An open study to evaluate topical treatment of equine chorioptic mange with shampooing and lime sulphur solution

Alleviating lesions of chronic progressive lymphedema in Belgian draft horses by successfully treating Chorioptes bovis infestation with moxidectin 0.5% pour-on

The aim of this prospective, randomized, single-blinded, and placebo-controlled clinical trial was to investigate the efficacy of a moxidectin pour-on solution for the treatment of Chorioptes bovis infestation in Belgian draft horses, and in addition, to evaluate the effect of this treatment on the clinical signs and lesions associated with chronic progressive lymphedema (CPL). Nineteen privately owned Belgian draft horses were randomly assigned to either a treatment group (moxidectin pour-on formulation, n = 10) or a placebo group (phosphate-buffered saline (PBS), n = 9). On Day 0, all 19 horses tested positive for the presence of C. bovis in superficial skin scrapings. Prior to treatment, all feathering on the distal limbs of the horses was clipped. Treatment was applied twice (Day 0 and 7). Pour-on moxidectin (Cydectin 0.5% Pour-On; Zoetis) was evenly distributed over the distal legs of the horses at a dose of 1.5 mg moxidectin/kg body weight. Animals in the placebo group were treated with PBS. Pretreatment and follow-up examinations consisted of counting living mites in superficial skin scrapings, scoring pruritus, and scoring mange-associated and CPL-associated lesions (skinfold score and skin lesion score). Horses in the placebo group and moxidectin group were followed up to 8 weeks and 24 weeks after the first treatment, respectively. On Day 14, no living mites were found in any of the horses in the moxidectin group (p = 0.013). These horses continued to remain free of mites, until the final sampling conducted at 24 weeks following the initial application of moxidectin, when three horses again showed living mites in skin scrapings. Treatment with moxidectin resulted in a significant reduction of both CPL-associated skin lesion scores (p = 0.003) and pruritus scores (p = 0.001) after only seven days. By Day 56, still no signs of pruritus (p < 0.0001) were detected, with significant improvement of mange-associated lesions (p < 0.0001). Although the skinfold score did not show a significant reduction by Day 56, the score for skin lesions associated with CPL had significantly improved (p < 0.0001). In conclusion, the results of this study demonstrate that pour-on moxidectin, at a high dose and applied directly to the mite predilection site, was an effective treatment for C. bovis infestation in feathered draft horses, providing positive effects on CPL lesions, pruritus and mange-associated lesions. Furthermore, these findings emphasize the therapeutic significance of addressing mange in the management of CPL-affected draft horses.

Chronic Progressive Lymphedema in Belgian Draft Horses: Understanding and Managing a Challenging Disease

Chronic progressive lymphedema (CPL) in draft horses is characterized by increased dermal thickness and fibrosis, with the development of skinfolds and nodules, hyperkeratosis, and ulcerations on the distal limbs of affected horses. Secondary bacterial, fungal, or parasitic infections frequently complicate and aggravate the lesions, as well as the progression of this disease. CPL has a particularly high prevalence of up to 85.86% in the Belgian draft horse breed. Due to the disease's progressive and incurable nature, affected horses are often euthanized prematurely. The treatment options are solely symptomatic, aimed at improving the horse's quality of life. Despite the severity of this condition, many uncertainties about its etiology and pathogenesis still remain to date. The established scientific research on CPL is rather limited, although there is an urgent need for strategies to tackle this disease. This review summarizes the available knowledge, serving as a guideline for practitioners, and provides perspectives for future research programs.

Approach to the pruritic horse

Pruritus in the horse may be due to several causes, the most common being a hypersensitivity response to salivary proteins in the Culicoides genera, which may coexist with atopic dermatitis, also known as an environmental allergy to pollens, molds, dust, storage mites, etc. Less common etiologies are food allergy and contact allergy, the latter often caused by owners applying various products to the skin. Other ectoparasites, such as Chorioptes mites, may also initiate pruritus. Secondary bacterial infections (usually Staphylococcus spp) may be pruritic in and of themselves. This article reviews the questions that need to be asked of owners to obtain a relevant history, always important for any organ system, but perhaps none more so than the skin. The various clinical findings such as alopecia and crusts and their location on the horse, diagnostic methods such as intradermal or serum testing for allergies, and subsequent hyposensitization are also discussed. Therapeutic options currently available for the potential underlying diseases, in particular for the hypersensitivity reactions to Culicoides spp or environmental allergens, are reviewed with the studies of hyposensitization over the last 40 years, as well as medications that may be effective. While the most common causes of pruritus in the horse are known, the current understanding of the pathophysiology still needs to be investigated, and consequently, the most effective treatments for those causes need to be improved. Newer research is discussed that may eventually add to the diagnostic and therapeutic options currently available for the pruritic horse.

A review on the treatment and control of ectoparasite infestations in equids

Ectoparasites infestations are a growing concern to horse owners and equine veterinarians alike. Ectoparasites cause significant health and welfare issues and can potentially can serve as vectors for a variety of pathogens. The prevalence of ectoparasites increases around the world, and especially in horses information on the successful prevention and treatment of ectoparasite infestations in scarce and in many instances anecdotal. This poses a challenge to the equine veterinarian and off-label use of drugs can lead to detrimental effects in horses. In this review we describe the current available evidence for the prevention and treatment of ectoparasite infestations in horses. Only a very limited number of products is approved for the use in horses and fortunately many of the other products that are used in an off-label manner appear to be safe in horses. Future research in this area should aim at providing PK/PD modelling data to assure appropriate and safe dose regimen to prevent and treat ectoparasite infestations in horses.

Immune responses to ectoparasites of horses, with a focus on insect bite hypersensitivity

Horses are affected by a wide variety of arthropod ectoparasites, ranging from lice which spend their entire life on the host, through ticks which feed over a period of days, to numerous biting insects that only transiently visit the host to feed. The presence of ectoparasites elicits a number of host responses including innate inflammatory responses, adaptive immune reactions and altered behaviour; all of which can reduce the severity of the parasite burden. All of these different responses are linked through immune mechanisms mediated by mast cells and IgE antibodies which have an important role in host resistance to ectoparasites, yet immune responses also cause severe pathological reactions. One of the best described examples of such pathological sequelae is insect bite hypersensitivity (IBH) of horses; an IgE-mediated type 1 hypersensitivity to the salivary proteins of Culicoides spp. associated with T-helper-2 production of IL4 and IL13. Importantly, all horses exposed to Culicoides have an expanded population of Culicoides antigen-specific T cells with this pattern of cytokine production, but in those which remain healthy, the inflammatory reaction is tempered by the presence of FoxP3+ CD4+ regulatory T cells that express IL10 and TGF-beta, which suppresses the IL4 production by Culicoides antigen-activated T cells.