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Abstract

Objective—To determine the cardiac anesthetic index (CAI) of isoflurane in green iguanas and whether butorphanol affected the CAI.

Design—Prospective randomized controlled trial.

Animals—7 healthy mature iguanas.

Procedure—In 5 iguanas, CAI was determined after induction of anesthesia with isoflurane alone, and in 5 iguanas, CAI was determined after induction of anesthesia with isoflurane and IM administration of butorphanol (1 mg/kg [0.45 mg/lb]). Three iguanas underwent both treatments. Animals were equilibrated for 20 minutes at 1.5 times the minimum alveolar concentration (MAC) of isoflurane and observed for evidence of cardiovascular arrest. If there was no evidence of cardiovascular arrest, end-tidal isoflurane concentration was increased by 20%, and animals were allowed to equilibrate for another 20 minutes. This process was repeated until cardiovascular arrest occurred or vaporizer output could no longer be consistently increased. The CAI was calculated by dividing the highest end-tidal isoflurane concentration by the MAC.

Results—None of the iguanas developed cardiovascular arrest and all survived. Mean ± SD highest endtidal isoflurane concentration during anesthesia with isoflurane alone (9.2 ± 0.60%) was not significantly different from mean concentration during anesthesia with isoflurane and butorphanol (9.0 ± 0.43%). The CAI was > 4.32.

Conclusions and Clinical Relevance—Results suggest that the CAI of isoflurane in green iguanas is > 4.32 and not affected by administration of butorphanol. Isoflurane appears to be a safe anesthetic in green iguanas. (J Am Vet Med Assoc 2003;222: 1565–1568)

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine minimum alveolar concentration (MAC) of isoflurane in green iguanas and effects of butorphanol on MAC.

Design—Prospective randomized trial.

Animals—10 healthy mature iguanas.

Procedure—In each iguana, MAC was measured 3 times: twice after induction of anesthesia with isoflurane and once after induction of anesthesia with isoflurane and IM administration of butorphanol (1 mg/kg [0.45 mg/lb]). A blood sample was collected from the tail vein for blood-gas analysis at the beginning and end of the anesthetic period. The MAC was determined with a standard bracketing technique; an electrical current was used as the supramaximal stimulus. Animals were artificially ventilated with a ventilator set to deliver a tidal volume of 30 mL/kg (14 mL/lb) at a rate of 4 breaths/min.

Results—Mean ± SD MAC values during the 3 trials (2 without and 1 with butorphanol) were 2.0 ± 0.6, 2.1 ± 0.6, and 1.7 ± 0.7%, respectively, which were not significantly different from each other. Heart rate and end-tidal partial pressure of CO2 were also not significantly different among the 3 trials. Mean ± SD heart rate was 48 ± 10 beats/min; mean end-tidal partial pressure of CO2 was 22 ± 10 mm Hg. There were no significant differences in blood-gas values for samples obtained at the beginning versus the end of the anesthetic period.

Conclusions and Clinical Relevance—Results suggest that the MAC of isoflurane in green iguanas is 2.1% and that butorphanol does not have any significant isoflurane-sparing effects. (J Am Vet Med Assoc 2003;222:1559–1564)

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To evaluate the effectiveness and treatment outcome of a minimal surgical debridement and antimicrobial-impregnated gauze packing technique for treatment of dental abscesses in rabbits.

Design—Retrospective case series.

Animals—13 rabbits with 14 dental abscesses.

Procedures—Medical records of pet rabbits with dental abscesses were reviewed. Rabbits that underwent a wound-packing treatment protocol with a follow-up period of > 6 months were included. Pretreatment evaluation included physical examination, skull radiography, CBC and plasma biochemical profile, and an endoscopically guided dental examination. The surgical procedure consisted of lancing the abscess, cleaning the cavity, minimal debridement, and packing with strips of synthetic gauze impregnated with a selected antimicrobial. Purulent material from abscesses was submitted for bacterial culture. The procedure was repeated weekly until abscess resolution. Rabbits also received systemic treatment with antimicrobials.

Results—Rabbit ages ranged from 1 to 5 years. Anaerobic bacteria were cultured from 6 abscesses and aerobic bacteria from 5; no bacteria were cultured from 4 abscesses. Antimicrobials most commonly used in packing procedures were ampicillin and clindamycin; trimethoprim-sulfamethoxazole with metronidazole and azithromycin were given most often for systemic treatment. Thirteen of 14 abscesses resolved, and rabbits were followed for a mean ± SD period of 32.6 ± 24.3 months. Number of packing procedures used to obtain resolution of infection was 4.8 ± 2.2.

Conclusions and Clinical Relevance—Minimal surgical debridement followed by antimicrobial-impregnated gauze packing of the abscess cavity is an effective and practical option for the long-term resolution of dental abscesses in rabbits when combined with systemic treatment with appropriate antimicrobials.

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To compare hydromorphone with oxymorphone, with or without acepromazine, for preanesthetic sedation in dogs and assess changes in plasma concentration of histamine after drug administration.

Design—Randomized clinical study.

Animals—10 healthy mixed-breed dogs.

Procedure—Dogs were treated IM with hydromorphone (group H), oxymorphone (group O), hydromorphone with acepromazine (group H/A), or oxymorphone with acepromazine (group O/A). Sedation score, heart rate, respiratory rate, systolic blood pressure, and oxygen saturation were recorded at baseline immediately after drug administration (T0) and every 5 minutes for 25 minutes (T25). Plasma histamine concentration was measured at baseline and T25.

Results—Sedation was similar between groups H and O at all times. Sedation was significantly greater for groups H/A and O/A from T10 to T25, compared with other groups. Systolic blood pressure was significantly reduced at T25 in group H/A, compared with group H, and in group O/A, compared with group O. Prevalence of panting at T25 was 50% for groups H and O, compared with 20% for group H/A and 30% for group O/A. By T25, heart rate was significantly lower in all groups. Oxygen saturation was unaffected by treatment. Mean ± SD plasma histamine concentration was 1.72 ± 2.69 ng/ml at baseline and 1.13 ± 1.18 ng/ml at T25. There was no significant change in plasma histamine concentration in any group.

Conclusions and Clinical Relevance—Hydromorphone is comparable to oxymorphone for preanesthetic sedation in dogs. Sedation is enhanced by acepromazine. Neither hydromorphone nor oxymorphone caused an increase in plasma histamine concentration. (J Am Vet Med Assoc 2001;218:1101–1105)

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine minimum alveolar concentration (MAC) of isoflurane in mechanically ventilated Dumeril monitors (Varanus dumerili).

Design—Prospective study.

Animals—10 healthy adult Dumeril monitors.

Procedure—Anesthesia was induced with isoflurane in oxygen delivered through a face mask. Monitors were endotracheally intubated, and end-tidal and inspired isoflurane concentrations were continuously measured. After equilibration at an end-tidal-toinspired isoflurane concentration ratio of > 0.9 for 20 minutes, an electrical stimulus (50 Hz, 50 V) was delivered to the ventral aspect of the tail for up to 1 minute and the monitor was observed for purposeful movement. End-tidal isoflurane concentration was then decreased by 10%, and equilibration and stimulation were repeated. The MAC was calculated as the mean of the lowest end-tidal isoflurane concentration that prevented positive response and the highest concentration that allowed response. A blood sample for blood gas analysis was collected from the tail vein at the beginning and end of the anesthetic period.

Results—Mean ± SD MAC of isoflurane was 1.54 ± 0.17%. Mean heart rates at the upper and lower MAC values were 32.4 ± 3 beats/min and 34 ± 4.5 beats/min, respectively. During the experiment, Paco2 decreased significantly from 43.1 mm Hg to 27.9 mm Hg and blood pH and HCO3 concentration increased significantly from 7.33 to 7.64 and from 25.3 to 32.9 mmol/L, respectively.

Conclusions and Clinical Relevance—The MAC of isoflurane in Dumeril monitors was similar to that reported in mammals but lower than values reported in other reptiles. This difference may be reflective of the more advanced cardiovascular physiologic features of monitor lizards. (J Am Vet Med Assoc 2005; 226:1098–1101)

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in Journal of the American Veterinary Medical Association

Abstract

CASE DESCRIPTION A 13-year-old female green iguana (Iguana iguana) was examined because of a 6-day history of vomiting, anorexia, and lethargy and a 4-day history of decreased fecal and urate output.

CLINICAL FINDINGS Physical examination revealed a distended abdomen, signs of depression, pallor, tachycardia, harsh lung sounds, and vomiting. Abdominal radiographs revealed gas distention of the stomach and small intestine with fluid lines evident on the lateral view. Plasma biochemical analysis indicated hypochloremic metabolic alkalosis, hyperglycemia, and hyperuricemia.

TREATMENT AND OUTCOME Exploratory laparotomy confirmed a diagnosis of small intestinal entrapment and 170° volvulus involving approximately 80% (20 to 30 cm) of the small intestine. The portion of the small intestine extending from the middle portion of the duodenum to the caudal extent of the ileum was resected, and end-to-end anastomosis of the remaining small intestine was performed. The iguana recovered without apparent complications and was reportedly doing well 1 year after surgery.

CLINICAL RELEVANCE Findings suggested that iguanas, as hindgut fermenters, may tolerate > 70% resection of the small intestine with a good outcome and no clinical evidence of residual gastrointestinal dysfunction.

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in Journal of the American Veterinary Medical Association

Abstract

OBJECTIVE To assess rheological properties and in vitro diffusion of poloxamer 407 (P407) and butorphanol-P407 (But-P407) hydrogels and to develop a sustained-release opioid formulation for use in birds.

SAMPLE P407 powder and a commercially available injectable butorphanol tartrate formulation (10 mg/mL).

PROCEDURES P407 and But-P407 gels were compounded by adding water or butorphanol to P407 powder. Effects of various concentrations of P407 (20%, 25% and 30% [{weight of P407/weight of diluent} × 100]), addition of butorphanol, and sterilization through a microfilter on rheological properties of P407 were measured by use of a rheometer. In vitro diffusion of butorphanol from But-P407 25% through a biological membrane was compared with that of a butorphanol solution.

RESULTS P407 20% and 25% formulations were easily compounded, whereas it was difficult to obtain a homogenous P407 30% formulation. The P407 was a gel at avian body temperature, although its viscosity was lower than that at mammalian body temperature. The But-P407 25% formulation (butorphanol concentration, 8.3 mg/mL) was used for subsequent experiments. Addition of butorphanol to P407 as well as microfiltration did not significantly affect viscosity. Butorphanol diffused in vitro from But-P407, and its diffusion was slower than that from a butorphanol solution.

CONCLUSIONS AND CLINICAL RELEVANCE But-P407 25% had in vitro characteristics that would make it a good candidate for use as a sustained-release analgesic medication. Further studies are needed to characterize the pharmacokinetic and pharmacodynamic properties of But-P407 25% in vivo before it can be recommended for use in birds.

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in American Journal of Veterinary Research

Abstract

Objective—To determine the minimum alveolar concentration (MAC) of sevoflurane and assess the sevoflurane-sparing effect of coadministration of nitrous oxide in mechanically ventilated Dumeril monitors (Varanus dumerili).

Design—Prospective crossover study.

Animals—10 healthy adult Dumeril monitors.

Procedure—Anesthesia was induced with sevoflurane in 100% oxygen or sevoflurane in 66% nitrous oxide (N2O) with 34% oxygen, delivered through a face mask. Monitors were endotracheally intubated, and end-tidal and inspired isoflurane concentrations were measured continuously; MAC was determined by use of a standard bracketing technique. An electrical stimulus (50 Hz, 50 V) was delivered to the ventral aspect of the tail as the supramaximal stimulus. A blood sample for blood gas analyses was collected from the ventral coccygeal vessels at the beginning and end of the anesthetic period. An interval of at least 7 days was allowed to elapse between treatments.

Results—The MAC ± SDs of sevoflurane in oxygen and with N2O were 2.51 ± 0.46% and 1.83 ± 0.33%, respectively. There was a significant difference between the 2 treatments, and the mean MAC-reducing effect of N2O was 26.4 ± 11.4%. Assuming simple linear additivity of sevoflurane and N2O, the MAC for N2O was estimated to be 244%. No significant differences in blood gas values—with the predictable exception of oxygen pressure—were detected between the 2 groups.

Conclusions and Clinical Relevance—The MAC of sevoflurane in Dumeril monitors is similar to that reported for other species. The addition of N2O significantly decreased the MAC of sevoflurane in this species. (J Am Vet Med Assoc 2005;227:575–578)

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To provide an updated evaluation of the efficacy and safety of sometribove zinc suspension (rbST-Zn), a form of recombinant bovine somatotropin, in lactating dairy cows.

Design—Meta-analysis.

Sample—26 studies published in peer-reviewed journals or reviewed by a regulatory agency.

Procedures—To be included, a study had to involve the use of the rbST-Zn formulation available to US producers in accordance with the label instructions for treatment initiation (57 to 70 days postpartum), dose (500 mg, q 14 d), and route (SC).

Results—For cows treated with rbST-Zn, mean milk, 3.5% fat-corrected milk, fat, and protein yields were increased by 4.00, 4.04, 0.144, and 0.137 kg/d (8.8, 8.89, 0.32, and 0.30 lb/d), respectively; however, the concentration of milk components did not change. Pregnancy proportion for the first 2 breeding cycles was increased by 5.4%, and pregnancy proportion for the duration of the trial was reduced by 5.5% for rbST-Zn–treated cows, compared with proportions for untreated cows. Mean body condition score (1 to 5 scale) was reduced by 0.06 points during the period of rbST-Zn use for treated cows. Administration of rbST-Zn had no effect on milk somatic cell count, the number of days to pregnancy, or inseminations per pregnancy; rates of fetal loss, twins, cystic ovaries, clinical lameness, lameness lesions, or traumatic lesions of the integumentary system; and odds of clinical mastitis or culling.

Conclusions and Clinical Relevance—Results indicated that rbST-Zn administration to dairy cows effectively increases milk production with no adverse effects on cow health and well-being.

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in Journal of the American Veterinary Medical Association

Abstract

OBJECTIVE To determine pharmacokinetics of butorphanol tartrate incorporated into poloxamer 407 (P407) after SC administration to Hispaniolan Amazon parrots (Amazona ventralis).

ANIMALS 11 adult Hispaniolan Amazon parrots (6 males and 5 females; 11 to 27 years old).

PROCEDURES A sterile formulation of butorphanol in P407 (But-P407) 25% (percentage determined as [weight of P407/weight of diluent] × 100]) was created (8.3 mg/mL). Five preliminary experiments (2 birds/experiment) were performed to determine the ideal dose for this species. The formulation then was administered (12.5 mg/kg, SC) to 8 birds. Blood samples were collected before (time 0) and 0.08, 0.5, 1, 2, 4, 8, 12, and 24 hours after drug administration. Some birds were used more than once, with a washout period of ≥ 3 months between subsequent treatments. Butorphanol concentrations were quantitated by use of liquid chromatography-tandem mass spectrometry. Pharmacokinetic analysis was performed by use of noncompartmental analysis.

RESULTS Maximal plasma butorphanol concentration was reached at 1.31 hours. Plasma concentrations of butorphanol remained > 100 ng/mL for > 3 hours (all birds) or > 4 hours (5/8 birds) but < 8 hours (all birds). Half-life of the terminal slope was 3.41 hours. No adverse effects were detected.

CONCLUSIONS AND CLINICAL RELEVANCE Butorphanol was absorbed well from the But-P407 25% by Hispaniolan Amazon parrots, and absorption followed a pharmacokinetic profile compatible with a sustained-release drug. A dose of 12.5 mg/kg, SC, would theoretically provide analgesia for 4 to 8 hours. No adverse effects were detected. Studies on the pharmacodynamics of this formulation are necessary to confirm the degree and duration of analgesia.

Full access
in American Journal of Veterinary Research