Evaluation of non-ECG and ECG-gated computed tomographic angiography for three-dimensional printing of anomalous coronary arteries in dogs with pulmonic stenosis.

INTRODUCTION/OBJECTIVES: Coronary artery abnormalities are described sporadically in dogs, most commonly with pulmonic stenosis. Computed tomographic angiography (CTA) allows non-invasive assessment of coronary anatomy. Three-dimensional (3D) models improve the understanding and visualization of spatially complex anatomy. The study objective was to evaluate coronary artery anomalies using CTA imaging and using rapid prototyping technology to create life-sized coronary artery models of these studies. ANIMALS, MATERIAL AND METHODS: Combined retrospective case and prospective pilot study. Inclusion criteria were dogs with reported coronary artery anomalies. The CTA data sets were imported into a medical imaging framework for the analysis of the coronary arteries and into a 3D-planning and printing software for creating printable 3D models. The 3D models were printed using fusion deposition modeling technology. RESULTS: Six male dogs with an R2A coronary artery anomaly and pulmonic stenosis diagnosed by CTA were included. Electrocardiogram (ECG)-gated CTA allowed better identification of anomalous coronary arteries than non-gated CTA. In all dogs, the right coronary artery had a smaller diameter than the left and the left coronary artery or its branch had a prepulmonic course. All ECG-gated studies were 3D printed while non-gated studies were not printable due to CTA artifacts. CONCLUSION: In dogs, CTA is effective for diagnosis of coronary artery anomalies. Printed 3D models of ECG-gated CTA studies were of excellent quality and allowed direct visualization of abnormal coronary artery anatomy. The usefulness of these models to improve the understanding of anomalous coronary artery anatomy could be evaluated in future studies.

Megaesophagus in 15 llamas: a retrospective study (1985-1993).

Megaesophagus was diagnosed in 15 llamas on the basis of survey and contrast radiography. Age of onset ranged from 13 months to 9.5 years. Clinical signs varied, with salivation being the most common; regurgitation or dysphagia were noted in only 33% of the cases. Duration of the disorder ranged from 1 week to 5 years. Organophosphate toxicity was the cause of megaesophagus in 1 llama. While most cases were of unknown etiology, the 3 with histological abnormalities included 1 with vagal neuropathy and 2 with a degenerative myopathy of esophageal muscles. The causes in most were undetermined.

Orotracheal and nasotracheal intubation in llamas.

Orotracheal or nasotracheal intubation was performed in 304 llamas and 6 alpacas during general anesthesia for surgical and diagnostic procedures. The mouth not opening wide and the presence of a prominent torus linguae make orotracheal intubation difficult, but it can be accomplished with the aid of a laryngoscope, using a technique similar to that used in small domestic ruminants. The presence of a pharyngeal diverticulum necessitates modification of nasotracheal intubation techniques to make them applicable for use in llamas and alpacas. When nasotracheal intubation, with phenylephrine lubricant-coated tubes, is not successful, oral laryngoscopy and use of a stylet in the endotracheal tube will improve chances for success. Because llamas are obligate nasal breathers, airway obstruction can develop following removal of endotracheal tubes during recovery from anesthesia. This complication can be prevented by maintaining orotracheal tubes until the animal is able to protect its airway or by using nasotracheal tubes, which allow the llama to stand before the tube has to be removed.

Evaluation of Janeway gastrostomy in llamas.

To provide long-term gastric fistulas for collection of third-compartment gastric contents, Janeway mucosal tube gastrostomy was performed, using a gastrointestinal stapling instrument, in 6 castrated adult male llamas. Mean operative time (+/- SEM) was 65 +/- 4.16 minutes. All llamas survived the 6-week study period. Of the 6 llamas, 5 did not have signs of abdominal pain and returned to preoperative food consumption amounts within 36 hours. One llama had mild intermittent signs of abdominal pain daily for 7 days before returning to preoperative amount of food consumption. All gastrostomies leaked small amounts of gastric contents around indwelling 6- to 8-mm cannulas at the skin surface. Gastric contents did not leak when cannulas were dislodged from gastrostomy stomas. Replacement of cannulas was rapid and easy. Gravity-flow sample collection was best accomplished through 8-mm cannulas. Mean (+/- SEM) weight loss was detected in all llamas (15 +/- 3 kg) and was associated with frequent nonfeeding and stress of sample collection. Gross necropsy findings were unremarkable in 5 of 6 llamas. All mucosal tube gastrostomies were patent, and there was no evidence of peritonitis. One llama had a single fibrous adhesion connecting the operative site with the ascending colon. Histologically, small (2.5- to 15-mm diameter) partial-thickness mucosal erosions identified at the tube gastrostomy-gastric wall junctions may have been associated with indwelling gastric cannulas. The Janeway gastrostomy was generally well tolerated in the llamas and should be considered as a useful long-term fistulation technique.

Evaluation of lidocaine, xylazine, and a combination of lidocaine and xylazine for epidural analgesia in llamas.

Epidural analgesia was achieved at weekly intervals in 6 adults llamas by injection of 2% lidocaine, 10% xylazine, and a combination of 2% lidocaine/10% xylazine at the sacrococcygeal junction. Analgesia was determined by lack of response to pin prick or hemostat pressure in the perineal area. Ataxia could not be accurately evaluated because of the llamas' tendency to assume sternal recumbency when restrained. Time to onset of analgesia was not different between lidocaine (3.16 +/- 0.31 minutes) and lidocaine/xylazine (3.50 +/- 0.56 minutes), but results for both groups were different than those for xylazine (20.67 +/- 3.37 minutes). Duration of analgesia was different among all groups (lidocaine, 71.0 +/- 6.15 minutes; xylazine, 186.83 +/- 14.86 minutes; lidocaine/xylazine, 325.83 +/- 29.39 minutes). Mild sedation developed in 4 llamas given xylazine alone. Lidocaine/xylazine caused mild sedation in 2 llamas and moderate sedation in 1 llama. Significant changes in pulse or respiratory rates were not observed among drugs, but changes were observed over time with all drugs. As has been reported in other species, lidocaine/xylazine provided rapid onset and prolonged duration of analgesia.

Effect of surgical removal of endometrial cups on concentrations of chorionic gonadotrophin and subsequent fertility in the mare.

Seven pregnant mares underwent general anaesthesia, laparotomy, hysterotomy and removal of a 50-day conceptus. Eversion of the uterine horn through the hysterotomy site allowed direct visualisation and electrosurgical removal of endometrial cup tissue from 5 randomly selected mares (Nos 1-5), while cup tissue in 2 mares (Nos 6 and 7) was left intact. Two pregnant mares served as unoperated controls (Nos 8 and 9). Efforts to re-establish pregnancy were initiated 20 days after surgery. Serum samples collected before surgery and during the post-operative period were analysed for concentration of horse chorionic gonadotrophin (CG) by radioimmunoassay. Mean (+/- sd) weight and area of removed tissue was 9.91 +/- 4.6 g and 22.4 +/- 5.9 cm2, respectively. Concentrations of CG ranging from 3440 to 21,220 ng/ml were highest at the time of cup removal (50 days) and declined thereafter. Peak concentrations of CG at the time of surgery were not linearly correlated (r = -0.59) with mass of excised cup tissue. Individual CG half-life values for Mares 1-5 ranged from 5.4 to 8.8 days (mean 7.1 +/- 1.2 days). Peak CG concentrations occurred 68 days after conception with a rate of disappearance (half-time) of 13.4 +/- 0.4 days in Mares 6 and 7 and at 74 and 78 days after conception with a half-time of 14.0 +/- 5.7 days in Mares 8 and 9. Mares 1-5 exhibited behavioural oestrus and ovulation 30-44 days after surgery. Pregnancy occurred in 3 mares within 41 days after surgery and was associated with concentrations of CG below 200 ng/ml.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of lidocaine, xylazine, and xylazine/lidocaine for caudal epidural analgesia in horses.

Caudal epidural analgesia was achieved in 6 adult horses on 3 successive occasions at weekly intervals by injection of lidocaine, xylazine, and a combination of lidocaine/xylazine through indwelling epidural catheters. Analgesia was defined as a lack of response to pinprick and hemostat pressure in the skin of the perineal area. A significant (P < 0.05) difference was not found for time of onset of analgesia between lidocaine (4.3 +/- 0.8 minutes, mean +/- SEM) and the lidocaine/xylazine combination (5.3 +/- 1.3 minutes). Time to onset of analgesia after administration of xylazine was significantly (P < 0.05) longer (32.0 +/- 3.4 minutes) than that for either of the other 2 treatments. Duration of analgesia was significantly (P < 0.05) longer for the combination (329.8 +/- 6.2 minutes) than for either drug used alone (lidocaine, 87.2 +/- 7.5 minutes; xylazine, 204.2 +/- 12.9 minutes). Pulse and respiratory rates were not significantly altered by any of the drugs. Neurologic sequelae were not clinically apparent after administration of the drugs or after chronic epidural catheterization.

Fate and effect of autogenous osteochondral fragments implanted in the middle carpal joint of horses.

Four autogenous osteochondral fragments removed from the lateral trochlear ridge of the talus were arthroscopically placed as loose bodies in a randomly selected middle carpal joint in each of 10 horses. The contralateral middle carpal joint, subjected to a sham procedure, served as control. Postoperative treatment was consistent with that for clinical arthroscopic patients. Lameness evaluation, radiographic examination, carpal circumference measurement, and synovial fluid analysis were performed before and at scheduled intervals after surgery. After a 2-month confinement, horses were subjected to an increasing level of exercise. Horses were euthanatized at intervals through 6 months. Gross and microscopic evaluations were performed on remaining fragments, articular cartilage, and synovial membrane of each middle carpal joint. Increased joint circumference, effusion, lameness, and degenerative joint disease distinguished implanted from control joints over the 6-month period. Implanted joints were characterized by grooved, excoriated cartilage surfaces, and synovium that was thick, erythematous, and irregular. At 4 weeks, implants were found to have adhered to synovium at their subchondral bone surface. The bone within fragments was undergoing necrosis, while cartilage was preserved. At 8 weeks, fragments were radiographically inapparent, grossly evident as pale plaques on the synovial surface, and composed of dense fibrous connective tissue. Synovial membrane specimens from implanted joints had inflammatory change characterized by mononuclear cell infiltration 2 months after implantation. Physical damage was apparent within articular cartilage of implanted joints at 2 months, and was significant (P less than 0.05) at 6 months after surgery. Chondrocyte degenerative change was significant (P less than 0.05) at 6 months after surgery. Focal reduction in safranin-O uptake was observed in cartilage layers adjacent to physical defects. Osteochondral loose bodies of the size implanted in the middle carpal joint of horses in this study were resorbed by the synovium within 2 months. Synovitis and significant articular cartilage damage were associated with the implanted fragments. Regardless of origin, free osteochondral fragments within the middle carpal joint should be removed, and methods to prevent residual postoperative debris should be implemented to reduce potential for articular pathologic change.

Steady-state response characteristics of a pulse oximeter on equine intestine.

The steady-state response characteristics of a pulse oximeter were evaluated on intestinal segments of seven clinically normal halothane-anesthetized horses. Arterial oxygen tension greater than 200 mm of Hg, end tidal carbon dioxide from 30 to 35 mm of Hg, and systemic mean arterial pressure greater than 70 mm of Hg were maintained throughout the recording periods. Values for percentage of pulse oximeter oxygen saturation, pulsatile blood flow, and percentage of signal strength were recorded from jejunum, ileum, cecum, left ventral colon, left dorsal colon, and descending colon. Probe placement on intestinal segments was recorded as over or not over visible subserosal or transmural vessels. There was no significant difference between median values on the basis of vessel codes for pulse oximeter oxygen saturations, pulsatile flow, and signal strength. Median values recorded for pulse oximeter oxygen saturation were 93% from jejunum and ileum and 95% from cecum, left ventral colon, left dorsal colon, and descending colon; median values for pulsatile flow were 576 from jejunum, 560 from ileum, 560 from cecum, 574 from left ventral colon, 578 from left dorsal colon, and 560 from descending colon; median values for signal strength were 50% from jejunum, 67.5% from ileum, 60% from cecum, 75% from left ventral colon, 50% from left dorsal colon, and 52.5% from descending colon. Median values obtained from each anatomic location were not significantly different for pulsatile flow or signal strength. Median pulse oximetry oxygen values recorded from jejunum and ileum were significantly lower than values obtained from other intestinal segments.(ABSTRACT TRUNCATED AT 250 WORDS)

Chemical involution of the equine parotid salivary gland.

The efficacy of eliminating parotid salivary secretions by retrograde infusion of 10% formalin, 2% chlorhexidine, or 2% or 3% silver nitrate solutions was evaluated in 10 horses. Solutions were kept within the parotid salivary gland for 90 seconds after infusion through parotid duct cannulae and then allowed to drain freely. Severed parotid ducts and surgical incisions were left to heal by second intention. All agents eliminated glandular secretions. There was less necrosis and suppurative inflammation after formalin infusion than after chlorhexidine and silver nitrate. Silver nitrate (2% and 3%) caused the most necrosis and inflammation.

Monitoring equine anesthesia.

In conclusion, monitoring the depth of anesthesia plays an integral role in the anesthetic regimen. Although the use of sophisticated monitoring equipment has replaced some of the art of anesthesia and made assessment of depth of anesthesia more precise, a vigilant clinician still needs to serve as the animal's advocate. He or she must gather the data that are generated by machines, acquire data that monitoring equipment cannot obtain, assimilate all the facts, and make appropriate changes in anesthetic management.

Fracture repair with transfixation pins and fiberglass cast in llamas and small ruminants.

Transfixation pinning with fiberglass casting is an effective and adaptable method of longbone fracture fixation in llamas and small ruminants. Treatment of fractures in 7 limbs of 4 llamas and 2 small ruminants with this technique are described. Steinmann pins are placed transcortically proximal, and if necessary, distal to the fracture. The pin ends and limb are encased in fiberglass cast material. The cast is strong enough in animals of this size to eliminate the need for external frames or connecting bars. Severely comminuted fractures and fractures near joints are especially suited to fixation with this technique. Complications encountered in these cases included loosening of pins and one delayed union. All fractures healed to permit full use of the limb.

Anesthesia in the llama.

Anesthesia for llamas is similar to other domestic species, although adjustments in technique are required to allow for species variations. Xylazine (0.4-0.6 mg/kg) is well tolerated for sedation. The thiobarbiturates (8-10 mg/kg), ketamine (2.5-5.0 mg/kg), or combinations of guaifenesin and thiobarbiturates or guaifenesin and ketamine (to effect) can be used for induction of anesthesia. In juvenile or debilitated animals, anesthesia can be induced with halothane or isoflurane administered by mask. After tracheal intubation, anesthesia can be maintained with the inhalation agents, usually halothane or isoflurane. Supportive therapy and many anesthetic monitoring techniques used in domestic animals can be used in llamas. While under marginal planes of anesthesia, llamas can have more active physiologic responses to pain, including bradycardia and vasoconstriction, than domestic animals. Llamas are more prone to airway obstruction after tracheal extubation than domestic ruminants but otherwise recover as well from general anesthesia as domestic ruminants.

Comparison of bronchodilators in alleviating clinical signs in horses with chronic obstructive pulmonary disease.

A representative of each of 3 types of bronchodilators was given iv to horses with clinical signs of chronic obstructive pulmonary disease. We used atropine (0.01 mg/kg of body weight) as an anticholinergic, isoproterenol HCl as a beta-adrenergic, and aminophylline, the soluble salt of theophylline, as a methylxanthine. Response to these drugs was evaluated by measuring maximal change in intrathoracic pressures (delta Ppl) and observing clinical signs. Atropine caused a significant (P less than 0.01) reduction in delta Ppl, compared with that caused by aminophylline. Atropine caused the delta Ppl to decrease an average of 83 +/- 15% toward normal. Clinical improvement was noticed in 87% of the cases. Maximal changes in pleural pressures were reduced by an average of 21 +/- 14 mm of Hg, with 27% returning completely to normal. Isoproterenol helped 77% of horses clinically, and caused delta Ppl to decrease an average of 68 +/- 31% toward normal. The average reduction in delta Ppl was 16 +/- 10 mm of Hg. Aminophylline helped alleviate clinical signs of 50% of the horses and caused delta Ppl to decrease an average of 41 +/- 36% toward normal. The average reduction in delta Ppl was 10 +/- 11 mm of Hg.

Surgical correction of congenital medial patellar luxation in a llama.

Unilateral congenital medial patellar luxation in a young llama was corrected by medial joint capsule release, tibial crest transposition, trochleoplasty, and lateral joint capsule imbrication. The techniques used were the same as described in the dog. One year after surgery, the llama was not lame, but had a valgus deformity originating at the stifle, most likely caused by lateral femoral condyle hypoplasia.

Management of intraoperative and postoperative anesthetic complications in ruminants and swine.

Complications that can occur during and following anesthesia in ruminants and swine are discussed. Because many of these complications can be life-threatening, they must be avoided to allow provision of safe general anesthesia. Emphasis is placed on prevention and recognition of these complications and the institution of therapy when they do occur.

Reversal of xylazine-induced sedation in llamas, using doxapram or 4-aminopyridine and yohimbine.

For each of 3 separate evaluations, 6 fasted llamas (Lama glama) were sedated with xylazine (1.1 mg/kg of body weight, IV) and then 15 minutes later were given normal saline solution (5.0 ml, IV; control values), doxapram (2.2 mg/kg, IV), or 4-amino-pyridine (0.3 mg/kg, IV) and yohimbine (0.125 mg/kg, IV). After administration of 4-aminopyridine and yohimbine, the llamas stood in a mean of 11 minutes and resumed eating in a mean of 34 minutes; both means were significantly less (P less than 0.05) than control values (46 minutes and 67 minutes, respectively). Doxapram induced muscle fasciculations, and (compared with control values) did not significantly decrease the time to standing (41 minutes) or the time until the animals resumed eating (68 minutes). Yohimbine and 4-aminopyridine in combination rapidly antagonized xylazine-induced sedation in llamas, whereas doxapram was ineffective as an antagonist of xylazine-induced sedation.

Clinical biochemical values of llamas: reference values.

Fifteen clinical biochemical measurements were done on serum from 64 clinically healthy adult llamas (26 males and 38 females). Values for several of these tests were different from those reported for llamas and from reference values for other domesticated ruminants. Comparison of values between males and females revealed significant differences for several tests. Clinical biochemical values reported in the present study can serve as reference values for adult llamas.