Proliferation and transmission patterns of <Emphasis Type="Italic">Pasteurella multocida</Emphasis> B:2 in goats

This report describes the proliferation and transmission patterns of Pasteurella multocida B:2 among stressful goats, created through dexamethasone injections. Thirty seven clinically healthy adult goats were divided into three groups consisted of 15 goats in group A, 11 goats in group B and the remaining 11 in group C. At the start of the study, all goats of group A were exposed intranasally to 1.97 × 10¹⁰ CFU/ml of live P. multocida B:2. Dexamethasone was immediately administered intramuscularly for 3 consecutive days at a dosage rate of 1 mg/kg. The exposed goats were observed for signs of HS for a period of 1 month. At the end of the 1-month period, 11 goats from group B were introduced into and commingled with the surviving goats of group A before all goats from both groups were immediately injected intramuscularly with dexamethasone for 3 consecutive days. The treatment with dexamethasone was then carried out at monthly interval throughout the 3-month study period. Goats of group C were kept separately as negative control. Three surviving goats from each group were killed at 2-week interval for a complete post-mortem examination. Two (13%) goats of group A were killed within 24 hours after intranasal exposure to P. multocida B:2 while another two (13%) goats from the same group were killed on day 40, approximately 10 days after the second dexamethasone injection. All four goats showed signs and lesions typical of haemorrhagic septicaemia. Bacteraemia was detected in 3 goats of group A that were having rectal temperature higher than 41°C. The P. multocida B:2 isolation pattern was closely associated with dexamethasone injections when significantly (p < 0.05) higher rate of isolations from both groups were observed after each dexamethasone injection. Transmission of P. multocida B:2 from goats of group A to group B was successful when P. multocida B:2 was isolated from goats of group B for a period of 28 days. There was a strong correlation between dexamethasone injections, rate of bacterial isolation and serum cortisol level. The IgG level showed an increasing trend 2 weeks after exposure to P. multocida B:2 and remained high throughout the study period.     

Oscillatory measurements,blood gas analysis and clinical observations after intravenous clenbuterol administration in healthy and acutely pneumonic calves

The effects of clenbuterol (Ventipulmin, Boehringer Ingelheim) on respiratory functions were investigated in 6 calves aged 4–6 weeks prior to and after experimental infection withPasteurella haemolytica A1. On days 1–3 (prior to infection) and on days 7–9 (after infection), blood gas analysis, monofrequency forced oscillation techniques and clinical examinations (heart rate, respiratory rate) were conducted for 135 min after the intravenous administration of clenbuterol (0.8 µg/kg body weight). In healthy calves prior toPasteurella infection, intravenous administration of clenbuterol induced a mild tachycardia and a reduction in the mean oscillatory respiratory resistance. Using the same dose of clenbuterol in diseased calves after infection, the statistically significant reduction in oscillatory respiratory resistance was more impressive and it was accompanied by a significant increase in the oxygen pressure of the arterialized blood. Heart rate and respiratory rate did not change significantly after the administration of clenbuterol in infected calves.Abbreviations HR heart rate - IV intravenous - MFOT monofrequency forced oscillation technique - PaO₂ arterial oxygen pressure - R_os oscillatory resistance - RR respiratory rate     

Reduction of <Emphasis Type="Italic">Theileria annulata</Emphasis> Infection in Ticks Fed on Calves Immunized with Purified Larval Antigens of <Emphasis Type="Italic">Hyalomma anatolicum anatolicum</Emphasis>

Larval antigen of Hyalomma anatolicum anatolicum, the vector of Theileria annulata, was purified by two-step affinity chromatography using anti-tick gut-specific rabbit IgG and IgG from immunized cattle. The purified antigen showed the presence of a single polypeptide of 37 kDa (GHLAgP) on SDS-PAGE. Two groups (I and II) of naive crossbred calves (Bos taurus × B. indicus) were immunized with 1 mg of GHLAgP in three divided doses. Immunized calves of group I were also infected with a sublethal dose of T. annulata along with a group of non-immunized calves (group III). Animals in groups I, II, III as well a control group (group IV) were challenged with live nymphs of H. a. anatolicum on the 10th day of immunization. There was a significant reduction in the number of emerging adults of 56.9% ± 1.67% in calves of group I (p < 0.01) and 63.09% ± 1.26% in calves of group II (p < 0.001) compared to the controls. The calves of groups I and II showed antibody responses to tick antigen up to day 70 post immunization. Infection with T. annulata was determined in the salivary glands of adult ticks that developed from the nymphs used for challenge infection. In ticks taken from group I calves, there was a 75.0% ± 0.00% infection compared with only 85.0% ± 2.88% infection in ticks taken from calves of group III. Using PCR, a lower infection (83.33% ± 3.33%) was detected in ticks that developed from calves of group I compared with calves from group III (90.00% ± 2.88%). The ground-up tick supernatants (GUTS) of the ticks taken from calves of group III yielded higher infection rate and exhibited higher infectivity titre in in vitro infection assay of bovine mononuclear cells than the GUTS of the ticks taken from calves of group I. The results suggest a partial reduction in growth rate of T. annulata in ticks feeding on calves immunized with GHLAgP.     

三黄连散预防罗非鱼链球菌病临床应用研究

在开展三黄连散对人工感染罗非鱼无乳链球菌病预防效果研究的基础上,进一步验证以每千克饲料中添加13.2 g的三黄连散为推荐剂量,在生产中大面积应用的临床效果及安全性。设立三黄连散试验组、中药对照组和空白对照组3个组,每组300尾罗非鱼,连续用药7 d后,每组随机取30尾,测定增重率、器官指数、血液生理生化指标和肝脏抗氧化指标。用药后第8天,采用同居感染的方法感染鱼群,于感染后第14天计算保护率。结果表明,给药7 d后,与空白对照组相比,三黄连散试验组罗非鱼的增重率明显提高,器官指数和多项肝脏抗氧化指标均明显升高,血液生理生化指标总体无明显异常,预防无乳链球菌感染的保护率为43.67%。综上提示,三黄连散能够提高罗非鱼机体抵抗力,降低无乳链球菌感染罗非鱼的死亡率。     

Caseous Lymphadenitis in Goats: The Pathogenesis,Incubation Period and Serological Response after Experimental Infection

Twenty goats, in two groups of 10, were injected intradermally with Corynebacterium pseudotuberculosis. The doses of infection were 1×10⁵ and 5×10⁴ colony-forming units (cfu) for groups 1 and 2, respectively. Thereafter, a goat from each group was killed every 2–3 days and examined for gross and microscopic caseous lesions in the draining lymph nodes. Bands or zones of macrophages and polymorphonuclear granulocytes were observed microscopically on the second day of infection in both groups. Gross caseous lesions were observed from days 8 and 9 of infection, respectively. Positive bacterial agglutination test and haemolysis inhibition test titres were detected after 15–17 days and 20–25 days of infection, respectively. These results indicated that caseous lymphadenitis is a subacute disease with an incubation period of 8–9 days, but that it is not detectable serologically until after 15 days of infection.     

Efficiency of feeding <Emphasis Type="Italic">Duddingtonia flagrans</Emphasis> chlamydospores to control nematode parasites of first-season grazing goats in France

A field trial, conducted over two consecutive years, was aimed at assessing the efficacy of the administration of spores of the nematophagous fungus Duddingtonia flagrans to young goats for the control of nematode parasite infections on a French commercial dairy goat flock. For both years, the first-year grazing kids were divided into two similarly managed groups (fungus and control groups): in 2003 a daily dose rate of 5 × 10⁵ spores/kg body weight was given to the fungus-group animals, while in 2004 a daily dose rate of 10⁶ spores/kg body weight was used; the other half of the kids, acting as control, did not receive the spores. Parameters measured every 3 weeks included nematode egg excretion, larval development in faecal cultures and pasture larval counts. Additionally, at the beginning, the middle and the end of each grazing season, the goats were weighed and blood samples for pepsinogen determination were collected. In 2003, similar results were recorded for all the measured parameters in the control and fungus groups. In contrast, in 2004, the kids receiving the spores showed lower faecal egg counts and pepsinogen levels at the end of the season and higher growth rate compared to kids of the control group.     

Experimental reactivation of latent canine herpesvirus-1 and induction of recurrent ocular disease in adult dogs

Latent canine herpesvirus-1 (CHV-1) infection is common in domestic dogs, but recrudescent CHV-1 diseases are poorly characterized. To determine if administration of an immunosuppressive dosage of prednisolone to adult dogs latently infected with CHV-1 results in recurrent ocular disease, adult beagles with and without experimentally induced CHV-1 latent infection were divided into groups: group 1 latently infected and administered prednisolone, group 2 latently infected and administered placebo, and group 3 not latently infected and administered prednisolone. Prednisolone (3.0 mg/kg/day) was administered to dogs in groups 1 and 3 for seven consecutive days beginning on study day 1. Samples for CHV-1 polymerase chain reaction and serum neutralization (SN) assays were collected, and physical, ophthalmologic, and in vivo ocular confocal microscopic examinations were performed at intervals for 42 days. Bilateral ocular disease (i.e., conjunctivitis or keratitis) was detected in 83% of group 1 dogs between study days 3 and 18. In vivo confocal microscopic abnormalities included conjunctival leukocyte infiltration and corneal leukocyte infiltration, abnormal epithelial cell morphology, and Langerhans cell infiltration. Ocular viral shedding was detected in 50% of group 1 dogs on study days 10 and 13. Fourfold elevations in CHV-1 SN titers were detected in 100% of group 1 dogs by study day 14. Dogs in control groups did not develop clinical ocular disease (P < 0.05), CHV-1 titer elevations (P < 0.005), or viral shedding. Administration of an immunosuppressive dosage of systemic prednisolone to adult dogs latently infected with CHV-1 may result in viral reactivation and ocular disease recrudescence.     

A Study of the Ability of a TK‐Negative and gI/gE‐Negative Pseudorabies Virus (PRV) Mutant Inoculated by Different Routes to Protect Pigs Against PRV Infection

The capacity of a TK‐negative (TK ^‐) and gI/gE‐negative (gI/gE ^‐) pseudorabies virus (PRV) mutant to protect pigs against Aujeszky's disease carried out by experimental infection with a virulent PRV strain, was tested. There were three groups, each of four susceptible pigs which were inoculated twice by two different schedules. Group 1 received the modified virus by the intradermal (first inoculation)‐intramuscular (second inoculation) routes; group 2 was treated by the intranasal (first inoculation)‐intramuscular (second inoculation) routes. The third group was left untreated as the control. All of the pigs were challenged intranasally with a virulent PRV strain and they were subsequently injected with dexamethasone. Two pigs in each group were necropsied on days 5 and 15 after dexamethasone inoculation. The challenge exposure resulted in mild clinical signs, increase in growth and a shorter period of virus shedding in vaccinated pigs, whereas the control group showed severe signs of Aujeszky's disease. No difference in the titre of the virulent virus which was excreted by pigs of all three groups, was observed and all animals seroconverted. Both the mutant strain and the wild‐type virus established a latent infection although only the latter was reactivated and shed. Slight lesions were observed in target tissues of the vaccinated animals and no significant differences were detected between the two inoculation schedules.     

Dexamethasone‐Induced Eosinopenia is Associated with Lower Progesterone Production in Cattle

Eosinophilic cells accumulate in the capillaries of the bovine Graafian follicle shortly before ovulation and in the early developing corpus luteum (CL). Suppressing the migration of these eosinophilic cells by dexamethasone allowed us to evaluate their possible function in the CL development. Brown Swiss cows (n = 10) were randomly subdivided into two groups (n = 5). Every group was used once as control group and once as experimental group with two oestrous cycles between each treatment. Eighteen hours (h) after oestrus synchronization, dexamethasone or saline was given. Ovulation was induced 24 h later with gonadotropin‐releasing hormone. Another injection of dexamethasone or saline was given 12 h later. Eosinophilic cells in the blood were counted daily until day 7 after the first dexamethasone injection. The collection of ovaries took place at days 1, 2 and 5. Gene expression, protein concentration and location of angiogenic factors, chemokines, insulin‐like growth factor 1 (IGF1) and eosinophilic cells were studied. No eosinophilic cells were found in the CL of the treatment group. Blood progesterone decreased significantly in the dexamethasone group from day 8 to 17. The protein concentration of FGF2 increased significantly in CL tissue at day 2 and VEGFA decreased. Local IGF1 gene expression in the CL was not regulated. We assume from our data that the migration of eosinophilic cells into the early CL is not an essential, but an important stimulus for angiogenesis during early CL development in cattle.     

The effects of stressful exercise on leukocytes in cattle with experimental pneumonic pasteurellosis

Seven yearling bulls were treated with stressful exercise and intrabronchial Pasteurella haemolytica A1. Group 1 bulls (nos. 1–4) underwent treadmill exercise and, 24 days later, intrabronchial instillation of P. haemolytica A1. Group 2 bulls (nos. 5–7) underwent treadmill exercise, followed 30 min later by intrabronchial P. haemolytica A1. Blood lactic acid values were raised (p<0.05) by treadmill exercise only, but plasma cortisol was raised (p<0.05) by treadmill exercise and by P. haemolytica A1 infection. Neutrophils in bronchoalveolar lavage (BAL) differed from control values 24 h after treadmill exercise, and 1 h and 4 h after P. haemolytica A1 infection.Respiratory disease was more severe and the gross lung lesions were larger in group 2 bulls than in group 1 bulls. P. haemolytica A1 was recovered from the livers, spleens and mesenteric lymph nodes of group 2 but not group 1 bulls, suggesting that group 2 bulls had experienced bacteraemia. Decreased neutrophils in BAL fluid from group 2 bulls at 1 h and 4 h after infection suggests that exercise transiently inhibited neutrophil egress from the blood to the alveoli; BAL neutrophils peaked at 1 h and 4 h after infection in group 1 bulls but declined at 24 h. We conclude that group 2 bulls were made more susceptible to experimental pneumonic pasteurellosis by stressful exercise.Abbreviations ADCC antibody dependent, cell-mediated cytotoxicity - AM alveolar macrophages - BAL bronchoalveolar lavage - CFU conlony-forming units     

Neutrophil Phagocytosis Following Inoculation of Salmonella choleraesuis into Swine

Neutrophils are an important mediator of host defence, especially in early stages of infection. A major function of neutrophils is the uptake and killing of invading microbes. Little is known about the effect of neutrophil activity on the pathogenesis and development of the carrier state in swine following infection with Salmonella choleraesuis. A human whole-blood microassay using flow cytometry was modified to measure the effect of S. choleraesuis infection in vivo on the rate of ingestion, or rate of uptake, of homologous bacteria by porcine neutrophils. Pigs were inoculated intranasally with 5–8×10⁸ CFU S. choleraesuis and blood was collected in heparinized tubes at –5, 0, 1, 2, 3 and 4 days post inoculation (PI). Heat-killed S. choleraesuis were labelled with fluorescein isothiocyanate and incubated for various times with diluted whole blood. Red blood cells were lysed, external non-phagocytized bacteria were quenched with a commercially available lysing solution, and fluorescence from internalized bacteria labelled with fluorescein isothiocyanate was detected by flow cytometry. The rate of uptake by neutrophils did not increase until 2 days PI and then remained elevated to 4 days PI. The minimal uptake of S. choleraesuis early after exposure to these organisms may provide an opportunity for the pathogen to colonize and/or replicate to levels that facilitate establishment of a carrier state or clinical infection in swine.     

Comparison of polymerase chain reaction methods for the detection of <Emphasis Type="Italic">Theileria equi</Emphasis> infection using whole blood compared with pre-extracted DNA samples as PCR templates

Rapid, efficient, and reproducible procedures for isolating DNA before PCR gene amplification are essential for the diagnosis of piroplasms. In this study, we evaluated the ease and reliability of detecting Theileria equi by PCR using pre-extracted DNA samples (by QIAamp DNA Mini Kit and phenol-chloroform methods) compared with blood spotted on FTA cards as PCR templates. Although minimal variations in limit of detection were observed among the methods compared, overall, the use of pre-extracted DNA samples and blood spotted on FTA cards had comparable detection limits. These results indicate that T. equi infection can be efficiently detected directly from FTA cards by PCR without the need for pre-extraction of DNA from blood samples.     

Effect of estrus synchronization treatment after luteolysis on Holstein heifers as embryo transfer recipients

This study was designed to evaluate the effect of estrus synchronization treatments on recipient heifers for embryo transfer (ET). Holstein heifers were separated into the following three groups: (i) an administration of 50 µg GnRH (gonadotropin‐releasing hormone) analog was given to heifers at a random stage of the estrus cycle, followed 7 days later by two administrations of 7.5 mg prostaglandin F2 alfa analog (PG) as control; (ii) another administration of 100 µg GnRH was given to the control group at 48 h after the administration of PG as the second GnRH group; and (iii) an administration of 0.75 mg estradiol benzoate (E2) was given to the control group at 24 h after the administration of PG as the E2 group. Each method caused estrus synchronization. Fresh embryos were nonsurgically transferred into the suitable recipients that had a functional corpora lutea (CL) 7 days after estrus. The E2 group showed a significantly higher (P < 0.01) rate of estrus synchronization (98.9%) at 1–3 days after PG administration and the final pregnancy rate of the E2 group (50.6%) was also significantly higher than the other groups (37.1%, P < 0.05 and 30.9%, P < 0.01, respectively). These findings demonstrate that E2 administration 24 h after PG protocol is effective for estrus synchronization of Holstein heifers, thus improving the productivity of ET.     

Efficacy of Minocycline in Naturally Occurring Nonacute Ehrlichia canis Infection in Dogs

Background

Minocycline has been used in the treatment of Ehrlichia canis infection in dogs as an alternative to doxycycline, the recommended treatment. However, efficacy of this alternative therapy is unknown.

Objective

To assess the efficacy of minocycline in the treatment of natural occurring E. canis infection in dogs.

Animals

Ten privately owned dogs of mixed breed positive for E. canis by blood PCR.

Methods

Prospective, randomized clinical study. Dogs positive for E. canis by PCR were housed in a kennel environment and randomly allocated to receive doxycycline 10 mg/kg bodyweight PO once daily (“gold standard” control group) or minocycline (extralabel) 10 mg/kg bodyweight PO twice daily (treatment test group) for 28 days. Blood, analyzed by PCR to determine the presence or absence of E. canisDNA, was collected weekly during treatment starting on the first day of treatment and including through day 35, 7 days after the last treatment.

Results

In both groups, one dog tested negative after 7 days of treatment. For the doxycycline group, the latest time to a negative PCR test was after 3 weeks of treatment. For the minocycline group, the latest time was on day 28 of treatment. All dogs tested negative 7 days after the end of treatment.

Conclusion and Clinical Importance

Minocycline can be an effective alternative to doxycycline for clearing E. canis from the blood in nonacute infections.     

A new rolling culture‐based in vitro fertilization system capable of reducing polyspermy in porcine oocytes

The high incidence of polyspermy is one of the major obstacles during in vitro fertilization (IVF) in pigs. To overcome this, we developed a novel IVF method, which involves constant rotation. Oocytes matured in vitro were mixed with spermatozoa (0.2 × 10⁵ sperm/mL) in an IVF medium (200 μL) using a 200 μL PCR tube. This tube was then rotated at 1 rpm for 6 h at 38.5°C in a rotation mixer (experimental group). A second PCR tube was simultaneously cultured without rotation (control group). The rate of polyspermy was evaluated 12 h after insemination and was significantly (P < 0.05; 21.0% vs. 48.3%) lower in the experimental group than in the control group. Sperm penetration rate was similar in oocytes from the experimental and control groups (75.2% vs. 83.1%). However, monospermic fertilization rate of the oocytes was significantly (P < 0.05; 44.8% vs. 21.2%) higher in the experimental group than in the control group. Furthermore, the rate of blastocyst formation (30.1% vs. 20.8%) increased in the experimental group, as compared to the control group. This present system will contribute to increase the efficacy of blastocyst production through reduction of polyspermic penetration.     

Efficacy of Sarafloxacin in Broilers after Experimental Infection with Escherichia coli

Infections of chickens with Escherichia coli serotypeO78 can be treated with the antibiotic sarafloxacin. Three experiments were conducted on the administration of this drug to chickens that had been experimentally infected with E. coli. The birds were monitored for 10 days after infection for their average daily gain (ADG) and feed conversion ratio (FCR), and the post-mortem pathology was assessed. In the first experiment, sarafloxacin (20 mg/L, equivalent to 5 mg/kg live weight per day), given in the drinking water for 3 days after infection, led to a reduction in the mortality from 75% to 27%, but the ADG of the treated birds was still less than that of the uninfected controls. In the second experiment, when the sarafloxacin was administered at the same dose in the water but over only 2 h, there was also a considerable reduction in mortality, and the ADG and the FCR also improved significantly. In the third experiment, the dose dependence of the drug was tested. The birds were given 5 and 10 mg/kg per day sarafloxacin in each group, starting within 2 h after infection. This rapid administration of the drug completely prevented mortality, while the ADG and FCR were similar to those of the uninfected controls.     

一定纯度中药复方多糖对鸡细胞免疫和体液免疫的影响

为筛选对鼠免疫增强效果显著的一定纯度中药复方多糖(cCHMPS)对雏鸡的最佳免疫增强剂量,本试验将300只1日龄雄性良凤青脚麻鸡随机分为6组,即空白对照组、盐酸左旋咪唑组、黄芪多糖组及cCHMPS高、中、低剂量组,每组各50只.分别于8日龄皮下注射生理盐水、盐酸左旋咪唑、黄芪多糖及不同剂量的cCHMPS,连续7 d,在免疫后第8、14、21、35、42天采血,测定外周血中T、B淋巴细胞增殖活性及血清中新城疫病毒抗体含量.试验结果表明,黄芪多糖和不同剂量cCHMPS均能显著或极显著促进外周血T、B淋巴细胞增殖(P<0.05;P<0.01),提高新城疫病毒抗体浓度,增强机体细胞免疫和体液免疫水平,且中剂量的cCHMPS的免疫增强效果最好.     

The effects of low doses of Senna occidentalis seeds on broiler chickens

The effects of 0.5%, 0.3% and 0.1% w/w concentrations of Senna occidentalis (So) seed mixed with commercial ration were studied in 18 groups of 32 broiler chicks each, from 1 day to 49 days of age. Three groups were fed one of the rations throughout their lives (TL). Three other groups were fed one of the rations from the 1st to the 28th day of life (starter phase, SP), and the final 3 groups were fed one of the rations from the 29th to 49th day (finisher phase, FP). Each experimental group was matched by a control group fed the same diet over the same period but without the inclusion of So. All the animals were killed at 49 days of age, and blood was collected from 10 birds in each group for biochemical studies (ALT, AST, GGT, LDH, UA). A complete necropsy was performed on 3 birds from each group. No significant differences in the biochemical parameters in the serum were found between the control and experimental chicks, but animals treated with 0.5% So in groups FP and TL, gained less weight and chicks that received 0.3% So or 0.5% So in the ration throughout life (TL) had a larger feed conversion ratio. Besides this, degenerative changes were found in the striated skeletal muscle in the chest, in the myocardium and in the liver in the animals that received the higher concentrations of So seeds.     

Effects of recent Leptospira vaccination on whole blood real-time PCR testing in healthy client-owned dogs

Background

Bacterin‐based canine Leptospira vaccines could present a challenge for the use of whole blood real‐time polymerase chain reaction (PCR) as a diagnostic tool. Recent vaccination could induce positive results if the targeted DNA fragment is present within the vaccine and in the blood of the recently vaccinated dog.

Objectives

The objective of this study was to assess whether 2 available 4‐serovar vaccines induce a positive real‐time PCR reaction in the blood of healthy recently vaccinated dogs.

Animals

Twenty healthy dogs.

Methods

This was a prospective study. Dogs were assigned to 1 of 2 vaccine groups. Both vaccines were culture‐based and include Leptospira interrogans serovars Pomona, Canicola, and Icterohaemorrhagiae and Leptospira kirschneri serovar Grippotyphosa. Whole blood for real‐time PCR and serum for the microscopic agglutination test (MAT) were collected prior to and 3 and 7 days after vaccination and weekly thereafter for 8 weeks. Two real‐time PCR tests targeting 2 different genes were performed independently in a blinded fashion.

Results

Both Leptospira vaccines produced positive real‐time PCR reactions when assayed undiluted or diluted 1 : 100 in canine blood. However, blood samples drawn from all dogs at all time points after vaccination were negative on PCR. All dogs developed MAT titers.

Conclusions and Clinical Importance

Recent vaccination with 2 commercially available vaccines does not interfere with the use of real‐time PCR for the identification of acute Leptospira infection in dogs.     

Chronic "Candidatus Mycoplasma turicensis" infection

"Candidatus Mycoplasma turicensis" infects felids. The pathogenesis of "Candidatus M. turicensis" chronic infection is poorly understood. The goals of the present study were to (1) induce reactivation of the infection in chronic carrier cats by attempted immunosuppression, (2) identify potential tissue sequestration using real-time TaqMan^® PCR and (3) monitor the humoral immune response by DnaK enzyme-linked immunosorbent assay (ELISA). Ten specified pathogen-free cats that had ostensibly recovered from experimental "Candidatus M. turicensis" infection were used: five cats (group 1) received high dose methylprednisolone (attempted immunosuppression), while five cats served as untreated controls (group 2). Besides weekly blood samples, tissue samples were collected from bone marrow, kidney, liver and salivary glands at selected time points. The cats in group 1 had significantly lower lymphocyte counts and higher blood glucose levels after methylprednisolone administration than the controls. After methylprednisolone administration one blood and three tissue samples from cats in group 1 tested PCR-positive; before the administration, only one sample was positive. All other samples tested PCR-negative. All cats stayed seropositive; the antibody levels of the cats in group 1 showed a significant transient decrease after methylprednisolone administration. This is the first study to report the presence of "Candidatus M. turicensis" in tissues of chronically infected cats and the persistence of anti-feline hemoplasma antibodies in the absence of detectable bacteremia. Methylprednisolone administration did not lead to a significant reactivation of the infection. Our results enhance the knowledge of "Candidatus M. turicensis" infection pathogenesis and are clinically relevant to the prognosis of hemoplasma-infected cats.