Biomedical subjects

R J Callan

Publications and source records attributed to R J Callan.

18 recordsLinked to original sources

PubMed2003

Occurrence of infectious upper respiratory tract disease and response to vaccination in horses on six sentinel premises in northern Colorado.

REASONS FOR PERFORMING STUDY: Horses vaccinated against common agents of infectious upper respiratory disease (IURD) may not have detectable serum antibody and may not be protected from clinical disease. OBJECTIVES: The objectives of this study were to 1) investigate the serological response of horses to vaccination against influenza virus (H3N8 and H7N7) and equine herpesviruses (EHV) in a field setting and 2) evaluate associations among vaccination status, serum antibody concentrations, and occurrences of IURD in monitored horses. METHODS: In this study, horses on 6 Colorado premises were vaccinated parenterally against influenza virus and EHV, and serological response evaluated. Horses were monitored, and biological samples collected from individuals with clinical IURD and control horses. RESULTS: Of 173 horses, 61 (35.3%), 21 (12.1%) and 4 (2.3%) seroconverted in response to vaccination against EHV, influenza virus H7N7 and influenza virus H3N8, respectively. CONCLUSIONS: Outbreaks of IURD in study horses were associated with influenza virus H3N8 and Streptococcus equi infection, and serological response to vaccination with conventional products was poor. POTENTIAL RELEVANCE: These results confirm that horses may not respond with detectable serological responses to conventional vaccination against common respiratory viruses and, therefore, suggest that alternate methods of protecting horses against common respiratory viruses should be sought.

Animals↗

PubMed2001

Bacteremia associated with naturally occuring acute coliform mastitis in dairy cows.

OBJECTIVE: To determine the incidence of bacteremia in dairy cows with naturally occurring acute coliform mastitis (ACM) with a wide range of disease severity. DESIGN: Cohort study. ANIMALS: 144 dairy cows with ACM from 6 herds. PROCEDURE: Cows were examined at time of identification of ACM (time 0) and classified as having mild, moderate, or severe mastitis on the basis of rectal temperature, hydration status, rumen contraction rate, and attitude. Cows were reexamined at 24 or 48 hours. Bacteriologic culturing of milk and blood (30 ml), CBC, and serum biochemical analysis were performed at each time point. Appropriate samples were obtained at a single point from herdmates without mastitis (controls) that were closely matched for lactation number and days since parturition. Blood culture results were compared among severity groups and controls by use of chi2 tests, as was outcome of an ACM episode for cows grouped by blood bacterial isolates. RESULTS: Bacteria were isolated from 52 blood samples from 46 of 144 (32%) cows with ACM, which was significantly more than control cows (11/156; 7.1%). Group-1 isolates (Escherichia coli, Pasteurella multocida, Mannheimia haemolytica, Klebsiella pneumoniae, Enterobacter agglomerans, and Salmonella enterica serotype Typhimurium) were identified in 20 of 144 (14%) cows with ACM and 0 of 156 control cows. Group-1 isolates were identified in 4.3, 9.1, and 42% of cows classified as having mild, moderate, and severe ACM, respectively. Escherichia coli and K pneumoniae milk and blood isolates obtained from the same cow were of the same genotype. Bacillus spp were identified in 21 of 144 (15%) cows with ACM, which was significantly more than control cows (3/156; 1.9%). Thirty-five percent of cows with a group-1 isolate died during the mastitis episode. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that bacteremia develops in a substantial proportion of cows with ACM. Classification of severity of disease is important for establishment of effective treatment protocols; parenteral antimicrobial treatment may be indicated in cows with ACM.

Acute Disease↗

PubMed2001

Use of systemic disease signs to assess disease severity in dairy cows with acute coliform mastitis.

OBJECTIVE: To evaluate the use of systemic disease signs for classifying severity of acute coliform mastitis in dairy cows. DESIGN: Prospective cohort study. ANIMALS: 144 dairy cows. PROCEDURE: Cows were examined at the time of initial identification of disease (time 0) and classified as having mild, moderate, or severe disease on the basis of rectal temperature, hydration status, rumen contraction rate, and attitude. A CBC and serum biochemical analyses were performed, and milk samples were submitted for bacterial culture at time 0 and 48 hours later. RESULTS: 69 cows were classified as having mild disease, 44 as having moderate disease, and 31 as having severe disease. Median WBC and neutrophil counts were significantly lower in cows with moderate or severe disease at time 0 than in cows with mild disease. Band neutrophil count was significantly higher at 48 hours and serum calcium concentration was significantly lower at time 0 and at 48 hours in cows with severe or moderate disease, compared with cows with mild disease. Twenty-eight, 51, and 77% of cows with mild, moderate, and severe disease, respectively, had > 100,000 colony-forming units/ml of milk at time 0. The odds that a cow with severe disease would die or be culled were 3.6 times the odds for a cow with moderate disease and 11.2 times the odds for a cow with mild disease. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that a classification scheme based on readily observable systemic disease signs can be used to classify disease severity in cows with acute coliform mastitis.

Acute Disease↗

PubMed2001

Selenium and vitamin E.

Deficiency of selenium and vitamin E has recently been identified as a major health concern of sheep producers in certain regions of the United States, and familiarity with published data on these nutrients seems to be of value to small ruminant practitioners. This article begins with a description of the biochemical roles and metabolism of selenium and vitamin E. A literature review follows in which the influence of these nutrients on the musculoskeletal, reproductive, and immune systems, as well as on flock productivity, is discussed. Methods for detection of deficiency and supplementation strategies are also described.

Animal Feed↗

PubMed2001

Reproductive techniques in sheep.

This article reviews current methods of evaluating reproductive performance in the sheep industry. The reproductive technologies of breeding soundness examination, reproductive ultrasonography, estrus manipulation, artificial insemination, and embryo transfer are also extensively discussed. The veterinarian's current and future role in the application of these technologies is discussed.

Animals↗

PubMed2000

Malignant catarrhal fever: polymerase chain reaction survey for ovine herpesvirus 2 and other persistent herpesvirus and retrovirus infections of dairy cattle and bison.

Using a polymerase chain reaction (PCR) test for sequences of ovine herpesvirus 2 (OHV2), this virus was shown to be significantly associated with sheep-associated malignant catarrhal fever (SA-MCF) in terminal cases of disease in 34 cattle and 53 bison. Ovine herpesvirus 2 was not detected in cattle (38) and bison (10) that succumbed to other diseases. Other persistent herpesviruses, retroviruses, and pestivirus, some of which have been previously isolated from cases of SA-MCF, were not associated with the disease. These included bovine herpesvirus 4 (BHV4), bovine lymphotrophic herpesvirus (BLHV), bovine syncytial virus (BSV, also known as bovine spumavirus), bovine immunodeficiency virus (BIV), and bovine viral diarrhea virus (BVDV). A PCR survey for OHV2 in DNA from individual cow's peripheral blood lymphocytes in 4 dairies showed that the 1 dairy that was in close contact to sheep had a prevalence of OHV2 of 21.3%, whereas the 3 other dairies had no OHV2. Prevalence of the other herpesviruses and retroviruses in the dairy cows was variable, ranging from 2% to 51% for BHV4, 52% to 78.7% for BLHV, and 10% to 34% for BSV. Bovine lymphotrophic herpesvirus and BSV were also found in a few (1-4 of 21 tested) cases of terminal SA-MCF, but BIV and BVDV were not found in either the dairy cows sampled, or in the cases of SA-MCE No significant correlation was found between the presence of any 2 viruses (OHV2, BHV4, BLHV, BSV) in the dairy cows or terminal cases of SA-MCE

Animals↗

PubMed1998

Association of excess sulfur intake and an increase in hydrogen sulfide concentrations in the ruminal gas cap of recently weaned beef calves with polioencephalomalacia.

During a 2-week period, 16 of 150 recently weaned calves developed signs of polioencephalomalacia (PEM). One calf was examined and treated at our veterinary teaching hospital and a necropsy was performed on a calf that died. During the peak of the outbreak, clinicians visited the ranch. Ruminal hydrogen sulfide (H2S) and blood thiamine concentrations were measured in 10 clinically normal penmates of PEM-affected calves. Ruminal H2S concentrations were high (> 0.695 mg/L [> 500 ppm]) in all cattle (mean, 12.19 mg/L [8,770 ppm]). All blood thiamine values were within the reference range. Within 12 hours after measurement of blood thiamine concentrations, 2 of the calves from which samples were obtained developed clinical signs of PEM. Dietary analysis revealed an estimated sulfur intake of 0.9% per calf on a dry-matter basis. Hay contributed most of this sulfur. In the investigation reported here, an outbreak of PEM was associated with high ruminal H2S concentrations and excess sulfur intake without evidence of thiamine deficiency.

Animal Feed↗

PubMed1997

Cleavage of influenza A virus H1 hemagglutinin by swine respiratory bacterial proteases.

Cleavage of influenza A virus hemagglutinin (HA) is required for expression of fusion activity and virus entry into cells. Extracellular proteases are responsible for the proteolytic cleavage activation of avirulent avian and mammalian influenza viruses and contribute to pathogenicity and tissue tropism. The relative contributions of host and microbial proteases to cleavage activation in natural infection remain to be established. We examined 23 respiratory bacterial pathogens and 150 aerobic bacterial isolates cultured from the nasal cavities of pigs for proteolytic activity. No evidence of secreted proteases was found for the bacterial pathogens, including Haemophilus parasuis, Pasteurella multocida, Actinobacillus pleuropneumoniae, Bordetella bronchiseptica, and Streptococcus suis. Proteolytic bacteria were isolated from 7 of 11 swine nasal samples and included Staphylococcus chromogenes, Staphylococcus hyicus, Aeromonas caviae, Pseudomonas aeruginosa, Stenotrophomonas maltophilia, and Enterococcus sp. Only P. aeruginosa secreted a protease, elastase, that cleaved influenza virus HA. However, compared to trypsin, the site of cleavage by elastase was shifted one amino acid in the carboxy-terminal direction and resulted in inactivation of the virus. Under the conditions of this study, we identified several bacterial isolates from the respiratory tracts of pigs that secrete proteases in vitro. However, none of these proteolytic isolates demonstrated direct cleavage activation of influenza virus HA.

Animals↗

PubMed1997

Manipulation of immune responses via particle-mediated polynucleotide vaccines.

Polynucleotide vaccines are a new approach to immunization that promises qualitative advances in vaccine technology. These vaccines mimic infection in that they result in expression of pathogen gene products in situ, which can elicit both cell-mediated immune responses and humoral responses. This approach has been applied primarily to vaccines against viral diseases, but may be significant for vaccines directed toward bacterial pathogens. Auragen has developed a generally applicable gene transfer technology and, for vaccine applications, has focused on particle-mediated gene transfer to epidermis. Results demonstrate that Accell polynucleotide vaccines induce immune responses toward human immunodefficiency virus (HIV) antigens, influenza A virus antigens, and hepatitis B virus (HBV) antigens in rodent,s swine and primates. Cellular immune responses toward these antigens have been demonstrated in rodents. In a swine influenza a challenge model Accell vaccination provides protection equivalent to that of a commercial killed-whole-virus vaccine. Vaccination of mice by this method toward a Chlamydia pneumoniae major outer-membrane protein elicits a species-specific antibody response.

AIDS Vaccines↗

PubMed1996

Control of an outbreak of salmonellosis caused by drug-resistant Salmonella anatum in horses at a veterinary hospital and measures to prevent future infections.

Salmonella anatum was isolated from horses treated at a private veterinary clinic or at a university veterinary medical teaching hospital. All isolates were resistant to most commonly used antibiotics. Because of the severity of disease resulting from outbreaks of infections with drug-resistant strains of S anatum, an epidemiologic investigation was conducted. Enteric bacteria, including S anatum, that were resistant to most antibiotics were isolated from the private veterinary clinic environment. Salmonella anatum was not isolated from the university teaching hospital environment. To prevent transmission, disinfection and isolation protocols were reviewed, and changes were implemented, including discontinuing use of power sprayers for cleaning, improving a two-step disinfection process, restricting movement of horses, and enhancing awareness of Salmonella spp transmission. Communication and prompt action are pivotal in preventing dissemination of resistant strains of Salmonella spp in a clinic or hospital environment.

Animals↗

PubMed1995

The appearance of H3 influenza viruses in seals.

Surveillance for influenza A virus infection of seals has continued following the association of influenza A virus with epizootics of pneumonia in seals off the New England coast in 1979-1980 and 1982-1983. In January 1991 and January to February 1992, influenza A viruses were isolated from seals that died of pneumonia along the Cape Cod peninsula of Massachusetts. Antigenic characterization identified two H4N6 and three H3N3 viruses. This was the first isolation of H3 influenza viruses from seals, although this subtype is frequently detected in birds, pigs, horses and humans. Haemagglutination inhibition assays of the H3 isolates showed two distinct antigenic reactivity patterns: one more similar to an avian reference virus (A/Duck/Ukraine/1/63) and one more similar to a human virus (A/Aichi/2/68). The haemagglutinin (HA) genes from two of the H3 seal viruses showing different antigenic reactivity (A/Seal/MA/3911/92 and A/Seal/MA/3984/92) were 99.7% identical, with four nucleotide differences accounting for four amino acid differences. Phylogenetic analysis demonstrated that both of these sequences were closely related to the sequence from the avian H3 virus, A/Mallard/New York/6874/78. This indicates that influenza A viruses of apparent avian origin, including the H3 subtype viruses, continue to infect seals.

Animals↗

PubMed1993

Early detection of bovine leukemia virus in cattle by use of the polymerase chain reaction.

A study was performed to determine whether experimentally induced bovine leukemia virus (BLV) infection in cattle could be detected earlier by use of polymerase chain reaction (PCR) amplification of genomic DNA extracted from leukocytes than by use of conventional agar-gel immunodiffusion (AGID). The PCR primers were designed to amplify a 375-base-pair region of the proviral gag gene. Five cows were identified that were BLV-negative on the basis of AGID and PCR results. At day 0, these cows were inoculated IM with blood pooled from 3 naturally infected cows. Blood samples were taken on days 0, 1, and 7, and every 2 weeks thereafter until 3 months after inoculation. Three of the cows were BLV-positive by AGID test results 3 weeks after inoculation, and the remaining 2 seroconverted at 5 weeks. In contrast, all 5 cows were BLV-positive by PCR results 7 days after inoculation and remained positive for the duration of the study. Five cows that were BLV-positive by AGID test and PCR results on day 0 and from which samples were obtained at the same times as those from the other 5 cows, remained BLV-positive by results of both tests during the course of the study. Results indicate that under experimental conditions, BLV infection in cattle can be detected as much as 2 to 4 weeks earlier by use of PCR than by use of the AGID test.

Animals↗

PubMed1992

Ancillary tests of the cardiovascular and lymphatic system.

Clinical signs of cardiovascular or lymphatic disease may not be specific. Even such signs as edema, cardiac murmur, or cyanosis require further investigation to make a final diagnosis, determine prognosis, or assess treatment response. This article describes indications, description, and interpretation of the electrocardiogram, echocardiogram, phonocardiogram, arterial blood gases, pericardiocentesis, cardiac catheterization, lymph node aspirate or biopsy, indirect blood pressure determination, and other tests associated with the investigation of cardiovascular or lymphatic disease of food animals.

Animals↗

PubMed1992

Assessment of the cardiovascular and lymphatic systems.

Assessment of the cardiovascular and lymphatic systems first requires a complete signalment, history, and general physical examination. Further assessment of the cardiovascular system begins with evaluation of the cardiac borders through palpation and thoracic percussion. Complete cardiac auscultation requires careful evaluation of several parameters. The location, intensity, and character of normal heart sounds are first determined. This is followed by assessment of heart rate and rhythm. Finally, special attention should be placed on identifying abnormal heart sounds and describing them based on their location, intensity, duration, sound quality, and radiation. Assessment of the arterial, venous, and capillary systems provides additional information on the status of the cardiovascular system. Assessment of the lymphatic system primarily involves evaluation of external and palpable internal lymph nodes. Commonly palpable external lymph nodes include the intermandibular, parotid, retropharyngeal, superficial cervical, subiliac, mammary, and scrotal lymph nodes. Palpable internal abdominal lymph nodes include the iliofemoral lymph nodes and the iliosacral lymph center. Other lymph nodes that may be palpable include the renal, ruminal, and mesenteric lymph nodes. Lymph nodes should be evaluated for size, consistency, and tenderness.

Animals↗

PubMed1992

Placental transfer of fluoride in Holstein cows.

Placental transfer of fluoride was studied in 40 Holstein cows and related to a previous 7 1/2 y study for comparative purposes. Animals were randomly assigned to fluoride dosage groups of control, 0.51, 1.31 or 2.66 sodium fluoride/d (10, 25, 50 or 100 ug/g feed). Each animal received the dose daily via gelatin bolus for 4-14 d prior to parturition. Maternal heparinized blood samples were collected before dosing and after parturition. Placental cotyledon and calf blood samples were collected from each animal immediately after parturition. Maternal and calf plasma and placental cotyledon fluorine concentrations were determined. Increased levels of fluoride given to pregnant cows resulted in significantly increased (p less than 0.05) maternal plasma and placental cotyledon fluorine concentrations. Calf plasma fluorine concentrations at birth did not significantly increase in relation to the fluoride treatment level of dams. The data support the concept that under normal circumstances in cattle there is a partial placental barrier to fluoride that operates to limit fluoride concentrations in the fetal circulation and tissues.

Animals↗

PubMed1991

Development of pneumonia in desert bighorn sheep after exposure to a flock of exotic wild and domestic sheep.

From 1986 to 1989, 5 desert bighorn sheep (3 Ovis canadensis mexicana and 2 O c nelsoni), ranging in age from 2 to 3 years, were exposed to a flock of exotic wild and domestic sheep to potentially achieve naturally acquired pneumonia. Pasteurella multocida was isolated from nasal samples from 4 of 6 sheep randomly sampled from the flock. Bighorn sheep were exposed individually and each exposure period was a trial. Treatment before and after exposure varied and included combinations of alpha interferon, antibiotics, anti-inflammatory drugs, and vaccines. Treatments were chosen on the basis of recommendations of others for treating pneumonia in desert bighorn sheep as well as our own experience in sheep and cattle. Regardless of treatment used, bighorn sheep in trials 1 to 4 developed signs of pneumonia within 10 to 14 days of exposure. Bighorn sheep in trials 1 to 3 died within 11 to 17 days of initial exposure. In trial 4, the bighorn sheep was isolated from the carrier sheep for treatment of pneumonia on day 14 and died on day 30. Pasteurella multocida was isolated from lung tissue in 3 of the 4 bighorn sheep. On the basis of results of trials 1 to 4, a more in depth clinical study was conducted in trial 5. Nasal and blood specimens were collected prior to and during trial 5 for bacteriologic culturing and serologic testing for bovine viral diarrhea virus, infectious bovine rhinotracheitis, parainfluenza-3 virus, and respiratory syncytial virus.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1990

Congenital skeletal malformations and cleft palate induced in goats by ingestion of Lupinus, Conium and Nicotiana species.

Three piperidine alkaloid containing plants, Conium maculatum (poison-hemlock), Nicotiana glauca (tree tobacco) and Lupinus formosus (lunara lupine), induced multiple congenital contractures (MCC) and palatoschisis in goat kids when their dams were gavaged with the plant during gestation days 30-60. The skeletal abnormalities included fixed extension or flexure of the carpal, tarsal, and fetlock joints, scoliosis, lordosis, torticollis and rib cage abnormalities. Clinical signs of toxicity included those reported in sheep, cattle and pigs--ataxia, incoordination, muscular weakness, prostration and death. One quinolizidine alkaloid containing plant, Lupinus caudatus (tailcup lupine), on the other hand, which is also known to cause MCC in cows, caused only slight signs of toxicity in pregnant goats and no teratogenic effects in their offspring.

Abnormalities, Multiple↗

PubMed1990

Multiple congenital contractures (MCC) and cleft palate induced in goats by ingestion of piperidine alkaloid-containing plants: reduction in fetal movement as the probable cause.

Fetal movement, observed by ultrasound imaging, was significantly reduced (P less than or equal to 0.001) in pregnant goats gavaged with Conium seed and Nicotiana glauca and temporarily reduced with fresh Conium plant. Conium seed and Nicotiana glauca induced cleft palate and multiple congenital contractures in 100% of the kids born to pregnant goats gavaged with these plants. Multiple congenital contractures included torticollis, scoliosis, lordosis, arthrogryposis, rib cage anomalies, over extension, and flexure and rigidity of the joints. However, in goats gavaged with fresh Conium plant, fetal movement was inhibited for only about 5 hours after each individual dosage and gradually returned to control levels 12 hours after dosing. Fetal malformations in this group were limited from modest to moderate contractures of the front limbs, which resolved by 8-10 weeks post partum. No cleft palates were induced. Fetal movement was not inhibited in goats fed Lupinus caudatus and no cleft palates or multiple congenital contractures were induced in their offspring. The duration of the reduction in fetal movement appears to be an important factor in the severity and permanence of the deformities, particularly with cleft palate, spinal column defects, and severe joint deviation and fixation.

Abnormalities, Drug-Induced↗