Risk factors and prognostic variables for survival of foals with radiographic evidence of pulmonary disease

The medical records of 163 neonatal foals that had thoracic radiographs taken within 48 hours of admission to a referral hospital were reviewed. The objectives of this study were (1) to identify risk factors for the development of thoracic radiographic changes and (2) to identify prognostic indicators for survival in foals with radiographic evidence of pulmonary disease. Failure of transfer of passive immunity (IgG concentration < or = 400 mg/dL) was the only risk factor for radiographic evidence of respiratory disease identified by multivariate analysis. Hypoxemic patients (PaO2 < or = 60 mm Hg) were 4.9 times more likely to reveal radiographic abnormalities in a subset of foals for which arterial blood gas results were available. Foals with a serum creatinine concentration > 1.7 mg/dL upon presentation, dyspnea, and a history of dystocia were significantly more likely to die based on the multivariate statistical outcome analysis. An anion gap > or = 20 mEq/dL was strongly associated with nonsurvival in a subset of foals with arterial blood gas results. These hematologic and biochemical variables can be readily obtained during the initial evaluation of sick foals. The presence of a high anion gap appeared to have the greatest clinical impact and may be a useful prognostic indicator in foals with radiographic evidence of respiratory disease. In contrast, the majority of physical examination variables, including evaluation of tachypnea, abnormal respiratory sounds, fever, weakness, and milk reflux from the nares, which are usually obtained during the general respiratory evaluation of foals, were unrelated to outcome.     

Lung surfactant function and composition in neonatal foals and adult horses

BACKGROUND: Lung surfactant function and composition are varied and adapted to the specific respiratory physiology of all mammalian species. HYPOTHESIS: Lung surfactant function and composition are different in neonatal foals as compared to adult horses. ANIMALS: Six adult horses, 7 term foals (<24 hours old), and 4 premature foals were used. Animals were part of the Auburn University teaching herd except for 3 client-owned premature foals. METHODS: Bronchoalveolar lavage fluid (BALF) was obtained from all animals. Ultracentrifugation of cell-free BALF separated surfactant into crude surfactant pellets (CSP) and supernatant. Both fractions were analyzed for phospholipid and protein content with the Bartlett and bicinchoninic acid method, respectively. Phospholipid composition of the CSP was determined by using high-performance liquid chromatography with an evaporative light scatter detector. Surface tension of the CSP was measured with a pulsating bubble surfactometer. Results from term foals (<24 hours old) were compared statistically to those from adult horses. Values of P < .05 were considered significant. RESULTS: BALF phospholipid content was similar between adult horses and term foals, but BALF protein content was significantly decreased in term foals. Phosphatidylglycerol was significantly decreased, phosphatidylinositol was significantly increased, and the minimum surface tension was significantly increased in the CSP from term foals compared to adult horses. CONCLUSIONS AND CLINICAL IMPORTANCE: Surface tension and phospholipid composition of surfactant in neonatal foals are significantly different compared to adult horses. These changes may influence biophysical and immunologic functions of surfactant.     

Thromboelastography in healthy, sick non-septic and septic neonatal foals

Objectives To evaluate citrated recalcified thromboelastography (TEG) in healthy newborn foals, and to determine intra‐assay, inter‐individual and intra‐individual (at 12 h, 24 h and 7 days after birth) variations. Additionally, to compare TEG variables, haematological values and conventional coagulation profiles from healthy, sick non‐septic, and septic foals. Design Prospective study. Methods The study group comprised 18 healthy, 15 sick non‐septic and 17 septic foals. Two citrated (3.2%; 1 : 9 anticoagulant : blood ratio) blood samples were submitted for haemostatic evaluation using a TEG analyser and conventional coagulation profile. TEG values (R time (R), K time (K), angle (α), maximum amplitude (MA) and G value (G)), complete blood count (CBC) and conventional coagulation profile (prothrombin time (PT), activated partial thromboplastin time (aPTT), fibrinogen concentration (Fib) and antithrombin (AT)) were evaluated. Signalment, presenting complaint, sepsis scores, blood culture results and outcome were taken from the medical records of the sick foals. Results Mean values ± SD for TEG variables in healthy neonatal foals were: R = 11.82 ± 5.35 min, K = 3.06 ± 1.34 min, α= 51.19 ± 12.66 degrees, MA = 55.06 ± 6.67 mm and G = 6361 ± 1700 dyn/cm². Mean coefficients of variation for intra‐assay/inter‐individual/intra‐individual in healthy foals were: R = 3.5/45.2/43.1%; K = 5.3/58.7/28.7%; α= 1.5/24.7/11.9%; MA = 0.3/12.1/6.1%; G = 1.6/26.7/14.7%. Septic foals had significantly greater α, MA and G values than sick non‐septic foals, and significantly greater MA and G than healthy foals, changes that are consistent with hypercoagulability. Weak correlations were detected between TEG variables and haematological or haemostatic values. Conclusions TEG could be used to provide additional information about the haemostatic system in equine neonates.     

Pharmacokinetics and pulmonary distribution of gamithromycin after intravenous administration in foals

The long‐acting azalide antibiotic gamithromycin is marketed for intramuscular treatment of bovine and swine infections. Off‐label use in foals leads to severe local lesions likely caused by hyperosmolality of the injected solution. We provide evidence from a pharmacokinetic study in 10 warm‐blooded healthy foals for intravenous bolus injection of gamithromycin diluted in distilled water to be a safe and well tolerated alternative. By intravenous dosing, markedly higher plasma exposure and better penetration into bronchoalveolar lavage cells but lower distribution into epithelial lining fluid are achieved as after intramuscular or subcutaneous administration. Intravenously injected gamithromycin was tolerated without any adverse drug reactions. The protocols for treatment of equine pulmonary infections caused by Rhodococcus equi should be revised accordingly.     

Outcome of tactile conditioning of neonates, or "imprint training" on selected handling measures in foals

Behavioural reactions to selected handling procedures were compared between conditioned, or imprint-trained, and untrained foals raised on the same farm. Nineteen randomly chosen healthy foals were imprint trained at birth and 24 h later (Group A). Twenty-one similar foals that were not imprint-trained served as age-matched controls (Group B). Training began within 10 min of birth and consisted of touch desensitization by gentle rubbing. Each tactile stimulus was repeated 30-50 times over 45-60 min, until the foal no longer resisted the procedure and appeared relaxed. The procedure was then repeated at 24 h of age. At that time a physical examination and blood analysis were performed to assess the foals' health status. Group B animals were not handled except for a brief physical examination and blood analysis at 24 h of age. Thereafter all foals were kept on pastures with their dams with no further handling until they were three months of age. Any foals handled for other reasons before that time were excluded from the study. At three months, each of the 28 foals that completed the study experienced the following handling procedures: acceptance of restraint, haltering, complete physical examination, acceptance of a plastic rebreathing bag, touching the whole body, intramuscular vaccination in the neck, intranasal vaccination, and deworming with oral paste. Response to each procedure was scored (1=not resistant, 2=low resistance, 3=strong resistance, 4=not possible without major physical restraint). Conditioned foals (Group A) were significantly less resistant to touching the front and hind legs and picking up the hind feet (P < 0.05). The administration of vaccines and paste dewormer and the collection of blood were tolerated by the majority of the foals of both groups with no or low resistance. It appeared that neonatal imprint training resulted in a learned behaviour that resulted in decreased self-defence responses towards handling the limbs at three months of age.     

Associations between thoracic radiographic changes and severity of pulmonary arterial hypertension diagnosed in 60 dogs via Doppler echocardiography: A retrospective study

Doppler echocardiography is a noninvasive method for estimating and grading pulmonary arterial hypertension. No current literature associates significance of radiographic findings with severity of pulmonary arterial hypertension. We hypothesized that the number and conspicuity of radiographic findings suggestive of pulmonary arterial hypertension would be greater based on the severity of pulmonary arterial hypertension. Dogs with pulmonary arterial hypertension and normal control dogs were included in this retrospective, case control study. Three radiologists blinded to echocardiographic results scored thoracic radiographs for right ventricular and main pulmonary artery enlargement and pulmonary lobar artery enlargement, tortuosity, and blunting by multiple methods. Presence or absence of each finding was scored in an additive fashion and averaged for each grade of pulmonary arterial hypertension severity. Seventy‐one dogs (60 dogs with pulmonary arterial hypertension and 11 control dogs) of which some had multiple studies were included: 20 mild, 21 moderate, 25 severe, and 11 absent pulmonary arterial hypertension. The following radiographic findings were significantly associated with increasing pulmonary arterial hypertension severity: right ventricular enlargement by “reverse D” and “3/5–2/5 cardiac ratio” methods, main pulmonary artery enlargement, and caudal lobar artery enlargement by the “3rd rib” method. Mean scores for severe pulmonary arterial hypertension and normal dogs were significantly different (P‐value < 0.0001). Mean scores between different pulmonary arterial hypertension grades increased with severity but were not statistically significant. Individually and in combination, radiographic findings performed poorly in differentiating severity of pulmonary arterial hypertension. Findings indicated that thoracic radiographs should be utilized in conjunction with Doppler echocardiography in a complete diagnostic work‐up for dogs with suspected pulmonary arterial hypertension.     

Interreader agreement of radiographic left atrial enlargement in dogs and comparison to echocardiographic left atrial assessment

Introduction

Assessing left atrial (LA) size is an integral part of the cardiac evaluation in dogs. Left atrial size is routinely evaluated by thoracic radiographs or echocardiography.

Diseases in neonatal foals. Part 1: The 30 day incidence of disease and the effect of prophylactic antimicrobial drug treatment during the first three days post partum

Reasons for performing study: Neonatal diseases have been grouped and analysed but up‐to‐date statistically significant information about the incidence and prevalence of diseases in foals is limited. Since the 1950s it has been a common management practice to administer a 3 day course of antimicrobial drugs to neonatal foals. This was shown to significantly reduce the incidence of infections (Platt 1977). Since then management practices have improved and it is widely believed that prophylactic antimicrobial drugs are no longer necessary in foal rearing. Objectives: To determine the 30 day incidences or prevalences (depending on case definition) of various diseases and conditions in the neonatal foal and ascertain the influence of a prophylactic 3 day treatment on the frequency of infections. Methods: The population consisted of Thoroughbred foals born on stud farms in the Newmarket (UK) area in 2005 (n = 1031). Depending on the stud farm's practice in the use of prophylactic antimicrobial drugs, 2 groups of newborn foals (treated and untreated) were identified and followed for 30 days. Results: The 30 day incidences of infectious diseases under study were between 0.2% (osteomyelitis) and 5.85% (systemic disease with diarrhoea). The overall incidence for ‘total infectious diseases’ was 8.27%. The most commonly observed noninfectious condition was limb deformities (12.11% of all foals). There was no significant difference in the incidence of infectious diseases between the 2 groups. Conclusion: Infectious diseases are still an important problem in neonatal foals requiring further investigation as to which factors other than antimicrobial prophylaxis are relevant for disease prevention. Potential relevance: The results provide an up‐to‐date overview about the frequencies of various neonatal foal diseases. They do not support the traditional prophylactic use of antimicrobials to prevent infectious diseases in healthy newborn foals. However, it should be noted that this study was not a randomised controlled trial and therefore does not provide the strongest possible evidence for this conclusion.     

Effect of breed, age, weight and gender on radiographic renal size in the dog

In the adult dog, kidney length has been reported as 2.98 ± 0.44 times the length of L2 on ventrodorsal views and 2.79 ± 0.46 times the length of L2 on lateral radiographs. Our aim was to test the hypothesis that the suggested maximum normal left kidney size is too high, and to evaluate the effect of breed type, gender, weight and age of the dog on kidney size. Abdominal radiographs of 200 dogs with no evidence of concurrent disease that might have an effect on renal size were included in the study. The mean ratio of kidney length to the second lumbar vertebra length was similar to previous reports. For the right lateral view it measured 2.98 ± 0.60 and for the ventrodorsal view 3.02 ± 0.66. Significant differences of this ratio between skull type were present, especially between brachycephalic and dolichocephalic dogs. On the right lateral view brachycephalic dogs had the highest median LK/L2 ratio of 3.1 (3.20 ± 0.40), whereas for dolichocephalic dogs it was 2.8 (2.82 ± 0.50), and for mesaticephalic dogs it was 2.97 (3.01 ± 0.6). A ratio >3.5 was found only in mesaticephalic dogs on the ventrodorsal view. There was a significant difference in the LK/L2 ratio between small (≤10kg) and large breed dogs (>30kg) where small dogs had a significantly higher LK/L2 ratio. There was no statistically significant relation between this ratio and age or gender. The previously reported ratios for kidney size seem valid, but because skull type has an impact on the LK/L2 ratio, a single normal ratio should not be used for all dogs.     

Effect of age, feeding, and omeprazole administration on gastric tonometry in healthy neonatal foals

BACKGROUND: Gastric tonometry is commonly used in humans as an assessment of intestinal mucosal perfusion. Values in healthy foals are currently unknown. HYPOTHESIS: Age, enteral feeding, and omeprazole administration would significantly alter gastric tonometry measurements in neonatal foals. ANIMALS: Nine clinically normal foals were used to assess the effect of age and feeding, and 8 similar foals were used to assess the effect of omeprazole. METHODS: At 1, 7, and 14 days of age, gastric intramucosal PCO2 (PgCO2) and arterial blood gas samples were obtained at baseline, immediately after feeding milk, and 1 and 2 hours after fasting for calculation of the intramucosal-arterial PCO2 difference (DeltaCO2). To evaluate the effect of omeprazole, foals were evaluated twice as above, 2 hours after fasting, comparing administration of omeprazole to no drug. RESULTS: There was a significant effect of age and feeding on PgCO2 and DeltaCO2, whereas arterial PCO2 was not significantly affected by these factors. Postfeeding DeltaCO2 values were significantly lower than fasted values. Baseline and postfeeding DeltaCO2 increased with age. There was no significant effect of age on data collected after 1 or 2 hours of fasting. The 90% reference interval for DeltaCO2 data collected after fasting was 0-54 mmHg. Foals had a significantly higher mean gastric pH and significantly higher DeltaCO2 and PgCO2 following omeprazole relative to no treatment. CONCLUSIONS AND CLINICAL IMPORTANCE: Because of the high and variable DeltaCO2, which is exacerbated by omeprazole administration, the reference interval in foals is extremely wide.     

Factors related to the risk of neonatal mortality,birth-weight and serum immunoglobulin concentration in lambs in the UK

Neonatal-lamb mortality represents an economic loss and welfare concern. Two factors often associated with the risk of mortality are birth-weight and serum immunoglobulin concentration. We used data from two studies to investigate risk factors for mortality between 2 and 14 days of age and factors affecting birth-weight and serum immunoglobulin concentration at 48 h of age. Dataset 1 included 1339 lambs born on eight farms during the 1995 spring lambing season; dataset 2 included 3172 lambs on seven farms during the 1991 spring lambing season. To account for some of the potential clustering within the data, multilevel models were used. Most (>75%) of the variation in the risk of mortality was at the lamb level. In dataset 1, factors significantly associated with increased odds of lamb mortality included low birth-weight and low serum immunoglobulin concentration. In dataset 2, significant risk factors for mortality included low birth-weight, ewe body-condition score, being born late in the season (relative to other lambs on the farm) and being born in multiple litters. There was a significant interaction between the effects of litter size and birth-weight. (Serum immunoglobulin concentration was not available for dataset 2.) More than half of the variation in birth-weight was at the ewe level, 27% at the lamb level, and 18% at the farm level (dataset 1). Single birth and being male were associated with increased birth-weight in both datasets. In dataset 2 only, increasing ewe condition score and birth early in the study period were also associated with increased birth-weight. Fifty-six percent of the variation in immunoglobulin concentration was at the lamb level, 36% at the ewe level and only 7% at the farm level. Factors associated with reduced serum immunoglobulin concentration included early or late birth in the lambing season, being born later than 14 days after the first lamb born on the farm, multiple-birth litters and maternal mastitis.     

Anatomical and radiological study of the thoracic paravertebral space in dogs: iohexol distribution pattern and use of the nerve stimulator

ObjectiveTo describe the landmarks and methodology to approach the thoracic paravertebral space in dogs; to evaluate if intercostal muscular response could be evoked by a nerve-stimulator; to radiographically assess the distribution pattern of a radio-opaque contrast medium after thoracic paravertebral injections.Study designRandomized, controlled, experimental trial.AnimalsTwo mongrel dog cadavers (anatomical study) and 24 mongrel dogs (experimental study).MethodsFor the anatomic study 0.2 mL kg^?1 of new methylene blue (NMB) was injected at the 5th thoracic paravertebral space; for the experimental study dogs were divided into three groups and received 1 (T₅), 2 (T₄ and T₆) or 4 (T₄, T₅, T₆ and T₇) paravertebral injections of iohexol. The paravertebral approach was performed with insulated needles using landmarks and a blind technique. When the needle tip reached the respective thoracic paravertebral space, the nerve-stimulator was switched-on and the presence/absence of intercostal muscular twitch was registered, thus a total volume of 0.2 mL kg^?1 of iohexol, divided into equal parts for each injection point, was administered. Radiological studies were performed with two orthogonal projections at different times. Positive injection was confirmed when the paravertebral space was occupied by iohexol in both projections.ResultsNMB was distributed in the T₅ paraverterbal space. In the experimental study, when the needle tip reached the respective paravertebral space, intercostal twitching was obtained in 80% of the total injections with a stimulating current of 0.5 mA. The incidence of positive cases when the intercostal twitch was obtained with 0.5 mA was 83.3%. The main distribution pattern observed was cloud like without longitudinal diffusion.Conclusion and clinical relevanceIntercostal muscular responses obtained with a stimulating current of 0.5 mA could be useful to locate thoracic spinal nerves in dogs and in our study the injected solution was confined to one thoracic paravertebral space.     

Differential expression of bone morphogenetic protein 4-6 (BMP-4, -5, and -6) and growth differentiation factor-9 (GDF-9) during ovarian development in neonatal pigs

Growth differentiation factor-9 (GDF-9) and bone morphogenetic proteins (BMPs), comprise the largest subgroups of ligands in the TGF-β superfamily, and have been shown to be involved in follicle development in mammals. However, whether these factors are involved in folliculogenesis in pigs is still unknown. The present study was performed to determine the relationships between early folliculogenesis and the expression of GDF-9 and BMP (BMP-4, -5 and -6) mRNAs in neonatal pigs. Ovaries were removed at 5, 16, 28 and 39 days after birth to examine the follicular population (the right ovary of each animal) and to detect mRNA expression (the left ovary of each animal). Primordial follicles accounted for >80% of the ovarian follicles from 5 days until 39 days after birth. A marked increase in primary follicles and the appearance of secondary follicles were observed in the ovaries at 28 days after birth. BMP-4, -5, and -6 and GDF-9 mRNAs were expressed by ovaries at 5-, 16-, 28- and 39-day-old pigs. The peak expression of BMP-4, -5, and -6 and GDF-9 mRNAs was observed in the ovaries at 5, 39, 28 and 16 days, respectively, after birth. These data demonstrate that folliculogenesis in piglets might be controlled by the interaction with these factors. We conclude that BMPs and GDF-9 may have distinct functions in several stages of follicle development in neonatal pig ovaries.     

Anatomic, radiographic and physiologic comparisons of the internal carotid and maxillary artery in the horse

The anatomy of the internal carotid and maxillary arteries was examined using angiography, subtraction angiography and arterial cast preparations in three horses. Subtraction angiography was superior to angiography in demonstrating the anatomy of the occipital, external ophthalmic, ethmoidal and palatine arteries. In three horses manipulation of the internal carotid and occipital arteries during angiography resulted in vasospasm which prevented filling of these vessels with contrast. Direct arterial blood pressure measurements of the maxillary artery impinging on the guttural pouches was measured in four anaesthetized and standing horses. Arterial pressure recordings from the maxillary artery indicate there is retrograde blood flow from contralateral vessels into the occluded arterial segment. Vasospasm prevented measurement of arterial pressure in the internal carotid artery.     

Clinical, morphologic, and morphometric features of cranial thoracic spinal stenosis in large and giant breed dogs

The clinical, morphologic, and morphometric features of cranial thoracic spinal stenosis were investigated in large and giant breed dogs. Seventy-nine magnetic resonance imaging studies of the cranial thoracic spine were assessed. Twenty-six were retrieved retrospectively and 53 were acquired prospectively using the same inclusion criteria. Images were evaluated using a modified compression scale as: no osseous stenosis (grade 0), osseous stenosis without spinal cord compression (grade 1), and osseous stenosis with spinal cord compression (grade 2). Morphometric analysis was performed and compared to the subjective grading system. Grades 1 and 2 cranial thoracic spinal stenosis were identified on 24 imaging studies in 23 dogs. Sixteen of 23 dogs had a conformation typified by Molosser breeds and 21/23 were male. The most common sites of stenosis were T2-3 and T3-4. The articular process joints were enlarged with abnormal oblique orientation. Stenosis was dorsolateral, lateralized, or dorsoventral. Concurrent osseous cervical spondylomyelopathy was recognized in six dogs and other neurologic disease in five dogs. Cranial thoracic spinal stenosis was the only finding in 12 dogs. In 9 of these 12 dogs (all grade 2) neurolocalization was to the T3-L3 spinal segment. The median age of these dogs was 9.5 months. In the remaining three dogs neurologic signs were not present. Stenosis ratios were of limited benefit in detecting stenotic sites. Grade 2 cranial thoracic spinal stenosis causing direct spinal cord compression may lead to neurologic signs, however milder stenosis (grade 1) is likely to be subclinical or incidental.