Assessing the sharpness of hypodermic needles after repeated use

Four gauges (14G, 16G, 18G, 20G) of single use hypodermic needles were evaluated for sharpness by measuring the force required to puncture rehydrated bovine leather. The needles began to dull after 1 use with maximum bluntness occurring within 4 to 5 uses.

Limited efficacy of Fever Tag(®) temperature sensing ear tags in calves with naturally occurring bovine respiratory disease or induced bovine viral diarrhea virus infection

Temperature sensing ear tags were tested in 1) auction-derived calves with 50% incidence of bovine respiratory disease, and 2) specific pathogen-free calves infected with bovine virus diarrhea virus. There were no false positives, but tag placement, probe displacement, and a high threshold for activation all contributed to failure to reliably detect sick calves.

Pacemaker malfunction due to mechanical failure of the lead-header interface

An 8 year old female spayed Boxer dog, diagnosed with concurrent vasovagal syncope and arrhythmogenic right ventricular cardiomyopathy, presented for routine evaluation approximately three months following epicardial pacemaker implantation. Routine device interrogation revealed intermittent loss of ventricular capture and intermittent failure to appropriately sense. Following evaluation of chronic impedance data, failure of the pacemaker lead-header interface or lead conductor fracture was suspected. Radiographic and pacemaker interrogator findings suggested incomplete lead insertion into the device header with intermittent loss of ventricular capture and variable pacemaker sensing. We hypothesize that either the presence of a loose or cross-threaded set screw or operator error at the time of device implantation may have caused this complication. This report details the diagnosis of mechanical failure of the lead-header interface, a complication not previously reported in a veterinary patient.

Comparison of noncontact infrared thermometry and 3 commercial subcutaneous temperature transponding microchips with rectal thermometry in rhesus macaques (Macaca mulatta)

This study compared a noncontact infrared laser thermometer and 3 different brands of subcutaneous temperature transponding microchips with rectal thermometry in 50 rhesus macaques (Macaca mulatta). The data were analyzed by using intraclass correlation coefficients and limits of agreement. In addition, the technical capabilities and practicality of the thermometers in the clinical setting were reviewed. None of the alternative techniques investigated was equivalent to rectal thermometry in rhesus macaques. Temperatures obtained by using microchips had higher correlation and agreed more closely with rectal temperatures than did those obtained by the noncontact infrared method. However, transponding microchips did not yield consistent results. Due to difficulty in positioning nonsedated macaques in their homecage, subcutaneous microchips were not practical in the clinical setting. Furthermore, pair-housed macaques may be able to break or remove microchips from their cagemates.

Prospective evaluation of a peripherally administered three-in-one parenteral nutrition product in dogs

OBJECTIVES

Peripheral parenteral nutrition is an option for short-term nutritional support in dogs which cannot be supported with enteral nutrition. The objective of this study was to examine the use of a three-in-one, 840 mOsmol/l peripheral parenteral nutrition product containing amino acids, lipids and glucose in separate compartments in dogs.

METHODS

Nine dogs were administered the three-in-one product, and two dogs were administered the amino acid part of the product, via a peripheral vein. Dogs were monitored for mechanical and metabolic complications.

RESULTS

Mechanical complications (apparent thrombus or thrombophlebitis) caused failure of infusion at a median of 36 hours. None of the dogs appeared to develop catheter-related sepsis. Using a 10-hour infusion period appeared to decrease the incidence of line failure. Mild and clinically non-significant hyperglycaemia was the only metabolic complication. In four of the dogs, serum folate, cobalamin and homocysteine concentrations were determined before and after peripheral parenteral nutrition administration. Oral and parenteral administration of methionine has been previously associated with lowered serum folate concentrations. Low serum folates and the subsequent hyperhomocysteinaemia have been associated with venous endothelial damage and venous thrombus in other species. Serum cobalamin also affects homocysteine metabolism. Median serum folate, cobalamin and homocysteine concentrations were not affected by the short-term administration of this three-in-one product.

CLINICAL SIGNIFICANCE

Using the product for 24 hours/day may require catheter replacement due to line failure. Other than line failure, which may be improved by 10- to 12-hour infusion times, this product was found to be safe and practical for short-term peripheral parenteral nutrition in dogs.

Gross and histopathological observations of long-term catheterized vessels in experimental sheep

Chronic indwelling central vessel catheters provide vascular access for compartmental infusion or sampling. However, complications with catheter patency during the postoperative and/or experimental period often arise. In order to identify physiological occurrences common with such complications, 10 multicatheterized sheep (61.8 +/- 7.8 kg BW), obtained from a previous nutrient flux study were used for gross and histopathological investigation. Catheters had been surgically placed in a hepatic portal vein (PVC), a hepatic vein (HVC), a distal mesenteric vein (MVC) and a mesenteric artery (MAC). In the previous study, catheters (PVC, HVC and MAC) were used to collect blood samples or infuse (MVC) p-aminohippurate. Catheters were maintained for a total of 58 days prior to necropsy. Histopathological findings indicated that catheter failures were associated with the following tissue responses: (i) thromboses with frequent focal vasculitis; (ii) euplastic tissues associated with extensive fibrosis; (iii) granulomas; (iv) neo-vascularization of the media; (v) calcification processes; and (vi) micro-abscesses. Additional studies are needed that address and incorporate improvement of catheter design and placement to minimize irritation of endothelium, improvement of catheter treatments and therapeutic regimes, and development and use of alternative anti-coagulants. A greater understanding of the mechanisms leading to failure will help researchers improve catheter performance and patency.

Identification of errors and factors associated with errors in data from electronic swine feeders1

Electronic swine feeders are used to automatically measure individual feed intake on group-housed pigs, but the resulting data contain errors caused by feeder malfunctions and animal-feeder interactions. The objectives of this study were to 1) develop criteria to identify errors in data from an electronic feeder that is predominant in the United States; 2) evaluate the frequency of errors in data from three consecutive experiments using the same feeders; and 3) identify factors associated with errors. Across experiments, data included 1,878,321 feed intake records (visits) on 1,721 pigs and 124 pens. Sixteen criteria were developed to detect errors in seven variables related to feed trough weights and times. Logistic regression was used to identify factors associated with the presence or absence of each error type in identified visits (visits where the feeder recognized a transponder) using a model that included the fixed effects of replicate, sex, linear and quadratic effects of day on test, and random effects of feeder within replicate, pig within feeder within replicate, test day within replicate, and week within feeder within replicate. Frequencies of error types in identified visits varied considerably within and between experiments. Errors in feed trough weights were more frequent than errors in time. Percentage of identified visits and of daily feed intake records with at least one error ranged from 4.3 to 18.7% and from 17.2 to 50.0%, respectively, and decreased from the first to the last experiment, reflecting the increasing ability of the managers to operate the feeders. Replicate, sex, test day, feeder within replicate, pig, and day within replicate affected the number of errors that occurred, but their effect varied among error types. Week-to-week variation within a feeder and replicate had the largest effect on number of errors, which was likely associated with feeder management. Results indicate that the frequency of errors in data from electronic swine feeders is substantial, but visits with errors can be identified and their frequency can be decreased by proper feeder management.

A Comparison of Knot Security of Commonly Used Hand-Tied Laparoscopic Slipknots

OBJECTIVE

To compare the peak force required for failure of hand-tied laparoscopic slipknot ligatures.

STUDY DESIGN

In vitro mechanical evaluation of suture material/knot combinations.

SAMPLE POPULATION

Four hand-tied laparoscopic slipknots were studied. Three suture materials and 2 suture sizes were evaluated. Twenty samples of each group were tested, for a total of 400 samples.

METHODS

The 4S modified Roeder, modified Roeder, and Weston and Brooks laparoscopic slipknots using 0 polyglyconate, 0 polyglycolic acid, 1 polyglyconate, and 1 polydioxanone (PDS) were tested. A vertical distracting force (5 mm/s) was applied until failure. Mean peak force to failure was obtained for each suture material, size, and knot combination.

RESULTS

Mean (+/-SEM) peak force to failure of hand-tied ligatures ranged from 156.8+/-9.1 N to 4.8+/-.4 N. The 4S-modified Roeder had the highest mean peak force to failure. Ligatures tied with polyglyconate and size 1 suture had the highest mean peak force to failure.

CONCLUSIONS

The 4S-modified Roeder was significantly and consistently stronger than the other slipknots. Polyglyconate was superior to other suture materials. The 1 polyglyconate had the highest mean peak force to failure followed by 0 polyglyconate that exceeded the 1PDS.

CLINICAL RELEVANCE

The 4S-modified Roeder slipknot using 1 polyglyconate has the greatest breaking strength of sutures tested and should be considered when performing laparoscopic ligatures.

Milk Leakage—An Increased Risk in Automatic Milking Systems

Milk leakage (ML), or milk observed dripping or flowing from one or more teats between milkings, has been associated with increased risk of udder infections and mastitis in dairy cows. Preliminary observations indicate that ML might occur more often in automatic milking systems (AMS) than in conventional milking systems (CMS), but comparative data on the incidence of ML in AMS or in CMS are not available. Therefore, the occurrence of ML at various observation periods was studied in one AMS with cows housed in a free-stall barn in comparison to CMS with cows housed either in a free-stall barn or a tie-stall barn and milked at regular intervals in a herringbone milking parlor. Relationships between ML and other cow and management factors were also examined. In each of 2 yr, all cows (n = 230 total; 46 cows present both years) were observed at 2-h intervals during six 24-h periods. At least one ML occurred in 39.0 (AMS) vs. 11.2% (CMS) of individual cows and in 16.2 (AMS) vs. 2.9% (CMS) of 24-h cow days studied. Milk leakage was not related to milk production, parity, stage of lactation, or estrous status. However, in the AMS, 62% of primiparous and 28% of multiparous cows leaked milk at least once. Milk leakage occurred more often in rear than in forequarters. Cows were usually lying down when ML was observed, but intervals from previous milking varied, especially in AMS. In AMS, about one-fifth of the ML observations occurred < or = 4 h after milking, and half of those were associated with disturbances at the previous milking. Milk flow rate was higher in quarters leaking milk than in other quarters. Strategies to reduce milk leakage in AMS may be important to minimize potential risks of udder disease.

Milkline vacuum stability in milking machine installations

Transient vacuum drops in the milkline during one ordinary milking were recorded as a measure of vacuum stability in milking installations on 184 Norwegian dairy farms in the summer of 1997. An association between the frequency of vacuum drops and technical data including milkline diameter, length and slope, number of milking units and effective reserve was demonstrated. The direct connection between the transient vacuum drop and its cause could be established for most drops during milking observations. A high frequency of transient vacuum drops in the milkline was associated with a high level of mastitis and a high new infection rate as inferred from changes in somatic cell counts for individual cows. The frequency of vacuum drops during one milking is only a rough indication of the long-term vacuum stability in a specific installation, and must be interpreted with care. The dimensions and slope of the milkline and the effective reserve probably give as good information about the installation's ability to maintain a stable vacuum.

Effect of covalently bound heparin coating on patency and biocompatibility of long-term indwelling catheters in the rat jugular vein

Many physiologic and pharmacologic studies require long-term vascular access for repeated substance infusion and/or blood sample collection. The study reported here was undertaken to determine whether a functionally active heparin coating would improve long-term patency of venous catheters in rats. Uncoated or coated catheters were surgically placed in the jugular vein, and patency was evaluated twice weekly for a total of 30 days. Culturing of blood and catheters, and histologic examination were performed for all rats. All heparin-coated catheters remained patent for the study duration, with patency defined as ability to infuse saline and withdraw a blood sample. Median patency for uncoated catheters was 17.5 days, with a range of three to 30 days. Histologic evaluation of vessels revealed more advanced and severe lesions in rats with uncoated, compared with coated catheters. Furthermore, uncoated catheters had increased association with bacteremia (3/8), compared with coated (0/9) catheters. Taken together, these results indicate that coating catheters with covalently bound heparin molecules can significantly prolong patency and cause less pathologic damage to the catheterized vessel.

Radiographic features of a lateral extracapsular wire suture in the canine cranial cruciate deficient stifle

Radiographs of 74 dogs (84 stifles) presented with a cranial cruciate ligament rupture and surgically treated using a lateral extracapsular wire (LEW) were reviewed. A strand of orthopaedic wire was surgically placed caudally around the lateral fabella and through a predrilled hole in the tibial crest. At six week follow-up, the LEW was broken at least once in 26 of 33 stifles, predominantly in the area of the lateral fabella. In five stifles, the LEW had slipped off the fabella and was displaced distally along the gastrocnemius muscle. Six months after surgery, the LEW was often broken at several sites. LEW migration was rare. Osteolysis and sclerosis at the site of LEW penetration through the tibial crest occurred in about two-thirds of the stifles examined.

A comparative mechanical study of 3 external fixator clamps

OBJECTIVE

To compare external fixator clamps from Kirschner-Ehmer (K-E), Synthes, and Meynard with respect to 6 mechanical parameters. Study Design-A bench test of mechanical properties.

METHODS

Specially designed fixtures were used to mechanically test 6 clamps of each type at 2.5, 5.0, and 7.5 Newton-Meters of clamp bolt-tightening torque.

RESULTS

Components slipped axially and torsionally in the K-E clamp at higher forces for all parameters except for clamp bolt axis pivot. No bolt axis pivot occurred with the Synthes clamp. Instead, the clamp plastically deformed at the fixator-pin interface. This failure occurred at a higher applied torque than the pivot torque for other clamps. The Meynard clamp withstood significantly greater force than the K-E clamp when torsion was applied to the clamp bolt axis in the clockwise direction. Pivot forces for the K-E clamp were significantly higher than the Meynard clamp in the counterclockwise direction.

CONCLUSIONS

Overall, the K-E clamp was able to resist higher axial and torsional forces before slipping than the Meynard clamp or the Synthes clamp. The Synthes clamp was best able to resist torsion around the clamp bolt axis. Torsional resistance at the clamp-fixator pin and clamp-connecting bar interface was the weakest parameter of clamp mechanics.

CLINICAL RELEVANCE

The ability to resist motion within a clamp is related to fracture-reduction stability. Knowledge of the mechanical properties of fixator clamps will improve a clinician's ability to apply rigid fixation.

Review of welfare concerns relating to commercial and special permit (scientific) whaling

This paper reviews recent data relating to the efficiency and humaneness of the methods used to kill minke whales in commercial and special permit whaling operations. In the 1980s a grenade-headed harpoon was developed for minke whaling. Most recent results indicate that in the Norwegian industry approximately 60 per cent of whales were considered to be killed immediately by this harpoon, with 40 per cent being wounded. However, in Japanese whaling operations, generally only 30 per cent of whales were killed immediately, with 70 per cent being wounded. In both operations, more than six minutes elapsed before half the wounded whales were pronounced dead, with some whales surviving for more than an hour after being harpooned. Many of the long killing times were associated with a failure of a part of the whaling equipment

Breakage and deformation characteristics of hypodermic devices under static and dynamic loading

OBJECTIVE

To characterize the strength and limitations of hypodermic needles to reduce the risk of leaving broken needles in the flesh of animals.

SAMPLE POPULATION

Skin of porcine cadavers. Procedure-Stainless steel needles of various gauges combined with aluminum and plastic hubs were subjected to standard test-stand conditions to compare strength under various loading regimens. A device that simulated animal motion was constructed to test breakage characteristics during animal movement.

RESULTS

Needles and needle/hub assemblies were resilient to needle breakage, except when bent needles were straightened and a load reapplied. Needle gauge and length drastically affected strength. For 16-and 20-gauge needles, a 1.0-in needle was 1.6 times stronger than a 1.5-in needle. Adding animal movement for 20-gauge, 1.5-in needles resulted in a 40% increase in hub failures for plastic, compared to aluminum hub needles.

CONCLUSIONS AND CLINICAL RELEVANCE

Findings of this study are important considerations for meat packers to address in their Hazard Analysis and Critical Control Points plans.

An inexpensive system to monitor air flow in isolation units

Isolation units are used extensively for conducting infectious disease research in poultry. By necessity, these units are airtight and receive air only through electrically powered ventilation systems. Therefore, interruptions in electrical service to these units present a serious hazard to the animals they contain. A system was designed to monitor the air flow through isolation units and to alert animal caretakers in the event of any interruption in air flow. The "intelligence" of the system relies on an electronic monitor connected to a telephone line that places alerting telephone calls when it detects loss of air flow to the units. The system is constructed from easily acquired and relatively inexpensive parts and components.