Is the detection of anti-Rhipicephalus sanguineus (Rs24p) antibodies a valuable epidemiological tool of tick infestation in dogs?

Antibodies against the 24 kDa Rhipicephalus sanguineus (Rs24p) protein were detected by ELISA to evaluate the relationship between antibodies and tick infestation. The mean titer of 3 dogs that underwent 2 experimental infestations with adult ticks was transiently increased after the second infestation. There was a significant difference in mean titers between positive control dogs naturally infested with ticks and tick-naive dogs. These results suggested that anti-Rs24p antibodies detected by ELISA are a marker of tick exposure. There was no significant difference in mean titers between tick-naive dogs and seropositive dogs to Ehrlichia canis. Some dogs positive for E. canis antibodies showed, however, higher titers than most tick-naive dogs. R. sanguineus may be related to the E. canis infection in Japan.     

Efficacy of selamectin against experimentally induced tick (Rhipicephalus sanguineus and Dermacentor variabilis) infestations on dogs

Seven controlled studies were conducted to investigate the efficacy of selamectin against weekly infestations of dogs with Rhipicephalus sanguineus and Dermacentor variabilis. Treatments (selamectin or vehicle alone) were applied topically at weekly, 2-week, or monthly intervals or in a "Monthly Plus" regimen (monthly treatment with an additional treatment at 14 days after the first treatment). Selamectin was supplied in unit dose tubes designed to deliver a minimum dosage of 6mgkg(-1). The studies ranged in duration from 37 to 90 days. Fifty adult ticks (+/-2) were applied approximately weekly, and tick counts were performed 3, 4, and 5 days after each infestation. The efficacy of selamectin was expressed as the percentage reduction in geometric mean tick counts on selamectin-treated dogs compared with those for dogs treated with the vehicle alone (negative-control). In one study, the engorgement of Dermacentor variabilis was assessed by weighing ticks after removal on the fifth day after each infestation. Weekly and 2-week interval treatments with selamectin provided efficacies against R. sanguineus of >89% across the entire study periods, with 100% efficacy being achieved from 21 days after the first dose and thereafter (study duration, 37 days for the weekly regimen and 44 days for the 2-week interval regimen). D. variabilis also was well controlled by the 2-week interval treatment regimen, with >96% efficacy being achieved from 21 days after the first treatment and thereafter until the end of the study (study duration: 90 days). In five of six studies incorporating three treatments at monthly intervals, the percentage reduction in R. sanguineus and D. variabilis counts 5 days after infestation ranged from 90 to 100% in the second and third months after treatment began. In the sixth study, reductions of > or =95% in D. variabilis counts 5 days after infestation were achieved for 2 weeks after each treatment in the second and third months. For the Monthly Plus regimen, from the second treatment (day 14) onwards, selamectin achieved 83-100% reductions in R. sanguineus and D. variabilis counts 3 days after infestation, and 94-100% reductions 5 days after infestation in three of the four studies. In the fourth study, selamectin demonstrated good efficacy against D. variabilis for 2 weeks after each treatment. In all seven studies, the counts from the selamectin-treated dogs were significantly (P< or =0.018) lower than those from the vehicle-treated dogs on 77 of the 80 assessments made 5 days after infestation. Selamectin also significantly (P< or =0.0105) reduced engorgement of female D. variabilis. These studies demonstrated that selamectin, administered topically to the skin in a single spot at a minimum dosage of 6mgkg(-1) at monthly intervals, was effective in the control of experimentally induced R. sanguineus and D. variabilis infestations on dogs.     

Efficacy of three dose volumes of topically applied 65% permethrin against Ctenocephalides felis and Rhipicephalus sanguineus on dogs weighing 30 kg or more

Twenty-five dogs were evenly and randomly allocated by weight to five treatment groups: untreated control, 2 ml 65% permethrin (dogs weighing 15 to 29 kg, "average dogs"), and 2, 3, or 4 ml 65% permethrin (dogs weighing > or = 30 kg, "big dogs"). Each dog was infested with 125 unfed, adult cat fleas, Ctenocephalides felis, and 50 unfed, adult brown dog ticks, Rhipicephalus sanguineus, on Days -3 (ticks only), -2 (fleas only), 3, 7, 14, 17, 21, 24, and 28. Fleas and ticks were counted 1 and 3 or 4 days after each infestation. The duration of efficacy (defined as >90%) against C. felis was 28 to 31 days. The efficacy against fleas 31 days after application of 2, 3, or 4 ml on big dogs ranged from 79.1% (2 ml) to 100% (4 ml). Big dogs that received either 3 or 4 ml of 65% permethrin had significantly (P < or = .05) fewer fleas at several evaluations between 15 and 31 days after treatment. The duration of efficacy against R. sanguineus was 15 (2 ml for big dogs) to 28 (2 ml for average dogs) days. The efficacy against R. sanguineus 28 days after treatment ranged from 79.1% (2 ml on big dogs) to 94.1% (2 ml on average dogs). Significantly (P < or = .05) fewer ticks were present at several evaluations after treatment on big dogs that received 3 or 4 ml than were present on big dogs treated with 2 ml. No significant differences were detected between the 3- and 4-ml groups from Days 10 to 31; however, the geometric mean number of ticks in the group treated with 4 ml was numerically lower than that for dogs treated with 3 ml on several occasions. These data indicate that a dose volume of 3 or 4 ml of 65% permethrin is needed to obtain an adequate level and duration of efficacy against both C. felis and R. sanguineus on dogs weighing 30 kg or more.     

Antibody and blood leukocyte response in Rhipicephalus sanguineus (Latreille, 1806) tick-infested dogs and guinea pigs

The dog is considered to be the natural host of Rhipicephalus sanguineus and is unable to develop appreciable resistance even after repeated feedings. The guinea pig develops strong resistance after one infestation with adult ticks. Antibody (IgG) titres against tick salivary gland antigens (SGAs) and blood leukocyte numbers in dogs and guinea pigs undergoing experimental R. sanguineus tick infestations were measured to detect a possible correlation with susceptibility or resistance of hosts. Since infested dogs develop an immediate hypersensitivity reaction to R. sanguineus antigens, total and anti-R. sanguineus SGA IgE levels were also measured in this host species. IgG and IgE antibody levels were determined by an enzyme-linked immunosorbent assay (ELISA) along three consecutive infestations of both hosts. Most dogs and guinea pigs displayed low IgG levels against R. sanguineus SGAs, though marked differences in individual response were observed. Although dog's total serum IgE levels increased significantly after infestations, no change in the amount of anti-salivary gland IgE was detected. Total and differential blood cell counts were determined in dogs and guinea pigs during primary and secondary infestation. In dogs, a tertiary infestation and a subsequent higher infestation level were also evaluated. Infested dogs did not display any alteration in blood leukocyte counts throughout the experiment. Guinea pigs, on the other hand, developed a significant basophilia during primary infestation which increased further during secondary infestation. These data reveal similarities and differences in the reactions of resistant and non-resistant hosts to ticks. They contribute for the understanding of such host-parasite relationships and will hopefully aid in the development of immune control of ticks.     

Long-term efficacy of a deltamethrin-impregnated collar for the control of the Australian paralysis tick, Ixodes holocyclus, on dogs

Objective To determine the duration of efficacy of a 4% deltamethrin‐impregnated collar for dogs (Scalibor® ProtectorBand, MSD Animal Health) against adult female paralysis ticks (Ixodes holocyclus). Procedures A controlled pen study was conducted. Dogs were artificially infested at 14‐day intervals with unfed adult female ticks for up to 140 days following application of the collar to the dogs. Efficacy was assessed by manually counting ticks on dogs at 24, 48 and 72 h after each infestation. Results Efficacy at the 72‐h count was 96% after the day 14 tick infestation. The 72‐h efficacy remained above 94% from the day 14 to the day 98 infestations, when efficacy was still 99.5%. Efficacy at 72 h was above 90% after the day 112 infestation and was still 93% at 72 h after the day 140 infestation. Conclusions The deltamethrin‐impregnated collar gave greater than 90% control of paralysis ticks for at least 14 weeks.     

Autochthonous cases of canine babesiosis in the canton Solothurn

Starting in November 2003 a series of five clinical cases of canine babesiosis was registered in the region of Oberg?sgen (canton Solothurn). All presented dogs showed increased body temperature, thrombocytopenia and hemoglobinuria, and none of the dogs had been abroad or visited endemic regions in the southern or western part of Switzerland so far. Babesia canis was detected in the blood smears of all five patients, but only three had detectable specific antibodies against this parasite. However, seroconversion was found in a second sample collected from the negative dogs at a later timepoint, confirming the diagnosis of canine babesiosis. The blood samples of two parasitized dogs were used for DNA-isolation and were tested with a Babesia-specific PCR, detecting the 18S rRNA-gene. Sequencing of the amplified products revealed a 100% identity with the sub-species B. canis canis. The ticks Rhipicephalus sanguineus and Dermacentor marginatus are potential vectors for B. canis. In the area where the infection with B. canis was suspected a total of 152 ticks was collected and characterized; one was a female R. sanguineus.Although babesia could not be detected in the latter tick and the final prooffor the complete life cycle is still lacking, it is very probable that B. canis has become autochthonous in the canton Solothurn.     

The prevention of attachment and the detachment effects of a novel combination of fipronil, amitraz and (S)-methoprene for Rhipicephalus sanguineus and Dermacentor variabilis on dogs

A novel combination of fipronil, amitraz and (S)-methoprene (CERTIFECT?, Merial Limited, GA, USA) was evaluated for the prevention of attachment of ticks and its ability to cause detachment of ticks. For the two prevention of attachment studies, 20 purpose-bred beagles were allocated each to two equal groups based on pretreatment tick counts (treated and untreated). Each dog was exposed to 50 adult Rhipicephalus sanguineus and Dermacentor variabilis weekly starting 24h after treatment. In study 1 infestations with R. sanguineus were discontinued after Day 7 but continued to Day 28 for D. variabilis in both studies. Counts of ticks by species were made 2, 4 and 24h after exposure to ticks. Ticks not attaching to dogs were evaluated for viability. For the evaluation of detachment study, 16 purpose-bred beagles were allocated each to two equal groups based on pretreatment tick counts (treated and untreated). Each dog was infested with 50 unfed R. sanguineus and D. variabilis adults on Day -2. Ticks were thumb counted without removal on all dogs on Day -1, and at 4, 12, and 24h after treatment. Ticks were counted and removed at 48 h after treatment. Dogs treated with the novel combination had significantly (p<0.05) lower total numbers of attached R. sanguineus and D. variabilis than untreated controls at 4h through Day 7. For R. sanguineus, percent reduction of attachment at 24h after infestation through Day 29 ranged from 94.5% to 100%. For D. variabilis, the percent reduction of attachment at 24h through Day 22 was above 98.0%. These studies demonstrate that novel combination can disrupt attachment of R. sanguineus and D. variabilis for up to 28 days following treatment. Of those ticks that are exposed to the treatment, even if they do not attach to the dog and remain in the environment, greater than 90% (p<0.05) die within 24h for 2-3 weeks following treatment. Also, for those dogs infested with ticks at the time of treatment, the novel combination causes significant detachment (p<.05) starting at 12h and reaching 98.9% by 48 h after treatment. This product provides an effective means for controlling ticks infesting dogs and limiting the spread of tick transmitted diseases. Additionally, the mortality of ticks exposed to CERTIFECT will reduce infestation of the dog's environment.     

First evidence of Anaplasma platys in Rhipicephalus sanguineus (Acari: Ixodida) collected from dogs in Africa

A total of 27 ticks, comprising Rhipicephalus sanguineus (Latreille) (n = 21), Haemaphysalis leachi (Andouin) (n = 4) and Haemaphysalis paraleachi (Camicas, Hoogstraal & El Kammah) (n = 2) were recovered from two clinically healthy female dogs in the Democratic Republic of the Congo. DNA of Anaplasma platys was detected in a female R. sanguineus, using primers derived from the 16S rRNA gene, which amplify members of the family Anaplasmataceae . Anaplasma platys DNA was also detected in the blood of one of the dogs. Phylogenetic analysis based on partial sequences of the 16S rRNA, the gltA and the groEL genes ranged the detected agent within the Anaplasma clade. This is the first reported detection of A. platys in ticks in Africa. This finding raises the question of the possible involvement of R. sanguineus in A. platys infection of dogs.     

Activity of a deltamethrin shampoo against Ctenocephalides felis and Rhipicephalus sanguineus in dogs

A controlled clinical trial was undertaken to assess the efficacy of an application of a 0.07% deltamethrin shampoo against fleas and ticks in dogs. Twenty beagles, housed in separate cages, were randomly allocated into two groups of 10. The dogs were infested with 50 Ctenocephalides felis and 50 Rhipicephalus sanguineus each, and parasites were counted 24 h (fleas) and 72 h (ticks) later (Day 0). Dogs, when state, were then treated with 25 ml of a shampoo containing 0.07% deltamethrin (Group 1). Dogs in Group 2 were the controls. Fleas and ticks were counted 24 h (Day 1) and 48 h (Day 2) after the shampoo was applied, and the parasites were then removed. All the dogs were reinfested with fleas and ticks on Days 2, 7, 9, 14, 16 and 20. Parasites were counted 24 and 48 h after each reinfestation. Effectiveness against fleas was calculated 24 h after infestation, and against ticks 48 h after infestation. This study showed that the application of 25 ml of shampoo containing 0.07% deltamethrin to beagle dogs weighing between 10.2 and 12 kg was very well tolerated. It controlled the parasites present on the animals at the time of application: with an efficacy of 100% against fleas 24 h after treatment and an efficacy of 95% against ticks 48 h after treatment. The treatment protected against flea reinfestations with an efficacy of 100% during the first week, >98% in the second week and >95% in the third week. It also gave >99% protection against tick reinfestations in the first week and >96% in the second week.     

The efficacy of collars impregnated with flumethrin and propoxur against experimental infestations of adult Rhipicephalus sanguineus on dogs

The efficacy of 2 sets of collars (Kiltix Collar, Bayer AG), containing different plasticisers and impregnated with the acaricides flumethrin (2.25%) and propoxur (10%), was compared against adult Rhipicephalus sanguineus on experimentally infested, kennelled dogs. Thirty individually penned dogs were infested with 25 male and 25 female, unfed R. sanguineus. On the following day they were allocated to 3 groups of 10 dogs each on the magnitude of their tick burdens. Two days after infestation, medicated collars containing 1 of the plasticisers were fitted to 10 of the dogs and similar collars containing the other plasticiser were fitted to 10 others. The remaining 10 dogs were the untreated controls. Seven and 28 days after having fitted the collars, all dogs were re-infested with 50 unfed adult ticks of both sexes, and again at approximately 28-day intervals up to the 5th month, and then at approximately 14-day intervals during the 6th month. Efficacy was determined by comparing the mean number of live, attached ticks on the untreated control group with those on the collared dogs 2 days after each re-infestation. Immediate efficacy of the collars (Day +2) was > 95%, and residual efficacy was > 98% up to and including Day +114, and > 93% up to Day +170 on both groups of collared dogs. The mean tick counts on the 2 groups of collared dogs did not differ significantly (P < 0.0001) for any of the assessment days.     

Detection of Bartonella henselae DNA in two dogs with pyogranulomatous lymphadenitis

CASE DESCRIPTION: 1 dog evaluated because of inappetence and lameness of the left hind limb of 1 day's duration and 1 dog evaluated because of inappetence, fever, and lymphadenopathy of 2 weeks' duration. CLINICAL FINDINGS: Histologic examination of excisional biopsy specimens from lymph nodes revealed pyogranulomatous lymphadenitis in both dogs. Quantitative real-time PCR assays detected Bartonella henselae DNA in blood samples and affected lymph node specimens from both dogs. Antibodies against B. henselae were not detected via immunofluorescent antibody testing during active disease in either dog. TREATMENT AND OUTCOME: 1 dog recovered after 6 weeks of treatment with doxycycline (5 mg/kg [2.3 mg/lb], p.o., q 12 h), whereas the other dog recovered after receiving a combination of azithromycin (14.5 mg/kg [6.6 mg/lb], p.o., q 24 h for 21 days), doxycycline (17.3 mg/kg [7.9 mg/lb], p.o., q 24 h for 4 weeks), and immunosuppressive corticosteroid (prednisone [3 mg/kg {1.4 mg/lb}, p.o., q 24 h], tapered by decreasing the daily dose by 25% every 2 weeks) treatment. CLINICAL RELEVANCE: B. henselae is implicated as a possible cause or a cofactor in the development of pyogranulomatous lymphadenitis in dogs. In dogs with pyogranulomatous lymphadenitis, immunofluorescent assays may not detect antibodies against B. henselae. Molecular testing, including PCR assay of affected tissues, may provide an alternative diagnostic method for detection of B. henselae DNA in pyogranulomatous lymph nodes.     

Efficacy of a single application of a 12.5% pyriprole topical solution against laboratory infestations with ticks (Ixodes ricinus, Dermacentor reticulatus, and Rhipicephalus sanguineus) on dogs

In three separate studies, the efficacy of a single treatment with a 12.5% pyriprole spot-on solution was investigated against induced infestation with Ixodes ricinus, Dermacentor reticulatus and Rhipicephalus sanguineus on dogs (both sexes; Beagles in Studies 1 and 2, mixed-breed in Study 3). For each tick species, one group of 8 dogs left untreated (Studies 1 and 2) or treated with a placebo solution (Study 3) was compared with another group treated once with the spot-on solution at a dose rate of at least 12.5mg/kg. The dogs were infested with 50 unfed adult ticks of the respective species at various time-points before and after treatment and the surviving attached and unattached ticks were recorded 48 h after re-infestation. For each tick species, efficacy was assessed for each time-point and cumulatively for the whole evaluation period. The dogs were submitted to general health observations and clinical assessments during the study. Efficacy against I. ricinus and R. sanguineus was 100% during the whole evaluation period of 30 days. For D. reticulatus cumulative efficacy for the 30 days after treatment was 98.9%. The product was well tolerated by all the animals.     

Amitraz: a tick and flea repellent and tick detachment drug

A topical formulation of amitraz (Mitaban Liquid Concentrate, The Upjohn Company, Kalamazoo, Michigan, U.S.A.) was evaluated as a tick repellent and detachment agent, and flea repellent. The diluted liquid concentrate (250 p.p.m. active drug) was topically applied as a single treatment to dogs; the concentration was identical to the rate recommended for treatment of demodicosis and scabies. Brown dog tick (Rhipicephalus sanguineus) and American dog tick (Dermacentor variabilis) populations were eliminated and repelled. Repellent activity (92-95%) was observed against R. sanguineus for 2 weeks post-treatment; the treatment was moderately active (63%) during the third week, and at 4 weeks post-treatment the drug was inactive. Established R. sanguineus populations were also treated, and the diluted liquid concentrate had 100% tick-detachment efficacy. Repellent activity (99%) was also detected against D. variabilis; the activity was monitored for only 7 days. The ectoparasiticide had low to moderate flea (Ctenocephalides felis) repellent activity (42%) for 4 days post-treatment; thereafter the treatment was ineffective. Side-effects were not observed in any of the dogs treated with amitraz, or the placebo.     

Transstadial and intrastadial experimental transmission of Ehrlichia canis by male Rhipicephalus sanguineus

The acquisition and transmission of rickettsial pathogens by different tick developmental stages has important epidemiological implications. The purpose of this study was to determine if male Rhipicephalus sanguineus can experimentally acquire and transmit Ehrlichia canis in the absence of female ticks. Two trials were performed where nymphal and male R. sanguineus were simultaneously acquisition fed on the same infected donor hosts, and transstadially or intrastadially exposed male ticks were fed on separate pathogen-free dogs as a test for transmission. A single-step p30-based PCR assay was used to test canine and tick hosts for E. canis infections before and after tick feeding. E. canis was detected after either intrastadial or transstadial passage in male ticks, the organism remained detectable in both tick groups after transmission feeding, and both tick groups transmitted the rickettsia to susceptible dogs. Infection of dogs via tick feeding resulted in milder clinical signs and lower antibody titers than intravenous inoculation of carrier blood, but further investigation is needed to understand the mechanisms responsible for this observation. These results demonstrate that male R. sanguineus can take multiple feedings, and that they can both acquire and transmit E. canis in the absence of female ticks. This tick development stage could be important in transmission of E. canis, and perhaps related pathogens, between vertebrate hosts under natural and experimental conditions.     

Canine antibody response to Blastomyces dermatitidis WI-1 antigen

OBJECTIVE: To assess whether dogs with blastomycosis produce antibodies against the WI-1 and A-antigens of Blastomyces dermatitidis and whether the antibodies are useful in serodiagnosis. SAMPLE POPULATION: 359 serum samples obtained from 245 dogs. PROCEDURE: 233 samples from 122 dogs with blastomycosis, and 1 sample each from 24 dogs with suspected blastomycosis, 51 control dogs without infection, and 48 healthy dogs from an enzootic region were obtained. Antibodies against WI-1 antigen were detected by radioimmunoassay (RIA). Serum samples were tested in parallel for antibodies against the A-antigen of B dermatitidis by commercial agar-gel immunodiffusion (AGID) in a reference laboratory. RESULTS: Antibodies were detected in 92% of infected dogs by RIA and in 41 % by AGID. For 29 serum samples that were obtained 11 to 1,545 days after diagnosis, antibodies were detected in 92% of samples by RIA and 7% by AGID. For 93 serial serum samples from 29 dogs with blastomycosis, the mean anti-WI-1 titer was 1:18,761 at the time of diagnosis, and decreased to a mean of 1:1,338 by 210 days after treatment was initiated. Of 24 dogs with suspected infection, antibodies were detected in 67% by RIA and 33% by AGID. Control dogs without blastomycosis had no detectable antibodies in either assay. Thus, sensitivity was 92% for RIA and 41 % for AGID, and specificity was 100% for both tests. CONCLUSIONS AND CLINICAL RELEVANCE: Anti-WI-1 antibodies are readily detected by RIA in dogs with blastomycosis. Titers become high, decline during treatment, and persist for months. Anti-A antibodies are sometimes detected with AGID, but these decrease quickly.     

Ectoparasitic species from Canis familiaris (Linné) in Buenos Aires province, Argentina

Several arthropods that live as ectoparasites on domestic dogs can cause severe dermatitis or act as vectors of pathogenic agents, resulting in serious diseases not only in dogs, but also in humans. We studied ectoparasites found on Canis familiaris sampled in five areas in Buenos Aires province, Argentina. The prevalence of fleas, ticks and lice was analyzed, as well as their seasonal variations through the different sites studied. The kind of infestation found in each host was determined and the intensity of natural infestation was estimated. The study was carried out from October 2001 to July 2002, with 116 dogs that lived in rural areas and did not receive control treatments. In order to remove the ectoparasites, the dogs' skin was rubbed with a piece of cotton soaked in ether. All dogs had at least one species of ectoparasites. A total number of 5193 ectoparasites were found corresponding to four species, 15.7% Ctenocephalides canis, 73% Rhipicephalus sanguineus, 1.8 Linognathus setosus and 9.4% Heterodoxus spiniger. R. sanguineus was the most abundant species, and C. canis was the only flea species found. This may be due to the dogs being exclusively rural animals. Within the zones sampled, Magdalena showed the greatest prevalence, maybe as a consequence of having the highest relative humidity in relation to the other areas. Triple infestation (ticks-fleas-lice) was observed in 56.9% of the dogs; 39.6% presented double infestation, most being ticks-fleas, and only 3.4% showed simple infestation (lice). Female hosts were the most affected. Even though there were records of ectoparasites throughout all the year, a higher intensity was observed during the spring months, most likely as a result of the increase in temperature after the winter months.     

Efficacy of a novel combination of fipronil, amitraz and (S)-methoprene for treatment and control of tick species infesting dogs in Europe

Four studies were conducted to show the effectiveness of a novel combination of fipronil, amitraz and (S)-methoprene in a spot-on formulation (CERTIFECT?, Merial Limited, GA, USA) for the therapeutic and preventive control of Ixodid tick species affecting dogs in Europe: Ixodes ricinus, Dermacentor reticulatus and Rhipicephalus sanguineus. In each, untreated control dogs were compared to others treated with the novel combination. All dogs were infested with 50 adult, unfed ticks prior to treatment and at 7-day intervals after treatment. Ticks on all dogs were counted at 18, 24 and 48 h after treatment (therapeutic efficacy) or infestation (preventive efficacy). Therapeutic efficacy of fipronil, amitraz and (S)-methoprene was excellent as shown by significant (p<0.05) and greater than 97% and up to 100% reductions in the 48 h tick counts and significant (p<0.05) detachment/death of ticks evident at 18-24h after treatment for all three tick species. Preventive efficacy was demonstrated by significant (p<0.05) and greater than 93% and up to 100% reductions in tick counts at 48 h after repeat infestations out to 35 days after treatment for I. ricinus and out to 42 days after treatment for D. reticulatus and R. sanguineus. The time to substantial disruption of establishment of new tick infestations after treatment was less than 18-24h and was maintained for up to 28 days after treatment of I. ricinus and D. reticulatus infestations, and 4h to at most 18 h and maintained up to 35 days after treatment of R. sanguineus. Similar preventive efficacy profiles for each of the Ixodid species tested suggest that CERTIFECT kills all Ixodid species starting 4h after contact as demonstrated for R. sanguineus.     

The effect of water and shampooing on the efficacy of a pyriprole 12.5% topical solution against brown dog tick (Rhipicephalus sanguineus) and cat flea (Ctenocephalides felis) infestations on dogs

The efficacy of a single treatment with a 12.5% pyriprole spot-on formulation against induced infestations with R. sanguineus ticks and cat fleas (C. felis) as well as its persistence after repeated washing and shampooing was investigated in four separate studies. In a first study on R. sanguineus involving 32 beagle dogs, the efficacy at various time-points during the 30 days that followed treatment assessed 48 h after re-infestation ranged from 100% to 99.3%. No engorged ticks, alive or dead, were found in the treated animals. Shampooing 2 days after treatment and weekly washings did not affect the efficacy. In a second study on R. sanguineus involving 32 beagle dogs, the efficacy at various time-points during the 30 days that followed treatment assessed 48 h after re-infestation ranged from 100% to 96.8%. Single washing 8h after treatment and single shampooing 24 h after treatment had no negative impact on the efficacy of the product. In a third study on C. felis involving 28 beagle dogs, the efficacy at various time-points during the 30 days that followed treatment assessed 48 h after re-infestation was always 100% and weekly washings did not diminish the efficacy. In a last study on C. felis involving 24 beagle dogs, the efficacy at various time-points during the 5 weeks that followed treatment assessed 48 h after re-infestation ranged from 100% to 99.8%, and shampooing 24 h after treatment did not reduce the efficacy. The product was well tolerated by the dogs.     

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.     

Outbreak of canine monocytic ehrlichiosis in Saudi Arabia

BACKGROUND: Canine monocytic ehrlichiosis (CME) is a widespread tickborne infection of canids caused by Ehrlichia canis, a gram-negative obligatory intracellular bacteria belonging to the family Anaplasmataceae. CME is reported to have worldwide distribution, but its presence in a region requires the presence of the vector, the brown dog tick Rhipicephalus sanguineus. OBJECTIVE: This purpose of this report was to describe an outbreak of CME in a colony of dogs resident in the eastern region of Saudi Arabia. METHODS: History, presenting clinical signs, and the results of a CBC, biochemical panel, and serology (using a commercial test for E canis antibodies) were evaluated in 9 male Labrador Retrievers between October and December 2006. RESULTS: The majority of dogs presented with severe lethargy (7/9) and acute anorexia (5/9), and had fever (7/9) and generalized lymphadenopathy (7/9). The most common laboratory abnormalities were anemia (8/9), leukopenia (7/9), and hypoalbuminemia (6/9). Thrombocytopenia was found in only 2 dogs, 1 of which had increased bleeding tendency. Ehrlichia morulae were identified in blood films from 4/9 dogs and serologic test results were positive in 7/9 dogs. Confirmation of Ehrlichia sp infection was obtained in 1 dog by using a genus-specific real-time PCR assay. Four dogs had tick infestation; the ticks on 1 dog were identified as R sanguineus. All of the dogs had a rapid clinical response to doxycycline hyclate. CONCLUSIONS: This report, to our knowledge, is the first to describe the presence of a pathogenic Ehrlichia organism affecting dogs in Saudi Arabia. Additional molecular studies are necessary to confirm E canis infection, and to identify the strain of the organism.