Page 743 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

718 CHAPTER 3

VetBooks.ir bacteria including S. zooepidemicus, R. equi or gram- by diffuse interstitial tissue and alveolar wall inflam-
mation. Ultimately, respiratory distress due to
negative organisms.
Management hypoxaemia occurs as there is progressive reduced
oxygen transfer from blood to air. This broad cat-
Treatment is focused on supplementing oxygen, egory of pulmonary disease has several reported
reducing inflammation and bronchoconstriction causes including hypersensitivity pneumonitis, toxic
and addressing any underlying infections. Foals plant ingestion and exposure to various infectious
most often require hospitalisation in a controlled agents. In many cases, however, a definitive cause is
climate, and provision of humidified intranasal not identified. One subset of EIP is equine multi-
oxygen. Treatment with NSAIDs is recommended. nodular pulmonary fibrosis (EMPF). A viral aetiol-
Clinicians will often also administer systemic corti- ogy for EMPF has been suggested, as EHV-2 and
costeroids to reduce inflammation. Bronchodilators, EHV-5 have been isolated from the lungs of affected
administered via inhalation, may be beneficial to animals at a higher rate than reported for normal
some foals. horses. However, a causal relationship has not been
established, and the exact role of the viruses in the
Prognosis pathogenesis of EMPF is unknown.
The prognosis is poor for foals unless rapid and
aggressive therapy is instituted. Foals that survive Clinical presentation
the first week of medical treatment have a favourable Affected horses most commonly present with pro-
prognosis. gressive weight loss and tachypnoea that does not
respond to antimicrobial therapy. Laboratory find-
EQUINE INTERSTITIAL PNEUMONIA ings are non-specific. Tachypnoea with increased
respiratory effort is present. Many horses will pres-
Definition/overview ent with a cough, and fever is commonly present
Equine interstitial pneumonia (EIP) refers to a with EMPF.
group of lung disorders in adult horses characterised
Differential diagnosis
Heaves, bacterial pneumonia or pleuropneumonia,
3.185 fungal pneumonia or neoplasia should be considered
as differential diagnoses.

Diagnosis
Thoracic radiographs of horses with EIP will reveal
a diffuse interstitial pattern. In horses with EMPF,
multiple nodular opacities will commonly be noted
throughout all lung fields (Fig. 3.185). Thoracic
ultrasonography of horses with EMPF will reveal
the presence of diffuse pleural roughening and
multiple discrete nodules. Tracheobronchial aspi-
ration with culture and BAL are recommended
to rule out infectious and non-infectious causes.
Detection of EHV-5 by PCR in BAL fluid of horses
Fig. 3.185 Thoracic radiograph of the caudodorsal with pulmonary nodules is supportive of a diagnosis
lung fields from an adult horse with equine of EMPF. Lung biopsy with histopathology is the
multinodular pulmonary fibrosis. A diffuse interstitial most definitive means of diagnosing EIP, but there
pattern with coalescing patchy nodules is present. is considerable risk associated with the procedure.