Infectious Agents in Acute Respiratory Disease in Horses in Ontario

Abstract

Abstract.A study of acute respiratory disease in horses in Ontario was undertaken to determine the identity of current causative infectious agents. A nasopharyngeal swab was designed and utilized to maximize isolation of viruses, mycoplasma, and pathogenic bacteria. Serum samples were collected for parallel determination of antibody titers to equine influenza virus type A subtype 1 (H7N7) and subtype 2 (H3N8), equine rhinovirus types 1 and 2, equine herpesvirus type 1, Mycoplasma equirhinius, and Mycoplasma felis. Equine rhinovirus type 2 was recovered from 28/92 horses tested, and equine influenza virus type A, subtype 2, was recovered from 5. The mycoplasma and bacteria isolated were consistent with those commonly associated with nonspecific respiratory diseases in horses, except that Streptococcus pneumoniae capsular type 3 was isolated from 10 horses.Contagious respiratory infections in horses are major causes of both acute and chronic respiratory diseases resulting in impaired pulmonary function and reduced performance. 12,13,39 The chronic sequelae are important to the horse industry and include bronchopneumonia, chronic obstructive pulmonary disease, and exerciseinduced hemorrhage. 26,39 Earlier studies conducted in Ontario on thoroughbred 8 and standardbred horses used isolation and serodiagnosis to demonstrate that equine influenza virus type A subtypes 1 (AE1; H7N7) and 2 (AE2; H3N8), equine rhinovirus types 1 (ERhV-1) and 2 (ERhV-2), and equine rhinopneumonitis virus, now termed equine herpesvirus type 4 (EHV-4), were the major causes of respiratory disease. Other infectious agents that can induce respiratory disease in the horse are equine abortion virus 1 (distinguished as equine herpesvirus type 1 [EHV-1] 33 ), equine cytomegalovirus (equine herpesvirus type 2 10 ), equine arteritis virus (EAV), 34 equine adenovirus, 14,26 equine rhinovirus-3, 26 mycoplasmas, 16,40 and bacteria. 18,22 Vaccines are currently available in Ontario only for AE1, AE2, EHV-1, EHV-4, and EAV. These viral agents are believed to be the most common causes of clinical respiratory disease in North America. 26 Received for publication March 18, 1996. cious vaccination for AE1, 39 AE2, 39 EHV-1 , 24 and EHV-4 24 using modern vaccines. This continuing disease problem may be due to partial vaccine-induced immunity, genetic diversity of 26 or the antigenic drift of influenza viruses. 13,26,39 This study was conducted to identify the infectious agents more recently implicated in respiratory disease in horses in Ontario . 37 We used patient data, clinical examination, isolation, and paired serology for specific infectious agents. Nasal swabs from 92 horses with acute clinical respiratory disease from 29 different premises were cultured for viruses, mycoplasma, and pathogenic bacteria. Paired sera were collected and tested for antibodies to AE1, AE2, ERhV-1, ERhV-2, and EHV-1. For an additional 89 horses from 13 stables where respiratory disease occurred annually, these same serologic tests and antibody tests for EAV were perf...

Investigation of the presence of Mycoplasma as an etiologic agent of inflammatory airway diseases in thoroughbred racehorses in İstanbul Province

“…The samples were submitted to the İstanbul Race Horse Hospital along with complaints of poor performance and/ or abnormal respiratory sounds at rest or while training. The same clinician evaluated the clinical signs of the horses, and the amount of tracheal mucus accumulation (classified as none, little, intermediate, or high), poor performance, coughing at rest or during exercise, and nasal discharge were recorded while collecting samples from the horses (2,5,(16)(17)(18). The sex, age, and strain (English or Arabian thoroughbred) of the horses were also recorded.…”

Equine rhinitis B virus: a new serotype

“…It is suggested that P313/75 can be classified as a new serotype of the genus Erbovirus, tentatively named ERBV2. Seroepidemiological data indicate that ERBV2 infection of horses may be common (24 %) in Australia.Equine rhinitis viruses (formerly named equine rhinoviruses) are known to cause clinical and subclinical upper respiratory infections in horses worldwide (Carman et al, 1997). Among those viruses that were formerly called equine rhinoviruses (classified as members of the family Picornaviridae, genus Rhinovirus), two serotypes were identified (Flammini & Allegri, 1970 ;Newman et al, 1973 ;Steck et al, 1978).…”

Evidence that Equine Rhinitis A Virus VP1 Is a Target of Neutralizing Antibodies and Participates Directly in Receptor Binding

“…Despite this difficulty, ERAV has been isolated from throughbred horses with acute respiratory disease in Australia, Canada, the United States, Japan, and Europe and is emerging as an important problem in these regions (5,7,18,21,25,30,31). This work firmly establishes the potential of recombinant ERAV VP1 polypeptides to serve as diagnostic reagents and vaccines to control infections with this virus.…”

“…The emerging significance of ERAV as a pathogen for horses (5,18), as well as its close relationship to FMDV (17,34), a virus of major worldwide importance, highlights a need to better understand the pathogenic processes adopted by ERAV. In this study, we show that ERAV VP1 is a target of protective antibodies and provide evidence that this molecule is involved directly in viral attachment to host cells.…”