Factors associated with outcome in foals with neonatal isoerythrolysis (72 cases, 1988-2003).

BACKGROUND: Neonatal foals with isoerythrolysis (NI) often die, but the risk factors for death have not been identified. OBJECTIVES: To identify factors associated with outcome in foals with NI and to identify factors associated with death from liver failure or kernicterus in the same population. ANIMALS: Seventy-two foals with NI examined at referral institutions. METHODS: Retrospective case series. Information on signalment, clinical examination findings, laboratory testing, treatment, complications, outcome, and necropsy results were obtained. RESULTS: The overall survival rate was 75% (54 of 72). Liver failure (n=7), kernicterus (n=6), and complications related to bacterial sepsis (n=3) were the 3 most common reasons for death or euthanasia. The number of transfusions with blood products was the factor most strongly associated with nonsurvival in a multivariate logistic regression model. The odds of liver failure developing in foals receiving a total volume of blood products >or= 4.0 L were 19.5 (95% confidence intervals [CI]: 2.13-178) times higher than that of foals receiving a lower volume (P= .009). The odds of kernicterus developing in foals with a total bilirubin >or= 27.0 mg/dL were 17.0 (95% CI: 1.77-165) times higher than that of foals with a lower total bilirubin (P= .014). CONCLUSIONS AND CLINICAL IMPORTANCE: Development of liver failure, kernicterus, and complications related to bacterial sepsis are the most common causes of death in foals with NI. Foals administered a large volume of blood products are at greater risk for developing liver failure.

Plasma adrenocorticotropin, cortisol, and adrenocorticotropin/cortisol ratios in septic and normal-term foals.

BACKGROUND: Little information exists on the hypothalamic-pituitary-adrenal axis in septic foals. HYPOTHESIS: The plasma concentrations of adrenocorticotropin (ACTH) and cortisol are expected to be higher in septic foals as compared to normal foals. The concentrations of hormones in septic foals also are expected to differ further depending upon survival. ANIMALS: Twenty-eight control foals and 46 septic foals <14 days of age were included in this study. METHODS: Blood was collected in EDTA once from 28 normal foals born in the University of Georgia or Cornell University equine research herds and from 46 septic foals within 12 hours after admission to 1 of the 3 tertiary care referral centers involved in the study. Septic foal selection was based on a sepsis score of >11 or a positive blood culture. The control foals were age matched to the septic foals in the study. ACTH and cortisol concentrations were measured by a chemiluminescent immunoassay system. RESULTS: Cortisol concentrations in control foals did not vary with age. Septic foals had significantly higher mean ACTH, cortisol, and ACTH/cortisol ratios than did normal foals. Within the septic foal group, 28 foals survived to discharge, and 18 were euthanized or died. The mean age was not significantly different between the septic surviving and nonsurviving foals. The mean ACTH/cortisol ratio was significantly higher in the septic nonsurviving foals as compared to the septic surviving foals. CONCLUSIONS AND CLINICAL IMPORTANCE: Septic foals had higher hormone concentrations as compared to normal foals, which is an expected endocrine response to critical illness. The increased ACTH/cortisol ratio in nonsurviving septic foals in comparison to surviving septic foals could indicate hypothalamic-pituitary-adrenal axis dysfunction at the level of the adrenal gland in critically ill septic foals.

Uterine infarctions in cynomolgus monkeys (Macaca fascicularis).

Uterine infarctions have not been reported in domestic animals, and there are few reports in the human medical literature. In a retrospective study, uterine infarctions were identified in 9 of 323 (2.8%) female cynomolgus monkeys (Macaca fascicularis) necropsied over a 13-year period. The infarctions were grossly visible, after fixation, on the serosal surface of the uterus in 2 monkeys; the remainder were first recognized in histologic sections. Histologically, the lesions consisted of well-demarcated regions of endometrial and myometrial necrosis and of hemorrhage. All affected monkeys had histologic evidence of a previous pregnancy, which included enlarged myometrial vessels with an expanded perivascular matrix. In all monkeys with uterine infarctions, there was clinical evidence of severe systemic illness, which included trauma, diarrhea, hypovolemia, or septicemia. The major pathologic findings in affected monkeys included cutaneous or skeletal muscle necrosis (n = 5), enterocolitis (n = 4), pulmonary edema or diffuse alveolar damage (n = 3), and intestinal amyloidosis (n = 1). Histopathologic evidence of intravascular fibrin thrombi in multiple organs of 5 monkeys was consistent with a diagnosis of disseminated intravascular coagulopathy (DIC). Based on these findings, it appears that uterine infarction is an uncommon finding in cynomolgus monkeys and may occur secondary to a severe systemic illness, predisposing to DIC.

Admission clinicopathological data, length of stay, cost and mortality in an equine neonatal intensive care unit.

Veterinary internists need to prognosticate patients quickly and accurately in a neonatal intensive care unit (NICU). This may depend on laboratory data collected on admission, the cost of hospitalisation, length of stay (LOS) and mortality rate experienced in the NICU. Therefore, we conducted a retrospective study of 62 equine neonates admitted to a NICU of a private equine referral hospital to determine the prognostic value of venous clinicopathological data collected on admission before therapy, the cost of hospitalisation, LOS and mortality rate. The WBC count, total CO2 (TCO2) and alkaline phosphatase (ALP) were significantly higher (P < or = 0.05) and anion gap lower in survivors compared with nonsurvivors. A logistic regression model that included WBC count, hematocrit, albumin/globulin ratio, ALP, TCO2, potassium, sodium and lactate, was able to correctly predict mortality in 84% of cases. Only anion gap proved to be an independent predictor of neonatal mortality in this study. In the study population, the overall mortality rate was 34% with greatest mortality rates reported in the first 48 hours and again on day 6 of hospitalisation. Amongst the various clinical diagnoses, mortality was highest in foals after forced extraction during correction of dystocia. Median cost per day was higher for nonsurvivors while total cost was higher in survivors.

Surgical repair of rib fractures in 14 neonatal foals: case selection, surgical technique and results.

REASONS FOR PERFORMING STUDY: Fractured ribs are encountered quite frequently in newborn Thoroughbred foals, often with fatal outcome. Surgical repair of fractures therefore requires consideration as a means of reducing mortality. OBJECTIVES: To evaluate the repair of rib fractures using internal fixation techniques in foals at 2 different equine hospitals following similar diagnostics and case selection. METHODS: The records of 14 foals that underwent internal fixation of fracture ribs were reviewed. Subject details, clinical presentation, diagnosis, surgical technique, post operative care and complications were recorded. Follow-up information was obtained in 7 foals. RESULTS: The fractured ribs were reduced and stabilised using reconstruction plate(s), self-tapping cortical screws and cerclage wire in 12 cases, Steinmann pins and cerclage wires in 1 case and both techniques in 1 case. Not every rib was reduced on each case. Surgical reduction was performed on an average of 2 ribs, range 1-3 ribs in each foal. At the time of writing, 4 foals had been sold, one age 2 years was in training and 2 others died from unrelated causes. CONCLUSIONS: Our data support the use of surgical stabilisation utilising reconstruction plates, self-tapping cortical screws and cerclage wire for selected cases of thoracic trauma in neonatal foals. The use of Steinmann pins may be suboptimal due to cyclic failure, implant migration and the potential for iatrogenic internal thoracic trauma. POTENTIAL RELEVANCE: Foals with existing extensive internal thoracic trauma resulting from rib fracture(s), or the potential for such trauma, previously considered to have a guarded to poor prognosis for survival, may be successfully managed with internal fixation of selected fracture sites.

Effect of hydroxyethyl starch infusion on colloid oncotic pressure in hypoproteinemic horses.

OBJECTIVE: To determine the effect of hydroxyethyl starch (HES) on colloid oncotic pressure (pi) during fluid resuscitation of hypoproteinemic horses and to evaluate the clinical usefulness of direct and indirect methods for determination of pi before and after infusion of a synthetic colloid. DESIGN: Prospective clinical study. ANIMALS: 11 hypoproteinemic horses. PROCEDURE: Horses received IV infusions of 8 to 10 ml of a 6% solution of HES/kg (3.6 to 4.5 ml/lb) of body weight during fluid resuscitation. Blood samples were obtained for determination of plasma measured colloid oncotic pressure (pi meas) and plasma total protein and albumin (A) concentrations. Plasma globulin concentration (G) was calculated as the difference between plasma total protein and albumin concentrations. Calculated values for colloid oncotic pressure (piA + G) were determined by use of a predictive nomogram previously developed for horses. RESULTS: There was no significant difference between the means of pi meas and piA + G at the beginning of HES infusion. After HES infusion, the mean of pi meas was increased significantly from baseline for 6 hours. Mean plasma total protein and albumin concentrations and piA + G were decreased significantly from baseline for 24 hours. Differences between mean pi meas and piA + G after HES infusion were significant for 24 hours. CONCLUSIONS AND CLINICAL RELEVANCE: There was good agreement between plasma pi meas and piA + G in blood samples obtained from hypoproteinemic horses immediately before infusion of HES. Use of a predictive nomogram did not, however, account for the oncotic effect of HES. Results of comparison of pi meas to piA + G after HES infusion suggest that a significant oncotic effect was maintained for 24 hours in the study horses.

Meningoencephalomyelitis in a foal due to Salmonella agona infection.

CASE HISTORY: A neonatal Thoroughbred foal was presented with rib fractures and left forelimb lameness secondary to dystocia. CLINICAL FINDINGS: The foal developed a head tilt, seizures and watery diarrhoea during hospitalisation and died at 7 days of age. Histological examination of the brain and spinal cord revealed a suppurative meningoencephalomyelitis with vasculitis, and numerous intralesional, gram-negative bacilli. Similar microscopic lesions were noted in the lungs, renal medullary interstitium, and umbilicus. Bacilli in the brain, spinal cord and umbilicus were identified immunohistochemically as Salmonella group B. Salmonella agona was isolated in pure culture from the brain, lung, liver, kidney, and intestine. CONCLUSION: This is the first report of meningoencephalomyelitis and septicaemia due to Salmonella infection in an equine neonate.

Congenital defects in newborn foals of mares treated for equine protozoal myeloencephalitis during pregnancy.

Three weak, recumbent neonatal foals with skin lesions, including a thin wooly coat, were born to mares being treated for equine protozoal myeloencephalitis. Mares received sulfadiazine or sulfamethoxazole-trimethoprim, pyrimethamine, folic acid, and vitamin E orally. Foals were anemic, leukopenic, azotemic, hyponatremic, and hyperkalemic. Serum folate concentrations in the 3 foals and 2 mares were lower than those reported in the literature for clinically normal brood mares. Treatment was unsuccessful. For each foal, necropsy revealed lobulated kidneys with thin cortices and a pale medulla, and the spleen and thymus were small. Histologic examination revealed marked epidermal necrosis without inflammatory cells, thin renal cortices, renal tubular nephrosis, lymphoid aplasia, and bone marrow aplasia and hypoplasia. These observations indicate that oral administration of sulfonamides, 2,4-diaminopyrimidines (pyrimethamine with or without trimethoprim), and folic acid to mares during pregnancy is related to congenital defects in newborn foals.

Severe mitral regurgitation in horses: clinical, echocardiographic and pathological findings.

Forty-three horses with mitral regurgitation (MR) and congestive heart failure were examined, using M-mode, 2-dimensional real-time and Doppler echocardiography. There was no breed or sex predisposition when compared to the general hospital population. The mean +/- s.d. age of affected horses was 7.6 +/- 8.1 years. Horses with MR and congestive heart failure had significant increases in mean values for left ventricular chamber size, left atrial size and heart rate and significant decreases in interventricular septal and left ventricular free wall thickness. Significant increases in pulmonary artery diameter were detected compared to aortic diameter. Mean values for fractional shortening were not significantly different from normal. All horses had a Grade 3-6/6 holosystolic or pansystolic murmur with its point of maximal intensity in the mitral to aortic valve area. Atrial fibrillation was found at presentation in 24 horses with MR and congestive heart failure. One horse presented with atrial tachycardia and subsequently developed atrial fibrillation. Seven horses had ventricular premature contractions. Exercise intolerance (n = 34), respiratory signs (n = 31), and fever (n = 21) were the most common presenting signs. Thickening of the left atrioventricular valve leaflets, endocarditis, flail valve leaflets, rupture of a chorda tendineae, and mitral valve prolapse were detected echocardiographically. Doppler echocardiography confirmed the presence of a large systolic regurgitant jet in the left atrium in all horses in which it was used, and in many horses, concurrent tricuspid and pulmonary regurgitation was detected. All horses died or were subjected to euthanasia due to the severity of their MR and/or lack of response to therapy. Post mortem examinations were performed in 35 horses and confirmed the echocardiographic findings. The echocardiographic detection of a flail mitral valve leaflet was significantly associated with the detection of a ruptured chorda tendineae at post mortem examination. There was a significant association between echocardiographic detection of a dilated pulmonary artery and its presence at post mortem examination. M-mode, 2-dimensional real-time, and Doppler echocardiography should be used to accurately characterise the valvular abnormalities and assess the severity of mitral regurgitation. Pulmonary artery dilatation, an echocardiographic indication of severe pulmonary hypertension, should be considered a grave prognostic indicator and may indicate impending pulmonary artery rupture.

Cytology of the respiratory tract.

Cytology can be a rewarding diagnostic technique in equine practice. The respiratory tract readily lends itself to sampling for cytologic evaluation from the upper to lower regions of the system. This article discusses preservation and staining techniques that will allow the practitioner to present satisfactory samples to the laboratory. General considerations for cytologic analysis are discussed as well as the specific findings for individual disorders of the respiratory tract. The proper use of cytologic findings in conjunction with other diagnostic techniques for the respiratory tract are also discussed.

Gastric infarction in cynomolgus monkeys (Macaca fascicularis).

Five cases of gastric infarction were observed in adolescent or adult cynomolgus monkeys (Macaca fascicularis) over a 20-month period. Gastric infarcts were encountered as striking and unexpected findings at necropsy. Gross and microscopic findings included gastric necrosis, hemorrhage, and edema that involved large areas of the fundus and pylorus. A consistent finding was the presence of thrombi in the gastric microvasculature, particularly in the venous system. All animals had acute clinical episodes with substantial tissue damage resulting from a variety of causes, including trauma, pancreatitis, necrotizing cystitis, and intestinal intussusception. In addition, three animals had microvascular thrombosis in nongastric tissues. Our findings suggest that cynomolgus monkeys may be predisposed to developing gastric infarction under conditions of severe systemic insult that predispose to disseminated intravascular coagulation.

Bone functional changes in intact, ovariectomized, and ovariectomized, hormone-supplemented adult cynomolgus monkeys (Macaca fascicularis) evaluated by serum markers and dynamic histomorphometry.

Several parameters of bone mass and function were investigated in three experiments involving intact, ovariectomized, or hormone-supplemented ovariectomized female cynomolgus monkeys. Ovariectomized animals had increased serum levels of alkaline phosphatase and acid phosphatase compared with intact and hormone-supplemented animals. Vertebral bone mass measured ex vivo by dual-photon absorptiometry was reduced by 11-19% in ovariectomized animals compared with intact and hormone-supplemented animals. The most dramatic effects observed with ovariectomy were markedly increased (30-60%) bone formation rates in vertebral cancellous bone, primarily caused by higher activation frequency of basic multicellular units of bone. In addition, combined resorption and reversal periods were decreased and formation period increased in untreated ovariectomized animals. Changes in static histomorphometry parameters were less dramatic, cancellous bone volume being 1-14% lower in ovariectomized animals compared with intact or ovariectomized hormone-supplemented animals. The data indicate that changes in bone resorption are primarily responsible for the lower bone mass of estrogen deficiency and increased bone mass in hormone-supplemented animals. Bone changes in ovariectomized cynomolgus monkeys resemble those in women after menopause and similarly respond positively to hormone supplementation. As such, cynomolgus monkeys are an excellent model for studying the basic mechanisms of osteoporosis and for the development of suitable therapeutic regimens.

Identification of a novel simian parvovirus in cynomolgus monkeys with severe anemia. A paradigm of human B19 parvovirus infection.

Although human B19 parvovirus infection has been clearly associated with a number of distinct syndromes (including severe anemia, abortion, and arthritis), detailed knowledge of its pathogenesis has been hindered by the lack of a suitable animal model. We have identified a novel simian parvovirus in cynomolgus monkeys with severe anemia. Sequencing of a 723-bp fragment of cloned viral DNA extracted from serum revealed that the simian parvovirus has 65% homology at the DNA level with the human B19 parvovirus but little homology with other known parvoviruses. Light microscopic examination of bone marrow from infected animals showed intranuclear inclusion bodies, and ultrastructural studies showed viral arrays characteristic of parvoviruses. Another striking feature was the presence of marked dyserythropoiesis in cells of the erythroid lineage, raising the possibility that B19 parvovirus infection may underlie related dyserythropoietic syndromes in human beings. Affected animals had concurrent infection with the immunosuppressive type D simian retrovirus, analogous to HIV patients who develop severe anemia because of infection with B19 parvovirus. The remarkable similarities between the simian and B19 parvoviruses suggest that experimentally infected cynomolgus monkeys may serve as a useful animal model of human B19 infection.

Decreased erythrocyte potassium concentration associated with exercise-related myopathy in horses.

To investigate the possibility that a disorder of potassium balance may have a role in the development of equine rhabdomyolysis, the potassium concentration within erythrocytes (RBC [K+]) and plasma (P [K+]) was measured in 3 groups of horses: group 1, eight 2-year-old fillies that had postexercise muscle soreness within 48 hours of sample collection; group 2, ten 2-year-old fillies subjected to identical management and training conditions (as fillies of group 1) and that did not have signs of myopathy; and group 3, 32 yearlings of both sexes on the farm of origin of groups 1 and 2 that were pastured and not in training. Creatine kinase activity in serum from horses of groups 1 and 2 was also measured. The mean P [K+] was not significantly different between groups, whereas the mean RBC [K+] was significantly (P less than 0.01) lower in group-1 fillies vs group-2 fillies and group-3 horses. Group-1 fillies also had markedly high serum creatine kinase activity. Results of the study revealed significantly lower RBC [K+] in horses that had had signs of myopathy within the preceding 48 hours. This does not prove a causal relationship between RBC potassium depletion and myopathy, but does suggest that decreased RBC [K+] may be observed in horses with exercise-related myopathy.

High-frequency jet ventilation in a neonatal foal.

High-frequency jet ventilation was performed on a premature foal for respiratory difficulty attributable to in utero-acquired pneumonia. The procedure involves delivery of compressed gas through a small-bore cannula at frequencies up to 400 cycles/min. Ventilation settings of drive pressure, frequency, and FIO2 were varied to optimize PaO2 and PaCO2 values. The foal was ventilated with this equipment for 14 hours. Evidence of a favorable response to this method of ventilation was observed in the form of improvement in arterial blood gas values as well as the foal's attitude and degree of respiratory effort. High-frequency jet ventilation appears to be a useful method of ventilation for respiratory disease in neonatal foals; however, there remains no clear-cut advantage over conventional positive-pressure ventilation.