Use of a national identification database to determine the lifetime prognosis in cattle with necrotic laryngitis and the predictive value of venous pCO2.

BACKGROUND: Necrotic laryngitis, caused by Fusobacterium necrophorum, frequently requires surgical intervention (laryngostomy) in the chronic stage. HYPOTHESIS/OBJECTIVES: To determine survival until slaughter of cattle surgically treated for necrotic laryngitis and to identify predictors of mortality. ANIMALS: A total of 221 cattle diagnosed with necrotic laryngitis by laryngoscopy and surgically treated METHODS: Retrospective cohort study. Clinical records were matched with the national cattle identification, registration, and movement database. Information on possible predictors including clinical examination, biochemistry, and surgery was collected. A multivariable Cox proportional hazard model was used to identify predictors of mortality. RESULTS: The overall survival rate was 65.2% and 58.6% of the animals with a completed life cycle could be slaughtered. Animals <6 months old experienced significantly higher mortality risk (hazard ratio [HR], 2.0; 95% confidence interval [CI], 1.1-3.5). The venous partial pressure of carbon dioxide (pCO2 ; HR, 2.4; 95% CI, 1.4-4.2) at a 64.5 mm Hg cut-off was most significantly associated with mortality. Sensitivity and specificity of the final model consisting of age and pCO2 were 49.1 and 86.4%, respectively. Instead of pCO2 , total carbon dioxide (TCO2 ) could also be used, with similar diagnostic accuracy. CONCLUSIONS AND CLINICAL RELEVANCE: The lifetime prognosis for chronic necrotic laryngitis in cattle with surgical intervention appears fair. Age, venous pCO2 and TCO2 are easily accessible predictors of survival to support owners and veterinarians in their decision process of whether or not to operate and to identify high risk animals that require more intensive follow-up.

Enhanced infection of avian influenza virus H9N2 with infectious laryngeotracheitis vaccination in chickens.

Avian influenza and infectious laryngeotracheitis viruses are common causes of respiratory diseases in chickens with economical importance worldwide. In this study, we investigated the effect of experimental co-infection of avian influenza virus-H9N2 (AIV-H9N2) with infectious laryngeotracheitis virus (ILTV) live-attenuated vaccine (LAR-VAC®) on chickens. Four experimental groups were included in this study: negative control group, AIV-H9N2 group, AIV-H9N2+LAR-VAC® group, and LAR-VAC® group. AIV-H9N2 was inoculated intranasally to challenged groups at 35 days of age. On the same day, LAR-VAC® was ocularly administered to vaccinated groups. Chickens were observed for clinical signs, changes in body weight and mortality rates. Tissue samples, sera, tracheal and cloacal swabs, and blood were also collected at 3, 6, 9 and 12 days post-infection (PI). A significant increase in clinical signs and mortality rates were observed in the AIV-H9N2 + LAR-VAC® group. Moreover, chickens coinfected with AIV-H9N2 and LAR-VAC® showed a significant decrease in body weight and lymphoid organs indices. The tracheal gross and histopathological lesions and the shedding titer and period of AIV-H9N2 were significantly higher in AIV-H9N2 + LAR-VAC® group when compared to other groups. Furthermore, AIV-H9N2 infection leads to humoral and cellular immunosuppression as shown by a significant decrease in the CD4+/CD8+ ratio and antibody responses to ILTV and a significant increase in H/L ratio. In conclusion, this is the first report of co-infection of AIV-H9N2 and ILTV vaccine in chickens, which leads to increased pathogenicity, pathological lesions, and AIV-H9N2 shedding titer and period, which can lead to severe economic losses due to poor weight gain and mortality.

Molecular epidemiology of infectious laryngotracheitis: a review.

Infectious laryngotracheitis (ILT) is an economically important respiratory disease of poultry that affects the poultry industry worldwide. The disease is caused by gallid herpesvirus I (GaHV-1), a member of the genus Iltovirus, family Herpesviridae, subfamily Alphaherpesvirinae. The current incidence of the disease is heavily influenced by live attenuated vaccines, which have been used extensively since their introduction in the mid-twentieth century. The capability of current live attenuated vaccine viruses to revert to virulence and spread from bird to bird has shaped the molecular epidemiology of ILT. Because of the antigenic homogeneity among GaHV-1 strains, differentiation of strains has been achieved by targeting genomic differences between outbreak-related isolates and vaccine strains. Numerous genes and genomic regions have been utilized in the development of DNA-based diagnostic assays to differentiate outbreak-related isolates from vaccine strains in countries where ILT outbreaks have occurred. More recently, full genome sequences have allowed determination of the origin of some of the outbreak-related isolates circulating in some poultry production countries. Overall, molecular typing data collected worldwide have identified live attenuated vaccine-related isolates as the primary source for outbreaks of the disease.

Gastroesophageal reflux and laryngeal dysfunction in a dog.

CASE DESCRIPTION: A 7-year-old neutered male Saint Bernard was evaluated because of a 6-month history of coughing, gagging, change in phonation, excessive panting, and chronic intermittent vomiting and diarrhea. CLINICAL FINDINGS: Physical examination revealed no remarkable findings other than panting. Total thyroxine concentration and results of a CBC, serum biochemistry analysis, urinalysis, and thoracic radiography were within reference limits. A laryngeal examination revealed edema, erythema, and ulceration of the larynx and pharynx, with normal laryngeal movement. Results of bronchoscopy and cytologic examination of bronchoalveolar lavage fluid were diagnostic only for distal tracheitis. Esophagoscopy and an esophagography revealed esophagitis consistent with gastroesophageal reflux. Gastroduodenoscopy and histologic examination of biopsy specimens revealed Helicobacter colonization and lymphocytic or plasmacytic enteritis. TREATMENT AND OUTCOME: Following treatment for gastroesophageal reflux and suspected Helicobacter infection with combination antacid and antimicrobial treatment, the dog's respiratory signs resolved but vomiting continued. Gastroduodenoscopy revealed complete resolution of the previous laryngitis, pharyngitis, and esophagitis. Treatment for the lymphocytic or plasmacytic enteritis was initiated with prednisone (1 mg/kg [0.45 mg/lb], p.o., q 12 h) and a novel protein diet. The previous treatment was also continued. Complete resolution of clinical signs was maintained 4 months after initiation of appropriate treatment. CLINICAL RELEVANCE: Laryngeal dysfunction induced by gastroesophageal reflux as occurred in the patient described in this report is a previously undocumented association in the veterinary literature. This association could be a potential consideration in dogs with concurrent respiratory and gastrointestinal signs. The present report may provide a basis for further studies investigating this association.

Detection and quantitation of gallid herpesvirus 1 in avian samples by 5' Taq nuclease assay utilizing Minor Groove Binder technology.

A 5' Taq nuclease assay utilizing Minor Groove Binder technology and targeting the thymidine kinase gene of gallid herpesvirus 1 (GaHV-1) was designed and optimized for use in diagnosing avian infectious laryngotracheitis. The assay was specific for GaHV-1 in that it did not react with other avian viral or bacterial pathogens. The detection limit was 1.0x10(-2) median tissue culture infectious dose per reaction or 90 target copies per reaction. Fifteen out of 41 diagnostic samples from sick birds reacted in the assay, five of which produced a typical alphaherpesvirus cytopathic effect (CPE) on chicken kidney (CK) cells. Sequencing, using amplicons generated by a polymerase chain reaction with primers flanking the 5' Taq nuclease amplicon, confirmed the presence of GaHV-1 in six samples (two producing alphaherpesvirus CPE on CK cells, three not producing alphaherpesvirus CPE, and one that was not inoculated onto CK cells). Tracheal swabs taken from 18 healthy broilers did not react in the assay. The ability of the assay to determine viral load in samples was demonstrated. Overall the assay is suitable for the rapid diagnosis of infectious laryngotracheitis.

Laryngeal disease in cats: a retrospective study of 35 cases.

The aim of this retrospective study was to review the medical records of cats referred to the University of Bristol for investigation of laryngeal disease (n=35). Cases were categorised into one of four groups: cats with laryngeal paralysis (LP, n=14), laryngeal neoplasia (n=10), laryngeal inflammation (n=6), or miscellaneous laryngeal diseases (n=5). Laryngoscopy and echolaryngography were useful diagnostic techniques but histology was required for diagnosis of diseases other than LP. Two cats with lymphoma received chemotherapy achieving survival times of 60 and 1440 days. Four cats with LP were treated surgically, with a median survival time of 300 days (range 10-360 days) and six were treated conservatively with a median survival time of 780 days (range 300-2520 days). Three cats with inflammatory disease were treated medically and one by excision of the lesion. Two cats achieved survival times of 120 and 2800 days. Cats with LP, laryngeal lymphoma or laryngitis had excellent long-term survival following appropriate treatment.

Diphtheroid necrotic laryngitis in three calves - diagnostic procedure, therapy and post-operative development.

Diphtheroid necrotic inflammation of the larynx in calves in its advanced stage mostly requires surgical therapy. Diagnostic procedure, surgery and post-operative care were described for three calves (aged 3-8 weeks). The clinical diagnosis was confirmed by laryngoscopy. In all three cases, a laryngotomy with resection of necrotic tissue was performed. After surgery two calves showed complications (tracheal stricture, mucosal hyperplasia). Both were cured in further surgery. In cases of post-operative complications, further surgical intervention can be very promising.

Deletion of the non-essential UL0 gene of infectious laryngotracheitis (ILT) virus leads to attenuation in chickens, and UL0 mutants expressing influenza virus haemagglutinin (H7) protect against ILT and fowl plague.

Infectious laryngotracheitis virus (ILTV), a member of the Alphaherpesvirinae, possesses several unique genes. One of them, UL0, encodes an abundantly expressed protein that accumulates in the nuclei of ILTV-infected cells. This study demonstrates that this protein is dispensable for in vitro virus replication and that UL0 deletion mutants exhibit only minor growth defects in cultured cells. The UL0 gene locus of ILTV was also used for insertion of foreign DNA sequences encoding enhanced GFP or haemagglutinin (HA), subtype H7, of a highly pathogenic avian influenza virus under the control of the human cytomegalovirus immediate-early gene promoter. Expression of foreign proteins was shown by (immuno)fluorescence tests and Western blot analyses. After experimental infection of chickens, UL0 deletion mutants proved to be attenuated when compared to both parental wild-type ILTV and an UL0 rescue mutant. Nevertheless, all animals immunized with UL0-negative ILTV were protected from clinical disease after subsequent infection with virulent ILTV. Furthermore, all animals immunized with HA-expressing ILTV survived a lethal challenge with H7 subtype avian influenza virus with minimal clinical signs. Thus, an UL0-negative and HA-expressing ILTV recombinant may be used as a bivalent live virus vaccine against ILT and fowl plague. Unlike inactivated influenza virus vaccines, HA-expressing ILTV recombinants should be suitable for mass application and would also permit serological discrimination between vaccinated and virus-infected animals in the field.

Detection and differentiation of CAV-1 and CAV-2 by polymerase chain reaction.

Canine adenovirus type 1 (CAV-1) and type 2 (CAV-2) can be categorized in the laboratory by haemagglutination and neutralization tests, but they are difficult to differentiate from each other in specimens, especially when infection occurs in the digestive tract. The object of this study was to develop a simple method of detecting and differentiating them. One pair of common primers was designed and synthesized according to the sequences of the E3 and flanking regions and a polymerase chain reaction (PCR) assay was established using these two primers to amplify the virus-specific DNA fragment from clinical specimens as well as from cell cultures. After elecctrophoresis, under the same amplification conditions, 508 bp and 1030 bp PCR products were observed for CAV-1 and CAV-2, respectively. These were further shown to be adenovirus specific by dot hybridization and sequencing. As only one pair of primers was involved in the PCR procedure, it was faster and easier to perform than any of the other assays used for detecting canine adenovirus, making it applicable in the rapid confirmation of diagnosis and differentiation of the two types of canine adenoviruses.

Effect of route of vaccination on the prevention of infectious laryngotracheitis in commercial egg-laying chickens.

Commercial egg-laying chickens were vaccinated for infectious laryngotracheitis (ILT) with one of five commercially available vaccines (designated A, B, C, D, and E) on five separate farms by either eyedrop (e), spray (s), or double dose in the water (w) method. Groups were identified by the vaccine designation and the method of vaccination. Birds from the test groups were transferred to an isolation facility and challenged intratracheally 3 wk after vaccination. The remaining birds were given a second vaccination with the original chicken embryo origin vaccine by spray or a chicken embryo origin vaccine if the first vaccine was of tissue culture origin. After challenge, birds were monitored for clinical signs. Those surviving were euthanatized on day 6 postchallenge, and tissues and blood were collected for histopathology, virus isolation, and serology. On the basis of histopathology and enzyme-linked immunosorbent assay (ELISA) results, after one vaccination, all chickens given vaccines by eyedrop were provided better protection than nonvaccinated controls (CTLs). Birds in groups Bs and Ds had lower microscopic lesion scores whereas only birds given Bs had higher ELISA titers than CTLs. Birds in groups As and Cs and groups Bw birds taken from the rear of the barn (r) had microscopic lesion scores that were no different from those of CTLs. These same birds in addition to vaccine Ds had ELISA titers no different from those of CTLs. Of all vaccines, only A given by eyedrop or spray produced higher virus isolation titers than those of CTLs. The remainder of the vaccines produced virus isolation titers that were no different from those of CTLs. After two vaccinations, all groups had lower microscopic lesion scores than CTLs. Only Bw birds from the middle of the barn Bs, EeDs, and AsAs had virus isolation results that were higher than those of CTLs. Only groups BwrBs, CsCs, and DsDs had ELISA titers no different from those of controls. These results suggest that a priming vaccination followed by a booster dose offers better protection against ILT than a single vaccination alone. Vaccine application by eyedrop provides more uniform protection if only one vaccination is given, whereas spray vaccination may serve as an alternative method of vaccination for birds receiving two doses of vaccine.

Obstructive inflammatory laryngeal disease in three cats.

Three cats with upper respiratory tract obstruction due to laryngeal inflammation are presented. Cervical radiography showed the presence of a soft tissue mass in the laryngeal region in all cases, and laryngoscopy allowed direct visualization of a mass associated with the larynx. Laryngeal samples were obtained by a combination of fine needle aspiration, cutting biopsy forceps, by ventral laryngotomy, and at post-mortem. Histopathology of the laryngeal samples showed the presence of a predominantly granulomatous inflammation, with macrophage and lymphocyte infiltration. One case was euthanased due to severe dyspnoea. The remaining two cases underwent combined medical (corticosteroid and antibiotic) and surgical (permanent tracheostomy or excision of laryngeal tissue by ventral laryngotomy) treatment. One case died of an undetermined cause 15 weeks after surgery while the other case remains clinically well 20 months after diagnosis. Recognition of the existence of granulomatous laryngitis is important as clinical signs and radiographic findings are indistinguishable from laryngeal neoplasia.

[Infectious laryngotracheitis (ILT) in Switzerland: recent situation and thoughts about future possibilities for control]. / Die Infektiöse Laryngotracheitis (ILT) in der Schweiz: Aktueller Stand und Gedanken zu zukünftigen Bekämpfungsmöglichkeiten.

This short review highlights the characteristics of infectious laryngotracheitis, the diagnostic methods and the actual disease situation in Switzerland and other European countries. Recommendations for a future control policy are outlined.

Comparison of the effects of infectious bronchitis and infectious laryngotracheitis on the chicken respiratory tract.

In infectious bronchitis (IB) virus infection of the chicken the upper and lower respiratory tracts were damaged, but infectious laryngotracheitis (ILT) virus caused lesions only in the upper respiratory tract. Secondary infection with Escherichia coli was apparent in the trachea of birds inoculated with either virus but was more striking in those given IB virus. Serum alpha 1-acid glycoprotein, an acute-phase protein, occurred in higher concentrations in chickens inoculated with IB virus than in those given ILT virus.

The effect of serial in vivo passage on the expression of virulence and DNA stability of an infectious laryngotracheitis virus strain of low virulence.

The effect of 35 serial passages in vivo on an infectious laryngotracheitis virus strain of low virulence was examined in terms of effect on virulence and DNA stability. Within 3 passages in live chickens there was evidence of increasing respiratory distress. Severe respiratory distress (with death in some cases) was observed after the 6th passage, except when there appeared to be a transient decline in pathogenicity following short term storage of the virus inoculum at -70 degrees C. Restriction endonuclease analysis of viral DNA derived from the original inoculum and the final passage did not reveal any genomic alteration. It is postulated that there is a potential for live ILTV vaccines to cause outbreaks of clinical disease in the event of inadequate or incomplete vaccination procedures.

Identification and characterization of the infectious laryngotracheitis virus glycoprotein C gene.

The infectious laryngotracheitis virus (ILTV) gene encoding a homologue to the glycoprotein C gene of herpes simplex virus has been sequenced and identified based on its genomic location, comparative analysis to other gC proteins, and the identification of a glycosylated protein product. Located near the small subunit ribonucleotide reductase gene, the ILTV gC gene is 1242 bp in length and is predicted to encode a membrane glycoprotein containing a characteristic N-terminal hydrophobic signal sequence, five potential N-linked glycosylation sites, and C-terminal transmembrane and cytoplasmic domains. Antibodies raised in rabbits against a Cro-ILTV-beta-galactosidase fusion protein expressed in Escherichia coli recognize a 60-kDa ILTV-specific glycoprotein from infected cell extracts. Transcriptional analysis, using a portion of the open reading frame as a probe, identified a 1.55-kb transcript expressed with late gene kinetics. Comparison to other herpesvirus gC proteins revealed limited amino acid sequence homology and the absence of a charged extracellular region, which would normally interact with cell surface proteoglycans.