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.

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)

Metabolism of toxic pyrrolizidine alkaloids from tansy ragwort (Senecio jacobaea) in ovine ruminal fluid under anaerobic conditions.

The ability of ovine ruminal fluid to metabolize pyrrolizidine alkaloid (PA) from Senecio jacobaea under anaerobic conditions was evaluated. Four fistulated sheep fed PA served as individual sources of ruminal fluid, which was incubated in a defined minimal salts medium under two different anaerobic conditions, denitrifying and methanogenic. Anaerobic cultures amended with ovine ruminal fluids (20%), PA (100 micrograms/ml), and a defined minimal salts medium were monitored for a period of several days. These cultures revealed that while PA was not depleted in sterile, autoclaved controls or under denitrifying conditions, it was metabolized during periods of active methanogenesis under methanogenic conditions. In addition, samples of ruminal fluid were separated by differential centrifugation under anaerobic conditions, and the resultant supernatants were tested for their ability to metabolize PA as compared with those of the respective uncentrifuged control fluids. Uncentrifuged controls exhibited a PA depletion rate of -4.04 +/- 0.17 micrograms of PA per ml per h. Supernatants 1 (centrifuged at 41 x g for 2 min), 2 (centrifuged at 166 x g for 5 min), and 3 (centrifuged at 1,500 x g for 10 min) exhibited significantly slower depletion rates, with slopes of data representing -1.64 +/- 0.16, -1.44 +/- 0.16, and -1.48 +/- 0.16 micrograms of PA metabolized per ml per h, respectively, demonstrating no statistically significant difference among the supernatant cultures. Microscopic evaluations revealed that protozoa were present in the control whole ruminal fluid and to a lesser extent in supernatant 1, while supernatants 2 and 3 contained only bacteria.(ABSTRACT TRUNCATED AT 250 WORDS)

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.

Dioxin intoxication from chronic exposure of horses to pentachlorophenol-contaminated wood shavings.

Investigations into the cause of health problems on a horse-breeding farm led to the discovery of high concentrations (630 to 9,810 mg/kg of bedding) of pentachlorophenol in wood shavings used as bedding for horses over a period of 2 to 4 years. Toxicologic signs in the horses were characteristic of toxic effects associated with exposure of polychlorinated dibenzo-p-dioxins and dibenzofurans. Tissue residue analysis confirmed presence of toxic polychlorinated dibenzo-p-dioxin and dibenzofuran isomers known to be in pentachlorophenol, substantiating the bioavailability of polychlorinated dibenzo-p-dioxins and dibenzofurans in the wood shavings. The findings provide evidence that residue concentrations in the range of 2 ng/g of toxic polychlorinated dibenzo-p-dioxin isomers in liver or fat correlate with toxicologic effects in horses.

Subchondral bone cysts with fractures of the extensor processes in a horse.

Probable cause of fracture in a Paint gelding was a congenital bone defect involving the extensor process area of the right and left forelimb distal phalanges. Radiographically and histologically, subchondral bone cysts at the fracture lines were suspected. These cysts were thought to have developed in association with abnormal ossification centers at the extensor process areas of the third phalanx. Partial avulsion of weak extensor processes would then occur from natural forces exerted on these weakened bony prominences via the common digital extensor tendon. Support for osteochondrosis as a cause of this bone cyst formation was seen in histologic examination of fragments removed. Within the bony trabeculae, a dysplastic focus of cartilage with mineralized plaques and osseous tissues was observed. Findings supported a diagnosis of osteochondrosis, to the extent that the disease is presently understood in horses. Surgical correction by fragment removal was performed to circumvent progression of degenerative joint disease, which was evident as partial cartilage erosion of the distal dorsal articular surface of the second phalanx and fracture fragments. Recovery from surgery was rapid, and several months after surgery, the horse was sound for pleasure riding.

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.

Local anesthetic techniques for diagnosis of lameness.

Successful diagnostic local anesthesia is dependent upon a thorough knowledge of appendicular anatomy, application of correct technique, and accurate interpretation. Use of cadaver specimens to review anatomy and practice needle placement is strongly recommended. A marker solution, such as new methylene blue, can be injected into cadaver limbs, which can be subsequently dissected to verify accuracy. Detailed interpretation of local anesthetic blocks in the lame horse reaches beyond the scope of this article. Interpretive difficulties, however, can be responsible for the failure of a block to provide useful information to the examiner, even though the block may have been performed in a technically correct manner.

In vitro regulation of mammary glucose-6-phosphate dehydrogenase activity by palmitoyl coenzyme A, acetate, and polyamines.

An in vitro study was conducted to determine whether bovine mammary glucose-6-phosphate dehydrogenase (G6PD) activity was regulated by palmitoyl coenzyme A (CoA), acetate, spermidine, and putrescine and whether these effects were dependent upon stage of lactation. Early lactation explants incubated in media containing palmitoyl CoA or acetate had reduced (P less than 0.01) G6PD activity compared with incubated control explants. G6PD activity in early lactation explants was reduced (P less than 0.05) when incubated with 5 microM palmitoyl CoA or 1 mM acetate compared with 25 microM palmitoyl CoA or 10 mM acetate. Spermidine (0.4 mM) reversed (P less than 0.05) palmitoyl CoA-induced inhibition of early lactation G6PD activity at 5 microM, but not at 25 microM palmitoyl CoA. G6PD activity in early lactation explants was decreased (P less than 0.05) when treated with putrescine (0.4 mM) compared with explants treated with spermidine. Addition of acetate in combination with 5 microM palmitoyl CoA reversed G6PD inhibition (P less than 0.05 for 1 mM and P less than 0.01 for 10 mM) while addition of either level of acetate in combination with 25 microM palmitoyl CoA failed to reverse G6PD inhibition. G6PD activity was higher (P less than 0.01) in early lactation than mid-lactation explants. No statistical differences (P greater than 0.1) were found among any treatments in explants from mid-lactation cows. We conclude that palmitoyl CoA and acetate will inhibit G6PD activity in early lactation, but not mid-lactation explants; addition of spermidine will reverse this inhibition.

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.

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.

Nasomaxillary fibrosarcomas in three young horses.

Nasomaxillary fibrosarcoma was diagnosed in 3 young horses. Clinical signs included epiphora, facial swelling, dyspnea, unilateral serosanguineous nasal discharge, or an external mass. Physical examination, radiography, and cytology were important diagnostic adjuncts. The definitive diagnosis in each case was based on biopsy. In one case, surgical removal of the tumor and extensive curettage of the affected sinus resulted in extended remission from neoplastic disease.

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.

Management of acquired flexural deformity of the metacarpophalangeal joint in Equidae.

Fifteen horses with flexural deformity of the metacarpophalangeal joint were evaluated and their conditions were designated as mild, moderate, or severe. Evaluations were made on the basis of clinical signs and lesions seen on radiography. Horses with mild deformities were treated with corrective trimming and shoeing; those with moderate deformities were treated with desmotomy of the accessory ligament of the deep digital flexor tendon and corrective shoeing. Desmotomies of the accessory ligaments of both deep and superficial digital flexor tendons were performed on horses severely affected, followed by corrective shoeing. In this long-term study, 4 horses with mild lesions and 4 horses with moderate lesions returned to useful work. None of the horses with severe disease responded enough to withstand strenuous athletic training.