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.

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]

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.

Diseases of the larynx

The procedure for examining the patient with laryngeal disease depends largely upon the degree to which its respiration is impaired. Laryngoscopy and electromyography are the principal diagnostic tools. Common laryngeal diseases, diagnoses, and treatments are discussed.

Functional changes induced by necrotic laryngitis in double muscled calves

The effects of necrotic laryngitis on the mechanics of breathing and gas exchange were investigated in five Belgian blue double muscled calves two to three months old. All the animals showed the typical clinical picture of the respiratory syndrome associated with naturally occurring necrotic laryngitis. Highly significant increases in total pulmonary resistance, minute viscous work of breathing and alveolar-arterial oxygen gradient, and highly significant decreases in dynamic lung compliance and arterial oxygen tension were recorded in the infected animals, when compared to reference values for healthy cattle. The ratio of inspiratory to expiratory viscous work of breathing was also significantly increased probably because of a partial collapse of the extrathoracic trachea during inspiration. It was concluded that necrotic laryngitis disturbs pulmonary function to such an extent that it impedes the growing process and predisposes the infected animals to secondary bronchopneumonia and ventilatory failure due to respiratory muscle fatigue.

Respiratory tract lesions from infectious laryngotracheitis virus of low virulence

The pathogenicity of the A4557-5 strain of infectious laryngotracheitis virus for eight-week-old chickens was investigated by aerosol route of infection; chickens were necropsied five days after infection. The virus caused mild catarrhal tracheitis, peribronchial lymphoid infiltration, and focal lymphocytic infiltration in the lung and focal lymphocytic infiltration in the air sacs of some chickens. Chickens infected with this virus developed low levels of humoral antibody and were resistant to intratracheal challenge with the virulent V154 strain. By comparison, aerosol infection with a similar dose of virulent V154 strain caused severe necrotizing laryngotracheitis with marked suppurative bronchopneumonia and airsacculitis.

Neoplasia of the larynx in the dog

The clinical, radiographic, gross pathologic, and histologic findings in 4 dogs with primary laryngeal neoplasia and 1 dog with secondary laryngeal neoplasia were reviewed. The clinical and radiographic findings were compared with those for proliferative inflammatory laryngeal conditions, since such conditions pose a problem in differential diagnosis. The most common clinical sign was hoarse bark or loss of voice, with subsequent onset of exertional dyspnea and cough.

Treatment regimen for air sacculitis in the chimpanzee (Pan troglodytes)

Six champanzees (Pan troglodytes) developed air sacculitis. Except for air sac distension and malodorous breath, clinical signs were rare. A variety of organisms, mainly enteric, were isolated from the air sacs. Only one case was treated surgically. Other cases were treated by the conservative method of irrigation which worked well.

Efficacy of lincomycin and spectinomycin on canine pathogens

Lincomycin (L), spectinomycin (S), and both (L-S) were evaluated in vitro and vivo against canine pathogens. In vitro, a wider spectrum of antimicrobial activity was achieved with L-S than with either L or S. The therapeutic effects of the antibiotics were investigated in 36 dogs inoculated with a mixture of the microbal agents. Tonsillitis, conjunctivitis, laryngitis, abscess formation, and necropsy findings were measured. The L-S combination was effective for the treatment of tonsillitis, conjunctivitis, laryngitis, and pneumonia in dogs.