Efficacy of dinotefuran-pyriproxyfen, dinotefuran-pyriproxyfen-permethrin and fipronil-(S)-methoprene topical spot-on formulations to control flea populations in naturally infested pets and private residences in Tampa, FL

Thirteen cats and 7 dogs living in 14 homes were treated topically with either a dinotefuran (22%, w/w)/pyriproxyfen (3.00%, w/w) (DP) or dinotefuran (4.95%, w/w)/pyriproxyfen (0.44%, w/w)/permethrin (36.08%, w/w) (DPP) topical spot-on, respectively. Twenty cats and 7 dogs living in 16 homes were treated topically with either a fipronil (9.8%, w/w)/(S)-methoprene (11.8%, w/w) or fipronil (9.8%, w/w)/(S)-methoprene (8.8%, w/w) topical spot-on (FM), respectively. All products were applied according to label directions by study investigators on day 0 and again between days 28 and 30. Flea populations on pets were assessed using visual area counts and premise flea infestations were assessed using intermittent-light flea traps on days 0, 7, 14, 21, 28-30, 40-45, and 54-60. A single application of the DP-DPP and FM formations reduced flea populations by 87.35% and 88.44%, respectively within 7 days. Following two monthly applications of either the DP-DPP or FM formulations, pet flea burdens were reduced by 95.24% and 95.47%, respectively. Flea numbers in the indoor-premises were also markedly reduced by days 54-60, with 98.05% and 96.15% reductions in intermittent-light flea trap counts in the DP-DPP or FM treatment groups, respectively.     

Accurate diagnosis of Giardia spp and proper fecal examination procedures

A series of investigations evaluated the ability of different testing methods - a swing-head centrifugation technique using two flotation solutions (1.18-specific gravity zinc sulfate and 1.27-specific gravity Sheather's sugar solution), a passive commercial flotation technique, and the SNAP Giardia Test Kit from IDEXX Laboratories - to identify Giardia-positive dogs and recover the eggs of other intestinal parasites. It was determined that the SNAP Giardia test can improve a practice's ability to identify Giardia-infected dogs. Because of its higher specific gravity, the sugar solution was better for recovering heavy parasite eggs, such as Taenia spp, and thus is the flotation solution of choice when conducting routine centrifugation fecal examinations.     

Assessment of owner-administered monthly treatments with oral spinosad or topical spot-on fipronil/(S)-methoprene in controlling fleas and associated pruritus in dogs

Monitoring of the performance of flea control products under conditions of natural challenge is valuable in assessing continued effectiveness and determining the ongoing relevance of laboratory studies. A multi-clinic, investigator-blinded study was undertaken in client-owned dogs to investigate and compare the flea control provided by 3 consecutive monthly treatments of oral spinosad (SPN) or fipronil/(S)-methoprene topical (FSM) spot-on. The first household dog meeting enrollment criteria and with at least 10 fleas (whole-body flea count) served as the index dog in a household against which primary objectives were set. Stratification was based on pruritus scores at the enrollment visit and on single or multiple pet household. Index pets were randomized to treatment with either SPN or FSM, dispensed on day 0 for at-home administration by owners. All other household dogs and cats, maximum 4 pets per household, were dispensed the same treatment as the index dog (spinetoram was dispensed for cats in SPN households). Subsequent treatments were dispensed when index dogs were returned for whole-body flea counts and pruritus-scoring at visits on days 30 and 60, with final assessments on day 90 (±5 days on each occasion). Primary endpoints were the number of flea-free index dogs in each group one month after the final treatment, the reduction in owner-reported pruritus, and the reduction from baseline mean flea counts. One hundred twenty eight index dogs were enrolled (65 in the SPN arm; 63 in the FSM arm) at 10 clinics in FL (6), NC (2), LA (1), and TX (1). On day 0, geometric mean flea counts were 57.7 (range: 10–1469) and 44.8 (10–717) for the SPN and FSM groups, respectively. On Day 90, 55 of 58 (95%) and 21 of 55 (38%) index dogs completing the study were flea-free in SPN and FSM groups, respectively; mean SPN pruritus scores declined to 0.92 (6.67 on day 0), and to 3.83 (6.33 on day 0) for FSM; geometric mean flea counts (% control) were 0.08 (99.9%) and 5.19 (88.4%), for SPN and FSM groups, respectively. Between-treatment differences were highly statistically significant (p < 0.0001). In conclusion, SPN provided reliable flea control in client-owned dogs, regardless of challenge level.     

The immunopathogenesis of flea allergy dermatitis in dogs, an experimental study

In this study, we investigated the development of clinical disease and immune responses in the development of an experimental model of flea allergy dermatitis. Dogs were randomly divided into four treatment groups and were infested with fleas on two different feeding schedules (continuous and episodic). Group 1 consisted of four non-exposed dogs (negative controls) and Group 2 consisted of six dogs exposed to fleas continually. Groups 3 and 4 consisted of 14 dogs each that were exposed to fleas on an episodic schedule (two consecutive days every other week for 12 weeks). Group 4 also received intraperitoneal injections of a low dose of lectin (ricin) with immunomodulatory properties. The purpose of Group 4 was to investigate the effects of ricin on enhancing the development of clinical signs, flea antigen-specific IgE levels and altering the number of CD4+ and CD8+ T cell subsets in peripheral blood. Clinical signs developed in all flea exposed dogs, however, the dermatology lesion scores were less and shorter in duration for continuously exposed dogs compared to episodic exposed dogs, independent of ricin treatment. Lesion development was concentrated in the flea triangle and consisted principally of erythema, followed by alopecia, excoriation, papules, and crusts. CD4+ and CD8+ lymphocyte subsets or IgE levels were not altered by ricin treatment. Flea antigen-specific IgE values were highest in dogs exposed to fleas on a continuous basis compared to those episodically exposed. A greater percentage of clinical responder dogs with negative flea-specific IgE titers or negative intradermal test (IDT) were present in the episodic exposure groups than in the continuous exposure group. IgE titers corresponded slightly better with clinical responders than the IDT. The agreement between the IgE titers and IDT was good (weighted K = 0.67). Histopathology of skin samples were consistent with a Type I hypersensitivity. In conclusion, we were able to develop a model of flea allergy dermatitis by experimentally exposing dogs to fleas on an episodic and continuous feeding schedule. In this study, continuously exposed dogs did not develop immunotolerance, and ricin did not enhance the development of FAD.     

Host association, on-host longevity and egg production of Ctenocephalides felis felis

Host association, on-host longevity and egg production of Ctenocephalides felis felis (Bouché) were evaluated using fleas from a commercial laboratory colony and first generation, laboratory-reared, native Indiana fleas. Fleas were placed on cats that were declawed, fitted with Elizabethan collars and housed in specially designed metabolic cages. An average of 85% of the female and 58% of the male fleas stayed continuously on the cats for at least 50 days, indicating that the cat flea is a permanent ectoparasite. The maximum longevity of the cat flea was not determined, but it was shown that it can survive and reproduce on the cat for at least 113 days. A female cat flea may produce up to 1745 eggs during a 50-day period.