Efficacy of selamectin in the treatment of cheyletiellosis in pet rabbits

Cheyletiellosis is a very common parasitic skin disorder of pet rabbits typically associated with pruritus and scaling. In this study, a total 23 rabbits with cheyletiellosis were treated with a single topical application of selamectin at a dose of 12 mg kg(-1). All rabbits were examined at 3 and 5 weeks after treatment. Five weeks after selamectin application, the scaling and pruritus had resolved in all 23 rabbits, and microscopic examination of epidermal debris collected by acetate tape and flea combing was all negative for mites and eggs. No side-effects were observed in any of the rabbits. This indicates that selamectin is an effective treatment for cheyletiellosis in rabbits.     

Efficacy of selamectin in the treatment of naturally acquired cheyletiellosis in cats

The purpose of this study was to evaluate the efficacy of a topical formulation of selamectin in the treatment of cheyletiellosis in cats. Fifteen adult domestic cats from the same household with naturally occurring Cheyletiella sp. infestation were enrolled in the study. On each cat, 45 mg of selamectin was applied on days 0, 30, and 60. No other treatment or environmental decontamination was performed during the trial. On days 0, 30, 60, and 120, all cats were examined, epidermal debris was collected over the dorsal area of the body with flea combs for microscopic examination, and fecal flotations were done. Clinical signs had subsided by day 60 in all 15 cats and no signs of recurrence were apparent on follow-up 1 year later. All epidermal and fecal samples were negative by day 60. No adverse reactions were observed. Under the conditions of our study, topical selamectin was a practical and well-tolerated means of treatment for cheyletiellosis in cats.     

Efficacy of a single dose of an otic ivermectin preparation or selamectin for the treatment of Otodectes cynotis infestation in naturally infected cats

Otodectes cynotis infestation is common in kittens housed in crowded environments like animal shelters. It is unknown how rapidly O cynotis is killed within the first 72h of treatment with currently available products. Kittens ≥4 weeks of age with live O cynotis in both ears (AU) were administered 0.5ml of 0.01% ivermectin otic suspension (Acarexx; Idexx Pharmaceuticals) once, AU or selamectin (Revolution; Pfizer Animal Health) once, on the skin following the manufacturer's instructions. Repeat microscopic examination was performed on individual ears based on a randomization schedule during the 72h after treatment. There was no evidence of toxicity with either drug and administration of 0.01% ivermectin significantly reduced the time to live mite-free status compared to selamectin. Both drugs have an effect against O cynotis as early as 10-12h after administration with an increasing effect over time.     

Observations on topical ivermectin in the treatment of otoacariosis, cheyletiellosis, and toxocariosis in cats

The purpose of this study was to observe the efficacy of a topical pour-on formulation of ivermectin in the treatment of otoacariosis, cheyletiellosis, and toxocariosis in cats. Forty-five cats were treated. All cats received 2 to 4 topical applications of ivermectin on the skin between the shoulder blades in a narrow strip, 14 days apart. This practical treatment was effective in 96% (23/24) of cases of feline otoacariosis and in 100% (20/20) of cats with toxocariosis. All cats with cheyletiellosis (16/16) received 4 treatments and had resolution of clinical signs, but one Cheyletiella egg could still be found 45 days after the last treatment. The viability of this egg could not be evaluated, but the cats were still free of clinical signs on follow-up 6 months later. The treatment was well tolerated in all the animals. A few cats developed a transient small alopecic area and mild scaling at the site of application of the drug.     

FC-44 The therapeutic effect of selamectin and ivermectin regimens in canine sarcoptic mange

Worldwide, sarcoptic mange in cats is seldom reported, and then only in sporadic individual cases. We describe an epidemic in a household with a dog and 25 cats. From September 2002, the dog was repeatedly treated with ivermectin for sarcoptic mange. The diagnosis was confirmed by skin scrapings. Fifteen months later, cats from the same household were diagnosed with severe sarcoptic mange. Twenty-one of the cats were euthanized and necropsies were performed. Skin samples were taken from all cats from different body sites for histology, and skin scrapings were examined for ectoparasites. Samples for bacterial and dermatophyte culture were taken from six cats. Smears for cytology were made from lesions on four cats with severe mange. Sera from 21 cats and the dog were analysed for specific antibodies to Sarcoptes scabiei . Molecular characterizations of six individual mites were done. Large numbers of S. scabiei were isolated from the infected skin of most of the cats. Two-thirds of the cats showed skin lesions compatible with chronic sarcoptic mange. Macroscopically, internal organs exhibited no obvious pathology. Yeast organisms and coccoid bacteria were found in the smears; penicillinase-negative Staphylococcus aureus was isolated from all samples and Malassezia pachydermatis was identified from four cats. Sarcoptes scabiei was seen histologically in all cats showing chronic skin lesions. No other ectoparasites were found. All analysed cats had specific antibodies against S. scabiei . Twenty-one cats tested negatively for FeLV and FIV. The mites had DNA sequences identical to S. scabiei from naturally infected dogs and Swedish wildlife.
Funding: Self-funded.     

Brain penetration of ivermectin and selamectin in mdr1a,b P-glycoprotein- and bcrp- deficient knockout mice

P-glycoprotein, which is encoded by the multi-drug resistance gene (MDR1), highly restricts the entry of ivermectin into the brain by an ATP-driven efflux mechanism at the blood–brain barrier. In dogs with a homozygous MDR1 mutation though, ivermectin accumulates in the brain and provokes severe signs of neurotoxicosis and even death. In contrast to ivermectin, selamectin is safer in the treatment of MDR1 mutant dogs, suggesting that selamectin is transported differently by P-glycoprotein across the blood–brain barrier. To test this, we applied selamectin to mdr1-deficient mdr1a,b ^−/− knockout mice and wild-type mice. Brain penetration, organ distribution, and plasma kinetics were analyzed after intravenous, oral, and dermal spot-on application in comparison with ivermectin. We found that in vivo both macrocyclic lactone compounds are substrates of P-glycoprotein and that these strongly accumulate in the brain of mdr1a,b ^−/− knockout mice compared with wild-type mice at therapeutic doses of 12 mg/kg selamectin and 0.2 mg/kg ivermectin. However, selamectin accumulates to a much lesser degree (5–10 times) than ivermectin (36–60 times) in the absence of P-glycoprotein. This could explain the broader margin of safety of selamectin in MDR1 mutant dogs. In liver, kidney, and testes, ivermectin and selamectin accumulated less than four times as much in mdr1a,b mutant mice as in wild-type mice. Breast cancer resistance protein (Bcrp)-deficient bcrp ^−/− knockout mice were also included in the application studies, but showed no differences in brain concentrations or organ distribution of either ivermectin or selamectin compared with wild-type mice. This indicates that Bcrp is not a relevant efflux carrier for these macrocyclic lactone compounds in vivo at the blood–brain barrier.     

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.     

Treatment with ivermectin of sarcoptic mange in pigs

Ivermectin injectable solution (1% w/v) was highly effective against Sarcoptes scabiei var suis when administered subcutaneously once to swine at 300 mcg/kg body weight. There were significantly (P < 0.05) fewer Sarcoptes mange mites counted on pigs treated with ivermectin than on untreated pigs at each count up to day 56 after treatment. The results indicate ivermectin should provide an efficient, practical means of control of sarcoptic mange in intensive piggeries.     

Sebaceous gland melanosis in dogs with endocrine skin disease or follicular dysplasia: a retrospective study

Abstract Skin biopsy specimens from 107 dogs with endocrine skin disorders were examined for the presence of melanin granules in the sebaceous glands or ducts (sebaceous gland melanosis). Nineteen of these cases (17.8%) had sebaceous gland melanosis. Skin biopsy specimens from 71 dogs with follicular dysplasia were similarly examined and 27 (38.0%) had sebaceous gland melanosis. Sebaceous gland melanosis alone cannot be used to differentiate histologically follicular dysplasia and endocrine skin disorders. Résumé— Des biopsies cutanées provenant de 107 chiens présentant des troubles cutanés associés à une dysendocrinie ont été examinées pour la rechereche de granules de mélanine dans les glandes sébacées ou dans leurs canaux (mélanose des glandes sébacées). Dix neuf de ces cas (17,8%) présentaient une mélanose des glandes sébacées. Des biopsies provenant de 71 chiens à dysplasic folliculaire ont été examinées de la même manière et 27 (38%) de ces cas présentaient également une mélanose des glandes sébacées. La mélanose des glandes sébacées seule ne peut être utilisée pour différencier histopathologiquement les dysplasies folliculaires des lésions cutanées associées à une dysendocrinie. [Bagladi, M.S., Scott, D.W., Miller, W.H. Sebaceous gland melanosis in dogs with endocrine skin disease or follicular dysplasia: A retrospective study (Mélanose des glandes sébacées chez des chiens présentant une dysendocrinic à expression cutanée et chez des chiens présentant une dysplasie folliculaire). Veterinary Dermatology 1996; 7 : 85–90.] Resumen Se examinó la presencia de gránules de melanina en las glándulas sebáceas (melanosis de glándulas sebáceas) en muestras de biopsia cutánea de 107 perros con desequilibrios endocrinos cutáneos. Diecinueve de estos casos (17.8%) mostraban melanosis de glándulas sebáceas. Las muestras de biopsia cutánea de 71 perros con displasia folicular se examinaron de forma similar y 27 (38.0%) mostraban melanosis de glándulas sebáccas. La melanosis de glándulas sebáceas en sí no puede utilizarse para diferenciar histológicamente entre la displasia folicular y los desequilibrios endocrinos. [Bagladi, M.S., Scott, D.W., Miller, W.H. Sebaceous gland melanosis in dogs with endocrine skin disease or follicular dysplasia: A retrospective study (Melanosis glandulas sebaceas en perros con enfermedad endocrina o dysplasia folicular: estudio retrospectivo). Veterinary Dermatology 1996; 7 : 85–90.] Zusammenfassung— Es wurden Hautbiopsien von 107 Hunden mit endokrinen Hauterkrankungen auf das Vorkommen von Melaningranula in den Talgdrüsen oder -ausführungsgängen (Talgdrüsenmelanose) untersucht. 19 dieser Fälle (17,8%) zeigten Talgdrüsenmelanose. Die Hautbiopsien von 71 Hunden mit follikulärer Dysplasie wurden auf ähnliche Weise untersucht, 27 davon (38,0%) wiesen ebenfalls Talgdrüsenmelanose auf. Talgdrüsenmelanose allein kann nicht dazu verwendet werden, um histologisch follikuläre Dysplasie und endokrine Hauterkrankungen zu unterscheiden. [Bagladi, M. S., Scott, D. W., Miller, W. H. Sebaceous gland melanosis in dogs with endocrine skin disease of follicular dysplasia: a retrospective study (Talgdrüsenmelanose bei Hunden mit endokrinen Hauterkrankungen oder follikulärer Dysplasie: eine retrospektive Studie). Veterinary Dermatology 1996; 7 : 85–90.]     

Treatment of inhibited Dictyocaulus viviparus in cattle with ivermectin

Fifteen calves, each infected with approximately 3000 third stage larvae, were used to compare the tendencies of two strains of Dictyocaulus viviparus to inhibit at the fifth larval stage and to evaluate the efficacy of ivermectin. There were notable differences between the strains. While greater than 99% of worms developing from infection with an Alpine strain remained inhibited 42 days after infection, only 0-26% of those recovered following infection with a U.K. laboratory strain were arrested. Neither adult nor immature D. viviparus were present in the lungs of animals treated with ivermectin subcutaneously at 200 micrograms/kg body weight 28 days after infection with the Alpine larvae.     

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.     

Reptile neoplasia: a retrospective study of case submissions to a specialty diagnostic service.

This retrospective study appears to be the largest publication to date regarding the prevalence of neoplasia in reptiles. As in previous publications, neoplasia is most common in snakes, followed by lizards, chelonians, and crocodilians. Several interesting trends were documented in this study, some of which appear to be previously unidentified, and some that support the findings of previous publications.     

Treatment of sarcoptic mange in canadian cattle with ivermectin

In 1982, approximately 13,000 Canadian cattle were treated once for sarcoptic mange with ivermectin at a dose of 10 mg per 45.4 kg of body weight. The results showed 100% efficacy against Sarcoptes scabiei and other ectoparasites present. All cattle showed marked improvement in general condition with new hair growth and apparent weight gains by 31 days posttreatment. Surveillance of treated herds for a year following treatment showed that one parenteral treatment with ivermectin eradicated the disease from closed herds.     

Rescue therapy with doxorubicin-based chemotherapy for relapsing or refractory feline lymphoma: a retrospective study of 23 cases

This study examined the efficacy of doxorubicin-based chemotherapy used for rescue therapy in refractory feline lymphoma. Records of 23 cats with lymphoma treated with chemotherapy who received doxorubicin for the first time in a rescue setting were reviewed. Seventeen (74%) of the 23 cats had only one treatment of doxorubicin. Five (22%) of the 23 cats had a positive response to doxorubicin and were given additional doses. The response to therapy in 4/5 of these responders could be assessed objectively, of which, two cats (9%) achieved partial remission (PR) and two cats (9%) achieved complete remission (CR). The two cats that achieved CR had differing response durations (6 weeks and greater than 47 months). Three of these five (60%) responders had also received concurrent other chemotherapy in addition to doxorubicin. Cell type and the use of concurrent chemotherapy were significant predictors of response. Cats with small-medium cell lymphomas (P=0.001) and cats that received concurrent chemotherapy with doxorubicin rescue (P=0.007) were more likely to respond favorably. This study suggests that doxorubicin-based chemotherapy is not an effective rescue protocol for feline lymphoma.