Intraoperative Ultrasound Applications in Intracranial Surgery.

The methods and use of intraoperative ultrasound in 33 canine and five feline patients and its ability to localize and identify anatomical structures and pathological lesions in canines and felines undergoing intracranial surgery are described from a case series. All were client-owned referral patients admitted for neurologic evaluation, with an advanced imaging diagnosis of an intracranial lesion, and underwent surgical biopsy or surgical removal of the lesion. Medical records, retrieval and review of imaging reports, and characterization of findings for all canine and feline patients show that intraoperative ultrasound guidance was used in intracranial procedures during the period of 2012 and 2019. Twenty-nine of the canine patients had intracranial tumors. The remainder had various other conditions requiring intracranial intervention. Three of the feline patients had meningiomas, one had a depressed skull fracture, and one had an epidural hematoma. The tumors appeared hyperechoic on intraoperative ultrasound with the exception of cystic portions of the masses and correlated with the size and location seen on advanced imaging. Statistical comparison of the size of images seen on ultrasound and on MRI for 20 of the canine tumors revealed no statistical differences. Neuroanatomical structures, including vascular components, were easily identified, and tumor images correlated well with preoperative advanced imaging. The authors conclude that intraoperative ultrasound is a valuable asset in intracranial mass removals and can augment surgical guidance in a variety of intracranial disorders that require surgery. This is the first known publication in veterinary surgery of using intraoperative ultrasound as a tool in the operating theater to identify, localize, and monitor the removal/biopsy of intracranial lesions in small animals undergoing craniotomy/craniectomy.

Evaluation of SNAP cPL, Spec cPL, VetScan cPL Rapid Test, and Precision PSL Assays for the Diagnosis of Clinical Pancreatitis in Dogs.

BACKGROUND: The sensitivity, specificity, and agreement of 4 diagnostic assays (SNAP canine pancreatic lipase (cPL), specific cPL (Spec cPL), VetScan cPL Rapid Test, and Precision PSL) for pancreatitis in dogs have not been directly compared. HYPOTHESIS/OBJECTIVES: To determine the level of agreement among each of the 4 assays and a clinical suspicion score, level of agreement among the assays, and sensitivity and specificity of each assay in a clinically relevant patient group. ANIMALS: Fifty client-owned dogs with clinical signs of gastrointestinal disease. METHODS: Prospective study. History, physical examination, complete blood count, serum biochemistry, abdominal ultrasound examination, and the 4 diagnostic assays for pancreatitis were performed. Intraclass correlation coefficients (ICC) were used to determine the level of agreement between each assay and a clinical suspicion score determined by a panel of 5 board-certified veterinary internists. RESULTS: The ICC between the clinical suspicion score and the 4 assays were SNAP cPL, 0.61; Spec cPL, 0.68; VetScan cPL Rapid Test, 0.68; and Precision PSL, 0.60. The sensitivities of the assays ranged from 73.9 to 100.0%, whereas the specificities were SNAP cPL, 71.1-77.8%; Spec cPL, 74.1-81.1%; VetScan cPL Rapid Test, 76.9-83.8%; and Precision PSL, 64.0-74.3%. CONCLUSIONS AND CLINICAL IMPORTANCE: A good to excellent level of agreement was demonstrated among the 4 assays. The previously unreported sensitivity and specificity of the VetScan cPL Rapid Test were 73.9-83.3% and 76.9-83.8%, respectively. Results of any of the 4 diagnostic assays alone, in the absence of supporting clinical findings, are insufficient to establish a diagnosis of clinical pancreatitis in dogs.

Acetylation and methylation of sperm histone 3 lysine 27 (H3K27ac and H3K27me3) are associated with bull fertility.

Epigenetic modifications in histones are crucial for proper sperm physiology, egg activation and reproductive development of males. The objectives of this study were to determine the conservation and interactomes of histone three (H3) and ascertain the expression dynamics of acetylated and methylated H3 lysine 27 (H3K27ac and H3K27me3) in spermatozoa from Holstein bulls with different fertility. Methods in immunocytochemistry and flow cytometry were used to evaluate the expression dynamics of H3K27ac and H3K27me3 in spermatozoa from 10 bulls with different in vivo fertility. Computational biology methods including Clustal Omega and Cytoscape were performed to determine the evolutionary conservation and interactome of H3. The post-translational modifications (PTM) of H3 (H3K27ac and H3K27me3) had different spatiotemporal dynamics in the sperm head. Intensities of methylation were higher than those of acetylation and inversely correlated between the two fertility groups (p = .0032). The interacting proteins of H3 are involved in critical subcellular processes such as regulation of methylation, nucleosome assembly, regulation of DNA replication and chromatin assembly. These results are significant because they help advance fundamental science and biotechnology of mammalian reproduction.

Effects of Leukoreduction and Storage on Erythrocyte Phosphatidylserine Expression and Eicosanoid Concentrations in Units of Canine Packed Red Blood Cells.

BACKGROUND: Storage of canine packed red blood cells (pRBCs) can increase erythrocyte phosphatidylserine (PS) expression and eicosanoid concentrations. HYPOTHESIS/OBJECTIVES: To determine the effects of leukoreduction on erythrocyte PS expression and eicosanoid concentrations in stored units of canine pRBCs. Our hypothesis was that leukoreduction would decrease PS expression and eicosanoid concentrations. ANIMALS: Eight healthy dogs. METHODS: In a cross-over study, units of whole blood were leukoreduced (LR) or non-LR and stored (10 and 21 days) as pRBCs. Samples were collected at donation, and before and after a simulated transfusion. PS expression was measured by flow cytometry, and concentrations of arachidonic acid (AA), prostaglandin F2α (PGF2α ), prostaglandin E2 (PGE2 ), prostaglandin D2 (PGD2 ), thromboxane B2 (TXB2 ), 6-keto-prostaglandin F1α (6-keto-PGF1α ), and leukotriene B4 (LTB4 ) were quantified by liquid chromatography-mass spectrometry. RESULTS: There was no change in PS expression during leukoreduction, storage, and simulated transfusion for non-LR and LR units. Immediately after leukoreduction, there was a significant increase in TXB2 and PGF2α concentrations, but during storage, these eicosanoids decreased to non-LR concentrations. In both LR and non-LR units, 6-keto-PGF1α concentrations increased during storage and simulated transfusion, but there was no difference between unit type. There was no difference in AA, LTB4 , PGE2 , and PGD2 concentrations between unit types. CONCLUSIONS AND CLINICAL IMPORTANCE: Leukoreduction, storage, and simulated transfusion do not alter erythrocyte PS expression. Leukoreduction causes an immediate increase in concentrations of TXB2 and PGF2α , but concentrations decrease to non-LR concentrations with storage. Leukoreduction does not decrease the accumulation of 6-keto-PGF1α during storage.

Rickettsia parkeri and "Candidatus Rickettsia andeanae" in Questing Amblyomma maculatum (Acari: Ixodidae) From Mississippi.

Amblyomma maculatum Koch (Acari: Ixodidae), the primary vector for Rickettsia parkeri, may also be infected with a rickettsia of unknown pathogenicity, "Candidatus Rickettsia andeanae." Infection rates with these rickettsiae vary geographically, and coinfected ticks have been reported. In this study, infection rates of R. parkeri and "Ca. R. andeanae" were evaluated, and rickettsial DNA levels quantified, in 335 questing adult A. maculatum collected in 2013 (n = 95), 2014 (n = 139), and 2015 (n = 101) from Oktibbeha County, MS. Overall infection rates of R. parkeri and "Ca. R. andeanae" were 28.7% and 9.3%, respectively, with three additional A. maculatum (0.9%) coinfected. While R. parkeri-infected ticks were detected all three years (34.7% in 2013; 13.7% in 2014; 43.6% in 2015), "Ca. R. andeanae" was not detected in 2013, and was detected at rates of 10.8% in 2014, and 15.8% in 2015. Interestingly, rickettsial DNA levels in singly-infected ticks were significantly lower in "Ca. R. andeanae"-infected ticks compared to R. parkeri-infected ticks (P < 0.0001). Thus, both infection rates and rickettsial DNA levels were higher for R. parkeri than "Ca. R. andeanae." Infection rates of R. parkeri were also higher, and "Ca. R. andeanae" lower, here compared to A. maculatum reported previously in Kansas and Oklahoma. As we continue to monitor infection rates and levels, we anticipate that understanding temporal changes will improve our awareness of human risk for spotted fever rickettsioses. Further, these data may lead to additional studies to evaluate potential interactions among sympatric Rickettsia species in A. maculatum at the population level.

Effects of oral cyclosporine on canine T-cell expression of IL-2 and IFN-gamma across a 12-h dosing interval.

The duration of immunosuppressive effects following oral cyclosporine in dogs is unknown. This study used flow cytometry and quantitative reverse transcription-polymerase chain reaction (qRT-PCR) to evaluate the effects of high-dose oral cyclosporine across a 12-h dosing interval. Expression of interleukin-2 (IL-2) and interferon-gamma (IFN-γ) was compared before and after 8 days of cyclosporine at 10 mg/kg every 12 h in six healthy dogs. Samples were collected at 0, 2, 4, and 8 h postdosing for analysis of unactivated and activated T-cell and whole blood cytokine expression using flow cytometry and qRT-PCR, respectively, and at 0, 2, 4, 6, 8, and 10 h postdosing for measurement of cyclosporine concentrations. Flow cytometry and qRT-PCR both demonstrated significant marked reductions in IL-2 and IFN-γ levels at 0, 2, 4, and 8 h after dosing compared to pretreatment levels (P < 0.05) for activated samples, with less consistent effects observed for unactivated samples. Both flow cytometry and qRT-PCR are viable techniques for measuring cyclosporine pharmacodynamics in dogs, yielding comparable results with activated samples. Two hours postdrug administration is the preferred time for concurrent assessment of peak drug concentration and cytokine expression, and T-cell activation is needed for optimal results.

Use of the cortisol-to-ACTH ratio for diagnosis of primary hypoadrenocorticism in dogs.

BACKGROUND: The ACTH stimulation test is currently required for definitive diagnosis of hypoadrenocorticism. Increased cost of synthetic ACTH (cosyntropin) has prompted a search for alternative diagnostic methods. OBJECTIVE: The purpose of this study was to determine whether a cortisol-to-ACTH ratio (CAR) can be used to differentiate dogs with hypoadrenocorticism from normal dogs and those with nonadrenal illness. ANIMALS: Eight healthy dogs (H), 19 dogs with nonadrenal illness (NAI), and 15 dogs with hypoadrenocorticism (HAD). METHODS: Dogs in the HAD group were retrospectively identified from PUVTH medical records. The NAI group consisted of hospitalized dogs with clinical signs, clinicopathologic findings, or both, consistent with a diagnosis of hypoadrenocorticism, but in which hypoadrenocorticism was ruled out based on ACTH stimulation test results. Healthy dogs were recruited from hospital staff and students. Endogenous ACTH concentrations and cortisol concentrations before and after ACTH stimulation were measured in all dogs. RESULTS: Baseline cortisol concentration was significantly lower, and ACTH concentration was significantly higher, in the HAD group versus the H and NAI group (P < .001). However, there was overlap among groups. Cortisol-to-ACTH ratio was significantly lower in the HAD group versus the H and NAI groups (P < .001), and there was no overlap between the HAD group and the other 2 groups. CONCLUSIONS AND CLINICAL IMPORTANCE: CAR can be used for definitive diagnosis of primary hypoadrenocorticism.

Associations between vaccinations against protozoal and viral infections and Salmonella in broiler flocks.

Reducing the burden of Salmonella in broiler flocks presents a challenge for public health. Worldwide, grow-out broilers are routinely vaccinated to prevent or lessen clinical manifestation of other infections. In this exploratory analysis we tested if details of a routine vaccination programme delivered to conventional grow-out broilers were associated with the burden of Salmonella in the flock as it progressed through its production cycle. None of the flocks studied were vaccinated against Salmonella or received a competitive exclusion product. The flocks were reared on conventional grow-out farms in southeastern USA, and sampled in a prospective field observational study. We observed significant associations between the content and design of a grow-out vaccination programme targeting other infections and the probability of detecting Salmonella in the broiler flock at different time points throughout the production cycle. To the best of the authors' knowledge, this is the first field report of such associations.

Risk factors associated with detection of Salmonella in broiler litter at the time of new flock placement.

In this study, we investigated risk factors associated with the probability to detect Salmonella in samples of litter collected within 2 h prior to new flock placement in 76 grow-out houses on 38 conventional broiler farms located in the US states of Mississippi, Alabama and Texas. We evaluated characteristics of location and layout of the farm; area adjacent to and surrounding the house; house construction; condition and type of equipment in the house; litter management and other production, sanitation, visitation and biosecurity practices; non-broiler animal species on the farm; and weather conditions on the 3 days leading up to flock placement. Logistic regression was used to model the relationships between probability to detect Salmonella in litter and potential risk factors. In the screening process, each risk factor was evaluated as a single fixed effects factor in a multilevel model that accounted for variability among the sampled farms and their production complexes and companies. Of almost 370 risk factors screened, 24 were associated with the probability to detect Salmonella in litter. These were characteristics of the surroundings of the house, house construction and conditions, litter management, length of downtimes between flocks in the house, biosecurity and farm location. After investigation of collinearity between these variables and building of models for important risk factor categories, the list of candidate variables for the final model was refined to eight factors. The final model demonstrated that a higher probability of detecting Salmonella in litter was strongly associated with the use of wood to construct the base of the walls or to cover the inside of the broiler house foundation, and with the use of fresh wood shavings to top-dress or completely replace the litter between flocks.

The change in prevalence of Campylobacter on chicken carcasses during processing: a systematic review.

A systematic review was conducted to evaluate the change in prevalence of Campylobacter on chicken carcasses during processing. A structured literature search of 8 electronic databases using the key words for "Campylobacter," "chicken," and "processing" identified 1,734 unique citations. Abstracts were screened for relevance by 2 independent reviewers. Thirty-two studies described prevalence at more than one stage during processing and were included in this review. Of the studies that described the prevalence of Campylobacter on carcasses before and after specific stages of processing, the chilling stage had the greatest number of studies (9), followed by washing (6), defeathering (4), scalding (2), and evisceration (1). Studies that sampled before and after scalding or chilling, or both, showed that the prevalence of Campylobacter generally decreased immediately after the stage (scalding: 20.0 to 40.0% decrease; chilling: 100.0% decrease to 26.6% increase). The prevalence of Campylobacter increased after defeathering (10.0 to 72.0%) and evisceration (15.0%). The prevalence after washing was inconsistent among studies (23.0% decrease to 13.3% increase). Eleven studies reported the concentration of Campylobacter, as well as, or instead of, the prevalence. Studies that sampled before and after specific stages of processing showed that the concentration of Campylobacter decreased after scalding (minimum decrease of 1.3 cfu/g, maximum decrease of 2.9 cfu/mL), evisceration (0.3 cfu/g), washing (minimum 0.3 cfu/mL, maximum 1.1 cfu/mL), and chilling (minimum 0.2 cfu/g, maximum 1.7 cfu/carcass) and increased after defeathering (minimum 0.4 cfu/g, maximum 2.9 cfu/mL). Available evidence is sparse and suggests more data are needed to understand the magnitude and mechanism by which the prevalence and concentration of Campylobacter changes during processing. This understanding should help researchers and program developers identify the most likely points in processing to implement effective control efforts. For example, if contamination will occur during defeathering and likely during evisceration, critical control points postevisceration are likely to have a greater effect on the end product going to the consumer.

Inter-relationships of Salmonella status of flock and grow-out environment at sequential segments in broiler production and processing.

In this study, we investigated how the likelihoods of Salmonella presence in various samples from broilers and their grow-out environment throughout one production cycle were related. Sixty-four broiler flocks from 10 complexes of two companies in the southern United States were included in the study. Samples from the gastrointestinal tracts of chicks, transport tray pads and litter and drag swabs from the house were collected on the day of placement of each flock. Approximately, 1 week before harvest, whole bird carcass rinses, caecum and crop samples were collected from birds from these same flocks. On the day of harvest, litter and drag swab samples were also taken from the house after the birds were removed. Upon arrival of the flocks at the processing plant, whole carcass rinses, caecum and crop samples were collected. As the flocks were processed, carcass rinses were collected just before the carcasses entered the immersion chill tank and as they exited the chill tank. Logistic regression was used to model the relationships between the likelihood of Salmonella in samples of each type collected at each sampling point and Salmonella frequencies in all the samples taken from the flock and grow-out environment at preceding production stages. The analysis demonstrated that increased likelihood of Salmonella contaminated carcasses entering the immersion chill tank was associated with higher contamination of the exteriors and crops of birds at arrival for processing as well as house environmental samples at the time of harvest and prior to placement. The best predictors of post-chill broiler carcass Salmonella status were the frequencies of Salmonella in the litter on the day of harvest and prior to placement. The immersion chilling appeared to disrupt some of the relationships between the processing plant and pre-harvest samples.

Use of secondary enrichment for isolation of Salmonella from naturally contaminated environmental samples.

Since the implementation of Hazard Analysis Critical Control Point (HACCP), the need for on-farm food safety risk assessment and management has greatly increased. In order to provide accurate risk assessments, attention should be focused on better characterization of the Salmonella isolation and identification techniques. In this work, we compared the isolation ability of 4 Salmonella-specific protocols: immunomagnetic separation (DB), tetrathionate (TT) broth, Rappaport-Vassiliadis R10 (RV) broth, and a secondary enrichment (TR) procedure as well as 2 selective solid media (brilliant green agar, BG; and xylose-lysine tergitol 4, XLT4). All 4 methods were compared in litter and drag swab samples that were collected weekly during the broiler grow out period in 7 houses. There were 65/126 (51.6%) pooled litter samples positive and 115/304 (37.8%) drag swab samples positive for Salmonella by at least one method. Of the 65 positive litter samples, DB, RV, and TT isolated 1 (2.7%), 31 (47.7%), and 23 (35.4%) of the samples as positive when using BG agar, respectively. The TR protocol identified 83.1% (54/65) of the positive samples as positive when using BG agar. In the drag swab samples, DB did not identify any samples as positive, whereas TT and RV found 28 (25.7%) and 26 (23.9%) of the 109 samples to be positive when using BG agar, respectively. Again, the TR protocol identified the highest percentage of positive samples (94.5%). An analysis of agreement, kappa, revealed that TT and RV did not always agree on which samples were positive, although the number of samples identified as positive by both were not different. A comparison between the 2 agar plates used, BG and XLT4, showed that they had high agreement when the secondary enrichment protocol was used, but agreement was only moderate to low when the other 3 methods were used.

Comparison of four Salmonella isolation techniques in four different inoculated matrices.

The poultry industry is now operating under increased regulatory pressure following the introduction of the pathogen reduction and hazard analysis critical control point (HACCP) rule in 1996. This new operation scheme has greatly increased the need for on-farm food safety risk management of foodborne bacteria, such as Salmonella. Information needed to make informed food safety risk management decisions must be obtained from accurate risk assessments, which rely on the sensitivity of the isolation techniques used to identify Salmonella in the production environment. Therefore, better characterization of the Salmonella isolation and identification techniques is warranted. One new technique, immunomagnetic separation (IMS), may offer a benefit to the poultry industry, as it has been shown to be efficacious in the isolation of Salmonella from various sample matrices, including some poultry products. In this work, we compared the isolation ability of 4 Salmonella-specific protocols: IMS, tetrathionate (TT) broth, Rappaport-Vassiliadis R10 (RV) broth, and a secondary enrichment (TR) procedure. All 4 methods were compared in 4 different spiked sample matrices: Butterfield's, poultry litter, broiler crops, and carcass rinses. IMS was able to detect Salmonella at 3.66, 2.09, 3.06, and 3.97 log10 cfu/mL in Butterfield's, poultry litter, carcass rinse, and broiler crop matrices, respectively. For the broiler litter and Butterfield's solution, there were no (P > 0.05) differences among the 4 isolation protocols. However, in the carcass rinse and crop samples, there were no differences among the isolation of Salmonella using RV, TR, or TT, but all 3 were (P < or = 0.05) more successful at recovering Salmonella than the IMS method.

Effect of wean-to-finish management on pig performance.

In each of three trials, 240 crossbred barrows weaned at 17 d of age (5.1 kg BW) were assigned to one of three experimental treatments based on light and heavy weight outcome groups. Experimental treatments were 1) wean-to-finish at 0.69 m2/pig and 15 pigs/pen; 2) wean-to-finish double-stocked at 0.35 m2/pig, 30 pigs per pen for 8 wk and then randomly split into two pens (either stayed in same pen or moved to new pen) for growth to slaughter at 0.69 m2/pig; and 3) nursery facility for 8 wk at 0.35 m2/pig and 15 pigs/pen followed by move to the same grow-finish facility housing wean-to-finish and double-stocked pigs and maintaining pen integrity. Beginning at 38 kg BW, diets were supplemented with either bacitracin methylenedisalicylate at 33 mg/kg to slaughter or tylosin at 44 mg/kg to 59 kg BW and 22 mg/kg thereafter. There were no trial x treatment interactions, even though there was considerable variation in health status among trials. At the end of the 56-d nursery period, wean-to-finish pigs weighed more than nursery (28.7 vs 27.7 kg; P = 0.071) and double-stocked pigs (28.7 vs 26.9 kg; P = 0.002), due to greater ADG (wean-to-finish vs nursery; P = 0.062; wean-to-finish vs double-stocked; P = 0.002) and greater ADFI (wean-to-finish vs nursery; P = 0.024; wean-to-finish vs double-stocked, P = 0.002). There was no effect of treatments (P > 0.1) on ADG, feed conversion, carcass lean percentage, or lean gain during the growing-finishing period. There was also no effect of treatment (P > 0.1) on ADG or ADFI from weaning to slaughter. There was no difference (P > 0.1) between bacitracin methylenedisalicylate and tylosin for ADG, feed conversion, carcass lean percentage, or daily lean gain. These data suggest that housing 5-kg weaned pigs in fully slatted growing-finishing facilities from weaning to slaughter was not detrimental to overall performance. In this experiment, dietary additions of bacitracin methylenedisalicylate or tylosin from 38 kg BW to slaughter weight resulted in similar growth performance.

Porcine reproductive and respiratory syndrome virus: description of persistence in individual pigs upon experimental infection.

We studied the persistence of porcine reproductive and respiratory syndrome virus (PRRSV) in individual experimentally infected pigs, during a period of up to 150 days postinfection (dpi). The results of this study suggest that the persistence of PRRSV involves continuous viral replication but that it is not a true steady-state persistent infection. The virus eventually clears the body and seems to do it in most of the animals by 150 dpi or shortly thereafter. High genetic stability was seen for several regions of the persistent PRRSV's genome, although some consistent mutations in the genes of envelope glycoproteins and M protein were also observed.

Synergism between porcine reproductive and respiratory syndrome virus (PRRSV) and Salmonella choleraesuis in swine.

Porcine reproductive and respiratory syndrome virus (PRRSV) and Salmonella choleraesuis are two leading causes of economic loss in the swine industry. While respiratory disease is common in both S. choleraesuis and PRRSV infections, the factors that contribute to its development remain largely undefined. We investigated the interaction of PRRSV, S. choleraesuis, and stress in 5-week-old swine. All combinations of three factors (inoculation with S. choleraesuis on Day 0, PRRSV on Day 3, and treatment with dexamethasone on Days 3-7) were used to produce eight treatment groups in two independent trials. Fecal samples, tonsil and nasal swabs, serum samples and postmortem tissues were collected for bacteriologic and virologic examinations. No clinical signs were observed in pigs inoculated with only PRRSV or only S. choleraesuis. In contrast, pigs which were dually infected with S. choleraesuis and PRRSV exhibited unthriftiness, rough hair coats, dyspnea, and diarrhea. The pigs which received all three treatment factors were the most severely affected and 43% (three of seven) of the animals in this group died. Individuals in this group shed significantly higher quantities of S. choleraesuis in feces and had significantly higher serum PRRSV titers compared to other treatments (p < or = 0.05). In addition, S. choleraesuis and PRRSV were shed longer and by more pigs in this group than other groups and S. choleraesuis was recovered from more tissues in this group on Day 21 post inoculation. These results suggested that PRRSV, S. choleraesuis, and dexamethasone acted synergistically to produce a syndrome similar to that observed in the field.

Diarrhea in growing-finishing swine.

Regardless of the etiology of an enteric disease in nursery age to finisher swine, making a prompt and accurate diagnosis is crucial. Eliciting a complete history, assessing clinical signs and pathology, and selecting and interpreting laboratory tests are essential components in achieving this. Early detection and diagnosis of enteric disease is particularly critical in the nursery through finisher phase because of economic impacts. Recurrent topics when discussing control and prevention of enteric diseases are reducing stress and improving pig comfort and reducing or eliminating exposure through sanitation and biosecurity. These are not new concepts; in fact, prior to the advent of antimicrobials, they were the mainstay of treatment of enteric diseases. With concern over the use of antimicrobials in food animal production increasing, exploiting disease ecology to control enteric diseases is increasing in importance. New vaccines and bacterins for postweaning swine enteric diseases are needed tools to exploit the pig's immune system. Recent advances in diagnostic capabilities allow an increase in understanding and exploitation of disease ecology.

Seroprevalence of antibodies against Toxoplasma gondii in free-ranging mammals in Iowa.

Serum samples from raccoons (Procyon lotor), striped skunks (Mephitis mephitis), Virginia opossums (Didelphis virginiana), and free-ranging house cats trapped in Iowa between 1984 and 1988 were tested for antibodies against Toxoplasma gondii using the modified direct agglutination test (MAT). Antibody titers > or = 1:32 were considered indicative of infection. Prevalence rates by species were estimated for raccoons at 134/885 (15%), skunks at 38/81 (47%), opossums at 12/53 (23%), and cats at 16/20 (80%).

Porcine reproductive and respiratory syndrome virus replicates in testicular germ cells, alters spermatogenesis, and induces germ cell death by apoptosis.

Like other arteriviruses, porcine reproductive and respiratory syndrome virus (PRRSV) is shed in semen, a feature that is critical for the venereal transmission of this group of viruses. In spite of its epidemiological importance, little is known of the association of PRRSV or other arteriviruses with gonadal tissues. We experimentally infected a group of boars with PRRSV 12068-96, a virulent field strain. By combined use of in situ hybridization and immunohistochemistry, we detected infection by PRRSV in the testes of these boars. The PRRSV testicular replication in testis centers on two types of cells: (i) epithelial germ cells of the seminiferous tubules, primarily spermatids and spermatocytes, and (ii) macrophages, which are located in the interstitium of the testis. Histopathologically, hypospermatogenesis, formation of multinucleated giant cells (MGCs), and abundant germ cell depletion and death were observed. We obtained evidence that such germ cell death occurs by apoptosis, as determined by a characteristic histologic pattern and evidence of massive DNA fragmentation detected in situ (TUNEL [terminal deoxynucleotidyltransferase-mediated digoxigenin-UTP nick end labeling] assay). Simultaneously with these testicular alterations, we observed that there is a significant increase in the number of immature sperm cells (mainly MGCs, spermatids, and spermatocytes) in the ejaculates of the PRRSV-inoculated boars and that these cells are infected with PRRSV. Our results indicate that PRRSV may infect target cells other than macrophages, that these infected cells can be primarily responsible for the excretion of infectious PRRSV in semen, and that PRRSV induces apoptosis in these germ cells in vivo.