Effects of subcutaneous injections of a long acting moxidectin formulation in grazing beef cattle on parasite fecal egg reduction and animal weight gain.

Trials were conducted in Arkansas, Idaho, Illinois and Wisconsin using a common protocol to evaluate effectiveness and safety of a long acting (LA), oil-based injectable formulation of moxidectin in beef cattle grazing spring and/or summer pastures. At each site, 150 cattle (steers and/or heifers) were blocked based on pretreatment fecal strongyle egg counts (EPG) and then randomly assigned to treatments within blocks. Presence of naturally acquired parasitic infections, confirmed by presence of parasite eggs in feces, was a prerequisite for study enrollment. Within each block of three animals, two received moxidectin LA injectable on day 0 at a dosing rate of 1.0 mg moxidectin/kg b.w. into the dorsal aspect of the proximal third of the ear, and one received a placebo control treatment. Cattle were weighed before treatment and on day 55 or 56 (55/56) after treatment. Fecal samples were also collected from 10 randomly selected blocks of animals at each site on days 14, 28 and 55/56 for EPG quantification. Average daily gain (ADG) was computed over the posttreatment period. Data pertaining to ADG and EPG were combined across sites and analyzed by mixed model analysis of variance to assess the fixed effect of treatment and random effects of site, block within site and the treatment by site interaction. Compared to placebo-treated controls, the geometric means of fecal EPG counts from cattle treated with moxidectin LA injectable were reduced 99.8% 14 days after treatment, 99.1% 28 days after treatment and 96.7% 55/56 days after treatment. Rate of weight gain by cattle treated with moxidectin LA injectable was 0.59 kg/day, or 23% (0.11 kg/day) more than placebo-treated controls (P<0.05). None of the cattle treated with moxidectin LA injectable exhibited signs of macrocyclic lactone toxicosis. Summarized across all study sites, proportions of cattle that received concurrent therapeutic treatments were similar among treatment groups. Study results demonstrate that moxidectin cattle LA injectable administered at a dosing rate of 1.0 mg moxidectin/kg b.w. to grazing beef cattle was effective and safe.

Activity of an injectable, sustained-release formulation of moxidectin administered prophylactically to mixed-breed dogs to prevent infection with Dirofilaria immitis.

OBJECTIVE: To test the ability of a single injection of a sustained-release formulation of moxidectin (moxidectin SR) to protect dogs against heartworm infection for 180 days after inoculation with infective third-stage larvae (L3) of Dirofilaria immitis. ANIMALS: 32 adult mixed-breed dogs. PROCEDURE: Dogs were allocated to 4 groups on the basis of weight and sex. Dogs were injected SC with saline (0.9% NaCl) solution or moxidectin SR at the rate of 0.06, 0.17, or 0.5 mg/kg of body weight (day 0). Each dog was inoculated SC with 50 D immitis L3 180 days later. On days 330 and 331, dogs were euthanatized. The heart, lungs, and thoracic cavity were examined, and number and sex of heartworms were determined. RESULTS: A mean of 35.9 heartworms was recovered from untreated control dogs. Fourteen worms were recovered from 1 of 8 dogs given moxidectin SR at the lowest dosage, and none of the dogs in the 2 highest moxidectin treatment groups were infected. Small barely palpable granulomas were detected at injection sites of moxidectin-treated dogs. Frequency and size of granulomas were positively correlated with dose of moxidectin administered. CONCLUSIONS AND CLINICAL RELEVANCE: A single dose of moxidectin SR at a dosage as low as 0.17 mg/kg can safely and reliably confer complete protection against infection after challenge-exposure with D. immitis L3, and protection lasts for at least 180 days. This mode of prophylactic treatment against infection with heartworms effectively eliminates failure of prophylaxis that results from erratic administration of medications designed for monthly administration.

Efficacy of chlorfenapyr (AC 303630) experimental pour-on and CyLence formulations against naturally acquired louse infestations on cattle in New York.

The four chlorfenapyr formulations examined provided 100% control of both the nymphal and adult stages of naturally acquired Bovicola bovis (L.) on cattle up to 35 days after application. Treatment with 6mg chlorfenapyr per kg BW in a 0.12ml per kg BW formulation was as effective as treatment with CyLence (cyfluthrin) in controlling naturally acquired Solenopotes capillatus (Enderlein) on cattle for 35 days. Percent reduction was never greater than 90% with any chlorfenapyr application against Linognathus vituli (L.). However, percent reduction was greater than 90% with CyLence from day 21 through 35. No adverse effects were noted on cattle from any of the chlorfenapyr dosages used.

Efficacy of nemadectin, a new broad-spectrum endectocide, against natural infections of canine gastrointestinal helminths.

Nemadectin, a new broad-spectrum endectocide, was highly efficacious against natural infections of all the major canine gastrointestinal helminths. At single oral dosages of 0.2-0.4 mg kg-1 body weight (BW), a liquid formulation administered in gelatin capsules was 100% effective in eliminating natural infections of Toxocara canis, Toxascaris leonina, Ancylostoma caninum and Uncinaria stenocephala. Tablets (267 mg) containing 4.6% nemadectin given at a rate of 1/3 tablet per 20 kg BW (0.2 mg nemadectin kg-1) were 100% active against T. canis, A. caninum and U. stenocephala. With both formulations, an increase in the dose rate to 0.6-0.8 mg kg-1 BW resulted in 99-100% elimination of Trichuris vulpis infections. No adverse reactions were observed in any of the treated dogs.