Mycotic omasitis and rumenitis as sequelae to sepsis in dairy cattle: six cases (1979-1986)

Medical records of 6 cows with mycotic rumenitis or omasitis, but no history of grain engorgement, were reviewed. A diagnosis was made at necropsy in all cows, although the condition was suspected before euthanasia in 3 cows. Common clinical findings included inappetence, rumen stasis, fluid rumen contents, and scant, pasty, or loose feces. Postmortem findings included severe ulcerative rumenitis or omasitis, with thrombosis of blood vessels in the submucosa, and branching, septate fungal hyphae abundant in inflamed tissues. In these cows, mycotic omasitis and rumenitis were thought to be sequelae of sepsis, with reflux of abomasal fluid into the forestomach and broad spectrum antimicrobial therapy as possible predisposing factors for mycotic infections.     

Associations between types of lameness and fertility

Four hundred and twenty-seven cases of first-reported foot lameness were recorded in 17 dairy herds in Somerset during the winter housing period. Lameness was classified into three categories: sole ulceration, digital disease (white line abscess, foreign bodies in the sole and pricked or punctured sole), and interdigital disease (lesions of the skin between claws and heel including foul in the foot, interdigital fibroma and dermatitis). In addition, a 'clinical effect score' was calculated to take account of the severity of lameness, the structures involved and the time for which the cows were clinically affected. The fertility records of lame cows were compared with those of the healthy cows nearest in parity and stage of lactation. In the lame cows the interval from calving to first service was four days longer, and the interval from calving to conception was 14 days longer than in the control cows, the pregnancy rate to first service was 46 per cent (controls 56 per cent), 2.14 services were required per conception (controls 1.72) and 16 per cent of lame cows were culled (controls 5 per cent). Lameness, first reported in the period 36 to 70 days after calving, was associated with a significant (P less than 0.01) increase in the interval from calving to first service of eight days; and sole ulceration, in the period 71 to 120 days after calving, was associated with an increase of 11 days (P less than 0.05). Lameness in all periods up to 120 days after calving was associated with significantly increased intervals from calving to conception (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)     

Porcine malignant hyperthermia susceptibility: halothane-induced increase in cytoplasmic free calcium in lymphocytes

We tested the hypothesis that lymphocytes from swine with susceptibility to malignant hyperthermia (MH) had increased sensitivity to the membrane-perturbing effects of halothane that increase cytoplasmic calcium. Cytoplasmic concentration of ionized calcium in lymphocytes isolated from blood was determined in the presence and absence of halothane for 10 Pietrain x Poland China swine that were susceptible to MH and 20 Yorkshire swine that were resistant to MH. Calcium was determined by dual-emission spectrofluorometry and by measuring the ratio of free to calcium-bound form of the fluorescent calcium dye Indo-1. Mean values for calcium concentrations in lymphocytes from MH-susceptible (MHS) swine were 80% less than control values (40.5 +/- 38.8 and 185.3 +/- 91.6 nmol/L; P less than 0.01). Untreated lymphocytes from MHS swine accumulated calcium at half the rate observed for controls. Exposure to 1 mmol/L halothane resulted in a 3-fold increase of free calcium concentration to 127.9 +/- 81.3 nmol/L in the lymphocytes of MHS swine, but had no significant effect on lymphocytes from control swine (225.0 +/- 91.4; P less than 0.01). Exposure to 2 mmol/L halothane resulted in a 6-fold increase of free calcium concentration to 255.9 +/- 91.4 nmol/L in lymphocytes from MHS swine and a 63% increase in lymphocytes from controls (303.8 +/- 116). The rate of halothane-induced increase in cytosolic calcium was 13 times greater in lymphocytes from MHS swine, compared with controls. These data indicated that the molecular defect that results in halothane-hypersensitivity and is characteristic of muscle of MHS swine also occurs in lymphocytes from MHS swine.     

Microlithiasis associated with chronic bronchopneumonia in a cat

Chronic bronchopneumonia associated with microlithiasis was diagnosed in a 9-year-old domestic shorthair cat with a 3-month history of coughing and dyspnea. Thoracic radiography revealed multifocal patchy alveolar infiltrates in all lung fields. Numerous acellular, concentrically laminated, periodic acid-Schiff-positive microliths were seen in mucus from tracheal washing. Microliths were composed primarily of calcium carbonate. A definite cause could not be identified. There was no response to treatment and the cat was euthanatized. Marked type-II alveolar cell proliferation, peribronchiolar smooth muscle proliferation, and alveolar microlithiasis were seen histologically. Microliths are rarely encountered in tracheal washings from companion animals. Their pathophysiologic properties and meaning remain to be established.     

The heterogenicity of Cowdria ruminantium stocks: cross-immunity and serology in sheep and pathogenicity to mice

Ten stocks of Cowdria ruminantium (Ball 3, Breed, Comoro, Germishuys, Kümm, Kwanyanga, Mali, Mara, Nonile and Welgevonden) were compared from a cross-immunity, serological and mouse pathogenicity point of view. They were found to differ in varying degrees. Except for the Ball 3, Comoro and Germishuys stocks that were similar but not identical, there was no pattern in the antigenic diversity of the 10 stocks. The Welgevonden stock emerged as the stock that elicits an immunity against most of the South African stocks. The inability of the reference Ball 3 stock to protect sheep against no fewer than 6 other stocks questions the advisability of retaining this stock as the vaccine stock. The antigenic diversity of the 10 stocks could not be correlated with the antibody levels detected with the indirect fluorescent antibody test, since the sera against all 10 stocks reacted positively to the Kümm stock antigen and the variation in titres was not stock-related.     

Prevalence of gastrointestinal nematodes in dairy heifers in western Canada

A survey was conducted to estimate the prevalence of gastrointestinal nematodes in grazing dairy replacement heifers in western Canada. Fecal samples were collected from 566 animals on 34 farms distributed over the three prairie provinces. Fecal egg counts were performed using a modified Wisconsin centrifugation technique. The overall mean farm fecal egg count was 16.0 eggs per gram feces (range 0.7-78.1 epg). Gastrointestinal nematodes were demonstrated on every farm examined, and 93.3% of all individuals tested were positive.     

Patterns of antimicrobial susceptibility in Michigan wildlife and bovine isolates of Mycobacterium bovis.

The state of Michigan has recognized the presence of Mycobacterium bovis in its free-ranging white-tailed deer population since 1994. This endemic infection is primarily located in a 12-county area in the northeastern lower peninsula of Michigan. A statewide surveillance and eradication program of the disease has been in effect since 1994. Worldwide, Mycobacterium tuberculosis complex organisms have a known predilection toward development of antimicrobial resistance. The objective of this study was to investigate the antimicrobial susceptibility of M. bovis isolates from white-tailed deer in Michigan and detect any changes in susceptibility over time. M. bovis isolates from 2 fall hunting seasons (1999 and 2004) were used in this study. The fall season of 2004 marked the first documented case of direct transmission of M. bovis from a wild deer to a human in Michigan. Since M. bovis is a zoonotic disease, knowledge of susceptibility can expedite treatment options in humans. M. bovis isolates were obtained from 58 deer, 4 coyotes, 3 cattle, 2 raccoons, and 1 human case from the 2 years combined. Methods of susceptibility testing included 1% proportion agar plates and Bactec radiometric broth testing. M. bovis was found to be uniformly resistant to the antibiotic pyrazinamide; this resistance is common to all M. bovis isolates. No other antimicrobial resistance was found in any of the tested M. bovis isolates, which may be, in part, attributed to the lack of any significant treatment pressure in wildlife.     

Fatal systemic phaeohyphomycosis caused by Ochroconis gallopavum in a dog (Canis familaris)

A 5-year-old Shetland Sheepdog was presented with a history of weakness, ataxia, anemia, thrombocytopenia, and occasional seizures. The dog had been treated for 6 months with prednisone for inflammatory bowel disease. A positive titer for Ehrlichia canis was detected 6 months before referral. The initial physical examination revealed a weak, laterally recumbent dog with pale mucous membranes. Neurologic examination revealed multiple neurologic deficits. A complete blood cell count (CBC) revealed normochromic, normocytic, nonregenerative anemia; lymphopenia; thrombocytopenia; and neutrophilic and monocytic leukocytosis. Urinalysis revealed proteinuria, with a specific gravity of 1.045. The dog was unresponsive to treatment and died. At necropsy, there was severe serofibrinous peritonitis and pleuritis, with randomly scattered dark brown necrotic foci present in multiple organs, including liver, spleen, kidney, and pancreatic lymph node. Histologically, there were extensive regions of parenchymal necrosis surrounded by neutrophils admixed with epithelioid macrophages, lymphocytes, and pigmented fungal organisms. Numerous brown, 2 to 6 microm in diameter, septate, branching hyphae, subsequently identified as Ochroconis gallopavum (formerly Dactylaria constricta var. gallopava), were observed.     

Farm management practices associated with macrocyclic lactone resistance on sheep farms in New Zealand

AIM: To identify farm practices associated with the presence of resistance to a macrocyclic lactone (ML) anthelmintic on sheep farms in New Zealand. METHODS: A cross-sectional study was conducted to test for associations between the presence of resistance to an ML anthelmintic (ivermectin) and management practices on sheep farms in New Zealand. Selection of farms was both random (n=80) and purposive (n=32; being farms with a history of suspected ML resistance). Resistance was inferred from faecal nematode egg count (FEC) reduction (FECR) tests (FECRTs) when there was <95% reduction in FEC 7-10 days after treatment with a half dose of ivermectin (0.1 mg/kg). A logistic regression model was built to identify farm-level factors that were associated with the presence or absence of ML resistance. RESULTS: Of the 112 flock managers that were approached for interview, 103 (92%) returned useable questionnaires. The odds of ML resistance were increased: on farms that had used long-acting ML products in ewes as a pre-lambing treatment for > or =3 of the previous 5 years (odds ratio (OR) = 7.2; 95% confidence interval (CI) = 1.7-30.3); on farms where <70% of the total stock units mid-winter were from sheep (OR=6.5; 95% CI=1.6-25.6); on farms which over the year purchased >10% of the number of sheep present mid-winter (OR=7.1; 95% CI=1.5-34.7); and on farms where the average wool diameter of the main flock was <37 (OR=4.1; 95% CI=1.1-14.7) microns. The model provided a good fit to the data (pseudo R2=0.64; Hosmer-Lemeshow statistic = 0.38). CONCLUSIONS: Explanatory factors identified as associated with the presence of ML (ivermectin) resistance on farms included the use of long-acting anthelmintic formulations in ewes pre-lambing, sources of refugia of unselected parasites on the farm, breed of sheep and their requirements for anthelmintic treatments, and the importing of resistant parasites with purchased stock. The study provides support for controls that aim to provide refugia of susceptible worms and that minimise the risk of introduction of resistance through effective quarantine drenching.     

Cloning and characterisation of the ahpA gene of Pasteurella multocida serogroup b:2 (strain P52): short communication

Pasteurella multocida B:2 is responsible for haemorrhagic septicaemia in cattle and buffaloes, causing severe economic losses in the developing countries. In the present study, the ahpA gene of P. multocida B:2 (P52) was cloned, sequenced and compared with the previously reported ahpA gene sequence in P. multocida A:1, which is responsible for its haemolytic phenotype. E. coli DH5a cells were further transformed with recombinant plasmid carrying the ahpA gene from P. multocida B:2 (P52) but SDS-PAGE analysis failed to show the expression of haemolysin protein. Slight haemolysis was albeit observed in horse blood agar plates streaked with recombinant E. coli carrying the ahpA gene. Our study indicates that there is 99.6% similarity and 0.4% divergence between ahpA gene of P. multocida B:2 (P52) and P. multocida A: 1, while membrane topology analysis has predicted that ahpA is an inner membrane protein with two strong hydrophobic regions at the N and C terminals. The presence of significant homology in ahpA sequence in A: 1 and B:2 perhaps suggests a common mechanism of pathogenesis in different species of animals.