Strategies of the control of an outbreak of leptospiral infection in dairy cattle in Northeastern Brazil

The aim of the present study was to describe the strategies of the control of an outbreak of leptospiral infection in dairy cattle in Maranhão State, Northeastern Brazil. In the period from January to July 2015, 18 (17%) out of 106 cows presented abortion, six (5.7%) stillbirth, and 12 (11.3%) repeated estrus, totaling 24 animals with reproductive problems. The diagnosis of leptospirosis was based on serology (microscopic agglutination test—MAT), bacteriological culture, and polymerase chain reaction (PCR). Antibiotic therapy, vaccination protocols, and changes in management practices were suggested as control measures. Of all animals on the farm (n?=?280), 136 (48.6%) were seropositive for at least one serovar of Leptospira sp. No pure leptospiral culture was obtained. Eight of the animals with reproductive problems yielded positive PCR results (vaginal fluid of seven animals and urine and vaginal fluid of one animal). Genetic sequencing of a vaginal fluid/urine PCR-positive sample revealed Leptospira borgpetersenii. One year after the adoption of control measures, no reproductive problems were observed. Thus, leptospirosis probably caused the reproductive failures in the herd, and the control and prevention measures implemented were efficient in controlling the disease.

     

Reproductive behavior in hair sheep rams under tropical conditions

The reproductive efficiency of sheep herds depends to a great extent on the ram. Male reproductive evaluation allows to select for the best and eliminate those with reproductive problems. The objective was to evaluate the effect of breed and age group on the reproductive behavior of hair sheep rams in the tropics of Mexico. Pelibuey (n?=?42), Blackbelly (n?=?30), Dorper (n?=?44), and Katahdin (n?=?30) rams of two age groups: young (n?=?74, 1–1.5 years old) and adult (n?=?72, 2–4 years old) were evaluated. Serving capacity (10-min duration) and breeding soundness evaluation (BSE) tests were carried out in each ram. In the first test, rams were classified as suitable and unsuitable, and in the BSE test, they were classified as satisfactory, questionable, or unsatisfactory. The response variables were analyzed using chi-square test or analyses of variance (ANOVA). ANOVA included the fixed effects of breed, age group, and their interaction. In the serving capacity test, 79.5% of the rams were considered suitable, with no breed differences (P?>?0.05). Adult rams (90.3%) had the highest proportion of suitable rams (P?<?0.05). In the BSE test, 80.2% of the rams were satisfactory; only breed being significant (P?<?0.05). Pelibuey breed had the highest proportion of satisfactory rams (91.4%). Breed × age interaction was no significant for any trait. After serving capacity and BSE tests, a high proportion of rams was found not suitable for reproduction (36.3%), which is expected to cause low fertility in the flock.

     

Characterization of the functional domain of major surface protein 1a involved in adhesion of the rickettsia Anaplasma marginale to host cells

The major surface protein (MSP) 1a of the genus type species Anaplasma marginale (Rickettsiales: Anaplasmataceae) has been shown to mediate adhesion, infection and transmission of the organism, as well as to contribute to protective immunity in cattle. MSP1a contains a variable number of tandemly repeated peptides in the amino-terminal region, while the remainder of the protein is highly conserved among isolates. The number of repeats varies among geographic isolates of A. marginale but is constant within an isolate and has been used as a stable genetic marker of isolate identity. Because the sequence of the tandem repeats is the most variable part of the protein among isolates, this region of the protein is most likely to be involved in adhesion to host cells, a prerequisite to infection. The purpose of this study was to characterize the organization and function of the MSP1a tandem repeats of A. marginale in adhesion to host cells. We demonstrated by use of recombinant mutant proteins that the tandemly repeated region of MSP1a was necessary and sufficient to mediate adhesion of MSP1a to tick cells and bovine erythrocytes. Synthetic peptides representing the predominant sequences of individual repeats were tested for their adhesive capacity for tick cell extract (TCE). Peptides containing acidic amino acids D or E at position 20 bound to TCE, while peptides with a G as the 20th amino acid were not adhesive to TCE. Antibodies produced in rabbits against a synthetic repeat peptide neutralized A. marginale infection of cultured tick cells, and the neutralization observed was similar to that effected by antibodies produced against the whole MSP1a recombinant protein. Analysis of tandemly repeated MSP1a peptides of several geographic isolates of A. marginale revealed a complex relationship between the msp1alpha genotype and the tick-transmissible phenotype of the isolate and suggested that both the sequence and conformation of the repeated peptides influenced the adhesive properties of MSP1a. These studies demonstrated that the tandemly repeated region of the protein mediates the adhesive function of MSP1a.     

Factors affecting the detachment rhythm of engorged Boophilus microplus female ticks (Acari: Ixodidae) from Charolais steers in New Caledonia

As in most parts of the world where the cattle tick Boophilus microplus is established, resistance of ticks to acaricides occurs in New Caledonia. In order to implement laboratory resistance tests on larvae, engorged females collected in suspected farms are necessary. Investigations on the detachment schedule of the engorged females were conducted to explain certain field situations such as the lack or scarcity of engorged females on highly infested cattle driven from the pasture to the pen in the morning. Three experiments on Charolais steers naturally infested on pastures showed that: (1) engorged female burdens at sunrise are similar whether the steers spend the night in pasture or in a pen; (2) compared with steers maintained in a pen, morning detachment of females increases when the steers stay on the pasture or move from the pasture to the pen; (3) detachment rhythm of engorged females on steers staying the morning in a pen, is not influenced by feeding activity or exposition of steers to sun; (4) detachment occurs earlier for females attached on anatomical sites exposed to sun, and earlier from these sites for the steers in pasture or walking than for steers in a pen.     

Adherence of Actinobacillus pleuropneumoniae to primary cultures of porcine lung epithelial cells

To study adherence of Actinobacillus pleuropneumoniae to porcine lower respiratory epithelium, a cell culture model was developed using primary cultures of porcine lung epithelial cells (LEC). Adherence assays were performed and results were compared with data obtained with swine kidney cells (SK6). A. pleuropneumoniae efficiently adhered to LEC with up to 62 bacteria per cell after 2h of incubation. Reference strain of serotype 3 (R3) adhered better to LEC than reference strains of serotypes 1 (R1), 7 (R7) and 8 (R8). Overall the adherence to LEC was more rapid and up to 30-fold more efficient than adherence to SK6 cells. In search for the mechanism involved in the adherence event, we tested the effect of LPS which has previously been demonstrated to cause adherence of the pathogen to upper respiratory epithelium. Adherence assays with LPS transposon mutants demonstrated unaltered (mutant with modification in core/lipid A moiety) or even three-fold more adherence (mutants lacking O antigen) compared to the parent micro-organisms. Purified LPS of strains R1, R3, R7 and R8 did not inhibit adherence of R8 to LEC either, suggesting that LPS and particularly the O-antigen are not essential for adherence of A. pleuropneumoniae to LEC. The efficient, LPS-independent adherence of A. pleuropneumoniae to LEC cells indicates that A. pleuropneumoniae may carry different, cell type-specific adhesins and that primary cultures of lower respiratory epithelium are valuable infection models in studying A. pleuropneumoniae pathogenesis.     

Risk factors associated with behavioural disorders of crib-biting,weaving and box-walking in Swiss horses

REASONS FOR PERFORMING STUDY: Studies on the prevalence of behavioural disorders in horses and on associated risk factors have revealed inconsistent results. There are many studies on the neuropharmacological, surgical or mechanical therapy of stereotypies, but little is known about their causation. OBJECTIVES: To explore risk factors associated with the occurrence of behavioural disorders in horses. METHODS: A sample of horse owners, selected randomly and representative for Switzerland, was contacted in a postal survey. Answers were provided for 622 stables (response rate 35.2%). Individual data of 2,341 horses were examined with path analysis (multivariable linear and logistic regression), and adjustment made for possible confounding effects due to age and breed. RESULTS: Out of 60 possible risk factors, 11 were associated with the outcome at the univariable level (null-hypothesis path model) and 3 factors remained after the backward logistic regression procedure. Mature Warmbloods and Thoroughbreds, assessed by the owners to be reactive, fed 4 times a day and without daily pasture, had increased odds of displaying crib-biting, weaving and box-walking. Furthermore, indirect associations of 5 factors with the outcome were identified. CONCLUSIONS: The final logistic regression model of risk factors leads to the hypotheses that causal prevention of stereotypic behaviours should be based upon housing and management conditions which allow tactile contact with other horses (e.g. mutual grooming), daily free movement (paddock or pasture), as well as the provision of high amounts of roughage but of little or no concentrates. POTENTIAL CLINICAL RELEVANCE: It is one of the aims of population medicine to prevent the development of behavioural disorders. Further research is needed to test the concluding hypotheses in experimental studies or to verify them in the context of similar observational studies.     

Hip dysplasia in a 6-year-old Salz ram

A 6-year old Salz ram was presented with a history of poor body condition, progressive gait abnormalities, pelvic limb lameness, and difficulty with copulation. Based on the history, clinical signs, hip palpation, and radiography, a diagnosis of hip dysplasia, previously unreported in sheep, was made.     

Gastric ulcers in standardbred racehorses: prevalence,lesion description,and risk factors

This study was performed to estimate the prevalence of gastric ulcers in Standardbred racehorses, to describe the lesion score and location, and to identify potential risk factors. Two hundred seventy-five (275) Standardbred horses from 5 training centers and 2 racetracks in Quebec, Canada, were studied. Historical data for the 2 months before examination were recorded for each horse, and the presence of gastric ulcers was determined by gastroscopy. A previously reported scoring system that used grades 0-3 for gastric lesions was used. Overall, 121 horses (44.0%; 95% CI, 38.1-50.1%) had gastric ulcers. The prevalence of gastric ulcers was significantly higher (P < .0001) in actively racing horses (63.3%; 95% CI, 54.7-71.2%) than in horses at rest. Multivariate analysis defined that horses in racing (OR = 9.29; 95% CI, 3.55-24.3) were significantly more likely to have gastric ulcers than horses at rest and that trotters (OR = 2.23; 95% CI, 1.28-3.86) were more likely to have gastric ulcers than pacers. The number of lesion sites (P < .0001) and poor body condition (P < .0001) were significantly associated with lesion scores. Gastric ulcers are highly prevalent in Standardbred racehorses. Furthermore, actively racing horses and trotters are more likely to have gastric ulcers. Also, poor body condition in Standardbred racehorses may be an indication that gastric ulcers are present and that lesion scores are high. The cause-and-effect relationship between poor body condition and the presence of gastric ulcers is unclear.     

Immediate semi-static loading using compression healing abutments: a stability study in dogs

Loading in implant dentistry to accelerate prosthodontic treatment has been receiving increasing interest. The aim of this study was to investigate the effect of an early controlled lateral loading (after 7 days) on the establishment of osseointegration by means of resonance frequency analysis. Two groups of six beagle dogs each were used. Group I had implants without loading. Group II had implants loaded with a new prototype compression abutment that created controlled semi-static loading. Loaded implants showed slightly better stability after 5 weeks of healing, but the difference was not significant. We concluded that controlled loading is beneficial to maintain, and even improve, stability during the early critical healing period.