Newly moulted adult females mate immediately and create new tunnels by eating skin and tissue fluids. Tick feeding can cause abscesses by the introduction of surface bacteria. The body of P. equi is oval-shaped and the head region is pointed (Fig. Severe infestations may cause anaemia. tend to swarm in significant numbers and attack most frequently at dawn and dusk. Females attach to the host, attract males and become fully engorged with blood after 6–12 days. The wings are clear and the antennae short. 34.01 of the QR&O). Myiasis is the invasion of living tissue by fly larvae and is a serious problem in livestock throughout the world. Stables located near poultry houses or birds’ roosts may be a source of hungry poultry, especially if bird hosts are absent. Movement is usually very easy to observe. are usually regarded as non-pathogenic, significant clinical disease can result if the health and immune status of the animal is compromised. Mites are transferred during physical contact but off-the-host survival may also be a significant route of transmission, particularly in winter. They are non-metallic bluish grey in colour and possess much reduced mouthparts. S. niger and S. sitiens are common species in Africa and east Asia, respectively. Males and females are similar and possess a typical strong proboscis which is black, shiny and forward pointing. When a pathologist receives a fixed specimen with a full history and a good clinical description of the clinical case (possibly even with photographic images of the sampled lesions) he/she will usually cut the specimen into the most appropriate ‘blocks’ for processing and in that way the best possible diagnostic information can be gleaned. Males emerge in mid-July and swarm around horses outside stables. Simulium spp. Stomoxys spp. Mites are best seen against a dark background, particularly when particles of debris adhere to the mite’s body hairs. Most cases are reported to be in horses receiving long-term glucocorticoid therapy. Flies are a persistent problem for many reasons. Stable flies are known to transmit equine infectious anaemia and ‘surra’ (a form of trypanosomiasis). Stains suitable for the range of tests routinely performed in the laboratory (including Gram’s, Ziehl–Neelsen, methylene blue, Wright–Giemsa, Giemsa, Leishman’s, lactophenol–cotton blue, etc. The anal plate is pear-shaped and not D-shaped as in D. gallinae. are between the ages of 19 and 44, are overweight or obese, and have one or more other diabetes risk factors; are a woman who had gestational diabetes 1; Medicare covers the cost of diabetes tests for people with certain risk factors for diabetes. The mouthparts of P. ovis can pierce the skin and mites then feed on serous exudates. This is a huge category and includes just about all major surgery and many diagnostic tests. Like psoroptic mange, this condition tends to be a winter disease and feathered horses are more liable to the condition. breed in animal dung on pasture or in other decaying organic matter. Flies in the family Tabanidae are all large and stout-bodied, between 10 and 15 mm in size. The most important families in temperate zones are the Muscidae and Fannidae. They possess a forward-pointing proboscis and hold their wings over the dorsal abdomen in a scissor-blade posture. Pigeons’ nests within or near stables may be a transient source of D. gallinae in autumn when young birds are fledged. Their larvae can be involved in secondary invasion of tissues, i.e. The lesions created by ticks may be attractive to screw-worm (fly) larvae in the tropics and subtropics (see p. 212). (e.g. The parasites that affect horses are usually fairly easy to recognize. Feeding around the corners of the eye can result in a conjunctivitis (fly eye) and they may be a vector for Moraxella spp. they usually breed in carrion but the flies may opportunistically lay eggs on animals. Adults are relatively large – up to 1 mm in length. equine encephalitis, and they contribute to the overall problem of fly attacks. Mites. Species of ticks in subtropical/tropical genera Ambylomma and Hyalomma are often very large – up to 1.0 cm in size even when flat and unengorged – and can be easily identified by their overall size and very long mouthparts. are 5–7 mm, brown/grey and house-fly-like in appearance (Fig. Mites may survive off the host and transmission may occur via the bedding as well as by direct contact. Figure 3.11 Stomoxys calcitrans, the stable fly. The return from the pathologists is proportional to the care with which samples are collected and handled. Adult flies do not infest animal accommodation; Lyperosia irritans does not bite horses inside stables. Surface-feeding files (‘nuisance files’or ‘sweat files’), Nematode parasites causing skin disease 58, Acetate (clear, adhesive) tape preparation. Mites are transmitted during physical contact. Feeding flies can cause severe irritation, dermatitis and hypersensitivity. Diagnostic procedure - definition of diagnostic procedure by The Free Dictionary Problems caused by red mites are likely to be transient; D. gallinae populations do not establish in horse accommodation and require continued poultry contact. Hydrotaea albipunta is another very common species, confined to the corners of the eyes. 4. They may be vectors of the virus that causes pinnal acanthosis (see p. 136). Despite their large size, tabanids fly silently and appear on any part of the horse’s body but very often it is the lower legs and the heels which are bitten. Figure 3.3 (A) Chorioptes equi are usually easy to recognize by their physical appearance (though very similar to Psoroptes). Males are rarely seen but all the life cycle stages may be present in a single hair follicle. Poultry mites are fairly easy to see with the naked eye or with a magnifying glass, appearing bright red when fully blood-engorged and almost black when the blood meal is more than 24 hours old. CD3 • 1); this feature is only seen if the specimen is cleared (see section examination for mange mites of horses). the tissues have already been invaded by primary myiasis species. He or she may also check your reflexes and muscle strength. Species of ticks in subtropical/tropical genera, Hard ticks tend to feed at specific sites, especially the ears, face, neck, axillae, groin, distal limbs and tail, but although the different species have preferential feeding sites, ticks may be found anywhere on the body. Arachnids possess eight legs in the adult and nymphal stages but only six in the larval stages. Figure 3.14 Hippobosca equi. Glossina spp. Adult flies are approximately 10 mm in length and are pale reddish brown (Fig. Only the larvae attack mammalian hosts, where they can cause a hypersensitivity response (see p. 198). The mouthparts pierce the skin, producing an exudate on which they feed for several days. Following mating the female mite tunnels into the sub-corneal layer of the skin. Adult soft ticks feed frequently and within a matter of minutes. The body cuticle is tougher than that of the soft-bodied permanent species such as Psoroptes spp. The name Chorioptes equi is used to describe chorioptid mites on equines. Oxford University Press makes no representation, express or implied, that the drug dosages in this book are correct. They require little technical skill or knowledge (e.g. The species that infest horses and companion animals are Trombicula (Neotrombicula) autumnalis, in Europe, Trombicula (Eutrombicula) alfredduges and Trombicula (Eutrombicula) splendens in the New World, and Trombicula (Eutrombicula) sarcina in Australasia. The equipment required to collect specimens for diagnostic purposes in shown in Table 3.1. Haemaphysalis spp. but the proboscis is of the non-biting type, ending in a pad for mopping up secretions. Both these genera are usually found in the perianal region and the underside of animals and may appear like bunches of grey grapes, 1–1.5 cm in size when full of blood. In contrast, Boophilus spp. Except where otherwise stated, drug dosages and recommendations are for the non-pregnant adult who is not breastfeeding. Due to the time spent on the host, one-host and two-host species are likely to induce a more severe host reaction than three-host species. In sheep these species usually initiate a ‘strike’ (primary myiasis) whereby eggs are laid on faecally soiled skin. Horses react by stamping the legs, biting and shivering the skin. Males also feed and have a yellow abdomen. There is a large number of host-adapted strains in different parts of the world which vary in pathogenicity but recent genotyping has suggested the existence of distinct species. Some are casual or opportunistic equine parasites such as Dermanyssus gallinae, the red poultry mite, which is a blood-feeding mite. Horses with feathered legs are frequently affected. An invasive procedures is defined as a medical procedure which breaks the skin in some way. They are aggressive blood-feeders and leave large visible bite sites with oedema and a purple central spot. the larvae of which cause granulomatous cutaneous lesions around the face (see p. 217). The clinician should recognize that the further test is being performed for a specific reason and that the findings will clarify the chosen treatment or will alter the treatment depending on the findings. mites are minute (100 μm) with a tapered and pointed abdomen, the cuticle of which is striated. The life cycle of Musca spp. Psoroptes and Chorioptes) is suspected, repeat surface samples should be obtained using a strong comb or preferably a stiff brush (see p. 60). dermatophyte test medium (DTM) or Fungassay fungal culture medium), but rely on careful reading of the instructions. 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). All Rights Reserved. Stomoxys spp. Readers must therefore always check the product information and clinical procedures with the most up to date published product information and data sheets provided by the manufacturers and the most recent codes of conduct and safety regulations. The following species are ‘facultative’, i.e. They usually feed on microorganisms and organic matter. This is a borrowing mite and the single species in the genus. The life cycle in dung is similar to that of the other species, so that new populations may emerge every 2–4 weeks, depending on temperatures and conditions. overwinter as puparia in temperate regions but breed all year round in warm climates. A gastroscopy often takes less than 15 minutes, although it may take longer if it's being used to treat a condition. Stable flies inflict a painful bite and are one of the most annoying pests of horses, mostly attacking the lower body and legs. In temperate regions, Myiasis in horses due to the calliphorid genera. 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