Clinical and prognostic significance of radiographic pattern, distribution, and severity of thoracic radiographic changes in neonatal foals

A total of 207 thoracic radiographs obtained from 128 foals were evaluated to assess the impact of pulmonary radiographic pattern, distribution, and severity of pulmonary changes on short-term survival of neonatal foals. The association between selected clinical variables and the radiographic manifestation of neonatal respiratory disease was also investigated. The evaluation of interstitial and alveolar-interstitial radiographic patterns within the caudodorsal, caudoventral, and cranioventral lung regions proved to be highly reliable between viewers in the study. A diagnosis of systemic inflammatory response syndrome was related to increased pulmonary infiltrates within the caudodorsal lung region. Dyspneic foals had more extensive pulmonary infiltrates within the cranioventral lung, advanced respiratory disease, and lower survival rates. A fibrinogen concentration >400 mg/dL was associated with increased cranioventral radiographic abnormalities. In addition, tachypnea most consistently related to diffuse (caudodorsal, caudoventral, and cranioventral) pulmonary changes. Neutropenia, milk reflux from the nares, upper airway pathology, abnormal respiratory sounds, failure of transfer of passive immunity (IgG concentration <400 mg/dL), immaturity, or fever, however, were not related to radiographic pattern, distribution, or severity of radiographic changes. Sixty-five percent of foals with radiographic pulmonary disease were discharged alive from our referral hospital. Concurrent caudodorsal and caudoventral radiographic disease was most frequently observed in this foal population. Increased caudodorsal radiographic scores retained statistical significance as a prognostic indicator for nonsurvival in a multiple stepwise logistic regression analysis.     

Mild exercise early in life produces changes in bone size and strength but not density in proximal phalangeal, third metacarpal and third carpal bones of foals

Exercise or lack of it in early life affects chondro-osseous development. Two groups of horses were used to investigate the effects of age and exercise regimen on bone parameters of diaphyseal, metaphyseal, epiphyseal and cuboidal bones of the distal limb of Thoroughbreds. One group had exercised only spontaneously from an early age at pasture (PASTEX group), while the other group of horses were exposed to a 30% greater workload through additional defined exercise (CONDEX). Longitudinal data from peripheral quantitative computed tomography (pQCT) were obtained from eight scan sites of the left forelimb (proximal phalangeal (P_p; 1 site), third metacarpal (Mc3; six sites) and third carpal (C₃; one site) bones) of 32 Thoroughbred foals scanned five times from ∼3 weeks to 17 months of age. The primary outcome measures were bone mineral content (BMC), bone area (BA), and periosteal circumference (Peri C) in diaphyseal bone, with cortical thickness (CortTh), volumetric bone mineral density (BMD_v) and a bone strength index (SSI) also being analysed.At the P_p site within the model there was a significant effect (P = 0.00–0.025) of conditioning exercise increasing bone parameters, except endosteal circumference (Endo C) and BMD_v. The BMC, BA, and SSI of P_p were significantly greater in the CONDEX than PASTEX groups at 12 and 17 months (P = 0.015–0.042) and CortTh at 17 months (P = 0.033). At the M55 site of Mc3 BMC, BA and SSI (P = 0.02–0.04), and at the M33 site, SSI (P = 0.05) were higher in the CONDEX than PASTEX group. The adaptive responses, consistent with diaphyseal strengthening, were more marked in the diaphysis of P_p than Mc3. In the Mc3, metaphysis, trabecular BMD_v was less in the CONDEX than PASTEX group, associated with greater bone mineral accretion in the outer cortical-sub-cortical bone in the CONDEX group. There were no significant between-group differences in any epiphyseal or cuboidal bone parameter. Although the early imposed exercise regimen was not intensive, it had significant effects on diaphyseal bone strength, through change in size but not bone density.