Collateral circulation in ferrets (Mustela putorius) during temporary occlusion of the caudal vena cava.

OBJECTIVE To determine whether extent of collateral circulation would change during temporary occlusion of the caudal vena cava (CVC) in ferrets (Mustela putorius), a pressure change would occur caudal to the occlusion, and differences would exist between the sexes with respect to those changes. ANIMALS 8 adult ferrets (4 castrated males and 4 spayed females). PROCEDURES Ferrets were anesthetized. A balloon occlusion catheter was introduced through a jugular vein, passed into the CVC by use of fluoroscopy, positioned cranial to the right renal vein, and inflated for 20 minutes. Venography was performed 5 and 15 minutes after occlusion. Pressure in the CVC caudal to the occlusion was measured continuously. A CBC, plasma biochemical analysis, and urinalysis were performed immediately after the procedure and 2 or 3 days later. RESULTS All 8 ferrets survived the procedure; no differences were apparent between the sexes. Vessels providing collateral circulation were identified in all ferrets, indicating blood flow to the paravertebral venous plexus. Complications observed prior to occlusion included atrial and ventricular premature contractions. Complications after occlusion included bradycardia, seizures, and extravasation of contrast medium. Mean baseline CVC pressure was 5.4 cm H2O. During occlusion, 6 ferrets had a moderate increase in CVC pressure (mean, 24.3 cm H2O) and 2 ferrets had a marked increase in CVC pressure to > 55.0 cm H2O. CONCLUSIONS AND CLINICAL RELEVANCE Caval occlusion for 20 minutes was performed in healthy ferrets with minimal adverse effects noted within the follow-up period and no apparent differences between sexes. The CVC pressure during occlusion may be prognostic in ferrets undergoing surgical ligation of the CVC, which commonly occurs during adrenal tumor resection.

Comparison of axillary and rectal temperatures for healthy Beagles in a temperature- and humidity-controlled environment.

OBJECTIVE: To compare axillary and rectal temperature measurements obtained with a digital thermometer for Beagles in a temperature- and humidity-controlled environment. ANIMALS: 26 healthy Beagles (17 sexually intact males and 9 sexually intact females). PROCEDURES: Dogs were maintained in a temperature- and humidity-controlled environment for 56 days before rectal and axillary temperatures were measured. Axillary and rectal temperatures were obtained in triplicate for each dog by use of a single commercially available manufacturer-calibrated digital thermometer. RESULTS: Mean rectal and axillary temperatures of Beagles maintained in a temperature- and humidity-controlled environment were significantly different, with a median ± SD difference of 1.4° ± 0.15°C (range, 0.7° to 2.1°C). Mean rectal and axillary temperatures were 38.7°C (range, 37.6° to 39.5°C) and 37.2°C (range, 36.6° to 38.3°C), respectively. CONCLUSIONS AND CLINICAL RELEVANCE: Results of this study indicated that the historical reference of a 0.55°C gradient between rectal and axillary temperatures that has been clinically used for veterinary patients was inaccurate for healthy Beagles in a temperature- and humidity-controlled environment. Rectal and axillary temperatures can be measured in veterinary patients. Reliable interpretation of axillary temperatures may accommodate patient comfort and reduce patient anxiety when serial measurement of temperatures is necessary. Further clinical studies will be needed.

Comparison of tissue oxygen saturation in ovariohysterectomized dogs recovering on room air versus nasal oxygen insufflation.

OBJECTIVE: To compare tissue oxygen saturation in ovariohysterectomized dogs recovering postoperatively on room air versus nasal oxygen insufflation. DESIGN: Prospective clinical study. SETTING: University teaching hospital. ANIMALS: Twenty dogs undergoing ovariohysterectomy. INTERVENTIONS: Dogs were randomized to breathe either room air or 100 mL/kg/min of nasal oxygen insufflation for 2 hours postoperatively. Tissue oxygen saturation (StO(2)) was evaluated at 2 mm and 20 mm lateral to the surgical incision, as well as in the inguinal region using a noninvasive tissue oximeter. MEASUREMENTS AND MAIN RESULTS: In dogs recovered on nasal oxygen insufflation (n = 10), tissue oxygen saturation was significantly higher--20 mm from the surgical site (88.44 ± 2.50%, P = 0.02) and in the inguinal region (83.56 ± 1.91%, P = 0.032)-- compared to dogs recovered on room air (n = 10, 79.11% ± 2.50 and 77.12% ± 1.91, respectively). CONCLUSIONS: In ovariohysterectomized dogs, oxygen supplementation for 2 hours postoperatively improves tissue oxygen saturation 20 mm adjacent to the linea alba and in the inguinal region. Oxygen supplementation in postoperative dogs is an inexpensive and easily applicable method to improve tissue oxygen saturation.

Assessment of oxygen transport and utilization in dogs with naturally occurring sepsis.

OBJECTIVE: To compare cardiac index (CI), oxygen delivery index (D(O(2))I), oxygen extraction ratio (O(2)ER), oxygen consumption index (V(O(2))I), and systemic vascular resistance index (SVRI) in dogs with naturally occurring sepsis with published values for healthy dogs; compare those variables in dogs with sepsis that did or did not survive; and compare CI and D(O(2))I in dogs with sepsis with values in dogs with nonseptic systemic inflammatory response syndrome (nSIRS). DESIGN: Cohort study. ANIMALS: 10 dogs with naturally occurring sepsis and 11 dogs with nSIRS. PROCEDURES: Over 24 hours, CI, D(O(2))I, O(2)ER, V(O(2))I, and SVRI were measured 4 and 5 times in dogs with sepsis and with nSIRS, respectively. The mean values of each variable in each group were compared over time and between groups; data for dogs with sepsis that did or did not survive were also compared. RESULTS: Mean D(O(2))I was significantly decreased, and mean CI, O(2)ER, V(O(2))I, and SVRI were not significantly different in dogs with sepsis, compared with published values for healthy dogs. Mean CI and D(O(2))I in dogs with sepsis were significantly greater than values in dogs with nSIRS. Among dogs with sepsis that did or did not survive, values of CI, D(O(2)I), O(2)ER, V(O(2))I, and SVRI did not differ significantly. CONCLUSIONS AND CLINICAL RELEVANCE: Compared with values in healthy dogs, only D(O(2))I was significantly lower in dogs with sepsis. Values of CI and D(O(2))I were significantly higher in dogs with sepsis than in dogs with nSIRS, suggesting differing degrees of myocardial dysfunction between these groups.

Evaluation of open versus closed urine collection systems and development of nosocomial bacteriuria in dogs.

OBJECTIVE: To determine whether use of a closed urine collection system would decrease the incidence of nosocomial bacteriuria in hospitalized dogs, compared with use of an open urine collection system (used, sterile IV bags). DESIGN: Randomized controlled trial. ANIMALS: 51 hospitalized dogs requiring indwelling urinary catheterization for >or= 24 hours. PROCEDURES: Dogs were randomly assigned to an open or closed urine collection system group. A standardized protocol for catheter placement and maintenance was followed for all dogs. A baseline urine sample was collected via cystocentesis for aerobic bacterial culture, with additional urine samples obtained daily from the urine collection reservoir. RESULTS: 27 dogs were assigned to the open urine collection system group, and 24 were assigned to the closed urine collection system group. The incidence of nosocomial bacteriuria in dogs with open urine collection systems (3/27 [11.1%]) was not significantly different from incidence in dogs with closed urine collection systems (2/24 [8.3%]). Median duration of catheterization was 2 days for dogs in both groups; the range was 1 to 7 days for dogs in the open group and 1 to 5 days for dogs in the closed group. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that for dogs requiring short-term indwelling urinary catheterization, the type of urine collection system (open vs closed) was not associated with likelihood of developing nosocomial bacteriuria. Use of a strict protocol for urinary catheter placement and maintenance was likely key in the low incidence of nosocomial bacteriuria in the present study.

Measurement of urinary F2-isoprostanes as markers of in vivo lipid peroxidation: a comparison of enzyme immunoassays with gas chromatography-mass spectrometry in domestic animal species.

F(2)-isoprostanes are useful markers for assessing oxidant injury; however, the validity of measuring urinary 15-F(2t)-isoprostane concentration by enzyme-linked immunosorbent assay (ELISA) has not been evaluated in veterinary species. The current study assesses the agreement between 2 commercially available urinary isoprostane kits and gas chromatography and negative ion chemical ionization-mass spectrometry (GC/NICI-MS). The results indicate that only feline urinary isoprostane measurement by glucuronidase (GL)-ELISA has acceptable agreement with GC/NICI-MS. Urinary isoprostane concentration was highly variable in critically ill animals, but there were too many variations between healthy and critically ill animals to draw meaningful conclusions. Currently, GC/NICI-MS is the only method that can be recommended for the assessment of urinary isoprostanes in dogs, cattle, and horses. Feline urinary isoprostanes can be assessed by GL-ELISA, but caution is still warranted when comparing data from manuscripts using different methods given the relatively low Spearman rank correlation coefficient. Future studies may require large sample sizes or focused inclusion criteria to account for variability in isoprostane concentration.

Comparison of continuous arterial pressure waveform analysis with the lithium dilution technique to monitor cardiac output in conscious dogs with systemic inflammatory response syndrome.

OBJECTIVE: To assess the agreement between cardiac output (CO) measured by use of arterial pressure waveform analysis (PulseCO) and lithium dilution (LiDCO) in conscious dogs with systemic inflammatory response syndrome (SIRS). ANIMALS: 14 dogs with naturally occurring SIRS. PROCEDURES: Pulse power analysis was performed on critically ill patients with a PulseCO monitor. All measurements were obtained with an indwelling arterial line and in accordance with the manufacturer's instructions. Intermittent measurements of CO were obtained with the LiDCO method to validate the PulseCO measurements at initial calibration (baseline; time 0) and at 4, 8, 16, and 24 hours. The 2 methods for measuring CO were compared by use of Bland-Altman analysis. An error rate for the limits of agreement between the 2 methods of < 30% was defined as being acceptable. RESULTS: Bland-Altman analysis did not indicate good agreement between measurements obtained by use of the PulseCO and LiDCO methods, despite no significant change in cardiac index (CI) over time as measured with the LiDCO method. The percentage error for the overall difference in CI values between the PulseCO and LiDCO measurements was 122%, which indicated that the PulseCO method was not an acceptable means of CO measurement when compared with the LiDCO method for this patient population. CONCLUSIONS AND CLINICAL RELEVANCE: Agreement between the PulseCO and LiDCO methods for measurement of CO was not acceptable at 4- and 8-hour intervals after calibration in conscious dogs with naturally occurring SIRS.

Use of a point-of-care urine drug test in a dog to assist in diagnosing barbiturate toxicosis secondary to ingestion of a euthanized carcass.

OBJECTIVE: To describe a case of barbiturate toxicosis in a dog secondary to ingestion of a previously buried euthanized goat carcass and to discuss the utility of urine drug testing in diagnosing barbiturate toxicosis. CASE SUMMARY: A 6-year-old neutered male Border Collie was presented to a university veterinary teaching hospital for evaluation of ataxia and acute collapse. Past pertinent history included Addison's disease that had been managed for 1 year. A companion dog was seen 12 hours earlier chewing on the partially decomposed head of a goat that had been euthanized 47 days previously and buried on the owner's property. The dog was laterally recumbent, unresponsive to stimuli, and hypothermic on physical examination. Initial blood work revealed hyponatremia and hyperkalemia, with a Na/K ratio of 18.5. The dog was volume resuscitated and received an injection of dexamethasone sodium phosphate due to a suspected Addisonian crisis. Despite this treatment, the dog remained laterally recumbent and unresponsive to stimuli. A urine drug screen was performed and was positive for barbiturates. A diagnosis of barbiturate toxicosis secondary to ingestion of a euthanized goat carcass was made. The dog was treated supportively over 12 hours with IV fluids and activated charcoal. The dog was able to walk 11 hours after presentation and was subsequently discharged from the hospital. NEW OR UNIQUE INFORMATION PROVIDED: Urine drug testing is a fast, easy, and point-of-care test that may be useful in dogs to assist in the diagnosis of barbiturate intoxication. Proper disposal of euthanized animals is necessary to prevent toxicosis and possible death of companion animals and wildlife.

Aerobic bacterial culture of used intravenous fluid bags intended for use as urine collection reservoirs.

Numerous studies have shown a relationship between indwelling urinary catheters and bacterial urinary tract infection. Some veterinary hospitals utilize stored, used intravenous (IV) fluid bags as part of the urine collection system. The authors cultured 95 such bags to see if they were potential sources of bacterial contamination. Forty-two unused IV bags were emptied of their contents for use as controls. Results indicated no aerobic bacterial growth in either group. The authors conclude that properly stored, used IV bags are unlikely sources of aerobic bacterial contamination when used in a urine collection system.

The effects of surgery and anesthesia on blood magnesium and calcium concentrations in canine and feline patients.

OBJECTIVE: To demonstrate the effect of anesthesia and surgery on serum ionized magnesium and ionized calcium concentrations in clinical canine and feline patients. ANIMALS: 37 client-owned dogs, ASA PS I-III and 10 client-owned cats, ASA PS I, all receiving anesthesia for elective or emergent surgery at a Veterinary Teaching Hospital. MATERIALS AND METHODS: Plasma ionized and serum total magnesium, and plasma ionized calcium were measured prior to and after a group-standardized anesthetic protocol. RESULTS: Regardless of pre-operative medication (hydromorphone or butorphanol), anesthetic induction (thiopental or lidocaine/hydromorphone/diazepam (LHD) and propofol combination), or type of surgical procedure (peripheral surgery or laparotomy), post-operative plasma ionized calcium concentration decreased in all groups of dogs, while post-operative plasma ionized magnesium increased in all groups, although the changes were not always significant. The dogs who were induced with an LHD and propofol technique had a greater increase in ionized magnesium (0.36 +/- 0.07 to 0.42 +/- 0.07 mmol L(-1)) than the group in which anesthesia was induced with thiopental (0.41 +/- 0.07 to 0.42 +/- 0.07 mmol L(-1), p = 0.009). The cats showed similar changes in ionized magnesium and ionized calcium, and also had a significant increase in serum total magnesium (2.17 +/- 0.20 to 2.31 +/- 0.25 mg dL(-1), p = 0.009) CONCLUSIONS, CLINICAL RELEVANCE: A post-operative decrease in ionized calcium was demonstrated in healthy animals, as well as an increase in ionized or total magnesium after various anesthetic protocols and surgeries. These changes, while statistically significant, do not appear to be clinically significant, as values remained within reference ranges at all times.

Anesthetic protocols for common emergencies.

Anesthesia, sedation, and pain management should be taken seriously in the emergency patient. Proper knowledge of the drugs available and their pharmacokinetics and pharmacodynamics are necessary to administer anesthesia safely to critical patients. A proactive approach regarding monitoring, titration of anesthetic drugs, and anticipation of life-threatening complications helps in achieving successful anesthetic outcomes.

Postoperative hypoxemia and hypercarbia in healthy dogs undergoing routine ovariohysterectomy or castration and receiving butorphanol or hydromorphone for analgesia.

OBJECTIVE: To determine frequency and severity of postanesthetic hypoxemia and hypercarbia in healthy dogs undergoing elective ovariohysterectomy or castration and given butorphanol or hydromorphone for analgesia. DESIGN: Prospective trial. ANIMALS: 0 healthy dogs weighing > 10 kg (22 lb). PROCEDURE: Dogs were anesthestized with acepromazine, glycopyrrolate, thiopental, and isoflurane, and butorphanol (n = 10) or hydromorphone (10) was used for perioperative analgesia. Arterial blood gas analyses were performed 10 and 30 minutes and 1, 2, 3, and 4 hours after extubation. RESULTS: In dogs that received hydromorphone, mean PaCO2 was significantly higher, compared with the preoperative value, 10 and 30 minutes and 1, 2, and 3 hours after extubation. Mean PaCO2 was significantly higher in dogs given hydromorphone rather than butorphanol 10 and 30 minutes and 1 and 2 hours after extubation. Mean PaO2 was significantly lower, compared with preoperative values, 30 minutes and 1 and 2 hours after extubation in dogs given hydromorphone and 30 minutes after extubation in dogs given butorphanol. Mean PaO2 was significantly lower in dogs given hydromorphone rather than butorphanol 1 hour after extubation. Four dogs had PaO2 < 80 mm Hg 1 or more times after extubation. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that administration of hydromorphone to healthy dogs undergoing elective ovariohysterectomy or castration may result in transient increases in PaCO2 postoperatively and that administration of hydromorphone or butorphanol may result in transient decreases in PaO2. However, increases in PaCO2 and decreases in PaO2 were mild, and mean PaCO2 and PaO2 remained within reference limits.