Technique for venipuncture of the transverse facial vein in the black rhinoceros (Diceros bicornis).

Through the use of operant conditioning, the authors developed a technique to facilitate obtaining blood samples from a black rhinoceros diagnosed with idiopathic epilepsy. The technique involved operant conditioning to facilitate venipuncture of the transverse facial vein, at an anatomic landmark on the lateral side of the face ventral to the medial canthus of the eye, and dorsal to the lateral commissure of the mouth. The investigators used standard operant conditioning protocols to train the animal for desensitization to a needle puncture in the facial vein. Blood samples obtained from the facial location were free of excessive hemolysis and allowed for large volumes to be collected. The procedure was well-tolerated by the rhinoceros and could be performed regularly without complication. Zoo Biol. 35:570-573, 2016. © 2016 Wiley Periodicals, Inc.

Ultrasound-guided cervical centesis to obtain cerebrospinal fluid in the standing horse.

Horses with intracranial lesions and severe ataxia are not good anesthesia candidates; however, only one method to obtain cerebrospinal fluid (CSF) from the cervical region in a standing horse has been reported. This method is not performed routinely due to the difficulty for sample acquisition. Our hypothesis is that standing cervical centesis can be performed in horses without complication. Ultrasound-guided centesis of the CSF between C1 and C2 in 11 clinically normal horses and two horses with neurologic signs were performed. Horses were sedated and ultrasound was used to identify the subarachnoid space and spinal cord between C1 and C2. With ultrasound guidance, a needle was introduced into the dorsal aspect of the subarachnoid space using a lateral approach. Ten milliliters of CSF was obtained and analyzed. Two normal horses in this study had moderate red blood cell contamination in the CSF (940 and 612 RBC/microl). One horse had 11 RBC/microl and the remaining horses had < 4 RBC/microl. The total procedure time was approximately 2 min. No reaction was observed and no complications were detected up to 48 h after the procedure. Ultrasound-guided centesis between C1 and C2 is a rapid procedure that causes minimal to no reaction in standing, sedated horses used in this study. The use of ultrasound to guide a standing C1-2 centesis of the subarachnoid space provides an additional route to obtain CSF for analysis in the equine patient.

Surgical amputation of a digit and vacuum-assisted-closure (V.A.C.) management in a case of osteomyelitis and wound care in an eastern black rhinoceros (Diceros bicornis michaeli).

A 14-yr-old female eastern black rhinoceros (Diceros bicornis michaeli) presented with progressive suppurative osteomyelitis in her left hind lateral toe. beta-Hemolytic Streptococcus sp. was isolated. The animal was treated with multiple systemic antibiotics, and topical wound cleansing. Repeated debridements and nail trimmings were performed for 5 mo prior to electing amputation. The toe was surgically amputated under general anesthesia between the first and second phalanges. Analgesia was diffused into the wound topically via a catheter and elastomeric pump. The open amputation site was covered with adherent drapes and a negative-pressure wound therapy device provided vacuum-assisted closure (V.A.C.) for 72 hr. Three months later this animal developed a deep dermal ulcer on the lateral aspect of the right hind limb, at the level of the stifle. Methicillin-resistant Staphylococcus aureus was isolated. The wound was managed by initial daily lavage, followed by 1 mo of V.A.C. therapy, with 72 hr between dressing changes. Clinically, this therapy expedited the formation of healthy granulation tissue and overall healing was accelerated. The animal tolerated the machine and bandage changes well via operant conditioning. The use of negative-pressure wound therapy appeared to shorten time to resolution of slow-healing wounds in black rhinoceros.

Iron sufficient to cause hepatic fibrosis and ascites does not cause cardiac arrhythmias in the gerbil.

Chronic iron overload associated with hereditary hemochromatosis or repeated red cell transfusions is known to cause cardiac failure. Cardiac arrhythmias have been incidentally noted in patients with iron overload, but they are often dismissed as being related to comorbid conditions. Studies with anesthetized iron-loaded gerbils using short recordings suggest a role for iron in the development of arrhythmias. Our goal was to characterize iron-induced arrhythmias in the chronically instrumented, untethered, telemetered gerbil. Electrocardiograms were recorded for 10 s every 30 min for approximately 6 months in iron-loaded (n=23) and control (n=8) gerbils. All gerbils in both groups showed evidence of frequent sinus arrhythmia. There was no difference in heart rate, electrocardiographic parameters, or number of arrhythmias per minute between groups. Gerbils rarely showed significant arrhythmias. Body weight and heart weight were not significantly different between groups, whereas liver weight increased with increasing iron dose in the treated group. Cardiac and hepatic iron concentrations were significantly increased in iron-loaded gerbils. Eight of 14 gerbils loaded to 6.2 g/kg body weight developed ascites. We conclude that an iron load sufficient to cause clinical liver disease does not cause cardiac arrhythmias in the gerbil model of iron overload.

Iron does not cause arrhythmias in the guinea pig model of transfusional iron overload.

Cardiac events, including heart failure and arrhythmias, are the leading cause of death in patients with beta thalassemia. Although cardiac arrhythmias in humans are believed to result from iron overload, excluding confounding factors in the human population is difficult. The goal of the current study was to determine whether cardiac arrhythmias occurred in the guinea pig model of secondary iron overload. Electrocardiograms were recorded by using surgically implanted telemetry devices in guinea pigs loaded intraperitoneally with iron dextran (test animals) or dextran alone (controls). Loading occurred over approximately 6 wk. Electrocardiograms were recorded for 1 wk prior to loading, throughout loading, and for approximately 4 wk after loading was complete. Cardiac and liver iron concentrations were significantly increased in the iron-loaded animals compared with controls and were in the range of those reported for humans with thalassemia. Arrhythmias were rare in both iron-loaded and control guinea pigs. No life-threatening arrhythmias were detected in either group. These data suggest that iron alone may be insufficient to cause cardiac arrhythmias in the iron-loaded guinea pig model and that arrhythmias detected in human patients with iron overload may be the result of a complex interplay of factors.

Evaluation of signs of postoperative pain and complications after forelimb onychectomy in cats receiving buprenorphine alone or with bupivacaine administered as a four-point regional nerve block.

OBJECTIVE: To evaluate signs of postoperative pain and complications after forelimb onychectomy in cats receiving buprenorphine alone or with bupivacaine administered as a 4-point regional nerve block. DESIGN: Prospective, randomized, double-blind clinical trial. ANIMALS: 20 cats. PROCEDURE: All cats received buprenorphine (0.01 mg/kg [0.004 mg/lb], IM) preoperatively. One forelimb of each cat also received bupivacaine (1 mg/kg [0.45 mg/lb] of a 0.75% solution) administered as a 4-point regional nerve block. After onychectomy, discomfort (lameness, foot reaction, and pain) scores were evaluated by 2 experienced observers 2, 4, 6, 8, 24, and 168 hours postoperatively. Complication (hemorrhage, swelling, and infection) scores were evaluated 24 and 168 hours postoperatively. Surgeries were performed by 1 experienced veterinary surgeon. Rescue analgesia was provided if needed. RESULTS: 6 cats required rescue analgesia postoperatively. There was no difference in discomfort or complication scores between control limbs and limbs in which a nerve block was administered. Additionally, there was no difference in discomfort and complication scores between cats that did or did not require rescue analgesia. CONCLUSIONS AND CLINICAL RELEVANCE: Bupivacaine administered as a 4-point regional nerve block in addition to a systemic analgesic did not decrease discomfort or complication scores in cats undergoing forelimb onychectomy.

Atrioventricular nodal ablation and His-bundle pacing: an acute canine model for proarrhythmic risk assesment.

INTRODUCTION: QT interval prolongation following drug exposure is considered a marker for increased risk of drug-induced arrhythmias. QT interval measurements are common components of the safety pharmacology assessment of new therapeutic compounds but are potentially confounded by concurrent changes in heart rate that also alter QT intervals. We describe an anesthetized canine model of AV dissociation with His-bundle pacing that overcomes the confounding effects of a change in heart rate. METHODS AND RESULTS: Transvenous radiofrequency ablation of the AV node was performed in isoflurane-anesthetized dogs and followed by open chest implantation of bipolar pacing electrodes in the vicinity of the His bundle. Pace rates were adjusted from 50 to 190 in steps of 20 beats/min, holding each step for 30 seconds. At each paced rate, QT intervals were measured manually to the nearest 1 ms to construct paced QT interval-heart rate (QT-HR) relationships. Paired QT-HR relationships using identical ascending ramps of pace rates were compared to paired QT-HR relationships with an ascending and descending pace ramp to evaluate short-term reproducibility and hysteresis effects. For proof of concept, an additional QT-HR relationship was constructed in three dogs after intravenous administration of a compound known to alter QT intervals: one dog received terfenadine (0.48 mg/kg bolus followed by 0.017 mg/kg/min infusion), one dog received quinidine (20 mg/kg), and the third dog received sotalol (1 and 3 mg/kg). Substantial inter-dog variation was found for QT-HR, although short-term reproducibility was high within one dog (average absolute difference for paired ascending ramps < 5 ms). QT intervals measured during descending paced ramps were generally lower than the value for the corresponding paced rate on an ascending ramp. This hysteretic effect was small, averaging < 7 ms over the entire ramp. All test compounds prolonged QT intervals and shifted the QT-HR relationship upward. Maximal QT prolongation was 30 ms for terfenadine, 50 ms for quinidine, and 59 ms for sotalol. CONCLUSION: AV nodal ablation and His-bundle pacing provide a sensitive animal model to identify acute effects of test compounds on indices of myocardial repolarization such as the QT interval. The model is devoid of confounding effects of changing heart rates while enabling identification of effects of drugs over a wide range of controlled rates.

Use of carbon dioxide laser for onychectomy in cats.

OBJECTIVE: To compare postoperative signs of discomfort and complications associated with use of CO2 laser for onychectomy with those of the scalpel technique in cats. DESIGN: Prospective, randomized, masked clinical trial. ANIMALS: 20 client-owned cats. PROCEDURE: Forelimb feet (right, left) were randomly assigned to laser and scalpel treatment groups. Signs of discomfort (lameness and signs of pain) and complications (hemorrhage, swelling, and discharge) were assessed on days 0, 1, and 7. Surgeries were performed by 1 experienced surgeon. Evaluations were performed by 2 individuals without knowledge of treatment group. Signs of discomfort and complications were scored on scales of 0 to 8 and 0 to 9, respectively. RESULTS: Onychectomy did not result in high discomfort or complication scores 1 day after surgery, regardless of technique used, although the laser-treated group had significantly lower scores for signs of discomfort and complications. Seven days after surgery, significant differences were not detected between groups for signs of discomfort or complications. CONCLUSIONS AND CLINICAL RELEVANCE: The CO2 laser can be an excellent tool for onychectomy in cats, with excellent hemostasis and minimal postoperative discomfort and complications. Differences in discomfort and complications between groups treated via scalpel versus CO2 laser were not clinically relevant and were only observed 1 day after surgery.