Thoracic radiographic appearance in the normal llama.

The goal of this study was to collect quantitative and qualitative radiographic information of the normal adult llama thorax. Standing right-left lateral radiographs of the thorax of 16 normal llamas were made. Normal ratios of cardiac height, width, and height plus width to thoracic vertebrae 3-5 and thoracic height were calculated. Normal values determined for tracheal angle of divergence from the thoracic spine, cardiophrenic and cardiosternal contact are additional potential indicators of cardiac enlargement. Ratios of normal pulmonary artery and vein, caudal vena cava and trachea to the height of the fourth thoracic vertebra should allow identification of pathology of these structures. Observations regarding pulmonary vessels and airways, thoracic spine, sternebrae and portions of the gastrointestinal tract observed on thoracic radiographs are also included. It is proposed that these normal values and observations can be used to better evaluate diseases of the cardiovascular and respiratory systems of adult llamas.

Characteristics of a recent isolate of Sarcocystis neurona (SN7) from a horse and loss of pathogenicity of isolates SN6 and SN7 by passages in cell culture.

An isolate of Sarcocystis neurona (SN7) was obtained from the spinal cord of a horse with neurologic signs. The parasite was isolated in cultures of bovine monocytes and equine spleen cells. The organism divided by endopolygeny and completed at least one asexual cycle in cell cultures in 3 days. The parasite was maintained by subpassages in bovine monocytes for 10 months when it was found to be non-pathogenic to gamma interferon knockout (KO) mice. Revival of a low passage (10th passage) of the initial isolate stored in liquid nitrogen for 18 months retained its pathogenicity for KO mice. Merozoites (10(6)) of the late passage (22nd passage) were infective to only one of four KO mice inoculated. Similar results were obtained with SN6 isolate of S. neurona. No differences were found in Western blot patterns using antigens from the low and high passage merozoites of the SN7 and SN6 isolates. These results suggest that prolonged passage in cell culture may affect the pathogenicity of some isolates of S. neurona.

Characterization of a Sarcocystis neurona isolate (SN6) from a naturally infected horse from Oregon.

An isolate of Sarcocystis neurona (SN6) was obtained from the spinal cord of a horse from Oregon with neurologic signs. The parasite was isolated in cultures of bovine monocytes and equine spleen cells. The parasite divided by endopolygeny and completed at least one asexual cycle in cell cultures in three days. Two gamma interferon knockout mice inoculated with cell culture-derived merozoites became ill 35 d later and S. neurona schizonts and merozoites were found in encephalitic lesions. The parasite in tissue sections of mice reacted with S. neurona-specific antibodies and S. neurona was reisolated from the brain of knockout mice.

Neospora caninum-associated equine protozoal myeloencephalitis.

Equine protozoal myeloencephalitis (EPM) was clinically diagnosed in a 20-year-old horse with severe ataxia. The cerebrospinal fluid was positive for Sarcocystis neurona antibodies by western blot. The horse was administered corticosteroids to facilitate in vitro culture of S. neurona from its spinal cord following necropsy. Microscopic lesions of EPM were present in the brain and in the spinal cord, including multifocal inflammatory cellular infiltrates and several large groups of protozoa. Immunohistochemical, and light and electron microscopic examinations revealed that the protozoa were Neospora caninum and not S. neurona. The protozoa divided by endodyogeny, tachyzoites had rhoptries, and organisms reacted specifically to N. caninum antibodies. Veterinarians should be aware of increasing diagnosis of N. caninum as another etiological agent responsible for the lesions of EPM.

Use of computed tomography in the diagnosis of a cerebral abscess in a goat.

A 7-month-old La Mancha doe was presented with a right head tilt and ventral strabismus while circling to the left. History and physical examination led to a tentative diagnosis of a cerebral abscess. Computed tomography revealed a large, complex mass with ring enhancement in the left cerebral hemisphere, supporting the diagnosis. Postmortem examination confirmed the cerebral abscess. Bacterial cultures yielded heavy growth of Actinomyces pyogenes.

Normal reference intervals and the effects of time and feeding on serum bile acid concentrations in llamas.

Fifty clinically healthy llamas, 0.5-13 years of age (22 intact males, 10 neutered males, 18 females), with no biochemical evidence of liver disease or hematologic abnormalities, were selected to establish serum bile acid reference intervals. Serum samples submitted to the clinical pathology laboratory were analyzed using a colorimetric enzymatic assay to establish bile acid reference intervals. A nonparametric distribution of llama bile acid concentrations was 1-23 micromol/liter for llamas >1 year of age and 10-44 micromol/liter for llamas < or = 1 year of age. A significant difference was found between these 2 age groups. No correlation was detected between gender and bile acid concentrations. The reference intervals were 1.1-22.9 micromol/liter for llamas >1 year of age and 1.8-49.8 micromol/liter for llamas < or = 1 year of age. Additionally, a separate group of 10 healthy adult llamas (5 males, 5 females, 5-11 years of age) without biochemical or hematologic abnormalities was selected to assess the effects of feeding and time intervals on serum bile acid concentrations. These 10 llamas were provided fresh water and hay ad libitum, and serum samples were obtained via an indwelling jugular catheter hourly for 11 hours. Llamas were then kept from food overnight (12 hours), and subsequent samples were taken prior to feeding (fasting baseline time, 23 hours after trial initiation) and postprandially at 0.5, 1, 2, 4, and 8 hours. In feeding trials, there was no consistent interaction between bile acid concentrations and time, feeding, or 12-hour fasting. Prior feeding or time of day did not result in serum bile acid concentrations outside the reference interval, but concentrations from individual llamas varied within this interval over time.

Upper airway obstruction in a llama caused by aberrant nasopharyngeal bots (Cephenemyia sp.).

A 9 month old female llama was presented with inspiratory dyspnea. Radiographically, there was a large soft tissue mass nearly occluding the nasopharynx. During endoscopic examination three nasopharyngeal bots were identified embedded in the mass. The larvae were removed and the patient treated with ivermectin. The patient was discharged one week later free of clinical respiratory disease. In follow-up radiographs made 6 weeks later, only residual radiopacity in the area of the mass remained.

Alterations in clinical, hematological and metabolic variables in bovine neonatal endotoxemia.

Endotoxemia is an important cause of morbidity and mortality in the neonate. Although many models are used to study the problem, none completely simulates the natural disease. To more clearly define a bovine neonatal endotoxemia model we studied the effects of dose of endotoxin on clinical, hematological and biochemical variables. Thirty-four neonatal calves were administered Escherichia coli endotoxin (LPS) at 0 (0.9% saline solution), 0.2, 2.0 or 20 micrograms/kg, by either IV bolus or infusion over 50 minutes. Variables monitored included mean arterial blood pressure (MAP), leukocyte (WBC) count, plasma glucose and lactate concentrations and clinical status. All LPS-treated calves displayed similar clinical signs within one hour. Dose-dependent differences in response to LPS among groups became evident over time. Substantial dose-dependent changes in attitude, appetite, mucous membrane character, capillary refill time, MAP, plasma glucose and lactate concentrations, and WBC count were noted in LPS-treated calves. Higher doses of LPS induced a more prolonged clinical response and significantly (p < 0.05) greater hypotension, lacticemia and hypoglycemia. While dose altered the response to endotoxin, the method of administration had no overall effect on the variables measured.

Effect of dose and method of administration of endotoxin on cell mediator release in neonatal calves.

The cellular response induced in the host animal by endotoxin contributes greatly to the morbidity and mortality of gram-negative infections in bovine neonates. We characterized the temporal sequence, magnitude, and duration of mediator release during endotoxemia and evaluated the effect of endotoxin dose and method of administration. Thromboxane B2 (TxB2), and 6-keto prostaglandin F1 alpha (PGF1 alpha) concentrations and tumor necrosis factor (TNF), and interleukin-1 beta (IL-1 beta) activities were measured in 34 newborn calves given Escherichia coli endotoxin at dosage of 0 (saline solution), 0.2, 2.0, or 20 micrograms/kg of body weight, either by IV administered bolus or infusion over 50 minutes. In all groups and at each lipopolysaccharide dosage, mediators peaked in this sequence: TxB2 and TNF, followed by PGF1 alpha, then IL-1 beta. Neither dose nor method of administration affected the sequence of mediator release. The magnitude of eicosanoid response to endotoxin was dose-dependent. During induced endotoxemia, duration and/or magnitude of mediator response reflected the dose of endotoxin administered, indicating that the outcome of endotoxemia, in neonatal calves, may be related to the amount of circulating endotoxin.

Choledocholithiasis attributable to a foreign body in a horse.

Cholelithiasis is the most common cause of biliary obstruction in horses. Proposed mechanisms include ascariasis, biliary stasis, ascending biliary infection, and changes in bile composition. In this horse, a foreign body acted as the nidus for bile-salt deposition and ascending cholangitis. Clinical signs (intermittent abdominal pain, icterus, and pyrexia) in conjunction with high serum activity of enzymes indicative of obstructive biliary disease led to a tentative diagnosis of cholelithiasis. Ultrasonography was used to confirm the diagnosis. Postmortem examination revealed a 7-cm wooden stick to be the core of a cholelith found in the common bile duct.