OBJECTIVE To assess effects of withholding feed on thyrotropin-releasing hormone (TRH) stimulation test results used in diagnosis of pituitary pars intermedia dysfunction in horses and determine effects of combined testing on results of the TRH stimulation test and the oral sugar test (OST) used in diagnosis of equine metabolic syndrome. ANIMALS 30 adult horses. PROCEDURES All horses underwent TRH stimulation tests under fed and nonfed conditions, an OST alone, and an OST combined with TRH stimulation testing. For TRH stimulation tests, plasma ACTH concentrations were measured before (baseline) and 10 minutes after (poststimulation) IV TRH administration. For the OST, plasma glucose and insulin concentrations were measured before (baseline) and 60 and 90 minutes after oral corn syrup administration. For combined testing, the TRH stimulation test was initiated immediately after 60-minute posttreatment sample collection for the OST. Results were compared among methods by Wilcoxon matched-pairs, signed rank tests, paired t tests, and Bland-Altman analysis. RESULTS Feeding conditions did not affect median ACTH concentrations when TRH stimulation tests were performed alone. Median baseline ACTH concentration did not differ between TRH stimulation tests performed alone (under fed or nonfed conditions) and those combined with OSTs. Median poststimulation ACTH concentration was significantly lower for combined tests than for solitary TRH stimulation tests. Mean 60-minute plasma glucose concentration was significantly lower for solitary OSTs than for combined tests, but this difference could not be attributed to TRH administration. CONCLUSIONS AND CLINICAL RELEVANCE Combined testing in the manner described impacted ACTH concentrations during TRH stimulation tests and is not recommended at this time.

OBJECTIVE To determine effects of anesthesia on plasma concentrations and pulsatility of ACTH in samples obtained from the cavernous sinus and jugular vein of horses. ANIMALS 6 clinically normal adult horses. PROCEDURES Catheters were placed in a jugular vein and into the cavernous sinus via a superficial facial vein. The following morning (day 1), cavernous sinus blood samples were collected every 5 minutes for 1 hour (collection of first sample = time 0) and jugular venous blood samples were collected at 0, 30, and 60 minutes. On day 2, horses were sedated with xylazine hydrochloride and anesthesia was induced with propofol mixed with ketamine hydrochloride. Horses were positioned in dorsal recumbency. Anesthesia was maintained with isoflurane in oxygen and a continuous rate infusion of butorphanol tartrate. One hour after anesthesia was induced, the blood sample protocol was repeated. Plasma ACTH concentrations were quantified by use of a commercially available sandwich assay. Generalized estimating equations that controlled for horse and an expressly automated deconvolution algorithm were used to determine effects of anesthesia on plasma ACTH concentrations and pulsatility, respectively. RESULTS Anesthesia significantly reduced the plasma ACTH concentration in blood samples collected from the cavernous sinus. CONCLUSIONS AND CLINICAL RELEVANCE Mean plasma ACTH concentrations in samples collected from the cavernous sinus of anesthetized horses were reduced. Determining the success of partial ablation of the pituitary gland in situ for treatment of pituitary pars intermedia dysfunction may require that effects of anesthesia be included in interpretation of plasma ACTH concentrations in cavernous sinus blood.

OBJECTIVE To determine the onset, duration, and extent of regional nerve blocks performed by administration of lidocaine or lidocaine-bupivacaine into the infraorbital canal in dogs. ANIMALS 6 healthy hound-type dogs. PROCEDURES Under general anesthesia, stimulating needles were inserted into the gingiva dorsolateral to both maxillary canine (MC) teeth and the maxillary fourth premolar (MPM4) and second molar (MM2) teeth on the treatment side. A reflex-evoked muscle potential (REMP) was recorded from the digastricus muscle after noxious electrical stimulation at each site. After baseline measurements, 1 mL of 2% lidocaine solution or a 2% lidocaine-0.5% bupivacaine mixture (0.5 mL each) was injected into the infraorbital canal (at approx two-thirds of the canal length measured rostrocaudally). The REMPs were recorded for up to 7 hours. The REMP data for the contralateral (untreated control) canine tooth were used to normalize results for all stimulation sites. RESULTS With both treatments, nerve block for MC teeth on the treated side was achieved by 5 (n = 5 dogs) or 10 (1) minutes after injection, but nerve block for ipsilateral MPM4 and MM2 teeth was successful for only 3 dogs and 1 dog, respectively. Mean duration of nerve blocks for MC teeth was 120 and 277 minutes following injection of lidocaine and lidocaine-bupivacaine, respectively. CONCLUSIONS AND CLINICAL RELEVANCE Local anesthesia, as performed in this study, successfully blocked innervation of MC teeth, but results for MPM4 and MM2 teeth were inconsistent. This specific technique should not be used during tooth extractions caudal to the MC teeth.

The objective of this study was to develop a time-resolved immunofluorometric assay (TR-IFMA) for quantification of salivary alpha-amylase in sheep. For that purpose, after the design of the assay, an analytical and a clinical validation were carried out. The analytical validation of the assay showed intra- and inter-assay coefficients of variation (CVs) of 6.1% and 10.57%, respectively and an analytical limit of detection of 0.09 ng/mL. The assay also demonstrated a high level of accuracy, as determined by linearity under dilution. For clinical validation, a model of acute stress testing was conducted to determine whether expected significant changes in alpha-amylase were picked up in the newly developed assay. In that model, 11 sheep were immobilized and confronted with a sheepdog to induce stress. Saliva samples were obtained before stress induction and 15, 30, and 60 min afterwards. Salivary cortisol was measured as a reference of stress level. The results of TR-IFMA showed a significant increase (P < 0.01) in the concentration of alpha-amylase in saliva after stress induction. The assay developed in this study could be used to measure salivary alpha-amylase in the saliva of sheep and this enzyme could be a possible noninvasive biomarker of stress in sheep.

OBJECTIVE To determine optimal techniques for CT enterography in clinically normal dogs and to evaluate luminal distention after oral administration of lactulose solution as a contrast agent. ANIMALS 15 healthy dogs. PROCEDURES CT was performed in a control group (2 dogs that underwent CT to evaluate metastasis and 5 other dogs). In a bolus administration group (5 dogs from the control group), lactulose solution (1.34 g/mL) was administered (60 mL/kg) rapidly via gastric tube to anesthetized dogs, and CT was performed every 10 minutes for 1 hour. In a continuous administration group of 8 other dogs, lactulose solution (60 mL/kg) was administered slowly via nasoesophageal tube over a period of 45 minutes. Then, 15 minutes after anesthetic induction, CT was performed every 10 minutes for 1 hour. Luminal distention of the small intestines was evaluated qualitatively by use of a 3-point scale. RESULTS All small intestinal segments had poor luminal distention in the control group. The terminal ileum had poor luminal distention for the bolus administration group. Nearly all segments had good luminal distention for the continuous administration group with mild adverse effects. Luminal distention scores from 0 to 20 minutes after lactulose administration were significantly higher than scores from 30 to 60 minutes. Interobserver reproducibility was high for all intestinal segments. CONCLUSIONS AND CLINICAL RELEVANCE CT performed between 0 and 20 minutes after continuous administration of lactulose solution (60 mL/kg) may reveal adequate luminal distention for examination of small intestinal segments in dogs.

OBJECTIVE To create an atlas of the normal CT anatomy of the head of blue-and-gold macaws (Ara ararauna), African grey parrots (Psittacus erithacus), and monk parakeets (Myiopsitta monachus). ANIMALS 3 blue-and-gold macaws, 5 African grey parrots, and 6 monk parakeets and cadavers of 4 adult blue-and-gold macaws, 4 adult African grey parrots, and 7 monk parakeets. PROCEDURES Contrast-enhanced CT imaging of the head of the live birds was performed with a 4-multidetector-row CT scanner. Cadaveric specimens were stored at −20°C until completely frozen, and each head was then sliced at 5-mm intervals to create reference cross sections. Frozen cross sections were cleaned with water and photographed on both sides. Anatomic structures within each head were identified with the aid of the available literature, labeled first on anatomic photographs, and then matched to and labeled on corresponding CT images. The best CT reconstruction filter, window width, and window level for obtaining diagnostic images of each structure were also identified. RESULTS Most of the clinically relevant structures of the head were identified in both the cross-sectional photographs and corresponding CT images. Optimal visibility of the bony structures was achieved via CT with a standard soft tissue filter and pulmonary window. The use of contrast medium allowed a thorough evaluation of the soft tissues. CONCLUSIONS AND CLINICAL RELEVANCE The labeled CT images and photographs of anatomic structures of the heads of common pet parrot species created in this study may be useful as an atlas to aid interpretation of images obtained with any imaging modality.

OBJECTIVE To determine serum and tissue concentrations of gallium (Ga) after oral administration of gallium nitrate (GaN) and gallium maltolate (GaM) to neonatal calves. ANIMALS 8 healthy neonatal calves. PROCEDURES Calves were assigned to 1 of 2 groups (4 calves/group). Gallium (50 mg/kg) was administered as GaN or GaM (equivalent to 13.15 mg of Ga/kg for GaN and 7.85 mg of Ga/kg for GaM) by oral gavage once daily for 5 days. Blood samples were collected 0, 0.25, 0.5, 1, 2, 4, 8, 12, and 24 hours after Ga administration on day 1; 4 and 24 hours after Ga administration on days 2, 3, and 4; and 4, 12, and 24 hours after Ga administration on day 5. On day 6, calves were euthanized and tissue samples were obtained. Serum and tissue Ga concentrations were measured by use of mass spectrometry. RESULTS Data were adjusted for total Ga dose, and comparisons were made between the 2 groups. Calves receiving GaM had a significantly higher dose-adjusted area under the curve and dose-adjusted maximum serum Ga concentration than did calves receiving GaN. Despite receiving less Ga per dose, calves receiving GaM had tissue Ga concentrations similar to those for calves receiving GaN. CONCLUSIONS AND CLINICAL RELEVANCE In this study, calves receiving GaM had significantly higher Ga absorption than did calves receiving GaN. These findings suggested that GaM might be useful as a prophylactic agent against Mycobacterium avium subsp paratuberculosis infection in neonatal calves.

OBJECTIVE To determine the effects of acepromazine maleate premedication on cardiovascular function before and after infusion of dobutamine hydrochloride for 30 minutes in isoflurane-anesthetized horses. ANIMALS 6 healthy adult horses. PROCEDURES Each horse was anesthetized once following premedication with acepromazine (0.02 mg/kg, IV) administered 30 minutes prior to anesthetic induction (ACP+ treatment) and once without premedication (ACP– treatment). Anesthesia was induced with IV administration of xylazine hydrochloride (0.8 mg/kg), ketamine hydrochloride (2.2 mg/kg), and diazepam (0.08 mg/kg). Horses were positioned in right lateral recumbency, and anesthesia was maintained via inhalation of isoflurane delivered in oxygen. End-tidal isoflurane concentration was adjusted to achieve a target mean arterial blood pressure of 60 mm Hg (interquartile range [25th to 75th percentile], 57 to 63 mm Hg) for at least 15 minutes. Cardiac index, oxygen delivery index, and femoral arterial blood flow indices were determined 60 minutes after anesthetic induction (baseline). Dobutamine was then infused to achieve a target mean arterial blood pressure of 80 mm Hg (interquartile range, 76 to 80 mm Hg). Data collection was repeated 30 minutes after the start of dobutamine infusion for comparison with baseline values. RESULTS Complete data sets were available from 5 of the 6 horses. Dobutamine administration resulted in significant increases in oxygen delivery and femoral arterial blood flow indices but no significant change in cardiac index for each treatment. However, at baseline or 30 minutes after the start of dobutamine infusion, findings for the ACP+ and ACP– treatments did not differ. CONCLUSIONS AND CLINICAL RELEVANCE In isoflurane-anesthetized horses, dobutamine administration increased oxygen delivery and femoral arterial blood flow indices, but these changes were unaffected by premedication with acepromazine.

OBJECTIVE To determine a treatment protocol for SC administration of dalteparin to cats on the basis of currently available detailed pharmacokinetic data and to assess the effect of SC administration of dalteparin to cats on coagulation variables such as activated partial thromboplastin time (aPTT), thrombin time, and results for thromboelastometry, compared with effects on anti–activated coagulation factor X (anti-Xa) activity. ANIMALS 6 healthy domestic shorthair cats. PROCEDURES Cats received 14 injections of dalteparin (75 anti-Xa U/kg, SC) at 6-hour intervals. Blood samples were collected before and 2 hours after the first and second injections on days 1, 2, and 4. Anti-Xa activity was measured by use of a chromogenic substrate assay, aPTT and thrombin time were measured by use of an automated coagulometer, and viscoelastic measurements were obtained with thromboelastrometry. RESULTS 2 hours after the second injection, the target peak anti-Xa activity range of 0.5 to 1.0 U/mL was achieved in all cats, whereas median trough values remained below this range. Peak anti-Xa activity had only minimal effects on coagulation variables; the maximum median ratio for aPTT (in relationship to the value before the first dalteparin injection) was 1.23. CONCLUSIONS AND CLINICAL RELEVANCE Results of this study indicated that this treatment protocol resulted in reproducible anti-Xa activity in cats that was mostly within the targeted peak range of anti-Xa activity recommended for humans. Treatment in accordance with this protocol may not require routine coagulation monitoring of cats, but this must be confirmed in feline patients.

OBJECTIVE To evaluate the effect of intra-abdominal pressure (IAP) on morphology and compliance of the lower esophageal sphincter (LES) by use of impedance planimetry in healthy dogs and to quantify the effect of changes in IAP. ANIMALS 7 healthy, purpose-bred sexually intact male hound-cross dogs. PROCEDURES Dogs were anesthetized, and cross-sectional area (CSA), minimal diameter (MD), LES length, LES volume, and distensibility index (DI) of the LES were evaluated by use of an endoscopic functional luminal imaging probe. For each dog, measurements were obtained before (baseline) and after creation of a pneumoperitoneum at an IAP of 4, 8, and 15 mm Hg. Order of the IAPs was determined by use of a randomization software program. RESULTS CSA and MD at 4 and 8 mm Hg were not significantly different from baseline measurements; however, CSA and MD at 15 mm Hg were both significantly greater than baseline measurements. The LES length and LES volume did not differ significantly from baseline measurements at any IAP. The DI differed inconsistently from the baseline measurement but was not substantially affected by IAP. CONCLUSIONS AND CLINICAL RELEVANCE Pneumoperitoneum created with an IAP of 4 or 8 mm Hg did not significantly alter LES morphology in healthy dogs. Pneumoperitoneum at an IAP of 15 mm Hg caused a significant increase in CSA and MD of the LES. Compliance of the LES as measured by the DI was not greatly altered by pneumoperitoneum at an IAP of up to 15 mm Hg.