Demonstration of reaginic antibody (IgE) in canine demodectic mange: An immunofluorescent study

The presence of reaginic antibody (IgE) in dogs with demodectic mange was investigated in an attempt to determine the extent to which atopic sensitization to the mites (Demodex canis Leydig, 1859) and their products contribute to the pathogenesis of this disease. Canine reagin bound to mast cells in cutaneous biopsies taken from demodectic and specific-pathogen-free (SPF) dogs was demonstrated. The fluorescent antibody technique employed made use of the homology between antigenic determinants present within the Fc region of both human and canine IgE. The specificity of the immunofluorescent system was checked by accepted standards.The percentage of fluorescing mast cells of 20 demodectic and 16 SPF dogs was not significantly different (P > 0.05). The average intensity of mast cell fluorescence varied from one dog to another and was graded from I to IV. The number of mast cells with demonstrable IgE in demodectic dogs ranged from 2% with an average intensity of grade I to 87% with an average intensity of IV. Similarly, the SPF dogs had a range of 3% with an average intensity of grade I to 33% with an average intensity of III to IV. Since the number of mast cells in the dermis of dogs suffering from demodectic mange is greatly increased, there may in reality be a higher concentration of IgE in these animals.     

Field efficacy of moxidectin in dogs and rabbits naturally infested with Sarcoptes spp., Demodex spp. and Psoroptes spp. mites

The efficacy of moxidectin 1% injectable for cattle was evaluated in dogs and rabbits with naturally acquired sarcoptic, demodectic or psoroptic mites. Twenty-two dogs with generalised demodicosis were orally treated with 0.4mg/kg moxidectin daily. Forty-one dogs suffering from sarcoptic mange were treated with 0.2-0.25mg/kg moxidectin either orally or subcutaneously every week for three to six times. Seven rabbits were treated orally with 0.2mg/kg moxidectin twice 10 days apart. Of the 22 dogs with demodicosis, 14% were stopped treatment because of side effects, 14% were lost and of the remaining 72% all were cured (mean therapy duration 2.4 months). Thirty-seven of the sarcoptic mange-infected dogs finished treatment and were cured. In 17% of dogs, side effects were noted. All seven rabbits treated for psoroptic mange were cured and did not show any side effect. Our results indicate that moxidectin is effective and a good alternative for the treatment of demodicosis and scabies in dogs and psoroptic mange in rabbits. Side effects seem to occur more frequently if applied subcutaneously, therefore the oral route should be preferred.     

Lymphocyte transformation suppression caused by pyoderma--failure to demonstrate it in uncomplicated demodectic mange

Three dogs with demodectic mange uncomplicated by a bacterial infection and 9 dogs with demodectic mange and pyoderma were tested for their lymphocyte response to phytomitogens in vitro and for the presence of the serum's lymphocyte immunoregulatory factors (SLIF) suppressing blastogenesis. None of the 3 dogs with uncomplicated demodectic mange showed any detectable dysfunction of their lymphocytes or presence of the blastogenesis suppressing SLIF. Their lymphocytes generally responded to the mitogens with more blastogenesis than lymphocytes from healthy controls. On the other hand, in the group of 9 dogs with demodicosis complicated by a bacterial infection, high levels of the blastogenesis suppressing SLIF for concanavalin A-sensitive cells were detected in 4 dogs, for phytohemagglutinin-sensitive cells in 2 dogs, and for pokeweed mitogen-sensitive cells in 1 (of only 3 tested) dog. Dysfunction of lymphocytes per se (detected by a decreased blastogenesis in nonsuppressive normal canine and bovine sera) was detected in 3 dogs with demodicosis with pyoderma. The success of the treatment of demodectic mange or the bacterial skin infection did not correlate with the previous presence or absence of the blastogenesis suppressing SLIF. The treatment of pyoderma was less successful in dogs with an increase in blastogenesis of unstimulated cells in fresh normal canine serum over that in autologous serum. All 3 dogs with a detected dysfunction of their lymphocytes either died or were euthanatized as untreatable cases. It is concluded that the development of demodectic mange per se did not cause the appearance of the blastogenesis suppressing SLIF, which was primarily related to the appearance and extent of the secondary bacterial skin infection.     

Immunodeficiency in canine demodectic mange. II. Skin reactions to phytohemagglutinin and concanavalin A

The T-lymphocyte mitogens phytohemagglutinin (PHA) and concanavalin A (Con A) were used as skin test agents to assess the cellular immune competence of dogs with demodectic mange. The intradermal injection of either mitogen into the abdomen of dogs produced a local erythematous and indurated papule characteristic of a delayed hypersensitive response. The mean diameter of the reaction at 24 and 48 following injection was significantly smaller in eight demodectic dogs than in eight dogs free from mite infestation (P < 0.05). This suppressed response suggested that dogs with demodicosis may have a hypoactive cellular immune system rendering them less capable of combating invading demodicids.The intradermal injection of PHA and Con A also produced an immediate wheal reaction. The mean diameter of the wheal after 15 min was significantly larger in demodectic dogs than in the control animals (P < 0.05). A possible reason for this difference and a potential mechanism for the reaction are discussed.     

Efficacy of a novel formulation of metaflumizone plus amitraz for the treatment of demodectic mange in dogs

A novel spot-on formulation containing metaflumizone plus amitraz (ProMeris/ProMeris Duo for Dogs, Fort Dodge Animal Health, Overland Park, KS) was evaluated for efficacy against demodectic mange mites in naturally infested dogs. Sixteen dogs were allocated to two equal groups and individually housed. Eight of the dogs were treated topically with metaflumizone plus amitraz at the proposed minimum dose rate (20mg/kg of each of metaflumizone and amitraz, 0.133ml/kg) on Days 0, 28, and 56. The other eight were treated with metaflumizone plus amitraz at the proposed minimum dose rate on Days 0, 14, 28, 42, 56, and 70. Mite numbers were estimated from skin scrapings taken on Days -3 to -1, 28, 56, and 84. Clinical signs of mange and the extent of demodectic lesions on each dog were evaluated when skin scrapings were conducted. Efficacy of the treatment was based on a reduction in mite numbers and an assessment of the clinical signs associated with canine demodectic mange. Treatment at monthly or two-weekly intervals for 3 months resulted in a rapid reduction in mite numbers (>94 and >99% for the monthly and two-weekly treatments, respectively) and an improvement in clinical signs. Success rates, based on zero mite counts in skin scrapings at Day 84 were 42.9 and 62.5% of dogs for the monthly and two-weekly regimens, respectively.     

Hyperpigmentation of the skin in canine demodicosis

The occasional development of hyperpigmentation of the skin of dogs with demodectic mange is reported. Of 50 randomly selected dogs treated for this disease at a Dublin clinic, five showed diffuse hyperpigmentation of the skin. The hyperpigmentation appeared to be the result of increased melanocyte activity in the epidermis. The dermis about infested hair follicles contained many histiocytes packed with melanin granules. Comparable reactions have been reported in man and hamsters with demodicosis. Adrenal cortical malfunction may be responsible for the observed increased melanocyte activity in these dogs.     

Mites and related disease

Parasitic mites cause a variety of dermatoses in domestic animals. The clinical signs, diagnosis, and treatment of canine and feline demodicosis, canine scabies, notoedric mange, cheyletiellosis, otodectic mange, and other mite infestations are discussed.     

Clinical Picture and Antibody Response to Experimental Sarcoptes scabiei var. vulpes Infection in Red Foxes (Vulpes vulpes)

Three red foxes (Vulpes vulpes) were experimentally infected with Sarcoptes scabiei isolated from a naturally infected wild red fox. A fourth red fox served as a control. The first signs of sarcoptic mange became evident on the 31st day post infection (dpi). The signs gradually increased thereafter and between dpi 49 and 77 characteristic lesions of hyperkeratosis developed. Two of the infected foxes developed severe sarcoptic mange, and one of these animals died on dpi 121. The third fox developed a chronic hyperkeratotic lesion on its back, at the site where the mites had been applied. On dpi 127 the surviving foxes were treated systemically with ivermectin, and within 4 weeks the skin lesions had healed except on the pinnae of one animal.Antibodies to S. scabiei var. vulpes were demonstrated in the infected foxes by an ELISA with which seroconversion was seen around 4 weeks post infection (wpi). Western blot analysis of sequential sera of the infected animals demonstrated antibody activity consistently after the 2nd wpi.The fourth, non-infected, fox did not show any skin lesions throughout the experimental period nor any specific antibodies to S. scabiei var. vulpes. kw|Keywords|k]sarcoptic mange; k]red fox; k]serodiagnosis; k]ELISA     

Clinical and therapeutic studies on mange in horses

At Kafr El-Sheikh province, Egypt, out of 117 examined drafting horses, mites were detected in 20 (17.09%) horses. The recovered mites were 14 Chorioptes, four Psoroptes and two Sarcoptes whereas mites were not detected in four cases clinically showed typical mange lesions. Interestingly, neither the age nor the sex of the examined horses had a clear influence on the prevalence of the infection. Clinical signs observed in mange infested horses were in the form of irregular skin lesions, severe itching and sometimes biting of affected skin areas and decrease feed consumption. The skin lesions mainly start as erythematous area followed by developing of papules and crust formation. Skin scratches as a result of traumatized lesions usually occurred. Hair was lost on the affected parts developing irregular alopecic areas. Distribution of the lesions was varied according to the type of mite. Chorioptic mite was detected in para-anal fold, distal portion of legs and tail lesions, Psoroptic mite was detected in withers, mane, shoulder and flank lesions whereas Sarcoptic mite was isolated mainly from lesions on the head and neck. Complete clinical and parasitological cure for mite infestation were obtained within 2 weeks in both moxidectin and ivermectin treated groups with 100% recovery rate. Our results indicated that moxidectin oral gel is effective and good alternative for the treatment of chorioptic mange in horse to avoid drug resistance that may develop as a result of the intensive use of ivermectin alone for long periods.     

New techniques for an old disease: sarcoptic mange in the Iberian wolf

Sarcoptic mange, a parasitic skin infection caused by the burrowing mite Sarcoptes scabiei, has been reported in over 100 mammals, including humans. In endangered species, mange causes conservation concerns because it may decimate isolated populations and contribute to extinction. The Iberian Peninsula still maintains one of the largest wolf (Canis lupus) populations in Europe. In Iberia, sarcoptic mange is endemic in red foxes (Vulpes vulpes) and the first confirmed wolf mange cases were recently reported. However, knowledge on S. scabiei in wolves is scarce because of the sampling difficulties inherent to research on scarce species. In order to describe wolf mange epidemiology and to infer conservation implications, this study combined traditional laboratory techniques with the revision of wolf carcass pictures taken by field biologists and original information obtained by camera trapping. A total of 125 necropsies and 8783 camera-trap days allowed insights into wolf mange epidemiology between 2003 and 2010. Living Sarcoptes mites were detected in 19% of the fresh carcasses. Alopecic (delayed) type IV hypersensitive response reactions were observed, while parakeratotic lesions were infrequent. The number of mites isolated per wolf ranged from 1 to 78, and had a negative correlation with the percentage of alopecic skin. No effect by sex on mange prevalence was found. Yearlings showed a lower probability to present mange-compatible lesions than pups or adults. Wolves with mange-compatible lesions had a lower kidney fat index than apparently healthy ones. ELISA testing of 88 sera yielded an antibody prevalence of 20%. Photo-trapping recorded mange-compatible lesions since 2003 with a peak in 2008. The percentage of wolves with mange-compatible lesions registered in camera-traps during 1 year correlated with the percentage of red foxes with lesions in the previous year. This is the first large survey on sarcoptic mange in the Iberian wolf. Necropsy data, with alopecia as the main feature and a slight effect on body condition, and trends derived from camera trapping coincided in showing a rather low prevalence and an apparently stable situation of the disease and its host, suggesting that this parasite is currently not a major threat for this wolf population. However, more information is needed in order to assess the effect of mange on aspects such as pup survival.     

Adult-onset demodicosis in two dogs due to Demodex canis and a short-tailed demodectic mite

Infestation with a short-tailed demodectic mite and Demodex canis was diagnosed in both a six-and-a-half-year-old and a four-year-old dog. The clinical picture was compatible with generalised demodicosis complicated by staphylococcal pyoderma (case 1), or localised demodicosis (case 2). In both cases, the short-tailed demodectic mite outnumbered D canis in superficial skin scrapings. The laboratory findings (lymphopenia, eosinopenia, increased serum alkaline phosphatase and alanine aminotransferase activities, diluted urine and proteinuria) and the results of a low dose dexamethasone suppression test were suggestive of underlying hyperadrenocorticism in the first case. Hypothyroidism was considered a possibility in the second case, owing to the sustained bradycardia and the extremely low basal total thyroxine value. Systemic treatment with ivermectin and cephalexin (case 1), or topical application of an amitraz solution in mineral oil, along with sodium levothyroxine replacement therapy (case 2), resulted in a complete resolution of the skin lesions and the disappearance of both types of demodectic mite after two and one and a half months, respectively.     

Transmission of Sarcoptes scabiei in Swine by Fomites

Transmission of sarcoptic mange by fomites was investigated by placing mange-free piglets in pens for either fixed or variable periods of time during the first six days following removal of mange infected swine. Transmission occurred in pigs with as little as 24 hours exposure to fomites. Clinical signs of pruritis and focal erythematous skin lesions developed in various pigs from four and a half to 13 weeks after exposure. Pigs with the longer exposure developed clinical signs more rapidly than those with a shorter exposure. Four of six pigs developed a chronic form of the disease characterized by thickened encrustations and scurf from which mites were readily demonstrated. The remaining two pigs developed only the pruritic form and mites were never found in numerous skin scrapings examined.     

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.     

The incidence of Chorioptes bovis (Acarina: Psoroptidae) on the feet of horses,sheep, and goats in the Netherlands

Summary

The feel of horses, sheep, and goats of different breeds and from many different localities were examined for Chorioptes bovis. In horses, mites were mainly found in the Belgian and Frisian breeds (40% and 62% infected, respectively). In sheep and goats, respectively 63% and 86% were infected. In horses as well as in sheep and goats, mange‐lesions were rarely seen. A number of sheep and goats were examined for mites and lesions quantitatively. In sheep all mites were restricted to the region close to the accessory digits and the claws. In goats the average number of mites was higher than in sheep, and mites could be found on all locations of the feet at least as far as the carpal and tarsal joint. Both in sheep and goats the biggest density of mites was found just below the accessory digits. When crusts were present, they were generally small and hidden under the coat. In sheep, which were housed for a long period, crusts were seen more often and were more distinct than in pastured animals. A negative correlation between the number of mites and the presence and extensiveness of crusts was observed A possible explanation for this phenomenon is suggested. From the results of this study it is clear that there is no necessity to list chorioptic mange in sheep and goats as a notifiable disease.     

Clinical evaluation and antibody responses in sheep after primary and secondary experimental challenges with the mange mite Sarcoptes scabiei var. ovis

In this work the clinical evolution and the specific serum IgG and IgE antibody responses in sheep after primary (n = 10) and secondary (n = 4) experimental challenges with the mange mite Sarcoptes scabiei var. ovis were studied. The primary infection was characterized by the development of mange lesions in all sheep, a detection of live S. scabiei mites in 70% skin scrapings taken in week 10 post-challenge (PC), strongly raised and sustained specific IgG levels and a more moderate but continuous rise in specific IgE levels. Seroconversion was detected for IgG and IgE by ELISA in 90% and 60% of the sheep in week 8 PC, respectively. By Western-blotting (WB), ten IgG-reactive bands (36–120 kDa) and four IgE-reactive bands (90–180 kDa) were observed in week 8 PC. Following the secondary challenge the ewes developed a smaller area of mange lesion than that seen following primary challenge and live S. scabiei mites were not detected in skin scrapings collected in week 8 PC, suggesting that sheep had developed immunity to re-infection. Compared to primary infection, the specific IgG secondary antibody levels were transient, but in contrast there was an anamnestic IgE response, resulting in an elicitation of specific serum IgE levels in week 2 PC significantly higher than those demonstrated after primary infection. WB analysis revealed one additional IgG-reactive band (180 kDa) and no additional IgE-reactive bands. Determining the immunodiagnostic or vaccination value of the IgG-reactive antigens and IgE-reactive allergens detected requires further studies.     

A Case of Atypical Psoroptic Mange in a Domestic Rabbit

A female checkered giant cross rabbit (Oryctolagus cuniculus) was presented with skin lesions on the perineal region. The cutaneous lesions extended 2 cm from the vulva and perineal glands. They were moist and erythematous, with abundant greasy yellowish scabs. Skin scrapings from the lesions were mounted in Amman’s chloral-lactophenol on microscope slides and examined at ×10 and ×40 magnification. Numerous mites were observed and identified as Psoroptes cuniculi, a common causal agent of otitis externa in rabbits. The rabbit was treated successfully with ivermectin. This case of psoroptic mange is atypical owing to the perineal location, apparent absence of auricular lesions, and the lack of contagion despite close contact with several other rabbits.     

Demodicosis of dogs--a factorial disease?

Demodex canis is a normal resident of the intact canine skin, being present in small numbers in virtually every dog. Most animals are only carriers of the mites and do not develop clinical symptoms, therefore, demodectic mange has already to be considered as a factorial disease. The modus operandi of transition of clinically inapparent colonization of the mites into a disease may be explained according to investigations so far published multifactorially and thereby essentially as consequences of primary or secondary immunodepression. A primary immunodepression is initially based most probably on a hereditary defect of T-cells and is subsequently reinforced by substances, which are presumably synthesized and liberated not only by mites but also by secondary bacterial agents. A secondary immunodepression operates as trigger mechanism of a clinical manifestation after corticosteroid or cytostatic therapy or in course of underlying diseases of potentially immunodepressive nature, i.e., malignant neoplasia, hepatopathies, hyperadrenocorticism and lymphosarcoma.     

Sarcoptic mange in captive maras: the first known outbreak and complete recovery with colony-wide acaricide treatment

Among 16 maras housed as a colony at a zoo, 2 initially showed generalized dermal lesions on the legs, head and abdomen. Approximately 1 month later, following completion of therapy with amitraz, 6 maras in the same colony, including the 2 previously diseased animals, showed dermal lesions with severe alopecia and crusting. Sarcoptic mange was diagnosed on skin scrapings on the basis of morphological criteria. The mites were highly mobile and abundant in all cases, and no other causative agents were detected. Colony-wide treatment with ivermectin and prednisolone was administered weekly for a total of 4 treatments. After therapy was completed in all cohabitants, follow-up scrapings were negative for Sarcoptes scabiei. This report describes the first known outbreak of sarcoptic mange in captive maras and successful treatment with acaricides.     

Influence of systemic antibiotics on the treatment of dogs with generalized demodicosis

Canine generalized demodicosis (CGD) is a skin disease with distinct breed predispositions. Secondary bacterial infections are common. Dogs typically receive miticidal therapy in combination with antibacterial treatment. Whether antibiotics influence the duration of acaricidal therapy is unknown at the moment. There is also debate over how common short-tailed Demodex mites occur in demodicosis. This study evaluated the influence of systemic antibiotics on the course of CGD, the occurrence of short-tailed Demodex mites in demodectic dogs and the influence of furunculosis on treatment outcome. Breed predispositions for CGD in Moscow were identified. Fifty-eight dogs were randomly distributed in two groups. Both were treated with ivermectin 600 mcg/kg q24h orally and benzoyl peroxide shampoo weekly. The dogs in one group (AB) were additionally treated with systemic antibiotics for at least 1 month, dogs in the other group (NAB) were not. Monthly examinations, skin scrapings and impression smears were performed. Prior to the study there was no difference in clinical severity, presence of pyoderma and mite numbers between groups. There was no significant difference in duration until first negative skin scrapings and resolution of bacterial infection. In dogs with furunculosis the number of the mites was significantly higher than in dogs without furunculosis but the duration until microscopic remission albeit longer, was not significantly different. Short-tailed Demodex mites were found in 25% of the cases. Pugs and English Bulldogs were predisposed. Based on these results, systemic antibiotics may not impact as much as previously thought on the actual success of CGD treatment.     

Unusual manifestation of a concurrent demodectic and sarcoptic mange in a Zebu-Friesian cross-bred heifer

We describe a rare case of a concurrent demodectic and sarcoptic mange in a 2-year-old heifer in Khartoum, Sudan. The lesions were massive lumps of granulomatous tumour-like dermatitis with thick, nodular folds mainly covering the head, neck and shoulders. Histopathological examination of the lesions revealed the presence of both Demodex bovis and Sarcoptes scabiei. The animal died regardless of the anti-parasitic treatment it received.