Investigation of neonatal disorders in New World camelids and factors associated with death during and after hospitalization of affected crias

OBJECTIVE

To assess signalment, clinical findings, and treatments for New World camelids (NWCs) hospitalized for evaluation and treatment of neonatal disorders and investigate associations between these factors and death during and after hospitalization.

ANIMALS

267 NWCs ≤ 30 days of age.

PROCEDURES

Medical records of a veterinary teaching hospital were retrospectively reviewed to identify NWCs admitted for evaluation and treatment of neonatal disorders between 2000 and 2010. Signalment, physical examination data, diagnostic findings, treatments, and outcomes were recorded. Factors were examined for association with death during hospitalization and the overall hazard of death by use of multivariable logistic regression and Cox proportional hazards analysis, respectively.

RESULTS

The sample comprised alpacas (n = 255) and llamas (12). Median age at admission was 3 days, and median hospitalization time was 2 days; 208 of the 267 (77.9%) neonatal NWCs survived to hospital discharge. Factors associated with increased odds of death during hospitalization included prematurity or dysmaturity, hypothermia, sepsis, toxic changes in neutrophils, and undergoing surgery. The odds of death during hospitalization also increased as anion gap increased. After discharge, 151 of 176 (85.8%) animals had follow-up information available (median follow-up time, 2,932 days); 126 (83%) were alive and 25 (17%) had died. Prematurity or dysmaturity, congenital defects, sepsis, oxygen administration, and undergoing surgery as a neonate were associated with an increased hazard of death; the hazard of death also increased as serum chloride concentration at the time of hospitalization increased.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggested the prognosis for survival during and after hospitalization is good for most NWCs hospitalized because of neonatal disorders.

Evaluation of intramuscular injection of oxytetracycline for use as an experimental model to induce pain and assess the efficacy of pain mitigation strategies in dairy cows

OBJECTIVE

To evaluate IM injection of oxytetracycline as an experimental model to induce pain and assess the analgesic efficacy of flunixin meglumine (FM) in dairy cows.

ANIMALS

15 healthy nonlactating Jersey (n = 10) and Holstein (5) cows.

PROCEDURES

In the first of 2 experiments, 5 Jerseys were administered oxytetracycline (10 mg/kg, IM), divided between the right side of the neck and left hind limb. The left side of the neck and right hind limb received sham injections. Cows were also randomly assigned to receive FM (2.2 mg/kg, IV; n = 3) or an equal volume of saline (0.9% NaCl) solution (0.044 mL/kg, IV; control; 2) once daily for 5 days. The mechanical nociceptive threshold (MNT) was measured before oxytetracycline administration and at predetermined times after each injection of the assigned treatment. Experiment 2 was similar to experiment 1 except it involved 5 Jerseys and 5 Holsteins, oxytetracycline was injected only in a hind limb, and the assigned treatment was administered for 10 days.

RESULTS

For both experiments, mean MNT for the oxytetracycline injection site was consistently less than that for the sham injection site in the hind limbs, and mean MNT at the hind limb oxytetracycline injection site for FM-treated cows was greater than that for control cows beginning on day 3.

CONCLUSIONS AND CLINICAL RELEVANCE

IM injection of oxytetracycline in a hind limb reliably induced signs of pain in dairy cows and, with validation, might be useful as an experimental model for assessing pain mitigation strategies in cattle.

Efficacy of non-antibiotic treatment options for digital dermatitis on an organic dairy farm

The objective of this study was to evaluate the efficacy of two non-antibiotic treatment options for digital dermatitis (DD) on an organic certified dairy farm. A randomized clinical trial was conducted using 70 multiparous Holstein cows with an early DD lesion at a USDA certified organic dairy farm in Northern Colorado, USA. Cows were enrolled in the study based on the presence of early DD lesions (scores M1 and M2) and randomly assigned to one of three treatments: (1) topical application of copper sulfate and iodine (CUI); (2) topical application of honey and iodine (HOI); and (3) control subject to no treatment (CON). Cows were evaluated at enrolment and on days 3, 12, 28, and 120 post treatment for pain and lesion size and received a locomotion and a lesion score. Cure was defined as the transition from active to non-active stages (M1/M2 to M0 or M4). The formulations had variable effects on the treatment of DD. The cure rate was numerically higher for CUI on all follow up days. The proportion of cows experiencing pain on d3 after treatment was greater in CON, followed by HOI and CUI. However, this proportion increased in HOI during the follow up period. The CUI group had a greater reduction in lesion size and larger lesions persisted in HOI. Non-antibiotic treatment formulations were partially effective in the treatment of DD in organic dairy cows: The two non-antibiotic formulations resulted in an earlier transition to mature lesions compared with the control group. The CUI combination was the most effective treatment in reducing lesion size, pain, and lameness in affected cows. However, this combination had short-term efficacy, which did not persist throughout the duration of the study. The HOI combination produced only transient reduction in lesion size.

Evaluation of horn bud wound healing following cautery disbudding of preweaned dairy calves treated with aluminum-based aerosol bandage

Pain management during and following disbudding procedures has been studied extensively, though few studies have evaluated wound healing following cautery disbudding in dairy calves. The purpose of this study was to observe wound healing following cautery disbudding with or without treatment using a topical aluminum-based aerosol bandage (ALU) in preweaned dairy calves. Dairy calves were disbudded within the first 3 wk of life using a standard cautery disbudding protocol. The ALU treatment was randomly allocated to the right or left horn bud within each animal. The outcomes measured were lesion score (LS) and wound diameter (WD). The LS was evaluated on a scale of 1 to 3, with LS = 1 representing normal healing without a scab or exudate, LS = 2 having the presence of a scab, and LS = 3 showing the presence of wound exudate. Lesion score and WD were evaluated on a weekly basis following dehorning for 3 wk. A total of 209 animals completed the study. No difference was observed in LS between groups during the first 2 wk postdisbudding, but the proportion of LS = 3 on wk 3 postdisbudding was greater for the control group when compared with ALU (17 vs. 8%, respectively). During wk 1 and 2 postdisbudding, the odds of having delayed healing, or a LS ≥2, were similar for both groups. However, the odds tended to be different at wk 3 postdisbudding with control disbudding sites being 1.42 times more likely to have delayed healing than ALU. In wk 3, WD was 1 mm smaller in the treatment group compared with the control, and treatment decreased diameter over time compared with controls. Overall, once abnormal wound healing was observed, the likelihood of having abnormal wound healing the following week was increased. However, treatment with ALU diminished this effect on delayed healing during the follow-up period. Based on these results, the use of ALU improved wound healing following cautery disbudding of preweaned dairy calves.

Effects of two-stage weaning with nose flap devices applied to calves on cow body condition, calf performance, and calf humoral immune response

The effects of nose flap devices in calves before dam separation on cow BCS, pre- and postseparation calf performance, and humoral immune response were compared with traditional weaning. Primiparous and multiparous Angus and Hereford cows ( = 113) and their Angus, Hereford, and Angus × Hereford calves (179.4 ± 3.92 kg and 161 ± 22.7 d of age) were used. Cow-calf pairs were allocated to 1 of 2 treatments in a completely randomized design: 1) nose flap for 21 d before separation from the dam (NF) or 2) no nose flap for 21 d before separation from the dam (CON). Calves were separated from dams on d 0, and calves were placed in group feed-yard pens for 28 d. A subset ( = 75) of weaned calves were placed into 1 of 8 pens to evaluate DMI. Cow BCS was measured on d -21 and 56, and calves were given modified live vaccinations (d -21 and 1), challenged with ovalbumin (OVA; d 1), and weighed (d -21, 1, 7, 14, 21, and 28). In addition, blood samples were collected (d -21, 1, 14, and 28) to measure primary humoral immune response. Control calves tended to have greater BW on d 14 ( = 0.09) and 21 ( = 0.07) than NF calves, and CON calves had greater ( < 0.05) ADG from d -21 to 1 vs. NF calves. Treatments did not differ ( ≥ 0.27) for postweaning DMI, G:F, or morbidity. Serum neutralization tests for bovine viral diarrhea virus type 1 (BVDV-1) and bovine herpesvirus type 1 (BHV-1) were used to measure humoral response to a viral vaccination. Serum antibody titers to BVDV-1 for CON calves tended ( = 0.08) to be greater on d 1 and were greater ( < 0.05) by d 28 vs. NF calves. By d 28, a greater percentage ( < 0.05) of CON calves seroconverted for BVDV-1 than NF calves (82.1 vs. 66.7%, respectively). Serum antibody titers for BHV-1 were greater ( < 0.05) on d 1 and 28 for CON vs. NF calves. Humoral immune response to OVA during the 28-d postseparation period from the dam was evaluated in a subset ( = 57) of calves. There was no difference ( = 0.92) in OVA-specific IgG between treatments on d 14 or 28 ( = 0.76); however, OVA-specific IgM was greater ( < 0.05) in CON vs. NF calves on d 28. Results indicate that nose flap devices did not influence feed intake, feed efficiency, or morbidity during the initial postseparation period from the dam. However, preweaning ADG, serum BVDV-1 and BHV-1 titers, and humoral immune response to OVA were decreased in calves that received the nose flap treatment.

Effects of oral powder electrolyte administration on packed cell volume, plasma chemistry parameters, and incidence of colic in horses participating in a 6-day 162-km trail ride

This study evaluated the effects of administering oral powder electrolytes on packed cell volume (PCV), plasma chemistry parameters, and incidence of colic in horses participating on a 6-day 162-km trail ride in which water was not offered ad libitum. Twenty-three horses received grain with powder electrolytes daily while 19 control horses received grain only. Horses were ridden approximately 32 km a day at a walk or trot. Packed cell volume and plasma chemistry parameters were analyzed daily. Episodes of colic were diagnosed and treated by a veterinarian unaware of treatment group allocation. Blood parameters and incidence of colic were compared between treatment groups. Electrolyte administration did not alter PCV or plasma chemistry parameters compared to controls. The incidence of colic was significantly higher in treated horses (P = 0.05). Oral powder electrolytes did not enhance hydration status or electrolyte homeostasis and may be associated with colic in horses participating on long distance trail rides similar to this model.

Evaluation of glucose response to 3 types of insulin using a continuous glucose monitoring system in healthy alpacas

Background

Persistent hyperglycemia is common in alpacas and typically requires insulin administration for resolution; however, little is known about alpacas’ response to different insulin formulations.

Objectives

To evaluate the effects of 3 insulin formulations on blood glucose concentrations and the use of a continuous glucose monitoring (CGM) system in alpacas.

Animals

Six healthy alpacas.

Methods

The CGM was installed in the left paralumbar fossa at the start of this crossover study and recorded data every 5 minutes. Regular insulin, NPH insulin, insulin glargine, and dextrose were administered to each alpaca over a 2‐week period. Blood samples were collected for glucose testing at 0, 1, 2, 4, 6, 8, and 12 hours, and then every 6 hours after each administration of insulin or dextrose. Data were compared by using method comparison techniques, error grid plots, and ANOVA.

Results

Blood glucose concentrations decreased most rapidly after regular insulin administration when administered IV or SC as compared to the other formulations. The NPH insulin produced the longest suppression of blood glucose. The mean CGM interstitial compartment glucose concentrations were typically lower than the intravascular compartment glucose concentrations. The alpacas had no adverse reactions to the different insulin formulations.

Conclusions and Clinical Importance

The NPH insulin might be more appropriate for long‐term use in hyperglycemic alpacas because of its extended duration of action. A CGM is useful in monitoring glucose trends and reducing blood collection events, but it should not be the sole method for determining treatment protocols.

Epizootic hemorrhagic disease in a yak

Epizootic hemorrhagic disease virus (EHDV) infection was diagnosed in a 3-year-old yak. The yak had signs of intermittent tremors, dysphagia, oral ulcerative lesions, hemorrhagic enteritis, tachypnea, and thrombocytopenia. Postmortem diagnostics confirmed EHDV (serotype 2) using reverse-transcriptase polymerase chain reaction (RT-PCR). Gross and histopathological results were consistent with EHDV reported in other species.

Effects of pain mitigation and method of castration on behavior and feedlot performance in cull beef bulls

The objectives of this study were to evaluate the effects of castration method (banding vs. surgical) and use of analgesia on behavior and feedlot performance in cull bulls. Angus, Hereford, and Angus-crossbred bulls (n = 20; initial BW = 384 ± 59.3 kg; 336 ± 20.1 d old) were housed in feedlot pens equipped with the ability to measure individual daily feed intake. A balanced randomized block design using a 2 × 2 factorial arrangement of treatments was used. A multimodal analgesia (MMA) protocol was used and consisted of sutcutaneous ketamine stun containing butorphanol (0.01 mg/kg BW), xylazine (0.02 mg/kg BW), ketamine (0.04 mg/kg BW), and a local 2% lidocaine hydrochloride anesthetic block of the spermatic cords (10 mL/cord) and scrotum (10 mL) on d 0. Flunixin meglumine (1.2 mg/kg) was administered intravenously on d 0, 1, 2, and 3 to MMA cattle. Cattle were stratified to treatments based on breed, BW, age, and a temperament score. Treatments included 1) band castration without analgesia (BND), 2) band castration with analgesia (BND-MMA), 3) surgical castration without analgesia (SURG), and 4) surgical castration with analgesia (SURG-MMA). All castrations were performed on d 0. Chute exit velocity (EV) and time in chute (TIC) were collected on d -9, 0, 1, 2, and 13. Willingness-to-enter-chute (WTE) score, rectal temperature (TEMP), heart rate (HR), and respiration (RESP) were collected on d 0, 1, 2, 3, and 13. Cattle were weighed on d -9 and 13 while feeding behaviors were collected continuously for 57 d precastration and 28 d postcastration. There was a tendency (P < 0.09) for ADG to be greater in cattle receiving analgesia. Both SURG treatments exhibited elevated TEMP on d 1 (P < 0.001) and 2 (P < 0.05) compared to BND treatments. Postcastration DMI was greater (P = 0.02) in MMA treatments compared with nonmedicated treatments throughout the trial. Meal duration was greater (P < 0.05) in BND than SURG castrates during the first week postcastration. Results suggest that pain mitigation reduces the impact of castration on ADG and DMI.

Impact of oral meloxicam administration before and after band castration on feedlot performance and behavioral response in weanling beef bulls

Two experiments evaluated the effects of band castration and oral administration of an analgesic in association with castration on performance and behavioral and physiological responses in yearling beef bulls. In Exp. 1 Angus and Charolais-crossbred bull calves (n = 127; 309.8 ± 59.04 kg BW) and in Exp. 2 Hereford, Angus, and Hereford × Angus crossbred bulls (n = 30; 300.8 ± 4.96 kg BW) were stratified by BW and randomly assigned to 1 of 3 treatments: 1) band castration (BAND), 2) band castration with oral administration of meloxicam (BAND-MEL), and 3) sham castration (SHAM). The BAND and SHAM procedures were completed on d 0. The SHAM treatment consisted of all animal manipulations associated with band castration without band application. Meloxicam was administered on d -1, 0, and 1 (1.0, 0.5, and 0.5 mg/kg, respectively) via an oral bolus. Body weight and a subjective chute score (CS) were collected on d -1, 0, 1, 7, 14, and 21 (d 28 Exp. 1 only). In Exp. 2, jugular blood samples were collected immediately before castration and 24 h postcastration for substance P (SP) analysis. In Exp. 2, video documentation on d 0 was used to determine range of vertical head motion (DIST) on a subset of animals during treatment administration. In both experiments, ADG was similar (P ≥ 0.50) between BAND and BAND-MEL, but ADG in SHAM cattle was greater (P < 0.001) and tended (P = 0.07) to be greater than castrates in Exp. 1 and 2, respectively. In Exp. 1, CS did not differ (P ≥ 0.26) between BAND and BAND-MEL on any day, but castrates exhibited less desirable CS on d 1 and 28 than SHAM cattle. In Exp. 2, CS was not affected (P ≥ 0.41) by castration or the presence of meloxicam. In Exp. 2, DIST did not differ (P = 0.57) between BAND and BAND-MEL, but when pooled, castrates exhibited greater (P = 0.04) DIST than SHAM. In Exp. 2, plasma SP concentrations were similar between BAND and BAND-MEL (P = 0.81) and between castrates vs. sham cattle (P = 0.67). Results indicate no impact of meloxicam administration on performance or behavioral and physiological responses to band castration. However, there was a negative impact of castration on ADG and DIST.

Inadvertent transvaginal administration of sodium phosphate enemas in 2 alpaca crias

OBJECTIVE

To describe the clinical presentation and resultant metabolic disturbances following retroperitoneal administration of hyperphosphate enemas in alpaca crias.

CASE OR SERIES SUMMARY

Two crias presented to the Colorado State University Veterinary Teaching Hospital after inadvertent transvaginal retroperitoneal hyperphosphate enema administration. The first cria developed an acute onset of neurologic signs, severe hypernatremia, and died soon after presentation. The second cria developed severe hyperphosphatemia, hypocalcemia, and acidemia. The metabolic derangements normalized within 24 hours of intensive treatment with calcium supplementation and IV crystalloid fluid diuresis. The cria was discharged after 1 week in the hospital.

NEW OR UNIQUE INFORMATION PROVIDED

This report provides a description of electrolyte disturbances secondary to inadvertent transvaginal retroperitoneal administration of hyperphosphate enemas in 2 crias and attendant clinical signs of these disturbances. Management of hyperphosphatemia and hypocalcemia in 1 cria via aggressive fluid therapy with calcium supplementation led to a rapid and sustained normalization of phosphorus, calcium, and acid-base balance.

Equine herpesvirus-1 infected peripheral blood mononuclear cell subpopulations during viremia

Infection with equine herpesvirus-1 (EHV-1) causes respiratory disease, late term abortions and equine herpesvirus myeloencephalitis (EHM) and remains an important problem in horses worldwide. Despite increasing outbreaks of EHM in recent years, our understanding of EHM pathogenesis is still limited except for the knowledge that a cell-associated viremia in peripheral blood mononuclear cells (PBMCs) is a critical link between primary respiratory EHV-1 infection and secondary complications such as late-term abortion or EHM. To address this question our objective was to identify which PBMC subpopulation(s) are infected during viremia and may therefore play a role in transmitting the virus to the vascular endothelium of the spinal cord or pregnant uterus. PBMCs from 3 groups of animals were collected between days 4 and 9 following experimental infection with EHV-1 strain Findlay/OH03 or strain Ab4. PBMCs were labeled with primary antibodies selective for CD4+ or CD8+ T lymphocytes, B-lymphocytes, or monocytes and positively selected using magnetic bead separation. Cell numbers and EHV-1 genome numbers in each subpopulation were then determined using quantitative PCR for β-actin and the EHV-1 glycoprotein B, respectively. Viral genomic DNA was found in all PBMC subpopulations; the CD8+ lymphocytes were most frequently positive for viral DNA, followed by B-lymphocytes. These differences were statistically significant in horses infected with the EHV-1 strain Findlay/OH03, and ponies with Ab4. These results differ from what has been reported in in vitro studies, and indicate that different PBMC subpopulations may play different roles in EHV-1 viremia.

Prevalence of bovine viral diarrhea virus infections in alpacas in the United States

OBJECTIVE

To determine the prevalence of bovine viral diarrhea virus (BVDV)-infected alpaca herds in the United States and investigate factors associated with seropositive herd status and, subsequently, determine the proportion of animals within seropositive alpaca herds that are persistently infected (PI) carriers for BVDV, obtain information regarding previous herd exposure to BVDV, determine titers of anti-BVDV antibodies of dams, and ascertain whether individual seropositive crias had received supplemental colostrum at birth.

DESIGN

Prevalence study.

ANIMALS

63 alpaca herds with >or= 12 registered female alpacas.

PROCEDURES

250 alpaca breeders were randomly selected from 562 eligible herds listed in the Alpaca Owner and Breeders Association membership directory and mailed a voluntary participation request. Sixty-three alpaca breeders participated in the study. From each herd, blood samples from >or= 4 crias were tested for BVDV, BVDV RNA, and serum neutralizing antibodies against BVDV. A region of the genome of BVDV recovered from PI crias was sequenced to determine genetic homology.

RESULTS

Among the 63 herds, 16 (25.4%) had seropositive crias and 4 (6.3%) had PI crias. Infections in 3 of the 4 herds with PI crias were linked as evidence by the genetic homologies of viruses. In addition to PI crias, feeding supplemental colostrum was associated with herd seropositivity.

CONCLUSIONS AND CLINICAL RELEVANCE

Results confirmed the importance of BVDV infections in alpacas in the United States and highlighted the importance of determining the BVDV infection status of animals before they are commingled to limit exposure of herds to BVDV infection.

Hepatic encephalopathy in two goat kids with common paternity

Two juvenile, intact, female mixed-breed goats from a common sire were presented for periodic neurologic deficits, seizures, and a generalized loss of body condition that occurred over a 4-6-week period. On physical examination, both goats were thin, obtunded, blind, and ataxic. Laboratory diagnostics revealed increased serum bile acids (95 micromol/l; reference interval: 0-50 micromol/l) in one of the goats. Both goats exhibited progressive physical and mental deterioration, and were eventually euthanized. Upon necropsy, no significant macroscopic lesions were noted. Microscopic examination, however, demonstrated hepatocellular atrophy and anomalies in the hepatic microvasculature, including duplication of hepatic arteries, small-to-indistinct portal veins, and oval cell hyperplasia. In addition, spongiform change was microscopically identified throughout the parenchyma of the brain, most notably within the white matter and along the junction of gray and white matter. The diagnosis of congenital portal vein hypoperfusion (suggestive of a portosystemic shunt) with resultant hepatic encephalopathy was proposed in each case based on the characteristic microscopic lesions in conjunction with the signalment and history of the goats. The observation that the affected kids were sired by the same buck suggests a hereditary basis for the condition in these animals as well.

Lack of correlation between antibody titers to fibrinogen-binding protein of Streptococcus equi and persistent carriers of strangles

Previously published studies have neither used nor reported the results of an indirect enzyme-linked immunosorbent assay (iELISA) to measure serologic responses in natural outbreaks of strangles. The concept of using serologic responses to identify persistent carriers of Streptococcus equi has been proposed but not scientifically evaluated. The specific aims of the current study were to determine the duration and level of truncated fibrinogen-binding protein-specific (SeM allele 1) antibody production in ponies involved in a natural outbreak of strangles and to determine if test results from this serologic iELISA could predict persistent carrier status. Serologic samples were obtained before and after an outbreak of naturally occurring strangles infection. Persistent carriers of S. equi were identified via culture and polymerase chain reaction (PCR) testing of lavage fluid collected from the guttural pouches and nasopharynx or swabs of the nasopharynx after recovery from acute disease and at postmortem examination. Logistic regression analysis was used to determine if an association existed between serologic response and persistent carrier state. The ELISA reported in the current study definitively confirmed a recent exposure to S. equi. However, the measured serologic response did not predict carrier status in this strangles outbreak. Therefore, a guttural-pouch endoscopy with subsequent culture or PCR testing to detect S. equi remains the most accurate method available for the identification of persistent carriers.

Cytology in food animal practice

Diagnostic cytology can greatly aid the clinician in determining a more refined diagnosis, prognosis, and treatment plan to serve the client and patient better. Sample collection is not difficult and can be done in the field as well as in a hospital setting. The collection and sample handling procedures described in this article can help the clinician to obtain diagnostically valuable samples. In many cases, preliminary cytologic evaluation can be performed by the general practitioner. Additional diagnostic evaluation and interpretation are readily available from trained pathologists at diagnostic laboratories.

Trichophytobezoar duodenal obstruction in New World camelids

OBJECTIVE

To describe clinical findings, surgical treatment, and outcome associated with trichophytobezoar duodenal obstruction in New World camelids.

STUDY DESIGN

Retrospective study.

ANIMALS

Alpacas (7) and 1 llama.

METHODS

Historical and clinical data were obtained from the medical records of New World camelids with a diagnosis of trichophytobezoar duodenal obstruction confirmed by surgical exploration or necropsy.

RESULTS

Seven camelids were <1 year old. Abnormal clinical findings included anorexia, reduced fecal output, recumbency, colic, abdominal distension, regurgitation, decreased serum chloride concentration, increased serum bicarbonate concentration, and/or elevated first gastric compartment chloride concentration. Survey abdominal radiographs obtained (4 animals) revealed gastric distension (4) and/or visualization of the obstruction (2). Diagnosis was confirmed at necropsy (1) or surgery (7). Right paracostal celiotomy was performed on all animals and duodenotomy (3) or retropulsion of the trichophytobezoar combined with third compartment gastrotomy (4) was used to remove the obstruction. Six animals survived to discharge and 5 were healthy at follow-up, 8-20 months later. The remaining discharged alpaca was healthy at 12 months but subsequently died of unrelated causes.

CONCLUSIONS

Diagnosis of trichophytobezoar duodenal obstruction should be considered in juvenile New World camelids with abdominal distension and hypochloremic metabolic alkalosis. Right paracostal celiotomy can be used for access to the descending duodenum and third gastric compartment for surgical relief of obstruction.

CLINICAL RELEVANCE

Duodenal obstruction from bezoars should be considered in New World camelids <1year of age with abdominal distension and hypochloremic metabolic alkalosis. Surgical relief of the obstruction by right paracostal celiotomy has a good prognosis.

Evaluation of ovine herpesvirus type 2 infections, as detected by competitive inhibition ELISA and polymerase chain reaction assay, in dairy cattle without clinical signs of malignant catarrhal fever

OBJECTIVE

To monitor ovine herpesvirus type 2 (OvHV-2) infection status and the association between OvHV-2 infection and development of clinical signs of malignant catarrhal fever (MCF) in cattle.

DESIGN

Longitudinal study.

ANIMALS

30 mature adult cows and 18 cattle submitted for necropsy.

PROCEDURE

Blood and milk samples were collected at monthly intervals from 30 adult cows for 20 consecutive months. Nasal and ocular swab specimens were also collected during months 9 through 20. Polymerase chain reaction (PCR) assay for detection of OvHV-2 was performed on blood, milk, nasal swab, and ocular swab specimens. Competitive inhibition ELISA (CI-ELISA) for detection of antibodies against MCF viruses was performed on serum samples obtained prior to study initiation and monthly during the last 12 months. Tissues obtained from herdmates without clinical signs of MCF that were submitted for necropsy were analyzed for OvHV-2 DNA via PCR assay for possible sites of latency.

RESULTS

Initially, 8 of 30 cows had positive CI-ELISA results. Seroconversion was detected in 4 cows. Ovine herpesvirus type 2 DNA was intermittently detected in blood, milk, nasal secretions, or ocular secretions from 17 of 30 cows. Twenty-one cows had positive CI-ELISA or PCR assay results. No cattle in the study developed clinical signs of MCF. Results of PCR assays performed on tissue samples from 2 of 18 animals submitted for necropsy were positive for OvHV-2. CONCLUSIONS AND CLINICAL RELEVANCE; OvHV-2 infection can occur in cattle without concurrent development of clinical MCF. Ovine herpesvirus type 2 DNA was detected intermittently, suggesting fluctuating viral DNA loads or reinfection in subclinical cattle. A definitive site of latency was not identified from tissues obtained during necropsy.

Comparison of the odds of isolation, genotypes, and in vivo production of major toxins by Clostridium perfringens obtained from the gastrointestinal tract of dairy cows with hemorrhagic bowel syndrome or left-displaced abomasum

OBJECTIVE

To compare the frequency of isolation, genotypes, and in vivo production of major lethal toxins of Clostridium perfringens in adult dairy cows affected with hemorrhagic bowel syndrome (HBS) versus left-displaced abomasum (LDA).

DESIGN

Case-control study.

ANIMALS

10 adult dairy cattle with HBS (cases) and 10 adult dairy cattle with LDA matched with cases by herd of origin (controls).

PROCEDURE

Samples of gastrointestinal contents were obtained from multiple sites during surgery or necropsy examination. Each sample underwent testing for anaerobic bacteria by use of 3 culture methods. The genotype of isolates of C. perfringens was determined via multiplex polymerase chain reaction assay. Major lethal toxins were detected by use of an ELISA. Data were analyzed with multivariable logistic regression and chi2 analysis.

RESULTS

C. perfringens type A and type A with the beta2 gene (A + beta2) were the only genotypes isolated. Isolation of C. perfringens type A and type A + beta2 was 6.56 and 3.3 times as likely, respectively, to occur in samples from cattle with HBS than in cattle with LDA. Alpha toxin was detected in 7 of 36 samples from cases and in 0 of 32 samples from controls. Beta2 toxin was detected in 9 of 36 samples from cases and 0 of 36 samples from controls.

CONCLUSIONS AND CLINICAL RELEVANCE

C. perfringens type A and type A + beta2 can be isolated from the gastrointestinal tract with significantly greater odds in cattle with HBS than in herdmates with LDA. Alpha and beta2 toxins were detected in samples from cows with HBS but not from cows with LDA.

Risk factors associated with hemorrhagic bowel syndrome in dairy cattle

OBJECTIVE

To determine risk factors associated with hemorrhagic bowel syndrome (HBS) among dairy cattle in the United States and identify characteristics of HBS in individual cows.

DESIGN

Cross-sectional, population-based survey.

SAMPLE POPULATION

A stratified random sample of 1,013 dairy operations with > or = 30 cows located in 21 states.

PROCEDURE

Information on management and animal health-related topics was collected with a questionnaire.

RESULTS

HBS was estimated to have been observed on 9.1% of operations during the preceding 5 years and on 5.1% of operations during the preceding 12 months. Factors found in multivariable analysis to be associated with the occurrence of HBS during the preceding 12 months were large herd size, administration of bovine somatotropin, and routine use of milk urea nitrogen concentration to determine ration composition. Use of pasture as part of the lactating cow ration during the growing season was associated with decreased odds of HBS in operations with rolling herd average milk production < or = 20,000 lb, whereas in operations with higher milk production, use of pasture was not associated with occurrence of HBS. For individual cows with signs consistent with HBS, the third lactation was the median of the parity distribution and the median time between parturition and the onset of clinical signs was 104 days.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggest that management practices implemented to achieve high milk production may increase the risk of developing HBS in dairy cattle. Increased consumption of a high-energy diet seems to be the most plausible common pathway for all of the risk factors that have been described.

Immunologic responses to West Nile virus in vaccinated and clinically affected horses

OBJECTIVE

To compare neutralizing antibody response between horses vaccinated against West Nile virus (WNV) and horses that survived naturally occurring infection.

DESIGN

Cross-sectional observational study.

ANIMALS

187 horses vaccinated with a killed WNV vaccine and 37 horses with confirmed clinical WNV infection.

PROCEDURE

Serum was collected from vaccinated horses prior to and 4 to 6 weeks after completion of an initial vaccination series (2 doses) and 5 to 7 months later. Serum was collected from affected horses 4 to 6 weeks after laboratory diagnosis of infection and 5 to 7 months after the first sample was obtained. The IgM capture ELISA, plaque reduction neutralization test (PRNT), and microtiter virus neutralization test were used.

RESULTS

All affected horses had PRNT titers > or = 1:100 at 4 to 6 weeks after onset of disease, and 90% (18/20) maintained this titer for 5 to 7 months. After the second vaccination, 67% of vaccinated horses had PRNT titers > or = 1:100 and 14% had titers < 1:10. Five to 7 months later, 33% (28/84) of vaccinated horses had PRNT titers > or = 1:100, whereas 29% (24/84) had titers < 1:10. Vaccinated and clinically affected horses' end point titers had decreased by 5 to 7 months after vaccination.

CONCLUSIONS AND CLINICAL RELEVANCE

A portion of horses vaccinated against WNV may respond poorly. Vaccination every 6 months may be indicated in certain horses and in areas of high vector activity. Other preventative methods such as mosquito control are warranted to prevent WNV infection in horses.

Viral diseases of the ruminant nervous system

This article presents the etiology, epidemiology, clinical features,and diagnosis of the primary viral neurologic diseases observed in ruminants. In general, these viral neurologic diseases are uncommon but often fatal. Rabies virus is perhaps the most important cause of encephalitis in cattle because of the public health implications. Other viral encephalitis diseases in ruminants include bovine herpesvirus encephalomyelitis, pseudorabies, malignant catarrhal fever, ovine and caprine lentiviral encephalitis, West Nile virus encephalitis, Borna disease, paramyxoviral sporadic bovine encephalomyelitis,and ovine encephalomyelitis (louping-ill).

Evaluation and treatment of decreased libido associated with painful lumbar lesions in two bulls

Painful lesions of the vertebral column may cause decreased libido in bulls. Radiographic evaluation of vertebral skeletal problems in mature bulls is limited because of high body mass. Two breeding bulls with signs of decreased libido and spermatozoa production were evaluated. Initial systemic medical treatment for the conditions had not focused on localized lesions and was unsuccessful. Nuclear scintigraphy was performed in both bulls to determine the location of vertebral column lesions and facilitate localized treatment. Localized medical treatment was successful and resulted in decreased signs of pain and increased spermatozoa production in both bulls.

Occurrence of infectious upper respiratory tract disease and response to vaccination in horses on six sentinel premises in northern Colorado

REASONS FOR PERFORMING STUDY

Horses vaccinated against common agents of infectious upper respiratory disease (IURD) may not have detectable serum antibody and may not be protected from clinical disease.

OBJECTIVES

The objectives of this study were to 1) investigate the serological response of horses to vaccination against influenza virus (H3N8 and H7N7) and equine herpesviruses (EHV) in a field setting and 2) evaluate associations among vaccination status, serum antibody concentrations, and occurrences of IURD in monitored horses.

METHODS

In this study, horses on 6 Colorado premises were vaccinated parenterally against influenza virus and EHV, and serological response evaluated. Horses were monitored, and biological samples collected from individuals with clinical IURD and control horses.

RESULTS

Of 173 horses, 61 (35.3%), 21 (12.1%) and 4 (2.3%) seroconverted in response to vaccination against EHV, influenza virus H7N7 and influenza virus H3N8, respectively.

CONCLUSIONS

Outbreaks of IURD in study horses were associated with influenza virus H3N8 and Streptococcus equi infection, and serological response to vaccination with conventional products was poor.

POTENTIAL RELEVANCE

These results confirm that horses may not respond with detectable serological responses to conventional vaccination against common respiratory viruses and, therefore, suggest that alternate methods of protecting horses against common respiratory viruses should be sought.

Hemorrhagic bowel syndrome in dairy cattle: 22 cases (1997-2000)

OBJECTIVE

To determine signalment, history, and clinical, necropsy, and microbiologic findings in dairy cows with hemorrhagic bowel syndrome.

DESIGN

Retrospective study.

ANIMALS

22 adult dairy cows from a single farm in Colorado.

PROCEDURE

Medical records were reviewed for information on signalment, medical and reproductive history, the owner's chief complaints, results of physical examinations and ancillary diagnostic tests, treatment and response to treatment, results of microbiologic testing, and, if applicable, postmortem findings.

RESULTS

Common clinical signs were acute signs of profound depression, decreased milk production, tachycardia, ruminal stasis, abdominal distention, and dark clotted blood in the feces. Rectal examination revealed distended loops of small intestine in 7 of 14 cows. Transabdominal ultrasonography revealed small intestinal ileus and distention in 12 of 12 cows and homogeneous echogenic intraluminal material compatible with intraluminal hemorrhage and clot formation in 4. Seven of 8 cows treated medically died; 9 of 13 cows that underwent surgery died or were euthanatized. Clostridium perfringens was isolated from fecal samples from 17 of 20 cows. The most common morphologic diagnosis at necropsy was severe necrohemorrhagic enteritis or jejunitis with intraluminal hemorrhage or blood clots. The most prominent histologic finding was severe, segmental submucosal hemorrhage and edema of the small intestine.

CONCLUSIONS AND CLINICAL RELEVANCE

Results confirm that in adult cattle, hemorrhagic bowel syndrome is a sporadic acute intestinal disorder characterized by intraluminal hemorrhage and obstruction of the small intestine. Clostridium perfringens was consistently isolated from the feces of affected cows. The prognosis for affected cows was grave.

Percutaneous collection of fetal fluids for detection of bovine viral diarrhea virus infection in cattle

OBJECTIVE

To develop a method for percutaneous collection of fetal fluid from cattle in the late stages of gestation and determine whether bovine viral diarrhea virus (BVDV) can be isolated from such fluids.

DESIGN

Case series.

ANIMALS

169 pregnant beef cattle.

PROCEDURE

Animals were restrained in a squeeze chute, and hair was clipped from a region of the right flank. Pregnancy was confirmed, and fetal fluids were identified by means of abdominal ultrasonography. Fetal fluid was collected with a spinal needle. Virus isolation was performed on fetal fluids, WBC lysates from 160 live calves, and tissues from 12 calves that died or were aborted. Blood samples collected from adult cattle were assayed with an immunoperoxidase monolayer assay.

RESULTS

Fourteen animals aborted or delivered premature calves within 3 weeks after fetal fluid collection; however, it could not be determined whether this was a complication of the procedure or attributable to other factors. Results of BVDV isolation from fetal fluid samples were negative for 168 animals. However, a noncytopathic BVDV was isolated from fetal fluid obtained from a 2-year-old heifer; results of the immunoperoxidase assay of serum from this heifer were also positive, and a noncytopathic BVDV was isolated from tissue specimens from a stillborn calf produced by this heifer.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggest that fetal fluids can be collected percutaneously from cattle in the late stages of gestation and that virus isolation performed on fetal fluids can be used to identify fetuses infected with BVDV in utero. However, safety of the procedure could not be evaluated.

Biosecurity and bovine respiratory disease

Although biosecurity practices play a role in minimizing respiratory disease in cattle, they must be used in combination with other management strategies that address the many other risk factors. Because the pathogens involved in bovine respiratory disease are enzootic in the general cattle population, biosecurity practices aimed at the complete elimination of exposure are currently impractical. Several animal husbandry and production management practices can be used to minimize pathogen shedding, exposure, and transmission within a given population, however. Various combinations of these control measures can be applied to individual farms to help decrease the morbidity and mortality attributed to respiratory disease.

Bacteremia associated with naturally occuring acute coliform mastitis in dairy cows

OBJECTIVE

To determine the incidence of bacteremia in dairy cows with naturally occurring acute coliform mastitis (ACM) with a wide range of disease severity.

DESIGN

Cohort study.

ANIMALS

144 dairy cows with ACM from 6 herds.

PROCEDURE

Cows were examined at time of identification of ACM (time 0) and classified as having mild, moderate, or severe mastitis on the basis of rectal temperature, hydration status, rumen contraction rate, and attitude. Cows were reexamined at 24 or 48 hours. Bacteriologic culturing of milk and blood (30 ml), CBC, and serum biochemical analysis were performed at each time point. Appropriate samples were obtained at a single point from herdmates without mastitis (controls) that were closely matched for lactation number and days since parturition. Blood culture results were compared among severity groups and controls by use of chi2 tests, as was outcome of an ACM episode for cows grouped by blood bacterial isolates.

RESULTS

Bacteria were isolated from 52 blood samples from 46 of 144 (32%) cows with ACM, which was significantly more than control cows (11/156; 7.1%). Group-1 isolates (Escherichia coli, Pasteurella multocida, Mannheimia haemolytica, Klebsiella pneumoniae, Enterobacter agglomerans, and Salmonella enterica serotype Typhimurium) were identified in 20 of 144 (14%) cows with ACM and 0 of 156 control cows. Group-1 isolates were identified in 4.3, 9.1, and 42% of cows classified as having mild, moderate, and severe ACM, respectively. Escherichia coli and K pneumoniae milk and blood isolates obtained from the same cow were of the same genotype. Bacillus spp were identified in 21 of 144 (15%) cows with ACM, which was significantly more than control cows (3/156; 1.9%). Thirty-five percent of cows with a group-1 isolate died during the mastitis episode.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggest that bacteremia develops in a substantial proportion of cows with ACM. Classification of severity of disease is important for establishment of effective treatment protocols; parenteral antimicrobial treatment may be indicated in cows with ACM.

Selenium and vitamin E

Deficiency of selenium and vitamin E has recently been identified as a major health concern of sheep producers in certain regions of the United States, and familiarity with published data on these nutrients seems to be of value to small ruminant practitioners. This article begins with a description of the biochemical roles and metabolism of selenium and vitamin E. A literature review follows in which the influence of these nutrients on the musculoskeletal, reproductive, and immune systems, as well as on flock productivity, is discussed. Methods for detection of deficiency and supplementation strategies are also described.

Reproductive techniques in sheep

This article reviews current methods of evaluating reproductive performance in the sheep industry. The reproductive technologies of breeding soundness examination, reproductive ultrasonography, estrus manipulation, artificial insemination, and embryo transfer are also extensively discussed. The veterinarian's current and future role in the application of these technologies is discussed.

Use of systemic disease signs to assess disease severity in dairy cows with acute coliform mastitis

OBJECTIVE

To evaluate the use of systemic disease signs for classifying severity of acute coliform mastitis in dairy cows.

DESIGN

Prospective cohort study.

ANIMALS

144 dairy cows.

PROCEDURE

Cows were examined at the time of initial identification of disease (time 0) and classified as having mild, moderate, or severe disease on the basis of rectal temperature, hydration status, rumen contraction rate, and attitude. A CBC and serum biochemical analyses were performed, and milk samples were submitted for bacterial culture at time 0 and 48 hours later.

RESULTS

69 cows were classified as having mild disease, 44 as having moderate disease, and 31 as having severe disease. Median WBC and neutrophil counts were significantly lower in cows with moderate or severe disease at time 0 than in cows with mild disease. Band neutrophil count was significantly higher at 48 hours and serum calcium concentration was significantly lower at time 0 and at 48 hours in cows with severe or moderate disease, compared with cows with mild disease. Twenty-eight, 51, and 77% of cows with mild, moderate, and severe disease, respectively, had > 100,000 colony-forming units/ml of milk at time 0. The odds that a cow with severe disease would die or be culled were 3.6 times the odds for a cow with moderate disease and 11.2 times the odds for a cow with mild disease.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggest that a classification scheme based on readily observable systemic disease signs can be used to classify disease severity in cows with acute coliform mastitis.

Malignant catarrhal fever: polymerase chain reaction survey for ovine herpesvirus 2 and other persistent herpesvirus and retrovirus infections of dairy cattle and bison

Using a polymerase chain reaction (PCR) test for sequences of ovine herpesvirus 2 (OHV2), this virus was shown to be significantly associated with sheep-associated malignant catarrhal fever (SA-MCF) in terminal cases of disease in 34 cattle and 53 bison. Ovine herpesvirus 2 was not detected in cattle (38) and bison (10) that succumbed to other diseases. Other persistent herpesviruses, retroviruses, and pestivirus, some of which have been previously isolated from cases of SA-MCF, were not associated with the disease. These included bovine herpesvirus 4 (BHV4), bovine lymphotrophic herpesvirus (BLHV), bovine syncytial virus (BSV, also known as bovine spumavirus), bovine immunodeficiency virus (BIV), and bovine viral diarrhea virus (BVDV). A PCR survey for OHV2 in DNA from individual cow's peripheral blood lymphocytes in 4 dairies showed that the 1 dairy that was in close contact to sheep had a prevalence of OHV2 of 21.3%, whereas the 3 other dairies had no OHV2. Prevalence of the other herpesviruses and retroviruses in the dairy cows was variable, ranging from 2% to 51% for BHV4, 52% to 78.7% for BLHV, and 10% to 34% for BSV. Bovine lymphotrophic herpesvirus and BSV were also found in a few (1-4 of 21 tested) cases of terminal SA-MCF, but BIV and BVDV were not found in either the dairy cows sampled, or in the cases of SA-MCE No significant correlation was found between the presence of any 2 viruses (OHV2, BHV4, BLHV, BSV) in the dairy cows or terminal cases of SA-MCE