Relationship of tibial plateau slope to limb function in dogs treated with a lateral suture technique for stabilization of cranial cruciate ligament deficient stifles

OBJECTIVE: To evaluate the effect of a lateral suture technique (LST) on tibial plateau angle (TPA) measurement and to compare TPA with functional outcome in dogs treated for cranial cruciate ligament (CrCL) rupture with LST. STUDY DESIGN: Prospective clinical study. SAMPLE POPULATION: Dogs (n=34) with unilateral CrCL instability. METHODS: All dogs had lameness examination, survey stifle radiographs, and force plate analysis before and at 6, 12, 24, and 48 weeks after surgery. Radiographic osteoarthritis (OA) scores and lameness scores were assigned using previously reported methods. Preoperative radiographs were performed in all dogs, and postoperative serial radiographs were performed in 6 dogs for measurement of TPA. Differences in TPA measurements were evaluated with a random effects repeated measures model. The significance of LST on TPA measurement was established in 6 dogs and the effect of TPA on vertical impulse, peak vertical force, progression of radiographic scores, and lameness score were analyzed by general linear models in all dogs. Differences were considered significant if P<.05. RESULTS: Significant differences were not noted between pre- and serial postoperative measurements of TPA. A significant correlation was not established between TPA and postoperative vertical impulse, peak vertical force, lameness score, or radiographic OA scores. CONCLUSIONS: TPA values were unchanged after LST and TPA does not affect outcome measures in dogs treated with LST. CLINICAL RELEVANCE: TPA has no predictive value on clinical outcome in dogs treated with LST for stabilization of CrCL deficient stifles.     

Canine parainfluenza-Bordetella bronchiseptica vaccine immunogenicity

The immunogenicity and safety of 3 serials of a canine parainfluenza (CPI) virus-Bordetella bronchiseptica vaccine was evaluated. Each serial was used to vaccinate 10 dogs with single doses given intranasally. The 30 vaccinated and 10 nonvaccinated controls dogs were challenge exposed with aerosols of virulent CPI virus and B bronchiseptica at 18 days and at 21 days, respectively, after vaccination. After challenge exposure, none of the 30 vaccinated dogs had clinical signs of disease; however, 9 of the 10 nonvaccinated dogs developed coughing problems. The CPI virus was isolated from nasal swab specimens obtained from nonvaccinated dogs on an average of 5.1 days after challenge exposure, but was not isolated from any of the specimens obtained from the vaccinated dogs. Bordetella bronchiseptica was isolated from nasal swab specimens obtained from both vaccinated and nonvaccinated dogs up to 18 days after challenge exposure. The erythrocyte sedimentation rates and total leukocyte counts for control dogs were generally increased, in contrast to those for the vaccinated groups. Dogs showed a primary serologic response to CPI virus and B bronchiseptica after vaccination and an anamnestic response to the bacterium after challenge exposure. Adverse local or systemic reactions attributable to the bivalent vaccine were not observed in the vaccinated dogs.     

Reduction and stabilization of hip luxation by the transposition of the ligamentum sacrotuberale in dogs: an in vivo study

OBJECTIVES: To evaluate the effectiveness of transposition of the sacrotuberous ligament (LST) for the treatment of coxofemoral luxation in the dog. STUDY DESIGN: In vivo experimental study. SAMPLE POPULATION: Ten mixed-breed dogs (weighing 12 to 26 kg). METHODS: After general anesthesia, the LST was exposed and released from the sacrum with a sacral bone fragment. Coxofemoral luxation was created by capsulotomy and transection of the ligament of the head of the femur. Suture was passed through 2 small holes in the bone fragment to guide transposition of the LST through a tunnel drilled through the acetabulum and femoral head and neck. The suture material was pulled tight and an interference screw was placed into the femoral tunnel to lock the sacral bone fragment and LST securely in the tunnel. Butorphanol was administered for pain relief and dogs were allowed unrestricted activity. Coxofemoral radiographs were obtained at 15-day intervals. Two dogs were euthanatized for macroscopic and histopathologic examinations at 3 months. RESULTS: Release of the sacral bone was moderately difficult. The transposed ligament and bone fragment were of an appropriate length and were easily and securely fixed by a interference screw method. Visible severe lameness, during the first 7 to 10 days improved to mild lameness within 10 to 21 days. Gait was subjectively normal after 5 weeks. No radiographic abnormalities were observed at any time point. Grossly, the LST was intact and apparently viable and functional. On histopathology, the space in the bone tunnel was filled with new tissue and a hyaline-like layer surrounded the LST. The sacral bone fragment attached to the LST was united with the femoral bone. CONCLUSIONS: Transposition of the LST reduced and stabilized experimentally induced coxofemoral luxation in 10 dogs. Survival of the LST up to 3 months and its adaptation to transposition suggest that this surgical technique could be considered as a permanent treatment option for hip luxations. Transposition and fixation of the LST was easy, but releasing the sacral edge of the LST was difficult because of its deep location and division of the origin into 2 branches in some dogs. CLINICAL RELEVANCE: Results of this experimental study suggest that the technique may be satisfactorily used in dogs with coxofemoral luxation.     

Canine infectious tracheobronchitis: effects of an intranasal live canine parainfluenza-Bordetella bronchiseptica vaccine on viral shedding and clinical tracheobronchitis (kennel cough)

A modified-live intranasal (IN) canine parainfluenza (CPI)-virus Bordetella bronchiseptica vaccine was evaluated in dogs for efficacy against laboratory-induced canine infectious tracheobronchitis. The comparative efficacies of IN and parenteral administrations of the CPI virus fraction were also evaluated. The frequency and duration of clinical tracheobronchitis, blood serum agglutination titer, humoral antibody response, and duration of CPI virus and B bronchiseptica shedding were measured. Group A dogs were vaccinated subcutaneously or IM with an experimental CPI vaccine and challenge exposed with CPI virus. Group B dogs were vaccinated IN with avirulent CPI virus-B bronchiseptica live antigens and challenge exposed with virulent CPI virus and virulent B bronchiseptica. The IN vaccination (group B) significantly reduced (P less than or equal to 0.001) the occurrence of clinical tracheobronchitis by 96%. The combined challenge exposure of virulent CPI and virulent B bronchiseptica produced a synergistic enhancement of the clinical signs of kennel cough. The percentage of days after challenge exposure that virus shedding was detected for controls equaled 70% as compared with 50% and only 1% for parenterally and IN vaccinated dogs, respectively. Isolation of virulent B bronchiseptica microorganisms was reduced 89% in dogs vaccinated IN compared to controls. The geometric mean humoral antibody titers to CPI virus after 2 parenteral vaccinations and 1 IN vaccination were 1:43 and 1:34, respectively.     

Depression of lymphocyte responses to phytohaemagglutinin in lambs experimentally infected with bovine respiratory syncytial virus.

Eight lambs were experimentally infected with bovine respiratory syncytial virus (BRSV) and the responses of their peripheral blood lymphocytes to the mitogen phytohaemagglutinin and BRSV antigen compared with that of control lambs injected with tissue culture fluid. The lymphocyte transformation responses to phytohaemagglutinin were significantly reduced five and 10 days after experimental infection with BRSV (P less than 0.05). It appears that these reductions were associated with CD4+ lymphocytes because CD4-enriched lymphocytes obtained five days after infection had more significantly reduced responses to phytohaemagglutinin than those obtained from the same group before infection and from the control group five days after inoculation (P less than 0.01). There were no significant lymphocyte transformation responses to BRSV antigen in both groups of lambs up to 21 days after inoculation (P greater than 0.05).     

Canine atopic disease: investigations of eosinophils and the nasal mucosa

Blood eosinophil counts were comparable in dogs with and without canine atopic disease. Eosinophils were not observed in the nasal smears of any of the dogs studied. Of 46 dogs with atopic disease, a significant increase (P less than 0.001) in nasal airway resistance was observed in 2 dogs after nasal provocation with nebulized allergens of grasses and in 1 dog after provocation with summer weed extracts.     

Anti-inflammatory effects of topical supernatant from human amniotic membrane cell culture on canine deep corneal ulcer after human amniotic membrane transplantation

The objective of this study was to examine the effect of topically applied human amniotic epithelial cell (HAEC) culture supernatant on corneal inflammatory reaction in dogs. Twenty-five dogs were randomly assigned into five groups. The control group consisted of five dogs with normal cornea. Inductions of corneal ulcers were performed using 0.45 cm trephine and human amniotic membrane was transplanted in 20 dogs. These 20 dogs were assigned into four treatment groups: topical antibiotic, topical corticosteroid, topical mock media and topical culture supernatant from HAEC, respectively. Administrations of the testing agents started at 24 h (h) after transplantation four times daily for nine consecutive days. Tears were collected before an operation 24 h after transplantation, but before application of the testing agents on consecutive odd days following transplantation. The concentrations of interleukin-1β (IL-1β) and nitric oxide (NO) in tear fluid were measured using canine IL-1β ELISA kit and Griess assay, respectively. Our analysis indicates that elevations of IL-1β and NO concentrations are associated with inflammatory conditions in the eyes. Corticosteroid, a reference anti-inflammatory drug, and the culture supernatant from HAEC significantly decreased IL-1β and NO concentrations. In addition, the clinical signs such as conjunctivitis and neovascularization were decreased in both topical corticosteroid and supernatant from HAEC treated groups. Mock and antibiotic solutions failed to decrease NO and IL-1β concentrations. In conclusion, topical application of the culture supernatant from HAEC alleviated inflammation in induced-corneal ulcer of dogs, possibly via inhibition of IL-1β and NO production.     

Changes in cell-mediated immune responses after experimentally-induced anaphylaxis in dogs.

Experimentally-induced type 1 hypersensitivities were induced in normal dogs to either ovalbumin or Ascaris antigen. In vitro and in vivo cell-mediated immune responses were measured before sensitization and again at 1 and 6 days after induction of anaphylaxis by intravenous challenge with antigen. Histamine-modulated lymphocyte functions, such as histamine-induced suppression, histamine co-mitogen induced blastogenesis and the in vivo cutaneous responses to intradermally injected mitogens decreased post anaphylaxis. Spontaneous suppression of the autologous mixed-lymphocyte reaction increased post anaphylaxis. Lymphocyte blastogenic response to Concanavalin A (Con A) decreased at 6 (but not at 1) days post anaphylaxis probably due to a mediator other than histamine. Blastogenesis of 24 h preincubated cells by suboptimal concentration of Con A, declined post anaphylaxis, but Con A-induced suppression was not significantly altered. Dogs with atopic dermatitis have some altered cell-mediated immune responses. Altered histamine-induced and spontaneous suppression, histamine suppression of mitogenesis and decreased contact sensitivity observed in this experimental type 1 hypersensitivity mimicked that of atopic dogs. Increased cutaneous response to mitogens observed in atopic dogs was not reproduced in the type 1 hypersensitive dogs. These findings suggest some of the altered cell-mediated immune functions observed in dogs with atopic dermatitis result from type 1 hypersensitivity. The other abnormalities may be intrinsic to the atopic state.     

Allergic pulmonary and ocular tissue responses in the absence of serum IgE antibodies (IgE) in an allergic dog model

Allergen-specific serum IgE may be insensitive as a marker for IgE-mediated reactions at the mucosal level. Five of six atopic beagle dogs developed high ovalbumin (OVA)-specific serum IgE levels after sensitization. This study aimed to show that these dogs still express allergen-specific IgE at the pulmonary and ocular mucosal levels and in the skin even when corresponding serum IgE was below the detection limit. When serum IgE levels were negative, all dogs exhibited allergic reactions at the tissue level. Specifically, they displayed positive ocular reactions after an ocular OVA challenge. After airway challenge with aerosolized OVA, five out of six animals reacted with decreased compliance and increased resistance of the lungs. Furthermore, an eosinophilia in the bronchoalveolar lavage fluid (BALF) was observed. Four weeks after the last exposure to OVA, IgE-positive BALF cells were seen in all animals. Six weeks on, all dogs still displayed positive skin reactions to OVA. This indicates that not only skin testing but also detection of ocular and pulmonary allergic tissue reactions including cell-bound IgE in BALF can serve as more sensitive and lasting surrogate markers of hypersensitivity in the allergic dog model than detection of allergen-specific serum IgE levels.     

Time-course effects of St John's wort on the pharmacokinetics of cyclosporine in dogs: interactions between herbal extracts and drugs

To clarify the interaction between St John's wort (SJW) and cyclosporine (CsA) in dogs, the pharmacokinetics of CsA before and during the repeated administration of SJW were analyzed. In the SJW group, SJW (300 mg) was given orally to four dogs every 24 h for 14 days. A single dose of CsA (5 mg/kg) was given orally 7 days before and 7 and 14 days after the initiation of the repeated administration of SJW. In the Control group, a single dose of CsA (5 mg/kg) was given orally to four other dogs in accordance with that in the SJW group. Blood samples from both groups were collected, and whole-blood concentrations of CsA were determined using high-performance liquid chromatography with UV detection. The maximum whole-blood concentration and AUC(0-∞) of the SJW group were significantly lower and the CL(tot) /F and V(d) /F were significantly higher than those in the Control group 7 and 14 days after the initiation of repeated SJW. Thus, repeated administrations of SJW affect the pharmacokinetic profiles of CsA in dogs. Further studies are necessary to elucidate the mechanisms of interaction between SJW and CsA in dogs.     

Pharmacokinetics of oestriol after repeated oral administration to dogs

The aim of the present study was to investigate the pharmacokinetics of oestriol in plasma in the dog after repeated oral administration of oestriol tablets, a preparation intended for the treatment of urinary incontinence in the bitch. The study was performed in six healthy, entire, adult female beagle dogs. The bitches were treated once daily with two tablets, containing 1 mg oestriol per tablet, for seven consecutive days (days 1-7). Blood samples were taken from the jugular vein before treatment, frequently on days 1, 3 and 7 of the treatment period and daily just before (C(trough)) and 1 h after dosing (C(t=1h)). During the washout period samples were taken at a 24 h interval up to four days post-treatment. Oestriol concentrations were determined in plasma by radioimmunoassay. Pharmacokinetic parameters, AUC, C(max) and t(max), were determined from the plasma concentration-time curves using non-compartmental methods. The between animal variation in C(max) and the AUC was high. Individual values of the C(max) varied from 206 pg/ml (day 1) to 1128 pg/ml (day 7) and the AUC(0-24h) from 789 pg x h/ml (day 1) to 5718 pg x h/ml (day 7). t(max) occurred within 1 h. The mean C(trough) value was slightly above the pre-treatment level ( 38+/-2 pg/ml vs. 18+/-5 pg/ml). Within 48 h after the last treatment the concentrations had returned to the pre-treatment values. C(max) and C(trough) did not increase during the treatment period, indicating that no accumulation occurred. A shoulder in the concentration-time curve around 8-12 h after treatment strongly suggested the existence of enterohepatic recirculation (EHR). The average relative contribution of the EHR to the AUC(0-24h) was estimated to be 22%, 38% and 44% on days 1, 3 and 7, respectively. These mean values were calculated from five animals per time point, because one dog failed to show EHR on days 1 and 3 and was therefore excluded from the calculations.     

Effects of renal impairment on the disposition of orally administered enalapril, benazepril, and their active metabolites

The pharmacokinetics of benazepril, enalapril, and their active metabolites (benazeprilat and enalaprilat) were compared after a single administration of each product by the oral route at the recommended dosage (0.5 mg/kg for both drugs) in the dog before and after moderate experimental renal impairment. Ten dogs were randomly assigned to 2 groups of 5 animals in a 2-period crossover design for angiotensin-converting enzyme inhibitor administration. Renal failure was surgically induced by right nephrectomy and electrocoagulation of the remaining kidney. Renal mass reduction induced a significant decrease (P < .001) in glomerular filtration rate (GFR) (1.7 +/- 0.3 versus 3.3 +/- 0.7 mL/kg/minute). No significant differences before and after surgery were observed for enalapril and benazepril kinetics. The area under the curve (AUC) for enalaprilat increased after surgery from 23.6 +/- 14.7 to 42.4 +/- 20.9 micrograms.minute/mL (P < .01). Mean peak plasma concentration (Cmax) was increased in the impaired dogs (59.1 +/- 23.3 versus 43.9 +/- 32.9 ng/mL), but this variation was not significant (P > .05). Renal failure had no significant effect on AUC for benazeprilat (13.8 +/- 9.8 versus 14.9 +/- 5.0 micrograms.minute/mL) (P > .05), but Cmax decreased significantly (from 55.0 +/- 26.4 to 31.9 +/- 17.7 ng/mL) (P < .05). Multiple regression analysis showed that both GFR and AUC for enalapril were highly significant variables that explained the variation in AUC for enalaprilat (R2 = .86, P < .001) but not for benazeprilat (R2 = .12, P > .05). The results of this study indicate that exposure to enalaprilat, but not to benazeprilat, is increased in dogs with subclinical renal impairment.     

Analgesic comparison of meloxicam or ketoprofen for orthopedic surgery in dogs

OBJECTIVE: To compare the safety and efficacy of 2 analgesic protocols (preoperative meloxicam or intraoperative ketoprofen administration) during the first 24 hours after orthopedic surgery in dogs. STUDY DESIGN: Double-blind, prospective randomized clinical trial. ANIMALS: Sixty client-owned dogs. METHODS: Dogs with surgical orthopedic disorders were randomly separated into 2 groups: 30 dogs were administered 0.2 mg/kg meloxicam intravenously (IV) immediately before induction and 30 dogs were administered 2 mg/kg ketoprofen IV, 30 minutes before the end of surgery. Pain was assessed with a visual analog scale (VAS) and a cumulative pain score (CPS) preoperatively and at 30 minutes, 1, 2, 3, 4, 6, 8, and 24 hours after extubation. Selected serum biochemical variables were measured before and 24 hours after surgery and, buccal mucosal bleeding time (BMBT) and whole blood clotting time (WBCT) were measured before and 8 hours after surgery. Dogs were anesthetized with propofol and maintained on halothane in oxygen. Any complications were documented for 7 days after surgery. Results were compared between the 2 groups for significant differences in VAS scores (2-sample t-test) and in CPS (Wilcoxon's 2-sample test). Moreover, results were analyzed for significant differences in area under the curve (AUC) for VAS (2-sample t-test) and CPS (Wilcoxon's 2-sample test) among groups. To assess the effects of treatments on biochemical and coagulation functions, pre- and postoperative mean values of BMBT and WBCT were compared within both treatment groups (paired t-tests) and between both groups (2-sample t-test). RESULTS: No significant differences in pain response or coagulation were found between meloxicam- and ketoprofen-treated dogs. In both groups, alkaline phosphatase and alanine aminotransferase concentrations were significantly increased compared with baseline. No serious complications occurred. CONCLUSIONS: Preoperative administration of meloxicam is a safe and effective method of controlling postoperative pain for up to 24 hours in dogs undergoing orthopedic surgery. CLINICAL RELEVANCE: Analgesia after administration of preoperative meloxicam was comparable with administration of ketoprofen at the end of the surgery.     

An ELISA for sensitive and specific detection of circulating antigen of Angiostrongylus vasorum in serum samples of naturally and experimentally infected dogs

Canine angiostrongylosis is an emerging cardiopulmonary disease in Europe which can be fatal if left untreated. We developed a sandwich-ELISA based on a monoclonal antibody (mAb Av 56/1/2) and on polyclonal rabbit antibodies directed against Angiostrongylus vasorum adult excretory/secretory - antigen for the detection of circulating serum antigen of A. vasorum. The sensitivity of the test was 95.7% (78.1-99.9, 95% CI) as determined with sera of 23 dogs naturally infected with A. vasorum. The specificity was 94.0% (83.5-98.7, 95% CI) using 50 dog sera (control group) submitted for reasons other than parasitic infections. Potential cross-reactions were investigated with sera of a group of totally 61 dogs with proven infections with Dirofilaria immitis (n=23), Crenosoma vulpis (n=14), Ancylostoma caninum (n=4) or Toxocara canis (n=20). No significant difference was observed concerning the proportion of positive reactions between the control group and the group with proven helminth infections other than A. vasorum. In experimentally inoculated dogs with proven worm burdens of A. vasorum, the proportion of seropositive dogs increased over the first 3 months of infection, starting from 35 days post inoculation (dpi) which was before the onset of larval excretion. Ten weeks post inoculation, 98.6% of the dogs were seropositive, and circulating antigen persisted in two dogs with long-term follow-up over 286 and 356 days, respectively. In contrast, in dogs with a single treatment with imidacloprid/moxidectin at four or 32 dpi, no circulating antigen was observed, while in dogs treated at 88-92 dpi, OD values decreased within 13-34 days. The specific detection of circulating A. vasorum antigen by ELISA represents a valid alternative for reliable diagnosis and for follow-up investigations after anthelmintic treatment. Moreover, the test can be used for mass screening in large epidemiological investigations.     

Use of Recombinant Canine Granulocyte Colony-Stimulating Factor to Decrease Myelosuppression Associated with the Administration of Mitoxantrone in the Dog

Ten dogs were given mitoxantrone at a dose of 5 mg/m2 body surface area intravenously. Recombinant canine granulocyte colony-stimulating factor (rcG-CSF) was administered subcutaneously daily for 20 days after an infusion of mitoxantrone in five of these dogs to determine the effect of the hematopoietic growth factor on the duration and severity of myelosuppression. The median neutrophil counts dropped below normal (less than 3,000/uL) for 2 days in the dogs that received rcG-CSF, and for 5 days in the dogs that received only mitoxantrone. Four of five dogs not treated with rcG-CSF and none of those receiving rcG-CSF developed serious neutropenia (less than 1,500/uL). The neutrophil counts were significantly (P less than 0.05) higher in the rcG-CSF treated dogs at all time points except before the administration of the colony-stimulating factor, and the sixth day after the mitoxantrone was administered. These findings demonstrate that rcG-CSF is capable of reducing the duration and severity of mitoxantrone-induced myelosuppression.     

Serum concentration and safety of intravenous drip versus subcutaneous administration of carboplatin in dogs

Carboplatin is used to treat certain cancers in dogs and cats and is routinely administered via intravenous drip (IVD). Subcutaneous (SC) administration has also been described. However, the toxicity, serum concentrations, and area under blood concentration-time curves (AUCs) of SC carboplatin are unknown. This study aimed to compare serum carboplatin concentrations in dogs after SC and IVD and to monitor any adverse events. In this crossover study, five dogs received SC or IV carboplatin (300 mg/m²). After a minimum of 3 weeks, each dog received the other treatment. No gross skin toxicity or abnormal clinical signs were observed in any of the dogs. Blood test abnormalities were detected in most dogs. Decreased neutrophil and platelet counts, and increased C-reactive protein (CRP) levels were found. There was no significant difference in the neutropenia, thrombocytopenia, and CRP scores between the groups. Systemic toxicities of SC carboplatin were comparable to those of IVD carboplatin. The time to maximum carboplatin concentration after SC was longer than that after IVD (P<0.001). SC carboplatin remained in the serum longer than IVD carboplatin (P=0.008). The AUC of SC was less than that of IVD (P=0.002). The AUC and time taken to reach the maximum concentration of SC carboplatin were lower than those of IVD carboplatin. This study suggests that SC carboplatin may be an efficacious option for the treatment of tumors in dogs, particularly where IVD administration is challenging.     

Susceptibility of domestic dogs and cats to Australian bat lyssavirus (ABLV)

The susceptibility of cats and dogs to Australian bat lyssavirus (ABLV; genotype VII) was investigated by intramuscular (IM) inoculation of 10(3.7)-10(5) 50% tissue culture infective doses (TCID(50)) of virus followed by observation of experimental animals for up to 3 months post-inoculation (pi). Each experiment also included positive and negative controls, animals inoculated with a bat variant of rabies virus (Eptesicus I, genotype I), or a 10% suspension of uninfected mouse brain, respectively. Each of the ABLV-inoculated cats showed occasional abnormal clinical signs, but none died. Necropsies performed at 3 months pi revealed no lesions, and no viral antigen, in the central nervous system of any cat. ABLV could not be recovered from any cats. However, rabies virus-neutralizing antibodies were detected between 4 and 14 weeks pi in the sera of all three ABLV-inoculated cats. At 2-3 weeks pi, three of the five ABLV-inoculated dogs showed very mild abnormal clinical signs that persisted for 1-2 days, after which the dogs recovered. At 3 months pi, when all dogs were necropsied, neither lesions nor ABLV antigen were detected in, and virus was not isolated from, any dog. No ABLV RNA was detected by polymerase chain reaction (PCR) in clinical or necropsy samples from the three ABLV-affected dogs. However, all ABLV-inoculated dogs seroconverted by 2 weeks pi, and serum antibody titres were higher than those observed in cats. CSF, collected at 3 months pi, was positive for rabies virus-neutralizing antibody in two ABLV-inoculated dogs.     

A COMPLEMENT-FIXATION TEST FOR ENZOOTIC PNEUMONIA OF PIGS USING A COMPLEMENT DILUTION METHOD

Complement-fixing antibody to Mycoplasma hyopneumoniae in the serums of pigs experimentally infected with enzootic pneumonia was demonstrated by comparing the haemolytic titre of guinea-pig complement titrated in the presence of heated test serum, M. hyopneumoniae antigen and unheated normal pig serum with the titre obtained when the antigen was omitted. The haemolytic titres against sensitised sheep erythrocytes were determined after a fixation period of 16 to 18 hours at 5°C. When serums, collected at intervals of 3 to 7 days, from 43 pigs exposed to pigs experimentally infected with enzootic pneumonia were tested, 4.6 or more complement units were first fixed 14 to 44 (mean 23.4) days after contact began. Serums collected subsequently fixed from 4.6 to more than 31 complement units. This positive reaction usually persisted until the pigs were killed 4 to 35 weeks after contact began. Thirty-three had gross enzootic pneumonia lesions and 9 had lung lesions detected microscopically. Serum antibody was not detected in 73 weaned pigs aged 7 weeks in a pneumonia-free herd but serums from 9 of 15 unweaned piglets aged 9 to 14 days in the same herd, fixed between 3 and 7 complement units.     

The serological response of dogs to Taenia ovis

The effect of 4-weekly anthelmintic dosing and other treatment regimes on the serological response of dogs to Taenia ovis was examined. Most dogs which were frequently fed infected meat and dosed with a cestocidal anthelmintic at 4-week intervals eventually showed a positive ELISA absorbance. The absence of dosing, or intermittent dosing, of repeatedly infected dogs raised ELISA absorbances to very high levels in most dogs and these absorbances took an increasingly longer time to fall after each new infection. The feeding of large numbers of frozen, dead cysts to sensitised dogs raised absorbance levels. The serological test for T. ovis infections in dogs does not detect false positives. Positive tests result from the dog being exposed to T. ovis scolex secretory antigen.     

The ability of a topical novel combination of fipronil, amitraz and (S)-methoprene to protect dogs from Borrelia burgdorferi and Anaplasma phagocytophilum infections transmitted by Ixodes scapularis

Healthy, purpose-bred laboratory beagle dogs that had not been exposed to ticks and were seronegative for Borrelia burgdorferi and Anaplasma phagocytophilum were randomly assigned to four groups of eight dogs each. Control group 1 was not treated. Groups 2, 3 and 4 were treated with a single topical application of a new formulation of fipronil, amitraz and (S)-methoprene (CERTIFECT?, Merial Limited, GA, USA) at 28, 21 or 14 days prior to tick infestation, respectively. Each dog was infested with 25 female and 25 male field-collected adult Ixodes scapularis ticks that had infection rates of 66% for B. burgdorferi sensu stricto and 23% for A. phagocytophilum, as determined by polymerase chain reaction. Two and five days after tick infestation, control dogs had an average of 9.5 and 13.9 attached adult female ticks, respectively, whilst the 24 treated dogs remained tick-free aside from a single tick on the 2nd day after infestation. Serial serological tests demonstrated that the ticks successfully infected 8/8 control dogs with B. burgdorferi and co-infected 6/8 with A. phagocytophilum. B. burgdorferi infection also was confirmed in most control dogs by culture (6/8) and PCR (7/8) of skin biopsies. In contrast, CERTIFECT protected all 24 treated dogs against infection by both B. burgdorferi and A. phagocytophilum, as demonstrated by their negative serological tests throughout the study and the absence of any positive skin biopsy culture or PCR in these dogs.