Acute Respiratory Distress Syndrome and Fatal Interstitial Pneumonia Associated with Equine Influenza in a Neonatal Foal

Abstract

A n approximately 36-hour-old Morgan/Friesian colt was referred to the large animal hospital at the University of Wisconsin for an evaluation of altered mentation, first noticed shortly after birth. Parturition had been unobserved, but the foal had been found separated from the mare by a fence at a few hours of age. The foal was ambulatory and able to nurse when first discovered but showed progressive disorientation, apparent blindness, and aimless wandering during the following 36-hour period. A Snap immunoglobulin G (IgG) assay a at 24 hours of age had shown an IgG concentration Ͼ800 mg/dL, and a CBC performed at that time was normal. The foal was treated twice with dimethyl sulfoxide 1 g/kg IV, diluted in 5% dextrose before referral.At presentation, the colt wandered aimlessly, bumped into objects, and appeared blind with sluggish but intact pupillary light responses. When positioned under the mare, the foal nursed successfully. Physical examination was unremarkable. A CBC and serum biochemistry were normal, including a serum IgG concentration of 937 mg/dL measured by radioimmunodiffusion.Initial treatment for presumptive hypoxemic, ischemic encephalopathy included a 250-mL loading dose of 20% magnesium sulfate for 1 hour, followed by a constant rate infusion at 42 mL/h and thiamine hydrochloride 2.2 mg/kg IV q24h. Antimicrobial therapy consisted of amikacin 20 mg/kg IV q24h and procaine penicillin G 22,000 U/kg IM q12h. Omeprazole 1 mg/kg PO q24h also was administered to the foal.The foal's mental status remained static during the next 24 hours, and additional treatment with mannitol 1 g/kg IV q24h and dexamethasone sodium phosphate 0.1 mg/kg IV q24h on days 2 and 3 of hospitalization was not associated with improvement. On day 3, the foal underwent general anesthesia for a computerized tomographic scan of the skull and proximal spine, which was normal. A cerebrospinal fluid sample was obtained from the lumbosacral space and was normal on cytologic evaluation and had a normal protein concentration.On day 4 of hospitalization, the foal developed a rightsided head tilt but otherwise remained static through day 5 of hospitalization. Magnesium sulfate therapy was discontinued on day 5, but the remainder of the therapeutic regimen was unchanged. On day 6, the foal had 2 brief, generalized seizures that were controlled with midazolam 0.05 mg/kg IV. Between seizures, the foal was still bright, afebrile, and nursing.On day 7 of hospitalization, the foal became febrile (40ЊC) and developed a mucopurulent nasal discharge and progressive tachypnea with diffuse adventitious crackles and wheezes on auscultation. Fever, mucopurulent nasal discharge, and coughing had been noted in several other mares and foals in the neonatal care unit during the previous 7 days. Antimicrobial therapy was changed to ticarcillin/clavulanic acid 50 mg/kg IV q8h and gentamicin 6.6 mg/kg IV q24h, and the foal was treated with polyionic fluids, although it was still nursing. During days 8-10, the foal's neurologic status continued to improve, wi...

Multinodular pulmonary fibrosis in five horses

“…Unfortunately, these findings are nonspecific and consistent with other reported cases of equine interstitial pneumonia. [7][8][9]20,[34][35][36] A marked inflammatory response was often detected in the affected horses. Neutrophilic leukocytosis and hyperfibrinogenemia were common findings.…”

“…39 Lymphopenia has not been reported in most cases of equine interstitial pneumonia in the literature. [6][7][8][9]11,20,[34][35][36]40 In the horses reported here, this may have been caused by persistent infection with EHV-5 or may have been secondary to administration of corticosteroids. Horse 1 survived and had a lymphocyte count within reference range at day 101; however, horses 3 and 4, both euthanized, had persistent lymphopenia.…”

The pathology of bronchointerstitial pneumonia in young foals associated with the first outbreak of equine influenza in Australia

“…There are few previous descriptions of lesions in foals specifically due to EIV, although it has been noted that pulmonary lesions can be extensive and involve necrosis of bronchiolar epithelium (Britton and Robinson 2002;Peek et al 2004;Caswell and Williams 2007). In the 1965 outbreak of EIV in the UK, severe and sometimes fatal pneumonia was also reported in young foals born to unvaccinated infected mares (Miller 1965a,b).…”

Ultrasonographic Examination of the Equine Neonate

“…Although the discussion in this article is weighted toward infectious causes of pneumonia and NARDS, it bears repeating that it is an inflammatory response, not just infection, that triggers the life-threatening escalation in immune response that results in NALI and NARDS. Conditions causing direct injury to pulmonary tissue (eg, traumatic chest injury; pneumonia of bacterial, viral, or fungal origin 27,28 ; and aspiration of gastrointestinal contents) as well as diseases that injure the lung indirectly by inciting a massive inflammatory response elsewhere in the body (sepsis, disseminated intravascular coagulation (DIC), traumatic injury to body regions other than the lung, and repeated blood transfusion 23 ) have all incited ALI and ARDS.…”