Cross-reactivity indices (CRIs) of 28 isolates of Moraxella bovis recovered from outbreaks of infectious bovine keratoconjunctivitis in Argentina (A, 11 isolates), Brazil (B, 7), and Uruguay (U, 10) between 1983 and 2000 were estimated. Hyperimmune sera were produced in rabbits and antibody titres determined with each isolate. Isolates showing CRIs3 70 were placed in the same group. Group I had 13 isolates (A, 1; B, 6; U, 6); group II had 6 isolates (A, 4; U, 2); groups III, IV, and V had 2 isolates each, recovered in Argentina; group VI had 2 isolates, from Uruguay; and group VII had 1 isolate, from Brazil. The CRIs3 70 between vaccine strains and isolates recovered before and after 1990 were 58% and 42%, 50% and 50%, and 33% and 67% with vaccine strains 2419, 2358, and 2439, respectively. Isolate 273, from Uruguay, showed CRIs > 70 with 78% of the isolates and is recommended as the vaccine strain.

Objective-To evaluate the association between airway reactivity and age, sex, body weight, and radiographic findings in cats. Animals-32 mature cats that constituted 2 age groups (17 young cats that were 1 to 2 years old and 15 old cats that were 12 to 13 years old). Procedure-Cats were placed in the chamber of a barometric whole-body plethysmograph (volume, 38 L), and box pressure was measured at baseline and after aerosol administration of increasing concentrations of carbachol. Airway reactivity was assessed by monitoring increases in enhanced pause (PENH), a unitless variable that measures bronchoconstriction as derived from dose-response curves. The endpoint chosen was the provocative concentration of carbachol that increased PENH to 300% of the baseline value (PCPENH300). Results-We did not find a correlation between PCPENH300 and sex, body weight, number of eosinophils, PENH before bronchoconstriction, respiratory frequency, tidal volume, or minute ventilation. Airway reactivity was significantly less in the old cats (mean +/- SD PCPENH300, 0.578 +/- 0.051%), compared with the value for the young cats (0.053 +/- 0.006%). Radiographic patterns differed significantly between groups of cats; a greater proportion of old cats (12/15) had bronchointerstitial patterns, compared with the proportion of young cats (4/17). Conclusion and Clinical Relevance-These data support the notion that age exerts a strong influence on airway reactivity in adult cats, and radiographic differences suggest that structural changes in older cats may contribute to this effect. These findings have important implications for interpretation of results of airway reactivity tests in cats.

Objective-To compare the minimum alveolar concentration (MAC) of isoflurane required to prevent corticocerebral activation, autonomic responses, and purposeful movements after somatic or visceral stimulation in cats anesthetized with isoflurane. Animals-17 healthy spayed female cats. Procedure-Bispectral index (BIS), autonomic parameters, and purposeful movements were monitored before and after somatic or visceral stimuli in cats anesthetized with isoflurane. End-tidal (ET) isoflurane concentration was varied to determine MAC values for cortical arousal (MACBIS), autonomic responsiveness (MACBAR), and purposeful movement (MAC). Bispectral index values greater than 60 were considered to represent corticocerebral activation. Results-Minimum alveolar concentration for purposeful movement was significantly less than MACBIS and MACBAR for both somatic and visceral stimulation. Individual MAC values for somatic stimulation were not significantly different from respective MAC values for visceral stimulation. The percentage of cats that had a BIS response greater than 60 was inversely related to the end-tidal isoflurane concentration. Conclusions and Clinical Relevance-Corticocerebral arousal and subcortical autonomic reflexes occured at isoflurane anesthetic concentrations at which reflexive or purposeful movements were absent. These results suggested that isoflurane had a preferential effect on voluntary motor output at low end-tidal isoflurane concentrations, and that sensory pathways, subcortical sympathetic output, and cortical responsiveness are less susceptible to the anesthetic effects of isoflurane. Bispectral index values obtained after somatic or visceral stimulation were sensitive for the detection of early changes in cortical excitability.

Objective-To determine the influence of age on results of quantitative analysis of electromyographic (EMG) needle examination in the subclavian, triceps, and lateral vastus muscles of Dutch Warmblood horses. Animals-7 healthy young Dutch Warmblood horses (range, 13 to 18 months old), 7 healthy adult Dutch Warmblood horses (range, 4 to 10 years old), and 7 healthy elderly Dutch Warmblood horses (range, 18 to 21 years old). Procedure-An EMG needle examination was performed to evaluate insertional activity, spontaneous activity, and motor unit action potential (MUAP) variables. Although all horses were conscious, young horses were sedated prior to examination. Results-Mean insertional activity in young horses was significantly lower than in elderly horses. Pathologic spontaneous activity was rarely found in young and adult horses but was frequently evident in all muscles in all elderly horses. The MUAP duration and amplitude were significantly lower in all muscles of young horses, compared with values for adult and elderly horses. The MUAP duration and number of phases and turns were significantly lower in adult horses than in elderly horses. Group differences for percentages of polyphasic and complex MUAPs were also found. The 95% confidence intervals for MUAP duration, MUAP amplitude, and number of phases and turns for the subclavian, triceps, and lateral vastus muscles were significantly lower in young horses than in adult or elderly horses. Conclusion and Clinical Relevance-Age of the horse being examined should be considered when EMG examination is performed.

The objectives of the study were to determine the duration of porcine reproductive and respiratory syndrome virus (PRRSV) survival in houseflies (Musca domestica Linnaeus) following feeding on an infected pig, and to determine whether the virus was present on the exterior surface or within the internal viscera of the fly. A total of 210 laboratory-colonized houseflies were allowed to feed to repletion on a pig, experimentally infected with PRRSV on day 7 postinoculation, and then maintained alive under laboratory conditions (27°C). Two subsets (A and B) of 30 flies were collected at each of the following sampling points; 0, 6, and 12 hours post feeding (pf). Subset A contained an extra group of 30 flies collected at 24 hours pf due to the availability of extra flies. Flies in subset A were processed as whole fly homogenates, while the exterior surface washes and digestive organs were collected from flies in subset B. Whole fly homogenates, collected at 0, 6, and 12 hours pf, were positive by both polymerase chain reaction (PCR) and swine bioassay. Digestive organs, collected at 0 and 12 hours pf, were positive by PCR and swine bioassay. The PRRSV RNA was detected by PCR from the exterior surface wash of subset B flies collected at 0, 6, and 12 hours pf; however, only the subset collected at 0 hour pf was swine bioassay-positive. This study indicates that infectious PRRSV can survive within the intestinal tract of houseflies for up to 12 hours following feeding on an infected pig, but only for a short period on the exterior surface of the flies.

In order to examine an association between porcine circovirus type-2 (PCV2) infection and reproductive failure in pigs, sera (n = 171) from stillborn fetuses were collected from 3 different farms with prolonged histories of reproductive problems. These sera were tested for the presence of antibodies to PCV2 using an immunoperoxidase monolayer assay. Of the 171 sera tested, 28 had PCV2 antibody titers of ≥ 1:16. When these 28 samples were tested by a polymerase chain reaction assay, 13 were found to contain PCV2 viral DNA. Of these 13 samples containing both PCV2 antibodies and viral DNA, 9 yielded PCV2 on virus isolation. Amino acid sequences comprising open reading frame 2 of PCV2 from 2 of these isolates were compared to PCV2 isolates from cases of post-weaning multi-systemic wasting syndrome (PMWS). The amino acid sequences of the 2 isolates from stillborn pigs were shown to be nearly identical to each other, as well as to other PCV2 isolates associated with reproductive failure. When compared with PMWS isolates, the isolates from the stillborn fetuses showed differences of at least 2 amino acids. These results confirm previous findings that transplacental infection of PCV2 occurs in the field and that stillbirths in pigs may be associated with PCV2 infections. At present, the significance of minor differences in amino acid sequences is not known.

Acupuncture analgesia is an important issue in veterinary medicine. This study was designed to elucidate central modulation effects in response to electroacupuncture (EA) at different acupoints. Manganese-enhanced functional magnetic resonance imaging was performed in Sprague-Dawley rats after sham acupuncture, sham EA, or true EA at somatic acupoints. The acupoints were divided into 3 groups: group 1, analgesic acupoints commonly used for pain relief, such as Hegu (LI 4); group 2, nonanalgesic acupoints rarely used for analgesic effect, such as Neiguan (PC 6); and group 3, acupoints occasionally used for analgesia, such as Zusanli (ST 36). Image acquisition was performed on a 1.5-T superconductive clinical scanner with a circular polarized extremity coil. The results showed that there was no neural activation caused by EA at a true acupoint with shallow needling and no electric current (sham acupuncture). When EA at a true acupoint was applied with true needling but no electric current (sham EA), there was only a slight increase in brain activity at the hypothalamus; when EA was applied at a true acupoint with true needling and an electric current (true EA), the primary response at the hypothalamus was enhanced. Also, there was a tendency for the early activation of pain-modulation areas to be prominent after EA at analgesic acupoints as compared with nonanalgesic acupoints. In conclusion, understanding the linkage between peripheral acupoint stimulation and central neural pathways provides not only an evidence-based approach for veterinary acupuncture but also a useful guide for clinical applications of acupuncture.

The aim of the present study was to determine and to compare through an indirect enzyme linked immunosorbent assay (ELISA) test, the presence of anti-Neospora caninum antibodies in city and farm dogs, as well as in farm cows, and the relationship among them. The correlation between anti-N. caninum antibodies in farm dogs and cattle was also assessed. The research was conducted in the dairy region of Tizayuca, Hidalgo, Mexico. The frequency of anti-N. caninum antibodies was significantly higher in farm dogs (n = 14) (51%) when compared to those from the city (n = 6) (20%) (P < 0.05), suggesting that farm dogs have a higher risk of exposure to the parasite. There was no significant difference in seropositivity between males (n = 11) (39%) and females (n = 9) (33%) (P > 0.05). The frequency of anti-N. caninum antibodies in farm cattle was significantly higher in farms with dogs (n = 158) (58%) when compared to those with no dogs (n = 43) (35%) (P < 0.05). These results suggest the possible transmission of the parasite from dogs to cattle.

Objective-To use threshold concentrations of acetone and beta-hydroxybutyrate in milk and serum, respectively; identify risk for ketosis and endometritis; and assess analyses of blood and milk samples as predictors of risk for ketosis in high-yielding dairy cows. Animals-90 multiparous Holstein cows. Procedure-At intervals before and after parturition, blood samples were obtained for determination of glucose, nonesterified fatty acids, leptin, insulin, insulin-like growth factor-1, and beta-hydroxybutyrate concentrations. Samples of milk were obtained at similar intervals after parturition for determination of fat content and concentrations of acetone, protein, and lactose. Reproductive examination of each cow was performed weekly. Results-For each cow, threshold concentrations of acetone and β-hydroxybutyrate were calculated as 75th and 90th percentiles of maximum postpartum concentrations of acetone in milk (0.40 and 0.87 mmol/L) and β-hydroxybutyrate in serum (2.30 and 3.51 mmol/L). Significant decrease in milk production (442 to 654 kg of energy-corrected milk/305-day period per cow) was associated with acetone or beta-hydroxybutyrate in excess of threshold values. Milk acetone concentrations > 0.40 mmol/L were associated with 3.2 times higher risk for endometritis. Low plasma glucose, high serum beta-hydroxybutyrate, and high milk acetone concentrations during week 1 after parturition were indicators of increased risk for ketosis later during lactation. Conclusions and Clinical Relevance-Determination of milk acetone concentration during the week after parturition may identify cows at risk for ketosis and endometritis; with appropriate interventions, development of disease and production losses may be reduced.

Objective-To develop a spatial epidemic model to simulate intraherd and interherd transmission of footand- mouth disease (FMD) virus. Sample Population-2,238 herds, representing beef, dairy, swine, goats, and sheep, and 5 sale yards located in Fresno, Kings, and Tulare counties of California. Procedure-Using Monte-Carlo simulations, a spatial stochastic epidemic simulation model was developed to identify new herds that would acquire FMD following random selection of an index herd and to assess progression of an epidemic after implementation of mandatory control strategies. Results-The model included species-specific transition periods for FMD infection, locations of herds, rates of direct and indirect contacts among herds, and probability distributions derived from expert opinions on probabilities of transmission by direct and indirect contact, as well as reduction in contact following implementation of restrictions on movements in designated infected areas and surveillance zones. Models of supplemental control programs included slaughter of all animals within a specified distance of infected herds, slaughter of only high-risk animals identified by use of a model simulation, and vaccination of all animals within a 5- to 50-km radius of infected herds.