Treatment of equine onchocerciasis with ivermectin paste

SUMMARY A single oral dose of ivermectin paste was administered to 12 horses with dermatitis and clinical signs typical of onchocerciasis. Two of the horses also had lesions of Queensland itch. Microfilarias of Onchocerca cervicalis were identified in fresh, macerated, skin biopsies from the neck, brisket or umbilical regions of all horses and microfilarias of O. gutturosa from the neck of 2. Eight of the horses developed skin reactions 4 to 24 h after the administration of the ivermectin, notably weals over the neck, shoulders and flanks and pitting oedema of the ventral midline and intermandibular space. Regression of the onchocerciasis lesions was evident within 7 days of treatment and affected skin had returned to normal within 3 months. The lesions of Queensland itch were not affected by the ivermectin treatment. Microfilarias were present in biopsies of skin, particularly in the superficial dermis, before treatment, but were absent from all skin biopsies taken one week after treatment. In some horses transient skin sensitivity reactions developed. Microfilarias began to reappear in the biopsies of some of the horses 2 months after treatment. It is concluded that the oral paste formulation of ivermectin, although not effective against adult onchocerca, is useful for the therapeutic control of microfilarias in the skin lesions of equine onchocerciasis.     

Successful treatment of equine sarcoids by topical aciclovir application

Based on the anecdotally reported eradication of a sarcoid using aciclovir cream, the curative potential of this ointment was investigated in 22 sarcoid-affected horses referred to the Equine Clinic Tillysburg, Austria, between 2006 and 2009. Sarcoid disease was diagnosed by clinical examination and bovine papillomavirus types 1 and 2 from intact skin and tumour tissue. As nine horses had more than one lesion, a total of 47 sarcoids were treated by daily topical application of aciclovir 5 per cent cream for a period of two to six months; in four horses, surgical tumour ablation was performed before treatment. Disease parameters, including the tumour type, number, location and size, were recorded before and after aciclovir therapy. All 47 (100 per cent) of the sarcoids responded to treatment, with complete tumour regression observed for 32 (68 per cent) lesions and no recurrences reported thus far. Incomplete resolution was observed for 15 (32 per cent) lesions, probably due to their thickness. Aciclovir is proposed to be routinely used for the treatment of mild-type sarcoids and as an adjuvant therapeutic agent in combination with surgery.     

Epidemiological investigation of equine hindlimb ataxia with Setaria digitata in South Korea

BackgroundSince 2013, the number of requests for diagnosis for horses based on neurological symptoms has increased rapidly in South Korea. The affected horses have commonly exhibited symptoms of acute seasonal hindlimb ataxia. A previous study from 2015–2016 identified Setaria digitata as the causative agent.ObjectivesThis study is an epidemiological investigation to find out risk factors related to the rapid increase in hindlimb ataxia of horses due to aberrant parasites in South Korea.MethodsAn epidemiological investigation was conducted on 155 cohabiting horses in 41 horse ranches where the disease occurred. The surrounding environment was investigated at the disease-causing horse ranches (n = 41) and 20, randomly selected, non-infected ranches.ResultsHindlimb ataxia was confirmed in nine cohabiting horses; this was presumed to be caused by ectopic parasitism. Environments that mosquitoes inhabit, such as paddy fields within 2 km and less than 0.5 km from a river, had the greatest association with disease occurrence.ConclusionsMost horse ranches in South Korea are situated in favorable environments for mosquitoes. Moreover, the number of mosquitoes in the country has increased since 2013 due to climate change. Additional research is required; however, these data show that it is necessary to establish guidelines for the use of anthelmintic agents based on local factors in South Korea and disinfection of the environment to prevent disease outbreaks.     

Successful outcome in a case of equine multinodular pulmonary fibrosis (EMPF) treated with valacyclovir

Equine multinodular pulmonary fibrosis (EMPF) is a progressive fibrosing interstitial lung disease, which has been associated with γ‐herpesviruses. This report describes a 22‐year‐old Warmblood stallion diagnosed with EMPF on the basis of clinical examination, laboratory results, lung radiographs and ultrasound, lung biopsy and inclusion bodies found in macrophages of broncho‐alveolar lavage fluid (BALF) as well as an identification of EHV‐5 DNA by polymerase chain reaction (PCR). The horse recovered after one week of treatment with valacyclovir (40 mg/kg bwt per os q. 8 h) and is clinically healthy 2 years later. To our knowledge this is the first report describing treatment of EMPF with valacyclovir.     

Re-evaluation of ivermectin efficacy against equine gastrointestinal parasites.

Two trials were conducted to confirm the efficacy of ivermectin paste against endoparasites of horses. In these trials, 20 ponies were treated with ivermectin oral paste at 200 mcg x kg body weight once on Day 0, and 20 ponies served as unmedicated controls. The animals carried naturally acquired parasite infections as confirmed by pretrial fecal examination. The animals were necropsied for worm recovery on Days 14, 15 or 16. Parasites recovered were identified to species. Horses treated with ivermectin had significantly (P<0.05) fewer (>99.0% reduction) adult small strongyles (Coronocyclus spp including C. coronatus, C. labiatus, C. labratus; Cyathostomum spp including C. catinatum, C. pateratum; Cylicocyclus spp including C. ashworthi, C. elongatus, C. insigne, C. leptostomum, C. nassatus, C. radiatus; Cylicodontophorus bicoronatus; Cylicostephanus spp including C. asymetricus, C. bidentatus, C. calicatus, C. goldi, C. longibursatus, C. minutus; Gyalocephalus capitatus; Parapoteriostomum spp including P. euproctus, P. mettami; Petrovinema poculatum; Poteriostomum spp including P. imparidentatum, P. ratzii) and adult large strongyles (Strongylus edentatus, S. vulgaris; Triodontophorus spp including T. brevicauda, T. serratus; Craterostomum acuticaudatum) than the controls. Ivermectin was also highly effective (94% to >99%, P<0.05-0.01) against Gasterophilus intestinalis larvae, Habronema spp., Oxyuris equi, Parascaris equorum. The data from these two trials confirm that ivermectin paste administered to horses orally at 200mcg x kg(-1) continues to be highly effective for treatment and control of a broad range of small and large strongyle species as well as other species of gastrointestinal parasites.     

Treatment of stephanofilariosis ('earsore') with ivermectin.

Thirty-four adult male buffaloes with clinical signs of 'earsore' were used to determine the efficacy of ivermectin against Stephanofilaria zaheeri. On the basis of parasite counts in skin scrapings, ivermectin was effective as a microfilaricide. Adult parasite counts were reduced, but removal of adults was incomplete. Clinical improvement was recorded in more than half of the treated buffaloes, but constant reinfection meant that meaningful interpretations were not possible.     

Topical (pour-on) ivermectin in the treatment of canine scabies.

The efficacy of a pour-on formulation of ivermectin at 500 micrograms/kg body weight applied on the dorsum on days 1 and 15 was evaluated in 90 dogs from a shelter, naturally infested with Sarcoptes scabiei. This very practical form of treatment was successful in eradicating scabies from this shelter.     

Successful treatment of equine sarcoids with cisplatin electrochemotherapy: a retrospective study of 48 cases

Reasons for performing study: Sarcoids are the commonest form of equine skin tumour. Several therapeutic measures have been described but none is considered to be universally effective. Electrochemotherapy (ECT) is a new anticancer therapy that utilises electrical field pulses to induce increased cell membrane permeability to antitumour hydrophilic drugs, such as cisplatin. The increased intracellular concentration of the drugs has a significant therapeutic benefit. The procedure has not been previously reported in a large number of horses. Objective: To validate ECT as a novel alternative treatment for equine sarcoids. Methods: A retrospective study evaluating the efficacy of cisplatin ECT in the treatment of equine sarcoids was performed. Electrochemotherapy treatments were applied under general anaesthesia at 2 week intervals with or without prior excision or debulking. Electric pulses were directly applied to the lesions following intra‐tumoural injections of an aqueous solution of cisplatin. Results: One‐hundred‐and‐ninety‐four sarcoids on 34 horses, 2 ponies, 11 donkeys and one mule were treated with ECT. The 4 year nonrecurrence rate was 97.9% for animals (47/48) and 99.5% (193/194) for tumours. When ECT was used as a single treatment, a significant influence of tumour size (ρ= 0.55) on the number of treatments required for cure was shown. When prior surgery was performed, there was a significant influence (P<0.001) of the excision quality (complete or incomplete) and the healing mode (closed or open wound) on the number of treatments. The most common adverse effect was a slight oedematous reaction for lesions located on thin skin regions. Conclusion and clinical relevance: Results demonstrate that ECT, with or without concurrent tumour debulking, is an effective alternative for treatment of equine sarcoids.     

Prevalence of equine herpesvirus type 2 (EHV-2) DNA in ocular swabs and its cell tropism in equine conjunctiva

Equine herpes virus 2 (EHV-2), a gamma(2)-herpesvirus, is common in horses of all ages. Its role as a primary pathogen is unclear but there is an association between EHV-2, respiratory disease and keratoconjunctivitis. The purpose of this study was to gain more information on the prevalence of EHV-2 DNA in conjunctival swabs from horses with and without ocular disease and to define the anatomical site and cell type harbouring viral genome or antigen. By polymerase chain reaction (PCR) 22 out of 77 (28.6%) ocular swabs of clinically healthy and only 4 out of 48 (8.3%) samples from diseased horses were positive. To define the main virus reservoir ocular tissue from 13 randomly selected horses without pathological evidence of ocular disease were analysed by nested PCR. In two horses optic nerve, lacrimal gland and conjunctiva, in further two cases lacrimal gland and conjunctiva and in four horses the conjunctiva only were EHV-2 PCR positive. For specifying the target cell we focused on conjunctivae and selected 3 out of 15 clinically healthy slaughterhouse horses positive for EHV-2 by PCR. In situ hybridisation on sections of these paraffin embedded conjunctivae localized viral genome in histiocyte-like cells of the submucosa. Immunohistochemical staining with an EHV-2 or S100 specific polyclonal antiserum demonstrated that Langerhans cells were co-localized in the same region of the sample section where virus positive cells were detected. Furthermore, we concluded that detection of viral antigen revealed a productive virus infection.     

Field performance of the equine parasiticide ivermectin in an oral paste

Ivermectin, a derivative of one of the avermectin compounds, was administered at 200 mcg per kg of body weight in an oral paste formulation to 80 mixed-breed ponies of both sexes and various ages. Twenty similar ponies received oral paste vehicle. Anthelmintic activity was determined by comparing fecal egg counts taken before and 14 days after ivermectin treatment to the counts of fecal samples from vehicle-treated controls. Commonly used equine vaccines were administered at the time of treatment. Sixteen of the 20 vehicle-treated ponies had positive counts prior to treatment and 17 were positive 14 days after treatment; 66 of the 80 ivermectin-treated ponies had positive counts prior to treatment; all 80 ponies had zero counts 14 days after treatment. The eggs were identified as strongylid in all the positive ponies while three ponies also hadOxyuris equi eggs prior to treatment.No adverse reactions were attributable to ivermectin oral paste treatment or concurrent vaccine administration.     

Ceratohyoidectomy for treatment of equine temporohyoid osteoarthopathy (15 cases)

This study investigated 15 horses diagnosed with temporohyoid osteoarthopathy (THO) and treated by ceratohyoidectomy between 2004 and 2012. The presenting complaint, duration and nature of the clinical signs, additional diagnostic procedures, and complications were reviewed retrospectively. Long-term follow-up on horses was used to determine prognosis. All horses were diagnosed by guttural pouch endoscopy. Follow-up was available for 14 horses that survived to discharge. Eight of 10 horses that were used athletically prior to surgery returned to previous levels of use. Persisting clinical signs included mild facial nerve paralysis (3/14; 21.4%) or head tilt (6/14; 42.8%) but these were not functionally limiting. It was concluded that equine THO affects a wide range of breeds, disciplines, and ages of horses, and has a variety of presenting clinical signs most commonly associated with vestibular and facial nerves. Prognosis following ceratohyoidectomy is good for resolution of ataxia but some cranial nerve deficits may persist.     

Topical (pour-on) ivermectin in the treatment of chronic generalized demodicosis in dogs

Twelve privately owned dogs with chronic generalized demodicosis were treated topically along the dorsal midline with 1.5 mg kg⁻¹ of 0.5% pour-on ivermectin for cattle three times per week for 3–6 months. All 12 dogs had a substantial reduction in clinical signs and in the number of Demodex canis mites found on skin scrapings. Only two dogs, however, became skin-scrapings negative after 3 and 5 months of treatment, respectively. In these two dogs treatment was prolonged for an additional 4 weeks past the negative scrapings. One dog relapsed 2 months after cessation of therapy; the other is still free of symptoms 1.5 years later. The cure rate, based on the lack of recurrence of clinical signs for 12 months after discontinuation of ivermectin administration, was 1 of 12 dogs (8%). Adverse reactions were not seen.