Efficacy of milbemycin oxime in the treatment of canine generalized demodicosis: a retrospective study of 99 dogs (1995-2000)

Ninety-nine dogs diagnosed with generalized demodicosis were treated with milbemycin oxime. Cases diagnosed before two years of age were classified as juvenile-onset (53%) and those diagnosed after two years of age as adult-onset (47%). Dogs were considered cleared of mites when none could be demonstrated in scrapings and cured if no relapse was seen for 12 months. Eighty-five per cent (84/99) were cured with milbemycin oxime used for 1-6 months (mean 2.3 months) at a dosage of 0.5-1.6 mg kg-1 body weight (mean 0.75 mg kg-1). No significant difference in dosage or treatment time was seen between juvenile and adult cases. Chance of cure was significantly better in young animals (cured cases mean age 2.97 years) than in older animals (not cured cases mean age 8.02 years). Start of treatment early in the course of disease gave a significantly better chance of cure. Cases with severe pododemodicosis had less chance of a cure (9/11 not cured).     

Efficacy of 1.25% amitraz solution in the treatment of generalized demodicosis (eight cases) and sarcoptic mange (five cases) in dogs

Eight dogs with generalized demodicosis and five with sarcoptic mange were treated with 1.25% amitraz solution applied weekly and associated with an antidote treatment (atipamezol, 0.1 mg kg⁻¹ IM once: and yohimbine 0.1 mg kg⁻¹ once daily for 3 days, orally). Results of skin scrapings were used to determine whether therapy should be continued or stopped. The median number of treatments for demodicosis and sarcoptic mange was three (range 2–5) and two (range 1–3), respectively. Some side-effects were observed but all were stopped with antidote treatment; no failure or relapses occurred at 6–36 months after treatment.     

Mastitis caused by Mycobacterium kansasii infection in a dog

A 2‐year, 7‐month‐old female Chihuahua was admitted for a mammary mass measuring one cm in diameter. The dog had a history of demodicosis for 4 months and showed signs of pseudopregnancy at the time of the visit. Cytologic examination of an aspirate of the mass revealed a large number of macrophages containing nonstaining bacterial rods, which were acid‐fast in a Ziehl–Neelsen stain, suggesting mycobacterial infection. Histologic examination of the mass revealed a pyogranulomatous mastitis characterized by an infiltration with macrophages containing acid‐fast bacteria. Mycobacterium kansasii was subsequently cultured and identified by PCR. Surgical excision of the mass resulted in the growth of other dermal masses, but antimycobacterial treatment with rifampin and clarithromycin resolved these masses within 1 month. Three months after discontinuation of the treatment, similar organisms were found in aspirates of the enlarged bilateral inguinal lymph nodes by cytologic examination. Despite antimycobacterial treatment for another 4 months, there was no improvement and demodicosis also recurred. The dog eventually died of lymphoma 5 months after the relapse of mycobacterial infection. Although M kansasii is considered an important pathogen for pulmonary and cutaneous disease in people, there is only one report in a dog with an infection in a pleural effusion. As both adult‐onset demodicosis in dogs as well as mycobacterial infection in people have been associated with T‐lymphocyte deficiency, the M kansasii infection in this dog may have been associated with a condition of immune compromise.     

Comparison of acetate tape impression with squeezing versus skin scraping for the diagnosis of canine demodicosis

This study compared the sensitivity of acetate tape impression and skin squeezing with that of deep skin scraping for the diagnosis of demodicosis in dogs. Demodex canis was detected in 100% of acetate tape impressions obtained after skin squeezing and in 90% of deep skin scrapings. There was a significant difference (P < 0.001) between the techniques in the total number of mites detected. Acetate tape impression with skin squeezing was found to be more sensitive than deep skin scraping and is an alternative diagnostic method for canine demodicosis.     

Deep and superficial skin scrapings from a feline immunodeficiency virus-positive cat

An 8-year-old, neutered male, domestic shorthair cat housed at the North Carolina State University, College of Veterinary Medicine, Laboratory Animal Research facility as part of a research colony was examined because of mulifocal skin lesions. The lesions consisted of patchy alopecia with mild crusting of the periauricular region, neck, and dorsum; periauricular excoriations; marked dorsal seborrhea and scaling; and generalized erythematous papules. A moderate amount of ceruminous exudate was present in both ear canals. Results of testing for feline immunodeficiency virus (FIV) were positive. An ear swab specimen and superficial and deep skin scrapings were obtained, mounted with oil on glass slides, and coverslipped for microscopic examination. Two populations of mites were observed: a large population of slender, long (approximately 200 microm), adult mites with long, tapering abdomens that comprised two-thirds of the total body length; and a smaller population of more translucent and shorter mites (approximately 100 microm) with wide, blunt abdomens that had prominent transverse ridges. The interpretation was demodicosis, with Demodex cati and D gatoi co-infection. Histologic sections of biopsies from skin lesions on the neck, dorsum, and periauricular area contained a mild perivascular and perifollicular inflammatory infiltrate composed predominantly of histiocytes, lymphocytes, and plasma cells. Diffusely within the follicular lumina and occasionally within the superficial keratin, a myriad of Demodex organisms were observed. Intrafollicular mites were compatible in appearance with D cati whereas those in the corneal layer were suggestive of D gatoi. Demodicosis is an uncommon disease of cats, and rare cases of dual infection have been documented, occasionally in FIV-infected cats. The dual infection emphasizes the importance of doing both superficial and deep skin scrapings and of recognizing the unique microscopic features of different Demodex mites.     

Efficacy of daily oral ivermectin in the treatment of 10 cases of generalized demodicosis in adult dogs

Abstract The purpose of this study was to evaluate the efficacy of oral ivermectin at the dosage of 0.35 mg kg^-1 day^-1 for the treatment of generalized demodicosis in 10 adult dogs. Five of these 10 dogs had failed to respond to previous topical amitraz therapy. The mean time to obtain negative skin scrapings was 2.7 months and the mean duration of treatment was 4 months (range 2.5–8.5 months). Three patients (30%) were cured and they remained free of mites within 1 year follow-up. Two dogs (20%) were in remission for less than 6 months and five dogs (50%) relapsed. These five cases that relapsed were retreated with the above dosage of ivermectin and topical amitraz solution (1 mL Taktic/30 mL mineral oil) applied to site(s) of recurrence. One of these five cases that relapsed was in remission for more than 6 months, two dogs were in remission for less than 6 months and two dogs are still receiving treatment. Résumé— Le propos de cette étude est d'évaluer l'efficacieté de l'ivermectine par voie orale à un dosage de 0,35 mg/kg/jour dans le traitement de la démodécie généralisée chez 10 chiens adultes. Cinq de ces chiens n'avaient pas répondu à une thérapeutique topique préalable à l'amitraz. Le délai moyen pour obtenir la négativation des raclages cutanés est de 2,7 mois, et la durée moyenne de traitement est de 4 mois (extrême 2,5–8,5 mois). Trois patients (30%) ont été guéris et n'ont pas rechuté dans l'année qui a suivi le traitement. Deux des chiens (20%) ont été en rémission pendant moins de 6 mois et 5 chiens (50%) ont rechuté. Ces 5 chiens qui ont rechuté ont été retraités avec l'ivermectine à la même posologie associée à une thérapeutique topique à l'amitraz (1 ml de Taktic dans 30 ml d'huile minérale), appliquée aux sites de rechute. Un de ces 5 chiens fut en rémission pendant plus de 6 mois, 2 chiens pendant moins de 6 mois, enfin, les deux derniers reçoivent encore le traitement. [Fondati, A. Efficacy of daily oral ivermectin in the treatment of 10 cases of generalized demodicosis in adult dogs (Efficacité de l'ivermectine administrée oralement tous les jours dans le traitement de 10 cas de démodécie généralisée du chien adulte). Veterinary Dermatology 1996; 7 : 99–104.] Resumen El objetivo de este estudio fue evaluar la eficacia de la ivermectina oral con una dosis de 0.35 mg/Kg-dia para el tratamiento de la demodicosis generalizada en 10 perros adultos. Cinco de los 10 perros no habian respondido previamente a la terapia tópica con amitraz. El tiempo medio de obtención de raspados cutáneos negativos fue de 2.7 meses y la duratión media del tratamiento, de 4 meses (de 2.5 a 8.5 meses). Tres pacientes (30%) se curaron y permanecieron sin ácaros en un año de seguimiento. Dos perros (20%) estuvieron en remisión durante menos de 6 meses y en cinco (50%) se produjeron recaidas. Los animales que recayeron fueron tratados con la dosis de Ivermectina especificada arriba y solutión tópica de amitraz (1 mL Taktic/30 mL aceite mineral) aplicado a la(s) zona(s) de recidiva. Uno de los casos que recayó había estado en remisión durante 6 meses, dos perros estuvieron en remisión durante menos de 6 meses y dos estan aún bajo tratamiento. [Fondati, A. Efficacy of daily oral ivermectin in the treatment of 10 cases of generalized demodicosis in adult dogs (Eficacia de la Ivermectina oral en dosis diarias en el tratamiento de 10 casos de demodicosis generalizada en perros adultos). Veterinary Dermatology 1996; 7 : 99–104.] Zusammenfassung— Zweck dieser Studie war, die Wirksamkeit von oralem Ivermectin mit einer Dosierung von 0,35 mg/kg und Tag bei der Behandlung von generalisierter Demodikose bei 10 erwachsenen Hunden auszuwerten. 5 dieser 10 Hunden hatten auf eine vorausgegangene topische Amitraz-Therapie nicht angesprochen. Die Durchschnittszeit, um negative Hautgeschabsel zu erhalten, lag bei 2,7 Monaten, die Durchschnittsdauer der Behandlung bei 4 Monaten (mit einer Spannweite von 2,5 bis 8,5 Monaten). 3 Patienten (30%) wurden geheilt und blieben innerhalb des überwachungszeitraumes von 1 Jahr milbenfrei. Zwei Hunde (20%) waren in Remission für weniger als 6 Monate und 5 Hunde (50%) hatten ein Rezidiv. Diese fünf Rezidivfälle wurden mit der oben genannten Dosis Ivermectin und topischer Amitraz-Lösung (1 ml Taktic/30 ml Mineralöl) an den Stellen erneuter Veränderungen behandelt. Einer dieser fünf Rezidivfälle war in Remission für mehr als 6 Monate, zwei Hunde waren in Remission für weniger als 6 Monate und zwei Hunde sind immer noch unter Therapie. [Fondati, A. Efficacy of daily oral ivermectin in the treatment of 10 cases of generalized demodicosis in adult dogs (Wirksamkeit einer täglichen oralen Ivermectingabe bei der Behandlung von 10 Fällen von generalisierter Demodikose bei erwachsenen Hunden). Veterinary Dermatology 1996; 7 : 99–104.]     

Treatment protocols for demodicosis: an evidence-based review

Publications discussing the treatment of demodicosis in the dog and cat are reviewed. Based on the evidence in the literature, amitraz rinses at 0.025-0.06% every 7-14 days, and oral daily ivermectin at 300 micro g kg(-1), milbemycin at 2 mg kg(-1) and moxidectin at 400 micro g kg(-1), respectively, can all be recommended for the treatment of generalized canine demodicosis. Ivermectin and moxidectin should be initiated at lower doses and patients monitored for possible adverse effects during therapy. In cats, 2% lime sulfur dips and amitraz rinses at 0.0125-0.025% have been used successfully.     

Cutaneous xanthomas with concurrent demodicosis and dermatophytosis in a cat

Multiple cutaneous xanthomas, associated with fasting hyperlipidaemia, are described in a 9-month-old domestic long-haired cat. A severely pruritic, papular, and crusting dermatitis affecting the head and neck, initially diagnosed as lesions of the eosinophilic granuloma complex, progressively developed on the head and pinnae. Pruritus was controlled with administration of prednisolone and chlorambucil. Repeat histological examination confirmed the diagnosis of cutaneous xanthoma and concurrent mild demodicosis. Marked fasting hypercholesterolaemia, hypertriglyceridaemia and transient hyperglycaemia were subsequently confirmed. Treatment for hyperlipidaemia and xanthomas with a low-fat diet (Hill's Feline r/d) and the previously unreported treatment for feline demodicosis of daily oral milbemycin were commenced. Multiple pink, alopecic plaques and papules gradually regressed, however pruritus recurred if immunosuppressive treatment was reduced, and well-demarcated areas of alopecia developed on the head, limbs and trunk, despite negative skin scrapings for demodex mites. Fungal culture of hair samples yielded Microsporum canis. All cutaneous lesions resolved with the addition of griseofulvin to the treatment regimen. Concurrent corneal ulceration and keratoconjunctivitis sicca ultimately resolved with treatment, including topical cyclosporin. Diabetes mellitus developed 6 months after resolution of skin lesions. No cutaneous or ocular abnormalities were present 6 months later with continued low-fat diet and insulin administration, although transient recurrence of papules and pruritus occurred after inadvertent access to a fatty meal. An underlying primary hyperlipidaemia was suspected, causing pruritic xanthomas. This may represent the first report of concurrent cutaneous xanthomas, demodicosis and dermatophytosis in a cat.     

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.     

Evaluation of interleukin-2 production and interleukin-2 receptor expression in dogs with generalized demodicosis

Abstract The experimental hypothesis testéd was that dogs with generalized demodicosis have significantly lower levels of interleukin-2 (IL-2) production and IL-2 receptor expression as compared with normal dogs. The specific objective of this study was to compare the production of IL-2 and IL-2 receptor expression of peripheral blood mononuclear cells in normal dogs and dogs with generalized demodicosis. Ten dogs with juvenile-onset generalized demodicosis were evaluated. Dogs with generalized demodicosis had a significantly lower in vitro lymphocyte blastogenesis response (P < 0.006), fewer cells expressing IL-2 receptors (P < 0.03), and decreased IL-2 production (P < 0.01) than control dogs. Resumen La hipótesis experimental fue que los perros con demodicosis generalizada tienen niveles significativamente inferiores de producción y expresión de receptores de interleuquina-2 (IL-2) comparado con perros normales. El objetivo especifico de este estudio fue el de comparar le producción y expresión de receptores de IL-2 en células mononucleares de sangre periférica en perros normales y en perros con demodicosis generalizada. Se evaluaron diez perros con demodicosis generalizada iniciada en edad temprana. Los perros con demodicosis generalizada tenian in vitro una respuesta blastogénica linfocitaria inferior (P < 0.006), menos células con expresión de receptores de IL-2 (P < 0.03) y una disminución en la producción de IL-2 (p<0.01) respecto a los perros control. [Lemarie, S.L., Horohov, D.W. Evaluation of interleukin-2 production and interleukin-2 receptor expression in dogs with generalized demodicosis. (Evaluación de la producción y expresión de recepetores de interleuquina-2 en perros con demodicosis generalizada.) Veterinary Dermatology 1996; 7 : 213–219.] Résumé L'hypothèse expérimentale est que les chiens à démodécie généralisée présente une diminution significative du taux d'interleukine 2 (IL-2) et de l'expression des récepteurs de l'interleukine 2 comparativement à des chiens sains. L'objectif de cette étude est de comparer la production d'I12 et l'expression des récepteurs de l'IL-2 par des lymphocytes sanguins périphériques de chiens témoins et de chiens atteints de démodécie généralisée. Dix chiens avec une démodécie généralisée juvenile ont été testés. Les chiens à démodécie généralisée présentent une transformation lymphoblastique plus basse (p< 0.006), moins de cellules exprimant les récepteurs IL-2 (p<0.03) et une diminution de la production d'IL-2 (p<0.01) par rapport aux chiens témoins. [Lemarie, S.L., Horohov, D.W. Evaluation of interleukin-2 production and interleukin-2 receptor expression in dogs with generalized demodicosis. (Evaluation de la production d'interleukine 2 et de l'expression des récepteurs de l'interleukine 2 chez des chiens à démodécie généralisée.) Veterinary Dermatology 1996; 7 : 213–219.] Zusammenfassung Es wurde die experimentelle Hypothese getestét, daß Hunde mit generalisierter Demodikose über signifikant niedrigere Spiegel an Interieukin2-(IL-2)Produktion und IL-2-Rezeptorexpression verfügen im Vergleich zu gesunden Hunden. Der wesentilche Gegenstand dieser Untersuchung war, die Produktion von IL-2 und die IL-2Rezeptorexpression in den mononukleären Zellen des peripheren Blutes bei gesunden Hunden und solchen mit generalisierter Demodikose zu vergleichen. Zehn Hunde mit juvenilem Beginn von generalisierter Demodikose wurden untersucht. Hunde mit generalisierter Demodikose hatten eine signifikant niedrigere in vitro-Reaktion der Lymphozytenblasogenese (P < 0, 006), weniger Zellen, die IL-2Rezeptoren zeigten (P < 0,03) und eine verminderte IL-2Produktion (P < 0,01) als die Kontrollhunde. [Lemarie, S.L., Horohov, D.W. Evaluation of interleukin-2 production and interleukin-2 receptor expression in dogs with generalized demodicosis (Untersuchungen über die Interleukin2-Produktion und Interleukin2-Rezeptorexpression bei Hunden mit generalisierter Demodikose) Veterinary Dermatology 1996; 7 : 213–219.]