Acquired urethral obstruction in New World camelids: 34 cases (1995-2008).

OBJECTIVE: Document the clinical features, short- and long-term outcomes and prognostic factors in New World camelids with acquired urethral obstruction. DESIGN: Retrospective case study. METHODS: Case data from medical records of 34 New World camelids presenting with acquired urethral obstruction were collected and follow-up information on discharged patients was obtained. Associations with short- and long-term survival were evaluated using Wilcoxon rank-sum tests, exact-logistic regressions and Kaplan-Meier survival curves. RESULTS: Of the 34 New World camelids 23 were intact males and 11 were castrated; 4 animals were euthanased upon presentation, 7 were treated medically and 23 surgically, including urethrotomy, bladder marsupialisation, tube cystostomy alone or combined with urethrotomy, urethrostomy or penile reefing. Necrosis of the distal penis was found in 4 animals and all were short-term non-survivors. Short-term survival for surgical cases was 65%, and 57% for medical cases. Incomplete urethral obstruction at admission and surgical treatment were associated with increased odds of short-term survival. Of 14 records available for long-term follow-up, 6 animals were alive and 8 were dead (median follow-up 4.5 years, median survival time 2.5 years). Recurrence of urethral obstruction was associated with long-term non-survival. CONCLUSIONS: Surgically treated New World camelids with incomplete urethral obstruction have the best odds of short-term survival and those with recurrence of urethral obstruction have a poor prognosis for long-term survival.

Exenatide dosing in alpacas.

In order to investigate whether exenatide could be used to stimulate glucose clearance and insulin secretion in alpacas without causing colic signs, six healthy adult alpacas were injected once a day with increasing subcutaneous doses. A follow-up intravenous glucose injection was given to induce hyperglycemia, and serial blood samples were collected to measure plasma concentrations of glucose, insulin, triglycerides, beta-hydroxybutyrate, and nonesterified fatty acids. The exenatide doses used were saline control (no drug), and 0.02, 0.05, or 0.1 mcg/kg injected subcutaneously. Alpacas had significantly lower plasma glucose concentrations and higher insulin concentrations on all treatment days compared with the control day, but the increase in insulin was significantly greater and lasted significantly longer when the alpacas received the two higher dosages. Two of the alpacas developed mild colic signs at the 0.05 mcg/kg dose and were not evaluated at the highest dose. Based on these findings, the 0.05 mcg/kg dose appears to offer the greatest stimulation of insulin secretion and glucose clearance without excessive risk or severity of complications.

Prevalence of Mycobacterium avium subsp. paratuberculosis fecal shedding in alpacas presented to veterinary hospitals in the United States.

BACKGROUND: The prevalence of Johne's disease in alpacas in the United States is unknown. The limits of polymerase chain reaction (PCR) detection of Mycobacterium avium subsp. paratuberculosis (MAP) in alpaca feces have not been determined. OBJECTIVES: To evaluate the use of PCR for MAP detection in alpaca feces; and to estimate the prevalence of MAP fecal shedding in alpacas presented to veterinary teaching hospitals. ANIMALS: Alpacas presenting to 4 US veterinary teaching hospitals from November 2009 to February 2011. METHODS: Prospective study. Ten dilutions of a wild MAP strain were added to negative alpaca feces and processed for MAP detection by means of a commercial real-time PCR (RT-PCR) assay, and cultured on Herrold's Egg Yolk Medium (HEYM) and liquid broth. The limits of detection for each method were determined. Fecal samples from alpacas admitted to the veterinary teaching hospitals during the study period were evaluated for MAP via PCR and HEYM. RESULTS: The lowest MAP dilution detectable via PCR was 243 MAP colony-forming units (CFU)/g of feces, at which concentration MAP growth was detectable on HEYM. Ten (6%; 95% confidence interval: 3-9%) of the 180 fecal samples collected were positive on PCR. CONCLUSIONS AND CLINICAL IMPORTANCE: Polymerase chain reaction can provide an accurate and rapid detection of MAP fecal shedding in alpacas; and the prevalence of MAP fecal shedding in hospitalized alpacas in 4 US veterinary teaching hospitals was 6%.

Effects of exenatide on plasma glucose and insulin concentrations in alpacas.

BACKGROUND: Exenatide is a degradation-resistant glucagon-like peptide 1 agonist used in the treatment of diabetes mellitus. It enhances the insulin response to hyperglycemia. Because of a poor insulin response, adult camelids are susceptible to hyperglycemia from stress, glucose administration, or energy metabolism disorders. Insulin often is administered to decrease plasma glucose concentration, but this approach has disadvantages such as the risk of hypoglycemia. Noninsulin medications targeting the incretin hormone pathway, such as exenatide, are providing alternate treatment options. HYPOTHESIS/OBJECTIVES: Exenatide will decrease plasma glucose and increase insulin concentrations in alpacas. ANIMALS: Six healthy adult alpacas. METHODS: After food was withheld for 8 hours, alpacas were given, on subsequent days in a randomly determined order, either 0.2 microg/kg of exenatide or similar volume of isotonic saline SC. Blood samples were collected before and 15, 30, 45, 60, 75, 90, 105, and 120 minutes after treatment. A rapid dextrose (0.5 g/kg) injection was given after the time 60 samples. Plasma glucose and insulin concentrations were measured at each time point. RESULTS: Alpacas had significantly (P=<.001-.015) lower plasma glucose and higher insulin concentrations for the hyperglycemic period after receiving exenatide than after saline injections. Colic signs were observed in 5 of 6 alpacas treated with exenatide. CONCLUSIONS AND CLINICAL IMPORTANCE: Exenatide appeared to increase insulin release and decrease plasma glucose concentrations in hyperglycemic alpacas. These findings are similar to findings in humans and could support therapeutic usage of exenatide in alpacas. However, induction of colic may limit practical application.

Malignant round cell neoplasia in llamas and alpacas.

Malignant round cell neoplasia was identified in 12 llamas and 12 alpacas aged 0-23 years. Mean age of affected alpacas (3.1 years) was significantly less than that of affected llamas (8.0 years). Tumor cell morphology varied from large and often pleomorphic (11 tumors) to small and often homogeneous (13 tumors). Neoplastic lesions were multicentric in 12 cases. Other sites were gastric (5 cases), intra-abdominal (perirenal; 4 cases), intrathoracic (2 cases), and cervical (1 case). Immunohistochemistry with antibodies to CD79alpha, BLA36, and CD3 identified B-cell lymphoma (12 cases) and T-cell lymphoma (6 cases). Six tumors did not express any lymphoid marker and were further immunostained for neuron-specific enolase (NSE), synaptophysin, S-100, glial fibrillary acidic protein (GFAP), and chromogranin A. All 6 of these tumors were negative for GFAP and chromogranin A but expressed 1 or more of the neural markers NSE, synaptophysin, and S-100 and were classified as primitive malignant round cell tumors (PMRCT). Tumor types could not be distinguished on the basis of animal age, gross pathologic appearance, tumor morphology, or tumor location. All animals with lymphoma and 5 with PMRCT died or were euthanatized. One alpaca with a focal cervical PMRCT lived for at least 20 months after diagnosis. Results of this study indicate that malignant round cell tumors in llamas and alpacas are a heterogeneous group that cannot be distinguished on the basis of signalment, postmortem findings, or routine light microscopic findings. Immunohistochemistry is a valuable diagnostic procedure when evaluating malignant round cell neoplasia in llamas and alpacas.

Thrombotic endocarditis in 10 alpacas.

BACKGROUND: A description of the clinical signs and necropsy findings in 10 alpacas with thrombotic endocarditis. ANIMALS: Clinical cases admitted to 2 veterinary referral hospitals between May 1998 and December 2006. METHODS: A retrospective study was performed by searching hospital records to identify alpacas diagnosed with endocarditis. RESULTS: Common clinical findings included sternal recumbency, tachycardia, tachypnea, and abdominal distension. Heart sounds were recorded as normal in 7 of 10 alpacas. Pleural and pericardial effusion and ascites were often present. Complete blood cell counts often suggested inflammation, and liver enzyme activity was often increased. When echocardiography was performed, a soft tissue density was imaged within the right ventricle. All alpacas died or were euthanized. Necropsy revealed mural endocarditis with right ventricular or biventricular fibrinous thrombi obliterating the ventricular lumina with no valvular involvement in 6 of 10 affected animals. Bacteria were not consistently identified as a cause for the endocarditic lesions. Eight of the 10 alpacas had evidence of hepatic fluke infestation. CONCLUSIONS AND CLINICAL IMPORTANCE: Valvular and mural thrombotic endocarditis should be included in the list of differential diagnoses for hepatomegaly, abdominal distension, and other signs of right-sided congestive heart failure in alpacas. The prognosis of this disease is grave.

Analysis of the genome sequence of an alpaca coronavirus.

Coronaviral infection of New World camelids was first identified in 1998 in llamas and alpacas with severe diarrhea. In order to understand this infection, one of the coronavirus isolates was sequenced and analyzed. It has a genome of 31,076 nt including the poly A tail at the 3' end. This virus designated as ACoV-00-1381 (ACoV) encodes all 10 open reading frames (ORFs) characteristic of Group 2 bovine coronavirus (BCoV). Phylogenetic analysis showed that the ACoV genome is clustered closely (>99.5% identity) with two BCoV strains, ENT and LUN, and was also closely related to other BCoV strains (Mebus, Quebec, DB2), a human corona virus (strain 043) (>96%), and porcine hemagglutinating encephalomyelitis virus (>93% identity). A total of 145 point mutations and one nucleotide deletion were found relative to the BCoV ENT. Most of the ORFs were highly conserved; however, the predicted spike protein (S) has 9 and 12 amino acid differences from BCoV LUN and ENT, respectively, and shows a higher relative number of changes than the other proteins. Phylogenetic analysis suggests that ACoV shares the same ancestor as BCoV ENT and LUN.

Comparative biochemical analyses of venous blood and peritoneal fluid from horses with colic using a portable analyser and an in-house analyser.

Fifty-six horses with colic were examined over a period of three months. The concentrations of glucose, lactate, sodium, potassium and chloride, and the pH of samples of blood and peritoneal fluid, were determined with a portable clinical analyser and with an in-house analyser and the results were compared. Compared with the in-house analyser, the portable analyser gave higher pH values for blood and peritoneal fluid with greater variability in the alkaline range, and lower pH values in the acidic range, lower concentrations of glucose in the range below 8.3 mmol/l, and lower concentrations of lactate in venous blood in the range below 5 mmol/l and in peritoneal fluid in the range below 2 mmol/l, with less variability. On average, the portable analyser underestimated the concentrations of lactate and glucose in peritoneal fluid in comparison with the in-house analyser. Its measurements of the concentrations of sodium and chloride in peritoneal fluid had a higher bias and were more variable than the measurements in venous blood, and its measurements of potassium in venous blood and peritoneal fluid had a smaller bias and less variability than the measurements made with the in-house analyser.

Effects of exogenous insulin on glucose tolerance in alpacas.

OBJECTIVE: To evaluate the effects of exogenous insulin on clearance of exogenous glucose in alpacas. ANIMALS: 7 adult castrated male alpacas. PROCEDURE: Prior to each of 2 trials, food was withheld for 8 hours. Glucose (0.5 g/kg of body weight) was then administered by rapid IV infusion. During 1 of the trials, regular insulin (0.2 U/kg, IV) was also administered 15 minutes later. Blood was collected immediately before (0 minutes) and 15, 20, 25, 30, 45, 60, 90, 120, 180, and 240 minutes after glucose administration. Plasma concentrations of glucose and lactate were determined, and glucose fractional turnover rate and plasma half-life were calculated. RESULTS: Insulin treatment caused a significant increase in fractional turnover rate of glucose and plasma lactate concentration. Plasma glucose concentrations were less in insulin-treated alpacas from 30 minutes after glucose administration (15 minutes after insulin administration) until the conclusion of each trial, compared with nontreated alpacas. In addition, plasma glucose concentration in insulin-treated alpacas returned to baseline values 1 hour sooner than in the nontreated group. CONCLUSIONS AND CLINICAL RELEVANCE: Glucose uptake in alpacas improves after insulin treatment, suggesting that administration of exogenous insulin will increase the therapeutic and decrease the pathologic effects of exogenous glucose administered to hypoglycemic alpacas. However, alpacas and other New World camelids should be monitored carefully during treatment with glucose or insulin, because these species appear to be partially insulin resistant.

Metabolic changes and induction of hepatic lipidosis during feed restriction in llamas.

OBJECTIVES: To determine whether feed restriction induces hepatic lipidosis (HL) in llamas and to evaluate the metabolic changes that develop during feed restriction. ANIMALS: 8 healthy adult female llamas. PROCEDURE: Llamas were fed grass hay at a rate of 0.25% of their body weight per day for 13 to 28 days. Llamas were monitored by use of clinical observation, serum biochemical analyses, and ultrasound-guided liver biopsies. RESULTS: All 8 llamas lost weight and mobilized fat. Five llamas developed HL, including 4 that were nursing crias. During the period of feed restriction, mean serum concentration of bile acids and activities of aspartate aminotransferase (AST), sorbitol dehydrogenase (SDH), and gamma-glutamyl transferase (GGT) were significantly higher in llamas that developed HL, compared with llamas that did not. Mean insulin-to-cortisol concentration ratios were lower in llamas with HL before and up to 7 days of feed restriction, compared with those that did not develop HL. CONCLUSIONS AND CLINICAL RELEVANCE: HL in llamas may be induced by severe feed restriction, particularly in the face of increased energy demand. Llamas with weight loss attributable to inadequate dietary intake may develop biochemical evidence of hepatopathy and HL. Increases in serum concentration of bile acids and activities of GGT, AST, and SDH may indicate the development of HL in llamas and identify affected animals for aggressive therapeutic intervention.

Peritonitis in a llama caused by Streptococcus equi subsp. zooepidemicus.

A 7-month-old, male llama was diagnosed with peritonitis caused by Streptococcus equi subsp. zooepidemicus. Clinical findings, medical treatment, and case outcome are described. Hematogenous dissemination from suspected pneumonia is proposed as the route of infection in this case. Possible transmission of the organism through contact with horses is discussed.

Glucose tolerance testing in llamas and alpacas.

OBJECTIVE: To determine blood glucose clearance in 2 species of New World camelids after IV challenge and to examine mechanisms of this clearance. ANIMALS: 5 adult female llamas and 5 adult gelded alpacas. PROCEDURE: After food was withheld for 12 hours, camelids received 0.5 g of glucose/kg of body weight by rapid IV infusion. Serum concentrations of glucose, nonesterified fatty acids, cortisol, and insulin, and plasma concentrations of lactate were determined before and 0, 1, 2, 3, 4, 5, 15, 30, 60, 90, 120, 180, and 240 minutes after infusion. Ratios of insulin to glucose and insulin to cortisol were calculated for each time point. RESULTS: Postinfusion glucose concentrations were significantly higher in llamas than alpacas for the first 15 minutes and remained significantly higher than baseline values in both species for 180 minutes. Lactate and cortisol concentrations did not change significantly; nonesterified fatty acid concentrations decreased in both species 30 minutes after infusion. Baseline insulin concentrations were < 6 microU/ml in both species and increased only to 10.1 +/- 0.7 microU/ml in llamas. Insulin concentrations did not change significantly in alpacas. CONCLUSIONS AND CLINICAL RELEVANCE: Llamas and alpacas clear glucose more slowly than other domestic species after challenge, mainly because of a weak insulin response and slow cellular uptake. This response may impair the assimilation of exogenous glucose as well as make llamas and alpacas prone to diabetes-like disorders when an abundance of endogenous or exogenous glucogenic agents are present.

Pathogenesis of Streptococcus zooepidemicus infection after intratracheal inoculation in llamas.

OBJECTIVES: To test whether generalized Streptococcus zooepidemicus infection could be induced by intratracheal inoculation in llamas and to characterize this infection. ANIMALS: 6 test and 3 control llamas. PROCEDURE: Test llamas received 1 of 3 dosages of S. zooepidemicus by intratracheal injection, whereas control llamas received sterile culture medium. Physical examination variables and results of clinicopathologic analyses of blood, peritoneal fluid, and tracheal wash fluid were compared in test llamas between, before, and during the development of bacteremia and with control llamas. Bacteriologic culture was performed on all collected body fluids and tissue specimens that were collected at necropsy. Tissue specimens that were collected at necropsy were examined histologically. RESULTS: Infection induced fever, anorexia, and signs of depression. Five of 6 infected llamas developed specific signs of inflammation in the thorax or abdomen, bacteremia, neutrophilic leukocytosis with toxic changes and high band neutrophil cell counts, hyperfibrinogenemia, and high peritoneal fluid WBC counts and protein concentrations. On development of bacteremia, llamas had significant decreases in serum iron (from 118+/-25 to 6+/-4 microg/ml) and increases in serum glucose (from 131+/-5 to 253+/-48 mg/dl) concentrations. CONCLUSIONS AND CLINICAL RELEVANCE: Streptococcus zooepidemicus spreads rapidly to other body compartments after intratracheal inoculation in llamas. Fever, anorexia, and signs of depression are the most consistent clinical signs, although other signs are possible. Clinicopathologic analysis of body fluids yields evidence of inflammation. Infection by S. zooepidemicus can be proven by bacteriologic culture of body fluids before death or of tissue specimens after death.

Hyperglycemia, hypernatremia, and hyperosmolarity in 6 neonatal llamas and alpacas.

Neonatal camelids can develop hyperglycemia, hypernatremia, and hyperosmolarity in response to a combination of stress and inadequate water intake. Clinical signs of this syndrome include a fine head tremor, ataxia, and a base-wide stance of the hind limbs, but biochemical analyses are necessary to confirm the diagnosis. Camelids appear to be susceptible to this syndrome because of a poor insulin response to hyperglycemia; hypernatremia results from free water loss associated with glucose diuresis. Water loss associated with glucose diuresis may necessitate a higher rate of fluid administration in camelids with this syndrome than is typically used for treatment of hypernatremia in calves.

Diagnosis and treatment of obstructive urolithiasis in a captive Rocky Mountain wapiti (Cervus elaphus nelsoni).

A captive 5-yr-old castrated male Rocky Mountain wapiti (Cervus elaphus nelsoni) developed stranguria. Rectal palpation and physical examination indicated urethral obstruction that was subsequently relieved by urethrostomy and required only minimal aftercare. The wapiti was able to urinate freely after surgery; however, the obstruction recurred 27 mo later. Urethral catheterization relieved the second obstruction, which was caused by a large calculus composed of calcium carbonate and magnesium carbonate. Urolithiasis may have been associated with a diet high in calcium, and urethral obstruction may have been associated with castration at an early age. The wapiti continued to urinate freely 9 mo after relief of the second obstruction and 3 yr after the initial surgery.

Diagnosis and treatment of torsion of the spiral colon in an alpaca.

A 14-year-old 61.7-kg (136-lb) alpaca was examined for colic of 24 hours' duration. An exploratory celiotomy was performed because of lack of response to medical treatment and ultrasonography revealed an abnormally large amount of free fluid in the peritoneal cavity. Exploration of the abdomen revealed a 20-cm diameter mass, consisting of most of the ascending colon. The spiral colon was thick and edemetous, and it was decided to resect the spiral colon. Following a few complications, the alpaca was discharged 17 days after surgery. Colic in camelids is considered a severe problem because clinical signs are subtle and often not recognized until the condition is untreatable. Camelids are reported to be stoic animals, and may have few signs of pain despite severe abdominal disease. Alpacas with signs of abdominal pain should undergo early and complete physical, laboratory, and diagnostic imaging evaluations. Rapid identification of the need for surgery is vital for a successful outcome.

Congenital joint laxity and disproportionate dwarfism in a herd of beef cattle.

Three calves from a herd of beef cattle were examined because of disproportionate dwarfism and excessive extension of metacarpophalangeal and metatarsophalangeal joints. Abnormalities had been noticed at birth, 1 to 6 days earlier. A thorough herd investigation revealed that 16 calves born to 70 multiparous cows were affected during the calving season. The condition did not adversely affect calf survival. Affected calves had limbs that were disproportionally short, compared with their trunk size, and wide epiphyses of the femurs and humeri. Radiographic evaluation revealed incomplete maturation of carpal and tarsal bones and incomplete maturation and abnormal flaring of epiphyses of the short humeri and femurs. Histologic findings were consistent with chondrodystrophy. This disorder had not been seen in the herd in previous years and was traced to feeding of dry, spoiled silage to the dams during midgestation. Covering the silage prevented problems in the subsequent year.