged in-river-migrating (IR) and transported (TR) smolts that were released below Bonneville Dam prior to and during the period of elevated TDG (>120%). The log odds of estimated daily survival in the lower river and plume was significantly lower for IR smolts that were released during elevated TDG (maximum possible exposure = 134%) than for IR smolts released when TDG was less than 120%. The TR smolts that were released 10–13 km below Bonneville Dam during elevated TDG had lower maximum possible exposure levels (126% TDG), and the log odds of estimated daily survival in the lower river and plume did not differ from that of TR smolts released when TDG was less than 120%. Direct mortality due to GBT is probably reduced in natural settings relative to laboratory experiments because smolts can move to deeper water, where pressure keeps gasses in solution, and can migrate downstream of the spillway, where TDG levels decrease as the river returns to equilibrium with the atmosphere. However, initially nonlethal GBT may reduce survival rates by increasing smolt susceptibility to predation and infection. Although our findings are limited by the observational nature of the study, our analysis is the first direct assessment of gas supersaturation’s potential influence on survival of free-ranging smolts in the river and coastal ocean below a large dam. Experiments using simultaneous releases of control and gas-exposed groups are warranted and should consider the possibility that the chronic effects of TDG exposure on survival are important and persist into the early marine period.

Received October 5, 2015; accepted August 18, 2016 Published online October 24, 2016     

EVALUATION OF THYROID TO BACKGROUND RATIOS AND COMPARISON OF VARIOUS SCINTIGRAPHIC MEASUREMENTS AND THEIR CORRELATION TO SERUM T4 IN HYPERTHYROID CATS

Thyroid‐to‐salivary ratio and percent dose uptake are the most widely recognized scintigraphic measurements. Recently, the thyroid‐to‐background ratio has been proposed as an alternate method. However, this method has not been validated. The purpose of this observational, cross‐sectional, prospective study was to determine the location of a background region of interest (ROI) that is most reflective of blood pool activity. We also hypothesized that the thyroid‐to‐background ratio using this background ROI would be a better predictor of thyroid function. Fifty‐six cats presented to the Virginia‐Maryland College of Veterinary Medicine seeking radioiodine therapy for hyperthyroidism were enrolled in this cross‐sectional study to evaluating thyroid‐to‐background ratio. A blood sample for measuring plasma radioactivity was collected at the time of scintigraphy. The plasma radioactivity was compared to the background ROIs in eight anatomic regions. Scintigraphic measures of thyroid‐to‐background and thyroid‐to‐salivary ratios, and percent dose were then compared to serum T₄. The heart ROI was most closely correlated with plasma pertechnetate activity (r = 0.70). Percent dose uptake was most closely correlated with serum T₄ (r = 0.74), followed by thyroid‐to‐salivary ratio (r = 0.66) and thyroid‐to‐background ratio using the heart ROI (r = 0.59). Thyroid‐to‐background ratio using the heart background ROI is a good predictor T₄ but percent dose uptake and thyroid‐to‐salivary ratio proved to be better predictors of T₄ than any of the thyroid‐to‐background ratios.     

Evaluation of piglet blood utilizing the Technicon H*1

The analytic precision of an automated blood analyzer, the Technicon H*1(R), was evaluated utilizing blood samples collected from 20 piglets at 1 and 14 days of age. The effect of storing the blood samples at 4 degrees C for 24 and 48 hours also was determined. Blood samples were analyzed twice on the first day and once on each of the subsequent tow days. Within-sample coefficient of variation was approximately 1% for hemoglobin concentration, erythrocyte count, hematocrit, mean cell volume, erythrocyte distribution width and hemoglobin distribution width (HDW); and approximately 5% for total leukocyte (WBC), neutrophils and lymphocyte counts. Mean HDW and automated differential WBC counts changed during storage to a degree that could be of clinical importance. Manual determination of differential WBC counts were compared with those obtained from the automated analyzer. Results correlated well for neutrophils (r=0.92 in 1-day-old and r=0.93 in 14-day-old piglets, P<0.001) and lymphocytes (r=0.85 in 1-day-old and r=0.93 in 14-day-old piglets, P<0.001). Other WBC values were too low to compare reasonably.     

Intrinsic radiosensitivity and repair of sublethal radiation-induced damage in canine osteosarcoma cell lines

OBJECTIVE: To characterize the radiosensitivity and capacity for sublethal damage repair (SLDR) of radiation-induced injury in 4 canine osteosarcoma cell lines. SAMPLE POPULATION: 4 canine osteosarcoma cell lines (HMPOS, POS, COS 31, and D17). PROCEDURES: A clonogenic colony-forming assay was used to evaluate the cell lines' intrinsic radiosensitivities and SLDR capacities. Dose-response curves for the cell lines were generated by fitting the surviving fractions after radiation doses of 0 (control cells), 1, 2, 3, 6, and 9 Gy to a linear quadratic model. To evaluate SLDR, cell lines were exposed to 2 doses of 3 Gy (split-dose experiments) at an interval of 0 (single 6-Gy dose), 2, 4, 6, or 24 hours, after which the surviving fractions were assessed. RESULTS: Mean surviving fraction did not differ significantly among the 4 cell lines at the radiation doses tested. Mean surviving fraction at 2 Gy was high (0.62), and the alpha/beta ratios (predictor of tissue sensitivity to radiation therapy) for the cell lines were low (mean ratio, 3.47). The split-dose experiments revealed a 2.8- to 3.9-fold increase in cell survival when the radiation doses were applied at an interval of 24 hours, compared with cell survival after radiation doses were applied consecutively (0-hour interval). CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that these canine osteosarcoma cell lines are fairly radioresistant; alpha/beta ratios were similar to those of nonneoplastic, late-responding tissues. Future clinical investigations should involve increasing the fraction size in a manner that maximizes tumor killing without adverse effects on the nonneoplastic surrounding tissues.     

Effect of orally administered tramadol alone or with an intravenously administered opioid on minimum alveolar concentration of sevoflurane in cats

OBJECTIVE-To compare the effect of oral administration of tramadol alone and with IV administration of butorphanol or hydromorphone on the minimum alveolar concentration (MAC) of sevoflurane in cats. DESIGN-Crossover study. ANIMALS-8 Healthy 3-year-old cats. PROCEDURES-Cats were anesthetized with sevoflurane in 100% oxygen. A standard tail clamp method was used to determine the MAC of sevoflurane following administration of tramadol (8.6 to 11.6 mg/kg [3.6 to 5.3 mg/lb], PO, 5 minutes before induction of anesthesia), butorphanol (0.4 mg/kg [0.18 mg/lb], IV, 30 minutes after induction), hydromorphone (0.1 mg/kg [0.04 mg/lb], IV, 30 minutes after induction), saline (0.9% NaCl) solution (0.05 mL/kg [0.023 mL/lb], IV, 30 minutes after induction), or tramadol with butorphanol or with hydromorphone (same doses and routes of administration). Naloxone (0.02 mg/kg [0.009 mg/lb], IV) was used to reverse the effects of treatments, and MACs were redetermined. RESULTS-Mean +/- SEM MACs for sevoflurane after administration of tramadol (1.48 +/- 0.20%), butorphanol (1.20 +/- 0.16%), hydromorphone (1.76 +/- 0.15%), tramadol and butorphanol (1.48 +/- 0.20%), and tramadol and hydromorphone (1.85 +/- 0.20%) were significantly less than those after administration of saline solution (2.45 +/- 0.22%). Naloxone reversed the reductions in MACs. CONCLUSIONS AND CLINICAL RELEVANCE-Administration of tramadol, butorphanol, or hydromorphone reduced the MAC of sevoflurane in cats, compared with that in cats treated with saline solution. The reductions detected were likely mediated by effects of the drugs on opioid receptors. An additional reduction in MAC was not detected when tramadol was administered with butorphanol or hydromorphone.     

Association of magnetic resonance imaging findings and histologic diagnosis in dogs with nasal disease: 78 cases (2001-2004)

OBJECTIVE-To determine whether magnetic resonance imaging (MRI) features correlated with histologic diagnosis in dogs with nasal disease. DESIGN-Retrospective case series. ANIMALS-78 Dogs undergoing MRI for evaluation of nasal disease. PROCEDURES-Medical records and MRI reports of dogs were reviewed to identify MRI features associated with histologic diagnosis. Features evaluated were presence of a mass effect, frontal sinus involvement, sphenoid sinus involvement, maxillary recess involvement, nasopharyngeal infiltration by soft tissue, nasal turbinate destruction, vomer bone lysis, paranasal bone destruction, cribriform plate erosion, and lesion extent (ie, unilateral vs bilateral). RESULTS-33 Dogs had neoplastic disease, 38 had inflammatory rhinitis, and 7 had fungal rhinitis. Lesion extent was not significantly associated with histologic diagnosis. Absence of a mass effect was significantly associated with inflammatory disease. However, presence of a mass was not specific for neoplasia. In dogs with evidence of a mass on magnetic resonance (MR) images, nasal turbinate destruction, frontal sinus invasion, and maxillary recess invasion were not useful in distinguishing neoplastic from nonneoplastic disease, but cribriform plate erosion, vomer bone lysis, paranasal bone destruction, sphenoid sinus invasion, and nasopharyngeal invasion were. CONCLUSIONS AND CLINICAL RELEVANCE-Results suggested that in dogs with nasal disease, the lack of a mass effect on MR images was significantly associated with inflammatory disease. In dogs with a mass effect on MR images, vomer bone lysis, cribriform plate erosion, paranasal bone destruction, sphenoid sinus invasion by a mass, and nasopharyngeal invasion by a mass were significantly associated with a diagnosis of neoplasia.     

Lack of correlation between antibody titers to fibrinogen-binding protein of Streptococcus equi and persistent carriers of strangles.

Previously published studies have neither used nor reported the results of an indirect enzyme-linked immunosorbent assay (iELISA) to measure serologic responses in natural outbreaks of strangles. The concept of using serologic responses to identify persistent carriers of Streptococcus equi has been proposed but not scientifically evaluated. The specific aims of the current study were to determine the duration and level of truncated fibrinogen-binding protein-specific (SeM allele 1) antibody production in ponies involved in a natural outbreak of strangles and to determine if test results from this serologic iELISA could predict persistent carrier status. Serologic samples were obtained before and after an outbreak of naturally occurring strangles infection. Persistent carriers of S. equi were identified via culture and polymerase chain reaction (PCR) testing of lavage fluid collected from the guttural pouches and nasopharynx or swabs of the nasopharynx after recovery from acute disease and at postmortem examination. Logistic regression analysis was used to determine if an association existed between serologic response and persistent carrier state. The ELISA reported in the current study definitively confirmed a recent exposure to S. equi. However, the measured serologic response did not predict carrier status in this strangles outbreak. Therefore, a guttural-pouch endoscopy with subsequent culture or PCR testing to detect S. equi remains the most accurate method available for the identification of persistent carriers.     

Evaluation of a digitally integrated accelerometer-based activity monitor for the measurement of activity in cats

OBJECTIVE: To assess the correlation between data generated by an accelerometer-based activity monitor and the distance moved in cats. STUDY DESIGN: Prospective experimental study. ANIMALS: Three, four-year-old, male, purpose-bred research cats, weighing between 5.1 and 5.9 kg. METHODS: Part I: Collar and harness mounted accelerometers were evaluated in three cats, comparing simultaneously collected accelerometer data with movement data from computer-analyzed video. Part II: Cats wore collar and harness mounted accelerometers, and data were recorded for 4 weeks to evaluate day-to-day and week-to-week variation in activity. RESULTS: Part I: 432 hours of simultaneous video and accelerometer data were collected. The correlation between accelerometer counts and distance moved was 0.82 overall. Agreement between collar and harness mounted accelerometers was excellent with only 6% of the differences in measurements lying outside the mean difference +/- 2 standard deviations. The adjusted R(2) for harness accelerometer output and 6% mobility was 0.75; for movement 0.84; and for mean velocity 0.83. Evaluation of video indicated eating, grooming and scratching created high accelerometer counts with little effect on movement. Part II: There was a significant effect of day on harness (p < 0.001) and collar (p < 0.002) counts, with counts being lowest at the weekend. There was a significant effect of week on harness-mounted accelerometer counts (p < 0.034), but not on collar-mounted accelerometer counts. Harness accelerometer counts were lowest in week 1. CONCLUSION: Output from an acceleration-based digitally integrated accelerometer correlated well with distance moved and mobility in freely moving cats provided the mobility threshold in the analysis software was > or = 6%. CLINICAL RELEVANCE: Acceleration-based activity monitors may allow for objective measurement of improved mobility following analgesic treatment for conditions such as osteoarthritis.