Factors affecting digestibility and in-vivo energy content of cat foods

Apparent digestibility and digestible energy (DE) content of 43 canned and 28 packeted samples of commercial cat foods were determined using panels of six adult domestic cats. Metabolizable energy (ME) content was also measured with 22 of the canned and 14 of the packeted foods. Mean apparent crude protein (CP), acid ether extract (AEE) and nitrogen-free extract (NFE) digestibility percentages of all foods (N = 71) were 78, 77 and 69. Apparent AEE and CP digestibility percentages increased in a curvilinear manner with intake; logarithmic regression curves explained 50 and 24 per cent of the variation in AEE and CP digestibility by intake. The use of modified Atwater factors over-estimated ME content of canned and packeted foods by 21 and 27 per cent respectively, compared with in vitro values. Twenty-one single or mulitple regression equations were generated predicting in-vivo DE or ME content of foods from laboratory analyses. The use of such equations in the practical definition of energy content of cat foods is discussed.     

Efficacy of four corn (Zea mays L.) herbicides when applied with flat fan and air induction nozzles

Twelve field experiments were conducted over a 4 year (2002–2005) period to determine the influence of the herbicide dose, nozzle type, spray volume, and spray pressure on herbicide efficacy in field corn ( Zea mays L.). The control of Abutilon theophrasti (velvetleaf ), Ambrosia artemisiifolia (common ragweed), Chenopodium album (common lambsquarters), Amaranthus powellii (green pigweed), and Echinochloa crus-galli (barnyard grass) was improved with the use of full herbicide doses compared to half doses of bromoxynil, glufosinate, dicamba, and nicosulfuron. The yield was increased for bromoxynil, glufosinate, and nicosulfuron when the full herbicide dose was used. When applied at the manufacturer's recommended dose, flat fan nozzles, compared to air induction (AI) nozzles, provided better control of A. theophrasti , A. artemisiifolia , and C. album with bromoxynil, A. artemisiifolia and C. album with dicamba, and E. crus-galli with nicosulfuron. Bromoxynil, in relation to weed control, was the only herbicide that was affected by the water carrier volume. By increasing the spray pressure with an AI nozzle, there was an improvement in the control of A. theophrasti , A. artemisiifolia, and C. album with the application of bromoxynil and E. crus-galli with the application of nicosulfuron, with a yield increase with bromoxynil. Overall, this study concludes that the optimum nozzle type, water carrier volume, and spray pressure is herbicide- and weed species-specific.     

In vitro prediction of canine urolith mineral composition using computed tomographic mean beam attenuation measurements

Determination of urolith mineral composition is critical for management of urolithiasis in dogs and cats. Using computed tomography, urolith physical density, and hence chemical composition, can be quantified using mean beam attenuation measurements (Hounsfield units; HU). This study was designed to establish in vitro reference ranges for three types of compositionally pure uroliths retrieved from dogs. Sixty-six canine uroliths (22 uric acid, 21 calcium oxalate, 14 struvite, nine mixed or compound) were placed in a phantom array. Uroliths were scanned at 120 kVp, 200 mA, and 80 kVp, 200 mA. The region of interest (ROI) for mean HU calculation was determined using two techniques, and reference ranges were calculated for each kVp using either ROI technique. HU for urolith types of pure composition were statistically different (Wilcoxon's two-sample test, P < 0.0083 [Bonferonni correction with six comparisons for total P < 0.05]) using both ROI techniques at either kVp. Struvite uroliths were not statistically different from mixed or compound uroliths. The accuracy for determination of composition of pure uroliths ranged from 86% to 93%; the prediction accuracy for each urolith mineral type and for all uroliths in general was highest when the ROI was hand-drawn just within the visible urolith border at 80 kVp. Technique of ROI determination and kVp that yielded the highest sensitivity, specificity, and positive and negative predictive values varied for each urolith type. Therefore, in this study, HU could be used to differentiate three types of uroliths of pure mineral composition in vitro. Further studies are needed to determine the predictive value of HU in vivo.     

SONOGRAPHIC FEATURES OF HISTIOCYTIC NEOPLASMS IN THE CANINE ABDOMEN

The purpose of this retrospective study was to describe the ultrasonographic features of malignant histiocytosis (MH), malignant fibrous histiocytoma, and histiocytic sarcoma in abdominal organs of dogs. The medical records of 18 dogs that had undergone abdominal sonography and had a histopathologic diagnosis of abdominal MH, malignant fibrous histiocytoma, and histiocytic sarcoma were reviewed. The organ most commonly affected was the spleen. MH was the most common followed by histiocytic sarcoma and malignant fibrous histiocytoma. In the spleen there were often multiple hypoechoic nodules with well-defined borders. In one dog, without focal lesions, the spleen was enlarged and hypoechoic. The liver was the second most commonly affected organ. MH was most common followed by histiocytic sarcomas and malignant fibrous histiocytoma. The most common sonographic feature in the liver was the presence of multiple hypoechoic nodules with well-defined borders. One dog without hepatic nodules had a liver that was ultrasonographically enlarged and hypoechoic. MH in the abdominal lymph nodes resulted in hypoechoic lymphadenopathy. Malignant fibrous histiocytoma was the only neoplastic type in the kidneys appearing as a single heteroechoic renal mass with well-defined borders. MH was observed in the stomach of one dog. Sonographically there was a single well circumscribed hypoechoic mass with well-defined borders and abnormal stomach layers. In this study it was not possible to differentiate between MH, malignant fibrous histiocytoma, and histiocytic sarcoma using sonography.     

ECHOCARDIOGRAPHIC PARAMETERS IN TRAINING COMPARED WITH NON-TRAINING GREYHOUNDS

Echocardiographic parameters were compared between training and non-training greyhound dogs. When indexed to body weight there was a statistically significant increase (p<0.05) in the interventricular septal thickness (systole) and when indexed to body surface area there were increased interventricular septal (systole) and left ventricular free wall measurements (systole) in training compared with non-training greyhounds. When each gender was analyzed separately and echocardiographic parameters were indexed to body size, both genders had an increase in the interventricular septal thickness (diastolic in the female, systolic in the male) in the training compared with non-training greyhounds. In male training greyhounds there was additionally an increase in the left ventricular internal dimension (systole) and free wall thickness (systole) when echocardiographic parameters were indexed to body surface area compared with non-training greyhounds (p<0.05). The results indicate that certain training greyhound echocardiographic parameters are larger than non-training greyhound echocardiographic parameters. The potential effects of training, body size and gender should be considered when interpreting echocardiographic parameters in populations of greyhounds.     

B-MODE AND DOPPLER ULTRASOUND IMAGING OF THE SPLEEN WITH CANINE SPLENIC TORSION: A RETROSPECTIVE EVALUATION

The ultrasonographic appearance of splenic torsion has been described; the splenic parenchyma can be normal, hypoechoic or anechoic with interspersed linear echoes (coarse/"lacy" appearance). The ultrasonographic parenchymal appearance of 15 dogs in this report with splenic torsion varied: mottled hypoechoic regions (n=2), diffusely hypoechoic (n=11) and normal (n=2). Because splenic torsion causes vascular congestion due to splenic vein compression and eventual thrombosis, visible splenic vein intraluminal echogenicities compatible with thrombi were seen in 13 dogs using B-mode. Using spectral Doppler and color Doppler imaging of the splenic veins, no measurable flow velocities were detected in any of the 15 dogs. The varied B-mode ultrasonographic appearance of the splenic veins for intraluminal echoes and spectral or color Doppler evaluation for absent velocity flow.     

Effect of Platelet-Activating Factor Antagonist L-691,880 on Low-Flow Ischemia-Reperfusion Injury of the Large Colon in Horses

Objective—To determine the effect of platelet-activating factor (PAF) antagonist L-691,880 on low-flow ischemia and reperfusion (I-R) of the large colon in horses. Animals —12 adult horses. Experimental Design—Horses were anesthetized, and the large colon was exteriorized through a ventral median celiotomy and instrumented. Colonic arterial blood flow was reduced to 20% of baseline (BL) and maintained for 3 hours; flow was then restored, and the colon was reperfused for 3 hours. One of two solutions was administered intravenously 30 minutes before reperfusion: group 1, 10 mL/kg 0.9% NaCl; and group 2, 5 mg/kg PAF antagonist L-691,880 in 0.9% NaCl. Hemodynamic variables were monitored and recorded at 30-minute intervals. Systemic arterial and colonic venous blood were collected for measurement of blood gas tensions, oximetry analyses, packed cell volume, and total plasma protein concentrations. Colonic venous blood was collected for determination of lactate, 6-keto prostaglandin F_1α (6-kPG), prostaglandin E₂ (PGE₂), and thromboxane B₂ (TXB₂) concentrations. Full-thickness biopsy specimens were harvested from the left ventral colon for histological evaluation. Results—There were no significant differences between the two groups for any hemodynamic or metabolic variables. Colonic venous pH decreased, and carbon dioxide tension and lactate concentration increased during ischemia but returned to BL values during reperfusion. Colonic venous 6-kPG concentration was significantly increased above BL value at 2 hours and remained increased through 6 hours in horses of both groups. Colonic venous PGE₂ concentration was significantly greater in group 2 compared with group 1 throughout the study. Colonic venous PGE₂ concentration was increased above BL value from 3 to 6 hours in horses of both groups. Colonic venous TXB₂ concentration was not different between groups but was significantly increased above the BL value for the first hour of reperfusion. Low-flow I-R of the large colon caused significant mucosal necrosis, hemorrhage, edema, and neutrophil infiltration; however, there were no differences in histological variables between vehicle-control and PAF antagonist-treated horses. Conclusion—No protective effects of PAF antagonist L-691,880 were observed on colonic mucosa associated with low-flow I-R. Additionally, deleterious drug-induced effects on hemodynamic and metabolic variables and colonic mucosal injury were not observed.     

A Comparison of the Synthes 4.5-mm Cannulated Screw and the Synthes 4.5-mm Standard Cortex Screw Systems in Equine Bone

Objective —To determine risk of failure of the Synthes 4.5-mm cannulated screw system instrumentation in equine bone and to compare its application with the Synthes 4.5-mm standard cortex screw system.
Study Design —The maximum insertion torque of the cannulated and standard cortex screw systems were compared with the ultimate torsional strengths of the equipment. Pullout strength and ultimate tensile load of cannulated and standard cortex screws were also determined.
Sample Population—Paired equine cadaver third metacarpal and third carpal bones.
Methods —Maximum insertion torque and ultimate torsional strengths were determined by using an axial-torsional, servohydraulic materials testing system and a hand-held torquometer. Pullout tests were performed by using a servohydraulic materials testing system.
Results —Maximum insertion torque of all cannulated instrumentation was less than ultimate torsional strength at all locations ( P < .05). Maximum insertion torques of cannulated taps and screws were greater than for standard taps and screws in the third carpal bone ( P < .002). Pullout strength of the cannulated screws was less than the standard cortex screws at all sites ( P < .001). Cannulated screws broke before bone failure in all but one bone specimen. Conclusions—The risk of cannulated instrument or screw failure during insertion into bone is theoretically low. The relatively low pullout strength of the cannulated screws implies that the interfragmentary compression achievable is likely to be less than with standard cortex screws. Clinical Relevance—The relatively low pullout strength of the cannulated screw suggests that its risk of failure during fracture repair is greater than with the standard cortex screw.