Dermanyssus gallinae is a temporary blood-feeding mite of domestic and wild birds. Haematopota spp. Some mite species are temporary ectoparasites, visiting animals to suck blood for relatively short periods. equi and P. natalensis. The larvae and puparia of anophelines require unpolluted fresh water sites whereas culicines breed in stagnant, organic-rich water. Medical diagnosis (abbreviated Dx or D S) is the process of determining which disease or condition explains a person's symptoms and signs.It is most often referred to as diagnosis with the medical context being implicit. In sheep these species usually initiate a ‘strike’ (primary myiasis) whereby eggs are laid on faecally soiled skin. Like psoroptic mange, this condition tends to be a winter disease and feathered horses are more liable to the condition. Adult are 3–10 mm long, slender with long legs, threaded antennae and scales on the wings. Deeper skin scrapings using a scalpel blade are necessary to recover burrowing mites such as Sarcoptes and Demodex. Psoroptes equi is a non-burrowing mite. Simulium spp. The population may double every 7–8 days. In other animals eggs are deposited near old poorly healing wounds or in damaged areas producing odours that are attractive egg-laying cues. appear crab-like and have a leathery, textured cuticle. The "medical care" provided encompasses medical and surgical treatment, diagnostic and investigative procedures, hospitalization, preventive medicine procedures, patient transportation, and the supply and maintenance of prosthetic appliances (art. The head is rather small compared to the overall body of the fly and the wings are elongated (Fig. They have small heads with bulging eyes and the proboscis is forward-pointing. Hippoboscids feed on the host for long periods (see p. 210). are vectors of the stomach worm Habronema spp. The return from the pathologists is proportional to the care with which samples are collected and handled. The period from egg to adult takes approximately 3 weeks. Females (Fig. Hard ticks are far more important and their life cycle is now described in detail. equine encephalitis, and they contribute to the overall problem of fly attacks. The adults emerge in late summer and bite the underside of horses or inside the ears, depending on the species. The head and thorax are fused to form the basis capituli. Feeding around the corners of the eye can result in a conjunctivitis (fly eye) and they may be a vector for Moraxella spp. and frustrating. Fleas. Sophisticated or expensive equipment is not usually necessary in practice, and for procedures that require the more advanced expertise of a pathologist the specimen should be sent directly to that specialist. Flies cause worry/nuisance and are a major cause of skin pathology. Deeper lesions are caused by species in the hard tick genera Amblyomma (Africa, North and South America, Asia) and Hyalomma (Asia and Africa) because they possess very long mouthparts. They may become problematic if rodent populations near stables are high. Soft ticks (family Argasidae) are more common in drier regions and are of generally lesser veterinary importance. are metallic black/blue in colour (7–8 mm) with grey-dusted thoracic stripes (Fig. There are many species but the commonest forage mite species is probably Acarus siro (Tyroglyphus farinae). Infestation may present as scaling and alopecia; papules and pustules may form on the face, shoulders, neck and limbs (see p. 196). There is little merit in sending prepared samples to a pathologist (such as mounted and stained sections) unless a second opinion is being sought – indeed the pathologist may not then be able to establish the true orientation of the specimen and might be unable to explore other stains and other orientations of the sample. Bone histology is also discussed. There is a distinct summer activity pattern in temperate zones and woodland with ponds or salt marshes providing breeding sites. Higher magnification is needed to see, Semi-permanent preparations of burrowing and non-burrowing mites, which are soft bodied, may be made by placing them directly into lactophenol or Berlese fluid on a microscope slide with a cover slip. Females tend to be smaller than the males and eggs may be seen in the abdomen. Table 3.1 Equipment that can be used to collect dermatological samples from the skin, • Clippers (preferably electric rechargeable type) with disinfectant spray lubricant, • Magnifying lens, preferably with incorporated illumination (an otoscope is useful in providing both light and magnification in a convenient form), • Petri dishes or collection pots for collection of specimens, • Microscope slides (with frosted ends ) and pencil for marking, • Bacterial swabs (with transport medium)), • Bottles containing 10% formal saline (and/or other fixatives), • Histological specimen baskets with appropriate fixatives, • Surgical scrub solution and sterile saline, • Camera (with high resolution (fine) capability). Although Demodex spp. in horses, the larvae of which cause cutaneous lesions. They are usually very keen to help and are often highly skilled but are seldom familiar with horse conditions and, unless they are in active contact with colleagues who can assist them with diagnoses, results can sometimes be very misleading and occasionally embarrassing. There may also be pruritus, papules and crusts. Many species are involved and it is almost impossible to list all those responsible for some pathology. A small verrucose sarcoid on the lateral sheath region was tormented by flies (Musca spp.) 3.14). These mites are not host specific and will feed from available hosts including horses and humans. The following species are ‘facultative’, i.e. Some tick genera have a metallic, shiny scutum whereas others do not. Access to the complete content on Oxford Medicine Online requires a subscription or purchase. They are responsible for transmission of trypanosome parasites. If all the relevant historical and clinical information is supplied, they can be a powerful ally in establishing a diagnosis in many cases or in establishing ‘rule outs’, and particularly so in complex or unusual conditions. The mouthparts are adapted to abrade the skin and this species may initiate small wounds or enlarge existing ones, particularly on warts and sarcoids. is dull and non-metallic. Mosquitoes can significantly contribute to fly ‘nuisance’. bacteria. Lucilia sericata are metallic green flies (Fig. Figure 3.5 Trombicula spp. The presence of cattle and pigs, on which this species also readily feeds, can influence the numbers of S. calcitrans pestering horses. To make preparations of mites such as Dermanyssus gallinae, which have tough cuticles like those of fleas and may have fed, clearing is necessary by incubation in 10% potassium hydroxide for 1 hour followed by washing and dehydration in a series of alcohols. They have a leathery, folded and pitted dorsal surface. size by feeding and moulting through three instars. The insects (class Insecta) such as flies and lice have an obvious head, thorax and abdomen and they always have six legs emerging from the thorax region. Another soft tick genus, Ornithodorus, may also attack horses. The family Calliphoridae contains several species which can cause cutaneous myiasis in horses. To make preparations of mites such as, All stages of ticks (both hard and soft) possess a characteristic hypostome, a toothed structure which anchors the tick into the skin. Parasitic mites irritate the skin by feeding on skin scales, lymph exudates, sebaceous secretions or blood. The equipment required to collect specimens for diagnostic purposes in shown in Table 3.1. Some species of Hyalomma and Rhipicephalus spp. They are prevalent in areas with chalky soils and are seasonal, showing most activity during late summer and autumn. These comprise the many free-living species associated with damp straw and hay. Boophilus spp. Rhipicephalus spp. Adult soft ticks feed frequently and within a matter of minutes. (Europe, Asia, Africa and Australia), Rhipicephalus spp. The mouthparts are recessed under the tick and cannot be seen from above. If it leaves a scar, it’s most likely an invasive procedure. Erythema, crusting, ulceration and alopecia with itching is common. When wounds are involved, myiasis is said to be ‘traumatic’; where larvae mature inside a boil, the form of myiasis is termed ‘furuncular’ (see p. 207). Populations can build up rapidly in bird accommodation. Please subscribe or login to access full text content. (family Fanniidae) are associated with decaying vegetation, compost heaps, etc. The males are identified by the presence of copulatory suckers in addition to the above features, which are specific to the genus Psoroptes. Figure 3.12 Lyperosia irritans. 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