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The Vetscan Imagyst system (Zoetis) is a novel, artificial intelligence-driven detection tool that can assist veterinarians in the identification of enteric parasites in dogs and cats. This system consists of a sample preparation device, an automated digital microscope scanner, and a deep-learning algorithm. The EasyScan One scanner (Motic) has had good diagnostic performance compared with manual examinations by experts; however, there are drawbacks when used in veterinary practices in which space for equipment is often limited. To improve the usability of this system, we evaluated an additional scanner, the Ocus 40 (Grundium). Our objectives were to 1) qualitatively evaluate the performance of the Vetscan Imagyst system with the Ocus 40 scanner for identifying Ancylostoma , Toxocara , and Trichuris eggs, Cystoisospora oocysts, and Giardia cysts in canine and feline fecal samples, and 2) expand the assessment of the performance of the Vetscan Imagyst system paired with either the Ocus 40 or EasyScan One scanner to include a larger dataset of 2,191 fecal samples obtained from 4 geographic regions of the United States. When tested with 852 canine and feline fecal samples collected from different geographic regions, the performance of the Vetscan Imagyst system combined with the Ocus 40 scanner was correlated closely with manual evaluations by experts. Sensitivities were 80.0‒97.0% and specificities were 93.7‒100.0% across the targeted parasites. When tested with 1,339 fecal samples, the Vetscan Imagyst system paired with the EasyScan One scanner successfully identified the targeted parasite stages; sensitivities were 73.6‒96.4% and specificities were 79.7‒100.0%., Competing Interests: Declaration of conflicting interestsTravis Cree, Michael Loenser, Cory Penn, Austin Rhodes, and Richard Goldstein are employees of Zoetis. Benjamin Larson is an employee of Techcyte. Yoko Nagamori was an employee of Oklahoma State University during our study and is now an employee of Zoetis. Ruth Hall-Sedlak was an employee of Zoetis when our study was conducted and is now an employee of Amgen.

Background: Bexagliflozin is a sodium-glucose cotransporter 2 (SGLT2) inhibitor. A pilot study has shown that bexagliflozin can decrease dependence on exogenous insulin in cats with diabetes mellitus (DM)., Objective: To evaluate the safety and effectiveness of bexagliflozin as a monotherapy for DM in previously untreated cats., Animals: Eighty-four client-owned cats., Methods: Historically controlled prospective open-label clinical trial. Cats were dosed PO with 15 mg bexagliflozin once daily for 56 days, with a 124-day extension to evaluate safety and treatment effect durability. The primary endpoint was the proportion of cats experiencing a decrease in hyperglycemia and improvement in clinical signs of hyperglycemia from baseline on day 56., Results: Of 84 enrolled cats, 81 were evaluable on day 56, and 68 (84.0%) were treatment successes. Decreases in mean serum glucose, fructosamine, and β-hydroxybutyrate (β-OHB) concentrations were observed, and investigator assessments of cat neurological status, musculature, and hair coat quality improved. Owner evaluations of both cat and owner quality of life were favorable. The fructosamine half-life in diabetic cats was found to be 6.8 days. Commonly observed adverse events included emesis, diarrhea, anorexia, lethargy, and dehydration. Eight cats experienced serious adverse events, 3 of which led to death or euthanasia. The most important adverse event was euglycemic diabetic ketoacidosis, diagnosed in 3 cats and presumed present in a fourth., Conclusion and Clinical Importance: Bexagliflozin decreased hyperglycemia and observed clinical signs in cats newly diagnosed with DM. As a once-daily PO medication, bexagliflozin may simplify management of DM in cats., (© 2023 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals LLC on behalf of American College of Veterinary Internal Medicine.)

Two lineages of brown dog ticks (Rhipicephalus sanguineus sensu lato (s.l.), Latreille [Acari: Ixodidae]) have been described in North America: temperate and tropical. To characterize the distribution of these lineages across this region and evaluate seasonal activity, a 12S rRNA mitochondrial gene fragment was sequenced from R. sanguineus s.l. collected from hundreds of dogs and cats from different locations across 25 of the 50 states from 2018 to 2021. Infestations with temperate lineage predominated (78.5%) and were identified on pets from 20 states, with most (83.5%) from areas with annual mean daily average temperature <20°C. Tropical lineage submissions were less common (19.3%), submitted from 15 states, and most (80.0%) tropical lineage ticks were from areas with an annual mean daily average temperature >20°C. Although travel history was not obtained for all dogs, when tropical lineage infestations were found in colder regions, follow up conversations with veterinarians suggested some of these infestations may have resulted from recent travel of dogs. A limited number (2.2%) of dogs from Arizona and Texas were co-infested with both lineages. Both temperate and tropical lineage ticks were collected from pets in every month of the year. Temperate lineage infestations were primarily collected March through August while tropical lineage infestations were more often collected June through November. These data confirm at least two lineages of R. sanguineus s.l. are present in the United States, each predominating in distinct, overlapping geographies, and suggest that peak activity of each lineage occurs at different times of the year., (© The Author(s) 2022. Published by Oxford University Press on behalf of Entomological Society of America.)

As tick-borne diseases continue to increase across North America, current research strives to understand how the tick microbiome may affect pathogen acquisition, maintenance, and transmission. Prior high throughput amplicon-based microbial diversity surveys of the widespread tick Dermacentor variabilis have suggested that life stage, sex, and geographic region may influence the composition of the tick microbiome. Here, adult D. variabilis ticks (n = 145) were collected from dogs and cats from 32 states with specimens originating from all four regions of the United States (West, Midwest, South, and Northeast), and the tick microbiome was examined via V4-16S rRNA gene amplification and Illumina sequencing. A total of 481,246 bacterial sequences were obtained (median 2924 per sample, range 399-11,990). Fifty genera represented the majority (>80%) of the sequences detected, with the genera Allofrancisella and Francisella being the most abundant. Further, 97%, 23%, and 5.5% of the ticks contained sequences belonging to Francisella spp., Rickettsia spp., and Coxiella spp., respectively. No Ehrlichia spp. or Anaplasma spp. were identified. Co-occurrence analysis, by way of correlation coefficients, between the top 50 most abundant genera demonstrated five strong positive and no strong negative correlation relationships. Geographic region had a consistent effect on species richness with ticks from the Northeast having a significantly greater level of richness. Alpha diversity patterns were dependent on tick sex, with males exhibiting higher levels of diversity, and geographical region, with higher level of diversity observed in ticks obtained from the Northeast, but not on tick host. Community structure, or beta diversity, of tick microbiome was impacted by tick sex and geographic location, with microbiomes of ticks from the western US exhibiting a distinct community structure when compared to those from the other three regions (Northeast, South, and Midwest). In total, LEfSe (Linear discriminant analysis Effect Size) identified 18 specific genera driving these observed patterns of diversity and community structure. Collectively, these findings highlight the differences in bacterial diversity of D. variabilis across the US and supports the interpretation that tick sex and geographic region affects microbiome composition across a broad sampling distribution., (Copyright © 2022 The Author(s). Published by Elsevier GmbH.. All rights reserved.)

In the United States, Dermacentor variabilis and Dermacentor andersoni are considered key vectors for Rickettsia rickettsii , the causative agent of Rocky Mountain spotted fever. Through regional surveillance, a wide diversity of Rickettsia spp. have been documented in D. variabilis , and Dermacentor spp. has been suggested as potential vectors for various other pathogens, including Babesia spp. and Ehrlichia canis . To better define the prevalence and diversity of pathogens in Dermacentor spp. across the United States, 848 ticks collected from dogs and cats in 44/50 states in 2018-2019 were tested by PCR for Rickettsia spp.-specific 17 kDa and ompA gene fragments; a subset of Dermacentor spp. was also tested with PCR, targeting fragments of the 18S and large subunit region rRNA genes of Babesia spp. and 16S rRNA genes of E. canis . Rickettsia spp. was identified in 12.5% (106/848) of ticks. Species detected include Rickettsia montanensis ( n  = 64 ticks), Rickettsia bellii ( n  = 15 ticks), Rickettsia rhipicephali ( n  = 13 ticks), Rickettsia peacockii ( n  = 8 ticks), Rickettsia amblyommatis ( n  = 3 ticks), Rickettsia cooleyi ( n  = 1 tick), and unclassified Rickettsia spp. ( n  = 2 ticks). Ticks with R. montanensis and R. bellii were submitted from every U.S. region; R. rhipicephali was predominantly detected in ticks from the southern half of the United States, and all R. peacockii -positive ticks were D. andersoni that originated from the Rocky Mountain states. Ehrlichia canis was not detected in any Dermacentor spp., and Babesia conradae was detected in two Dermacentor albipictus . Because most ticks had fed on dogs or cats before submission, these findings do not implicate a given Dermacentor sp. as a primary vector of these agents, but in regard to Rickettsia spp., the data do support other published work showing D. variabilis harbors a diversity of Rickettsia species with unknown implications for animal and human health.

A diverse array of ixodid and argasid ticks infest dogs and cats in North America, resulting in skin lesions, blood loss, and disease. The ticks most commonly found on pets in this region are hard ticks of the genera Amblyomma, Dermacentor, Ixodes, and Rhipicephalus, as well as the more recently established Haemaphysalis longicornis. Soft tick genera, especially Otobius and Ornithodoros, are also reported from pets in some regions. In this review, we provide a summary of the complex and diverse life histories, distinct morphologies, and questing and feeding behaviors of the more common ticks of dogs and cats in North America with a focus on recent changes in geographic distribution. We also review pathogens of dogs and cats associated with the different tick species, some of which can cause serious, potentially fatal disease, and describe the zoonotic risk posed by ticks of pets. Understanding the natural history of ticks and the maintenance cycles responsible for providing an ongoing source of tick-borne infections is critical to effectively combatting the challenges ticks pose to the health of pets and people., (Copyright © 2021 The Authors. Published by Elsevier B.V. All rights reserved.)

Throughout North America, Dermacentor spp. ticks are often found feeding on animals and humans, and are known to transmit pathogens, including the Rocky Mountain spotted fever agent. To better define the identity and distribution of Dermacentor spp. removed from dogs and cats in the United States, ticks submitted from 1,457 dogs (n = 2,924 ticks) and 137 cats (n = 209 ticks) from veterinary practices in 44/50 states from February 2018-January 2020 were identified morphologically (n = 3,133); the identity of ticks from regions where Dermacentor andersoni (Stiles) have been reported, and a subset of ticks from other regions, were confirmed molecularly through amplification and sequencing of the ITS2 region and a 16S rRNA gene fragment. Of the ticks submitted, 99.3% (3,112/3,133) were Dermacentor variabilis (Say), 0.4% (12/3,133) were D. andersoni, and 0.3% (9/3,133) were Dermacentor albipictus (Packard). While translocation of pets prior to tick removal cannot be discounted, the majority (106/122; 87%) of Dermacentor spp. ticks removed from dogs and cats in six Rocky Mountain states (Montana, Idaho, Wyoming, Nevada, Utah, and Colorado) were D. variabilis, suggesting this species may be more widespread in the western United States than is currently recognized, or that D. andersoni, if still common in the region, preferentially feeds on hosts other than dogs and cats. Together, these data support the interpretation that D. variabilis is the predominant Dermacentor species found on pets throughout the United States, a finding that may reflect recent shifts in tick distribution., (© The Author(s) 2021. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Dermacentor albipictus, a common one-host tick of large animals in North America, is most often reported from moose (Alces alces) and is rarely implicated as a parasite of cats and dogs. From 2018 to 2020, 4 dogs and 4 cats from United States and 3 dogs from Canada were infested with D. albipictus. The specimens were collected and submitted to university diagnostic specialists by veterinary clinics in Indiana, Kentucky, Minnesota, Colorado, Wyoming, Utah, Alberta, and British Columbia between the months of October to February (United States) and April to June (Canada). Six adults and five nymphal D. albipictus were collected in the United States while three adults were collected from pets in Canada, and most often a single D. albipictus was present. Identification of specimens collected in the United States were confirmed by amplification and sequencing of 16S rRNA and ITS-2 gene fragments. Rickettsia spp. were not detected in any D. albipictus collected in the United States by 17 kDa-based PCR. As tick populations continue to increase and expand in North America, correct identification of ticks collected from pets is critical to accurately track the progression and spread of ticks and tick-borne diseases., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Background: A variety of tick species infest dogs and cats in North America. Although most of these species also readily feed on people, national data regarding the species and abundance of ticks on dogs and cats are lacking. Here we report a large-scale study of ticks from dogs and cats in the USA over a 12-month period., Methods: Tick submissions were invited from veterinary practices in all 50 states. Ticks were submitted with information about the pet and the attachment sites of each tick marked on a biopsy chart. Upon receipt, ticks were identified to species and stage using morphologic keys; when necessary, species identification was confirmed molecularly., Results: From February 2018 through January 2019, 10,978 ticks were submitted from 1494 dogs and 336 cats in 49 states and ticks were collected in every month. Dog and cat infestation intensities ranged from 1 to 4765 and from 1 to 38 (median = 1, mean = 6.7 and 2.6), respectively. Dogs were primarily infested with Dermacentor variabilis (532/1494; 35.6%), Ixodes scapularis (409/1494; 27.4%), Amblyomma americanum (345/1494; 23.1%) and Rhipicephalus sanguineus (172/1494; 11.5%). Cats were primarily infested with I. scapularis (156/336; 46.4%), A. americanum (99/336; 29.5%) and D. variabilis (60/336; 17.9%). Other submitted ticks included A. maculatum, Haemaphysalis longicornis, Otobius megnini, and less common Dermacentor spp. and Ixodes spp. Co-infestations were documented in 93 dogs and 14 cats. Reported attachment sites of common tick species differed. In dogs, A. americanum was most commonly attached to the abdomen, axillary, and inguinal regions; D. variabilis and I. scapularis to the head, neck, and back; and R. sanguineus to the head, neck, abdomen, legs, and feet. In cats, I. scapularis was most commonly attached to the head and A. americanum was most commonly attached to the tail and perianal region., Conclusions: These data confirm that dogs and cats in the USA are at risk of tick infestation throughout the year and that tick species present in the region have apparent attachment site preferences.

We reviewed 62 new cases and 18 published reports of Dracunculus infections in domestic dogs and cats to describe the epidemiology of this parasite in dogs and cats in North America. We collected host and parasite data when available, including age, sex, and breed of dog, nematode location in the host, and any clinical signs at presentation and/or description of the apparent lesion. For dogs, infections were noted in six of the AKC breed groups, but none was reported from the toy group or the miscellaneous breed class. Age of infected dogs ranged from 7 months to 19 years (median 4 years; average 5.3 years), and infection rates were similar in male and female dogs. Most nematodes were associated with the distal extremities, but worms were also found in the chest/thorax, abdomen, head, and flank. Although most infected dogs had a single worm, three dogs had two or more worms that were collected from multiple lesions. Three new cat cases, with similar lesions, presentations and seasonality, were detected in Alabama, North Carolina and Texas. Cases were reported from a wide geographic range throughout eastern North America, during every month of the year, but 72% of infections were diagnosed in the late winter to early spring (December to May). All collected worms were larvigerous females which cannot be identified to species based on morphologic characters. Thus, we attempted to amplify and sequence a portion of the cytochrome c oxidase subunit I (COI) gene for specific identification. Although 13 worms from 12 cases were available, sequences were obtained for only eight worms from seven cases. These eight worms were D. insignis, a common parasite of raccoons (Procyon lotor) and other primarily carnivorous mammals. Female worms are the most likely to be detected in dogs and cats because male worms do not emerge, parasites should be preserved in ethanol for molecular identification. Although this study used convenience sampling of available data, we found that the parasite is widespread throughout the eastern US and Canada and that Dracunculus infections in dogs are more common than is revealed in published literature. However, more research is needed to understand the epidemiology, including transmission route(s), prevalence, and distribution of this parasite., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Ticks are an important but under recognized parasitic threat to cats in many areas of the United States. To characterize the species and stages of ticks most commonly recovered from cats and determine the prevalence of disease agents in the ticks, we conducted a survey of ticks removed from cats at veterinary practices in 18 states from April 2016-June 2017. A total of 796 ticks were submitted from 332 cats from 41 different veterinary practices. A single tick was submitted from the majority of cats, with a mean infestation intensity of 2.4 (range 1-46). The most common tick was Ixodes scapularis, accounting for 422/796 (53.0%) ticks submitted, followed by Amblyomma americanum (224/796; 28.1%) and Dermacentor variabilis (131/796; 16.5%); a few I. pacificus, I. banksi, D. occidentalis, A. maculatum, Rhipicephalus sanguineus, and Otobius megnini were also submitted. A majority of ticks were adults (593/796; 74.5%); females predominated in all adult tick submissions including I. scapularis (277/327; 84.7% female), A. americanum (66/128; 51.6% female), and D. variabilis (75/126; 59.5% female). Immature ticks included 186 nymphs and 17 larvae and were primarily I. scapularis and A. americanum. Adult I. scapularis were most reported to be attached to the dorsal head and neck; A. americanum to the abdomen and perianal region; and D. variabilis to the back and ear. Ticks were collected in every month; the largest number of submissions were in May and June (42.5% of ticks) and October and November (35.9% of ticks). Adults of I. scapularis were most commonly submitted October through December, A. americanum March through June, and D. variabilis May through July. Cats with ticks were predominantly male (58.8%) and altered (76.2%), and most reportedly spent >30% of time outdoors, although 64/294 (21.8%) for which lifestyle estimates were provided were reported to live primarily (≤30% of time outside; n = 54) or entirely (100%; n = 10) indoors. Assay of ticks removed from cats revealed I. scapularis were infected with Borrelia burgdorferi (25.7%) and Anaplasma phagocytophilum (4.4%); A. americanum were infected with Ehrlichia chaffeensis (1.3%); and D. variabilis were infected with spotted fever group Rickettsia spp. (3.1%). No ticks in this study tested positive for Cytauxzoon felis. Pet cats, including those that live primarily indoors, are at risk of tick infestation, potentially exposed to tick-borne disease agents, and would benefit from routine tick control., (Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.)

Objectives To determine whether pretreating diagnostic samples with heat increases the detection of Dirofilaria immitis antigen in adult cats, we evaluated feline serum and plasma samples collected in heartworm-endemic areas of the southern United States. Methods Commercial microtiter well assays for detection of D immitis antigen were used to evaluate serum or plasma samples from 385 shelter and free-roaming cats from the southcentral and southeastern United States before and after heat treatment; commercial antibody tests were performed on a subset of samples. Results Prior to sample heat treatment, 1/220 (0.5%) shelter cats and 4/165 (2.4%) free-roaming cats had detectable D immitis antigen. After heat pretreatment, the detection rate increased to 13/220 (5.9%) and 13/165 (7.9%), respectively. Antibody reactive to D immitis was significantly more common ( P <0.001) in the serum of cats that were antigen positive after heat treatment (10/13; 76.9%) than serum from cats that remained antigen negative after heat treatment (22/163; 13.5%). Conclusions and relevance Heat pretreatment of feline samples increased antigen detection by commercial assays for D immitis and improved overall concordance of antigen and antibody test results in antigen-positive samples in this population. Although further work to investigate the specificity of D immitis antigen assays when using pre-treated samples is warranted, this approach may be useful in the diagnosis of heartworm infection in individual cats and may increase the accuracy of surveys based on antigen detection.

Background: Infection of cats with Dirofilaria immitis causes seroconversion on antibody tests and pulmonary pathology, often without subsequent development of adult heartworms. Consistent administration of topical 10% imidacloprid-1% moxidectin has been shown to result in sustained plasma levels of moxidectin in cats after three to five treatments, a pharmacokinetic behavior known as "steady state"., Methods: To evaluate the ability of moxidectin at "steady state" to protect cats from subsequent infection with D. immitis, cats (n = 10) were treated with the labeled dose of topical 10% imidacloprid-1% moxidectin for four monthly treatments. Each cat was inoculated with 25 third-stage larvae of D. immitis 7, 14, 21, and 28 days after the last treatment; non-treated cats (n = 9) were inoculated on the same days, serving as infection controls. Blood samples were collected from each cat from 1 month prior to treatment until 7 months after the final inoculation and tested for antibody to, and antigen and microfilaria of, D. immitis., Results: Measurement of serum levels of moxidectin confirmed steady state in treated cats. Cats treated with topical 10% imidacloprid-1% moxidectin prior to trickle inoculation of D. immitis L3 larvae throughout the 28 day post-treatment period remained negative on antibody and antigen tests throughout the study and did not develop gross or histologic lesions characteristic of heartworm infection. A majority of non-treated cats tested antibody positive by 3-4 months post infection (6/9) and, after heat treatment, tested antigen positive by 6-7 months post-infection (5/9). Histologic lesions characteristic of D. immitis infection, including intimal and medial thickening of the pulmonary artery, were present in every cat with D. immitis antibodies (6/6), although adult D. immitis were confirmed in only 5/6 antibody-positive cats at necropsy. Microfilariae were not detected at any time., Conclusions: Taken together, these data indicate that prior treatment with 10% imidacloprid-1% moxidectin protected cats from subsequent infection with D. immitis for 28 days, preventing both formation of a detectable antibody response and development of pulmonary lesions by either immature stages of D. immitis or young adult heartworms.

Objective: To determine associations between oral health status and seropositivity for FIV or FeLV in cats., Design: Cross-sectional survey., Animals: 5,179 cats., Procedures: Veterinarians at veterinary clinics and animal shelters completed online training on oral conditions in cats and then scored oral health status of cats with no known history of vaccination against FIV. Age, sex, and results of an ELISA for retroviruses were recorded. Results were analyzed by means of standard logistic regression with binary outcome., Results: Of 5,179 cats, 237 (4.6%) and 186 (3.6%) were seropositive for FIV and FeLV, respectively, and of these, 12 (0.2%) were seropositive for FIV and FeLV. Of all 5,179 cats, 1,073 (20.7%) had gingivitis, 576 (11.1%) had periodontitis, 203 (3.9%) had stomatitis, and 252 (4.9%) had other oral conditions (overall oral disease prevalence, 2,104/5,179 [40.6%]). Across all age categories, inflammatory oral disease was associated with a significantly higher risk of a positive test result for FIV, compared with the seropositivity risk associated with other oral diseases or no oral disease. Stomatitis was most highly associated with risk of FIV seropositivity. Cats with any oral inflammatory disease were more likely than orally healthy cats to have a positive test result for FeLV. Increasing age was associated with a higher prevalence of oral disease in retrovirus-seronegative cats., Conclusions and Clinical Relevance: Inflammatory oral disease was associated with an increased risk of seropositivity for retroviruses in naturally infected cats. Therefore, retroviral status of cats with oral inflammatory disease should be determined and appropriate management initiated.

Background: Diagnosis of Dirofilaria immitis infection in cats is complicated by the difficulty associated with reliable detection of antigen in feline blood and serum samples., Methods: To determine if antigen-antibody complex formation may interfere with detection of antigen in feline samples, we evaluated the performance of four different commercially available heartworm tests using serum samples from six cats experimentally infected with D. immitis and confirmed to harbor a low number of adult worms (mean = 2.0). Sera collected 168 (n = 6), 196 (n = 6), and 224 (n = 6) days post infection were tested both directly and following heat treatment., Results: Antigen was detected in serum samples from 0 or 1 of 6 infected cats using the assays according to manufacturer's directions, but after heat treatment of serum samples, as many as 5 of 6 cats had detectable antigen 6-8 months post infection. Antibodies to D. immitis were detected in all six infected cats by commercial in-clinic assay and at a reference laboratory., Conclusions: These results indicate that heat treatment of samples prior to testing can improve the sensitivity of antigen assays in feline patients, supporting more accurate diagnosis of this infection in cats. Surveys conducted by antigen testing without prior heat treatment of samples likely underestimate the true prevalence of infection in cats.

Rationale: This Report was developed by the Feline Vaccination Advisory Panel of the American Association of Feline Practitioners (AAFP) to provide practical recommendations to help clinicians select appropriate vaccination schedules for their feline patients based on risk assessment. The recommendations rely on published data as much as possible, as well as consensus of a multidisciplinary panel of experts in immunology, infectious disease, internal medicine and clinical practice.

Infection of Cytauxzoon felis in domestic cats produces a severe disease characterised by fever, lethargy, inappetence, anorexia, depression, dehydration, icterus and often death. Transmission of C. felis to cats is dependent on being fed upon by infected Amblyomma americanum (lone star ticks). The purpose of the present study was to determine if application of a 10 % imidacloprid/4.5 % flumethrin collar (Seresto®, Bayer) on cats prevents transmission of C. felis by repelling ticks. Twenty cats were randomised to either a treated (n = 10) or non-treated control group (n = 10) based on their susceptibility to ticks. Cats of high, medium and low tick susceptibility were represented in both groups. Treated cats were fitted with 10 % imidacloprid/4.5 % flumethrin collars on study day 0 and both groups were then infested with C. felis-infected A. americanum on study day 30. Tick thumb counts were performed at 24 and 48 hours post infestation. Transmission of C. felis was determined by examining blood of cats by DNA extraction followed by PCR amplification with piroplasm-specific primers. Ticks did not attach to any of the 10 % imidacloprid/4.5 % flumethrin- treated cats. However, ticks attached and fed on all the non-treated control cats. The geometric mean number of ticks attached to the non-treated control cats at 24 and 48 hours was 15.3 and 14.2, respectively. Cytauxzoon felis was transmitted to 9 of 10 (90 %) non-treated control cats; C. felis was not transmitted to any of the treated cats. Transmission of C. felis to the non-treated cats was first detected between 8 and 16 days post infestation. Our results indicate that application of the 10 % imidacloprid/4.5 % flumethrin collar to cats prevented ticks from attaching, feeding and transmitting C. felis.

Rickettsial agents, including those in the genera Anaplasma, Ehrlichia, Neorickettsia, and Rickettsia, are important and common vector-borne pathogens of dogs and cats. Disease induced by these organisms ranges from clinically inapparent to severe and potentially fatal. However, laboratory confirmation of a rickettsial etiology can be complicated by a number of factors, including the wide spectrum of disease induced by these organisms, an often low and widely fluctuating level of organism present in infected animals, cross-reactions on serologic and molecular assays, and the presence of co-infections. Correct diagnosis is most likely to be reached when multiple diagnostic strategies, including careful microscopic examination of stained blood films or tissues, both specific and broad serologic tests, and a suite of molecular detection assays, are used in concert. Accurate interpretation of diagnostic tests requires awareness of the likelihood for multiple agents, including novel organisms, to be responsible for the results seen in a given patient. This review provides an overview of current strategies used to diagnose rickettsial infections in dogs and cats., (© 2013 American Society for Veterinary Clinical Pathology.)

In the time since canine ehrlichiosis due to Ehrlichia canis was first described in 1935 and first recognized in the United States in 1962, many key advances have been made in our understanding of the diversity of the rickettsial organisms responsible for ehrlichiosis and anaplasmosis in dogs and, occasionally, cats, the vectors capable of transmitting these agents, and the role these organisms play as both important veterinary pathogens and zoonotic disease agents. Despite considerable progress in the field, much remains to be learned regarding mechanisms contributing to pathogenesis, effective treatment modalities, and prevention strategies that best protect pet health. This article highlights current understanding of the transmission, diagnosis, and management of ehrlichiosis and anaplasmosis in dogs and cats., (Copyright © 2010 Elsevier Inc. All rights reserved.)

Amblyomma americanum was confirmed as a competent vector in the transmission of Cytauxzoon felis to domestic cats. Infection with C. felis was produced and replicated in four domestic felines by the bite of A. americanum adults that were acquisition fed as nymphs on a domestic cat that survived cytauxzoonosis. Numerous attempts to transmit C. felis with Dermacentor variabilis at the same time were not successful. All cats upon which infected A. americanum were transmission fed exhibited disease typical of cytauxzoonosis, and the eitiologic agent's presence was confirmed. Clinical signs including fever, inappetence, depression, and lethargy were observed beginning 13 d postinfestation. Pale mucus membranes, splenomegaly, icterus, and dyspnea were also observed during the course of the disease. Rectal temperatures of the C. felis-infected principal cats fluctuated from high to subnormal before returning to the normal range. Clinical signs of cytauxzoonsis improved by 24 d postinfestation in all but one cat, with survivors remaining parasitemic and subclinically infected with C. felis. Unengorged A. americanum and D. variabilis were collected from wild habitats to determine the minimum infection rate of C. felis in ticks from an enzootic area. Infection of C. felis was found only in wild-collected A. americanum. The minimum infection rate of C. felis in A. americanum was 0.5% (one of 178) in males, 0.8% (three of 393) in nymphs, and 1.5% (three of 197) in females. We found no wild-collected D. variabilis infected with C. felis. Our results confirm that A. americanum is a primary vector of C. felis.

Cytauxzoon felis was transmitted to a domestic cat by Amblyomma americanum. The infection was produced by the bite of A. americanum adults that were acquisition fed as nymphs on a domestic cat that naturally survived infection of C. felis. Fever, inappetence, depression, and lethargy were first noted 11 days post-infestation (dpi). Pale mucus membranes, splenomegaly, icterus, and dyspnea were also observed during the course of the disease. The body temperature of the experimentally infected C. felis cat was subnormal from 16 dpi until 24 dpi when it returned to within normal limits. All clinical signs of cytauxzoonsis began to resolve by 23 dpi when the cat became subclinically infected with C. felis. The cat developed a marked, regenerative anemia beginning by 13 dpi and reached a nadir at 20 dpi before recovering. A moderate neutrophilia and marked lymphocytosis also developed between 18 and 26 dpi. Schizonts of C. felis were observed in spleen aspirates of the infected cat at 15 dpi. DNA of C. felis was amplified by real-time PCR starting 17 dpi and piroplasms of C. felis were first noted by light microscopy 18 dpi. Dermacentor variabilis, Ixodes scapularis, and Rhipicephalus sanguineus were also tested in a similar manner at the same time but did not transmit C. felis. Prior to the present study, only D. variabilis had been shown experimentally to transmit infection of C. felis. This is the first report of C. felis being transmitted by A. americanum. The transmission of C. felis infection from one domestic cat to another indicates that domestic cats subclinically infected with C. felis may be a reservoir of infection for naive domestic cats.