Infarctive purpura hemorrhagica in five horses

Five horses were examined because of signs of muscle stiffness, colic, or both. All 5 had been exposed to Streptococcus equi within 3 weeks prior to examination or had high serum titers of antibodies against the M protein of S equi. Horses had signs of unrelenting colic-like pain and focal areas of muscle swelling. Four horses were euthanatized. The fifth responded to treatment with penicillin and dexamethasone; after 3 weeks of treatment with dexamethasone, prednisolone was administered for an additional 10 weeks. Common hematologic and serum biochemical abnormalities included neutrophilia with a left shift and toxic changes, hyperproteinemia, hypoalbuminemia, and high serum creatine kinase and aspartate transferase activities. Necropsy revealed extensive infarction of the skeletal musculature, skin, gastrointestinal tract, pancreas, and lungs. Histologic lesions included leukocytoclastic vasculitis in numerous tissues and acute coagulative necrosis resembling infarction. These horses appeared to have a severe form of purpura hemorrhagica resembling Henoch-Sch?nlein purpura in humans and characterized by infarction of skeletal muscles. Early recognition of focal muscle swelling, abdominal discomfort, neutrophilia, hypoalbuminemia, and high serum creatine kinase activity combined with antimicrobial and corticosteroid treatment may enhance the likelihood of a successful outcome.     

Pond-level risk factors associated with columnaris disease on Mississippi commercial catfish farms

A large commercial catfish enterprise encompassing over 500 food fish ponds from five farms covering multiple counties in the Mississippi Delta was included in this analysis of columnaris risk factors. A gram-negative bacterium, Flavobacterium columnare, is the cause of columnaris disease and is considered the second-most prevalent bacterial disease in farm-raised catfish. The objective of this study was to determine if pond-level risk factors reported by farm personnel were associated with columnaris disease mortalities. To identify risk factors affecting susceptibility of farm-raised channel catfish Ictalurus punctatus to columnaris disease, a Catfish Management database was developed. Logistic regression was used to model the relationships between probability of columnaris in ponds and risk factors examined. Generalized linear mixed models incorporating hierarchically structured random effects of ponds and one or more fixed-effects risk factors were fitted. In the screening process, each risk factor was evaluated in the basic model as a single fixed-effects factor, and if associated with the outcome (P ≤ 0.20), was retained for development of multivariable models. Two multivariable logistic regression models were constructed from data collected at the pond level by producers. The first was constructed from data in which water quality was not considered. Pond depth and reduced feed consumption for a 14-d period prior to disease outbreaks measured on a per hectare basis were significantly (P ≤ 0.05) associated with columnaris disease. The second, in which water quality variables were also considered, pond depth, reduced feed consumption, shorter intervals from stocking to disease outbreaks, and total ammonia nitrogen were significantly (P ≤ 0.05) associated with columnaris occurrence. This study showed some commonly recorded production variables were associated with columnaris disease outbreaks and, if monitored, could help identify "at risk" ponds before disease outbreaks occur.     

Aldosterone breakthrough with benazepril in furosemide‐activated renin‐angiotensin‐aldosterone system in normal dogs

Pilot studies in our laboratory revealed that furosemide‐induced renin‐angiotensin‐aldosterone system (RAAS) activation was not attenuated by the subsequent co‐administration of benazepril. This study was designed to evaluate the effect of benazepril on angiotensin‐converting enzyme (ACE) activity and furosemide‐induced circulating RAAS activation. Our hypothesis was that benazepril suppression of ACE activity would not suppress furosemide‐induced circulating RAAS activation, indicated by urinary aldosterone concentration. Ten healthy hound dogs were used in this study. The effect of furosemide (2 mg/kg p.o., q12h; Group F; n = 5) and furosemide plus benazepril (1 mg/kg p.o., q24h; Group FB; n = 5) on circulating RAAS was determined by plasma ACE activity, 4–6 h posttreatment, and urinary aldosterone to creatinine ratio (UAldo:C) on days ?1, ?2, 1, 3, and 7. There was a significant increase in the average UAldo:C (μg/g) after the administration of furosemide (Group F baseline [average of days ?1 and ?2] UAldo:C = 0.41, SD 0.15; day 1 UAldo:C = 1.1, SD 0.56; day 3 UAldo:C = 0.85, SD 0.50; day 7 UAldo:C = 1.1, SD 0.80, P < 0.05). Benazepril suppressed ACE activity (U/L) in Group FB (Group FB baseline ACE = 16.4, SD 4.2; day 1 ACE = 3.5, SD 1.4; day 3 ACE = 1.6, SD 1.3; day 7 ACE = 1.4, SD 1.4, P < 0.05) but did not significantly reduce aldosterone excretion (Group FB baseline UAldo:C = 0.35, SD 0.16; day 1 UAldo:C = 0.79, SD 0.39; day 3 UAldo:C 0.92, SD 0.48, day 7 UAldo:C = 0.99, SD 0.48, P < 0.05). Benazepril decreased plasma ACE activity but did not prevent furosemide‐induced RAAS activation, indicating aldosterone breakthrough (escape). This is particularly noteworthy in that breakthrough is observed at the time of initiation of RAAS suppression, as opposed to developing after months of therapy.     

Evaluation of a commercially available hyperimmune plasma product for prevention of naturally acquired pneumonia caused by Rhodococcus equi in foals

OBJECTIVE: To determine efficacy of a commercially available hyperimmune plasma product for prevention of naturally acquired pneumonia caused by Rhodococcus equi in foals. DESIGN: Randomized clinical trial. ANIMALS: 165 foals. PROCEDURE: Foals were randomly assigned to 1 of 2 groups (hyperimmune plasma or nontreated controls). Foals with failure of passive transfer (FPT) of immunity were treated with hyperimmune plasma and evaluated as a third group. Foals that received plasma were given 950 ml between 1 and 10 days of age and between 30 and 50 days of age. A tracheobronchial aspirate was obtained from foals with clinical signs of respiratory tract disease for bacteriologic culture. RESULTS: A significant difference in incidence of pneumonia caused by R equi in foals with adequate passive transfer was not detected between foals that received plasma (19.1%) and nontreated foals (30%). Of 13 foals without FPT that received plasma and developed pneumonia caused by R equi, 12 developed disease prior to administration of the second dose of hyperimmune plasma. Incidence of undifferentiated pneumonia of all causes was not different between groups. CONCLUSION AND CLINICAL RELEVANCE: Intravenous administration of the commercially available hyperimmune plasma was safe, and the product contained high concentrations of anti-R equi antibodies. However, within this limited foal population, the difference in incidence of pneumonia caused by R equi observed between foals that received plasma and control foals was not significant.     

Activation of the ovine hypothalamic-pituitary-adrenal axis and febrile response by interleukin-6: A comparative study with bacterial lipopolysaccharide endotoxin

Sheep were subjected to immune challenge with either recombinant human interleukin-6 (rhIL-6; 2.0 μg/kg; n = 5), Escherichia coli lipopolysaccharide (LPS) endotoxin (400 ng/kg; n = 7), or saline (n = 6) to determine if IL-6 activates the febrile and hypothalamic-pituitary-adrenal axis (HPAA) responses in sheep, and to compare these responses with those associated with endotoxemia. Blood was collected over time to measure plasma adrenocorticotropic hormone (ACTH) and serum cortisol concentrations as indicators of HPAA activity. Unlike LPS, rhIL-6 was not pyrogenic in sheep at this challenge dose. In contrast, rhIL-6 elicited ACTH and cortisol responses that peaked earlier than those induced by LPS. These results suggest that this dose of IL-6, alone, is not sufficient to elicit the febrile response in sheep, however, it is a potent activator of the ovine HPAA response.     

Airway inflammation is associated with mucous cell metaplasia and increased intraepithelial stored mucosubstances in horses

This study was performed to determine if a peripheral sample of lung from the site where biopsy is conducted is representative of the rest of the lung and to investigate the relationship between airway inflammation and intraepithelial mucous production in the peripheral airways. Lung parenchyma samples were collected from five different regions of the lung in five control and five heaves-affected horses. Horse groups were defined by clinical response to stabling. Tissue sections were used for semi-quantitative scoring of lesions, to count the number of airways, to quantify the amount of stored mucosubstances (Vs) within the epithelium, and to count the number of epithelial cells in terminal airways. No significant differences were found between lung regions or between groups of horses. Lack of regional differences in airway structures means that a biopsy sample can be used for diagnosis and investigation of diffusely distributed diseases. Airway inflammation was correlated with mucous cell metaplasia and Vs. Therefore, in horses, mucus accumulation is partly caused by increased number of mucous cells and is associated with airway inflammation. Therapy targeted to reduce airway inflammation will help reduce the excessive mucous accumulation in horses.