Efficacy of afoxolaner (NexGard®) on the treatment of myiasis caused by the New World screwworm fly Cochliomyia hominivorax (Diptera: Calliphoridae) in naturally infested dogs.

New World screwworm (NWS) myiasis is an infestation by Cochliomyia hominivorax larvae that consume the living tissue of warm-blooded animals, including humans. Domestic dogs are among the potential hosts of these flies that lay their eggs on the edges of wounds. NWS myiasis cases can be fatal if untreated. Treatment with parasiticides must be fast-acting, long-lasting and show 100% efficacy, since open wounds can be reinfested. Afoxolaner is a molecule from the isoxazoline family with proven ectoparasiticide action against fleas, ticks and mites in dogs. Fourteen healthy client-owned dogs, naturally infested by C. hominivorax larvae, were treated with afoxolaner (NexGard®) as per label recommendations, providing at least the minimum dosage of 2.5 mg/kg. Maggot infestations were classified as light (fewer than 10 larvae), mild (from 10 to 20 larvae) or severe (more than 20 larvae), according to the number of larvae found in the wound and/or collected from the ground after treatment. Twenty-four hours post-treatment, infested lesions were carefully inspected and collected larvae were counted and classified as live or dead. All maggots were identified as second and third instar larvae of C. hominivorax and were found dead within 24 h after treatment, demonstrating 100% larvicidal efficacy against C. hominivorax.

Assessment of the insecticidal activity of oral afoxolaner against Phlebotomus perniciosus in dogs.

Twelve healthy dogs were included in this laboratory efficacy study. Six dogs were randomly allocated based on body weight to an untreated control group and six to an afoxolaner (NexGard®) treated group. In the treatment group, afoxolaner was administered orally on Day 0 in accordance with label instructions. On Days 1, 14 and 28, each dog was exposed to 60 unfed female and 10 male Phlebotomus perniciosus sandflies for 1 h. At the end of each exposure period, sandflies were counted and assessed for viability and feeding status. There was no statistical difference in mortality (0.0-5.4%), nor in feeding proportion (61.6-78%) between the control and the treated groups at all 1-h post-exposure assessments. After collection, live fed and unfed sandflies were kept for viability assessments at 48 and 72 h post-exposure. In the untreated control group, the average percentages of live, fed, female sandflies after exposure, on Days 1, 14 and 28, ranged from 51% to 74% at 48 h and from 46% to 57% at 72 h, demonstrating model robustness over the 28 days of the study. Significantly fewer live fed sandflies were recorded for the afoxolaner treated group (p < 0.01). The insecticidal efficacy was 100%, 95.9% and 75.2% at 48 h post Days 1, 14 and 28 exposures, respectively, and 100%, 100% and 86.3% at 72 h post Days 1, 14, and 28 exposures, respectively. A single administration of oral afoxolaner (NexGard®) to dogs significantly killed P. perniciosus sandflies 48 and 72 h after blood feeding for 1 month.

TITLE: Évaluation de l'activité insecticide de l'afoxolaner par voie orale contre Phlebotomus perniciosus chez le chien. ABSTRACT: Douze chiens en bonne santé ont été inclus dans cette étude d'efficacité en laboratoire. Six chiens ont été répartis au hasard en fonction de leur poids corporel dans un groupe témoin non traité et six dans un groupe traité par afoxolaner (NexGard®), administré par voie orale le jour 0 conformément aux instructions de l'étiquette. Les jours 1, 14 et 28, chaque chien a été exposé à 60 femelles à jeun et 10 mâles de Phlebotomus perniciosus pendant une heure. À la fin de chaque période d'exposition, les phlébotomes ont été évalués en termes de viabilité et de statut alimentaire. Il n'y avait pas de différence statistique dans la mortalité (0,0 à 5,4 %), ni dans le taux d'engorgement (61,6 à 78 %) entre le groupe témoin et le groupe traité lors de toutes les évaluations après une heure. Après la collecte, les phlébotomes vivants gorgés et non gorgés ont été conservés aux fins d'évaluation de la viabilité 48 et 72 heures après l'exposition. Dans le groupe témoin non traité, le pourcentage moyen de phlébotomes femelles gorgées et vivantes après l'exposition aux jours 1, 14 et 28 variait de 51 à 74 % à 48 heures et de 46 à 57 % à 72 heures, démontrant la robustesse du modèle au cours des 28 jours de l'étude. Un nombre significativement moins important de phlébotomes gorgés vivants ont été enregistrés dans le groupe traité par afoxolaner (p < 0,01). L'efficacité insecticide était de 100 %, 95,9 % et 75,2 % 48 heures après les expositions des jours 1, 14 et 28, respectivement, et 100 %, 100 % et 86,3 % à 72 heures après les expositions des jours 1, 14 et 28, respectivement. Une seule administration d'afoxolaner (NexGard®) par voie orale à un chien tue de manière significative les phlébotomes P. perniciosus 48 heures et 72 heures après la prise de sang pendant un mois.

Infectious Disease Does Not Impact the Lying and Grooming Behaviour of Post-Parturient Dairy Cows.

Behaviour is commonly used to detect sickness in animals, but the impact of sickness on lying and maternal behaviours around parturition is not well understood. The objective was to assess the effects of sickness on the lying and grooming behaviours of dairy cows in the first 24 h after giving birth. Cows were categorized as 'sick' (n = 8) if they had at least one rectal temperature ≥39.1 °C and one clinical sign of illness (mastitis, pneumonia or an unknown infection) within 24 h of calving. These cows were match-paired for parity with cows that had no rectal temperature ≥39.1 °C and no clinical signs of illness up to 3 d after calving (n = 8; 'not sick'). The duration and latency of cow behaviours (standing, lying, lying bouts, lying close to calf, and grooming of the calf) and calf behaviours (standing and lying) were recorded for 24 h post-partum. We found no differences in the behaviour of sick and not sick cows and their calves post-calving, except that sick cows took longer to lie down near their calf after calving compared to those without illness. Cows may be more motivated to groom and spend time with their calf than to express sickness behaviours immediately after giving birth.