PARASITESAND

SKIN DISEASESPeter GrayMVB, MRCVS

J. A. AllenLondon

To the memory ofMolly

whose 93 years were eminently worthwhile

British Library Cataloguing in Publication DataA catalogue record for this book is available from the British Library

ISBN 0-85131-624-7

Published in Great Britain in 1995 byJ. A. Allen & Company LimitedI Lower Grosvenor PlaceLondon SW1W OEL

© Peter Gray 1995

No part of this book may be reproduced or transmitted in any way or by any means, elec-tronic, or mechanical, including photocopy, recording, or any information storage andretrieval system, without permission in writing from the publishers. All rights reserved.

Production editor: Bill IresonIllustrator: Maggie RaynorCover designer: Nancy LawrencePrinted in Hong Kong

Contents

ACKNOWLEDGEMENTS Xi

ILLUSTRATION ACKNOWLEDGEMENTS Xiii

INTRODUCTION I

1 The Effects of Infestation 5

Host Specificity 5 - Quantity of Parasite 6 - Endoparasites in Disease 6Specific Effects of Endoparasites 7 - Signs of Infestation 13

Management of Infestation 14 - Climatic Conditions 14 - MixedInfection 16 - Reproduction and Lactation 16 - Productivity 16

Ectoparasites 17

2 Internal Parasites 18

Roundworms (Nematodes) 18 - Large Redworm (Strongylus) 20 - Small

Redworm (including Cyathostomum) 25 - Threadworm (Strongyloides) 28

- Lungworm (Dictyocaulus) 32 - Horse Roundworm (Parascaris) 34 -

Hairworm (Trichostrongylus) 38 - Pinworm (Oxyuris) 41 - Neck

Threadworm (Onchocerca) 44 - Abdominal Worm (Setaria) 47 -

Eyeworm (Thelazia) 49 - Stomach Worms (Habronema and Draschia) 52

- Gullet Worm (Gongylonema) 54 - Cestodes 56 - Tapeworms 56 - Other

viii Parasites and Skin Diseases

Tapeworms 60 — Trematodes 60 — Liver Fluke 60 — Protozoan Infections64 — Other Protozoan Infections 65

3 Pasture Management and Worm Control 67

Cyathostomes 67 — Limiting Pasture Contamination 70 — Low-levelExposure 71 — Pasture Hygiene 71 — Removing Faeces 72 — Harrowingand Topping 73 — Resting 73 — Mixed Grazing 73 — Dosing Reminders 74— Vital Points 76 — Stable Hygiene 77 — Control Routines 77 — PracticalAspects of Worming 77 — Worming Procedures 78 — Specific Drugs 79 —Worming Calendar 84 — Insecticides 85 — Antifungals 86

4 Laboratory Procedures 88

Diagnosis 88 — Faecal Examination 89 — Materials 90 — Procedure 90 —Alternative Procedure 91

5 The Skin 92

Anatomy and Purpose 92 — Skin Musculature 93 — Skin Glands 94 —Sebum 94 — Sweat 94 — Hair 95 — Functions of Skin 96 — Diagnosis ofSkin Disease 96 — Laboratory Investigation 97

6 Wounds 99

Skin Repair 99 — Infected Wound Repair 100 — Other Complications 101— Treatment of Wounds 102 — Proud Flesh 106 — Burns 107

7 External Parasites 109

Fly Worry 110 — Midges (Culicoides) 113 — Stable Fly (Stomoxys) 117 —House Fly (Musca) 118 — Horse Fly (Tabanus) 118 — Tsetse Fly(Glossina) 119 — Hippoboscids (Hippobosca) 119 — Mosquitoes 119 —

Contents ix

Blowfly, Screw-worm 120 –. Wasps and Bees 121 – Botfly 121 – WarbleFly 125 – Lice 127 – Fleas 131 – Mites 131 – Ticks 136

8 Bacterial and Fungal Diseases 141

Rain Scald 141 – Greasy Heel or Mud Fever 142 – Folliculitis 144Abscess and Deeper Infection 145 – Cellulitis 146 – UlcerativeLymphangitis 146 – Acne 147 – Bacterial Granuloma 147 – SkinTuberculosis 148 – Glanders 148 – Ringworm 148 – Other FungalInfections 152

9 Allergies and Poisons 154

Management of Allergies 154 – Urticaria/Angioedema 158 – FoodAllergies 160 – Contact Dermatitis 161 – Other Causes 162 – Poisons 163

10 Tumours and Other Conditions 167

Tumours of Skin 167 – Amyloidosis 177 – Anhidrosis 178 –Collagenolytic Granuloma 178 – Ear Diseases 179 – Fistulous Withers180 – Filling in the Legs 180 – Haematomas 181 – Helminth Diseases182 – Hereditary Diseases and Pigment Disorders 182 – HormonalDiseases 185 – Hypothyroidism 186 – Immune Diseases 186 –Keratinization Disorders 189 – Lymphangitis 189 – Nodular Panniculitis190 – Unilateral Papular Dermatosis 190 – Poll Evil 191 – Protozoan SkinDiseases 191 – Saddle Sores and Girth Galls 191 – Viral Diseases 192

GLOSSARY 195INDEX 203

Acknowledgements

I would like to express my gratitude to Professor Brian J. Sheahan, MA,MVB, MS, PhD, MRCVS, MRCPath, of the Department of VeterinaryPathology, University College Dublin, for the photograhic material he hasso generously provided and for his help in reading the manuscript.

My thanks also to a number of individuals: Professor Kenneth P. Baker,MA, MSc, Phd, DVD, FRCVS, of the Department of Veterinary ClinicalMedicine, University College Dublin, for his help with that part of the bookon skin diseases; David Byron, of MSD AGVET, for his most generoushelp with material, especially the use of the many photographs included inthe text; Jane Parry, BVetMed, MRCVS, also of MSD AGVET, for refer-ence material she supplied; Jacqueline Meldon, of Pfizer Animal HealthLimited, who also very kindly provided photographic material; andDeborah J. Baker, BVetMed., MRCVS, of Hoechst UK Limited.

To Raymond Hopes, BVMS, MRCVS, of Rossdale and Partners,Newmarket, Suffolk, I am indebted for the use of photographs and slideson skin conditions. For the photographs they supplied, my thanks to: PeterD. Rossdale, MA, PhD, DESM, FRCVS; Colin K. Peace, MA, VetMB,MRCVS; and Alan Wright, BVSc, MRCVS.

For help provided I would also like to thank: Roger R. Dawson, BSc,PhD, Animal Medicines Training Regulatory Authority (AMTRA); RogerCook, National Office of Animal Health (NOAH); and the staff of theWellcome Library, Royal College of Veterinary Surgeons (RCVS).

My special thanks, too, to Maggie Raynor for her excellent artwork; toBill Ireson for his production editing; to Nancy Lawrence for the coverdesign; and to my publishers for their help and encouragement.

Illustration Acknowledgements

I am grateful to the individuals and organisations listed below for givingtheir permission to reproduce original material. Each subject used is listedby the relevant page number in this book.

Note that many subjects have been enlarged or reduced and are thereforenot to scale.

J. A. Allen & Co. Ltd.: p. 31, p. 93.Raymond Hopes: p. 101 (bottom), p. 135, p. 159 (two), p. 172 (two),

p. 181, p. 186, p. 188, p. 190, p. 191.MSD AGVET: p. 24 (two), p. 26, p. 30, p. 36, p. 40 (top), p. 43 (top), p. 46,

p. 51 (two), p. 58 (top and centre), p. 63, p. 114, p. 120 (two), p. 124(three), p. 130 (bottom), p. 134 (top), p. 139 (two).

Colin K. Peace: p. 100 (two).Pfizer Limited: p. 8, p. 43 (centre and bottom), p. 58 (bottom), p. 71.Peter D. Rossdale: p. 176.Brian J. Sheahan: p. 9, p. 40 (bottom), p. 169 (three).Alan Wright: p. 130 (top), p. 134 (bottom), p. 150 (two), p. 171.

Introduction

Parasites and skin diseases of horses are two subjects about which theaverage horse owner knows little. The difficulty lies in that they are spe-cialist subjects, filled with their own technical terminology and thereforehard to interpret.

However, the clinical importance of these fields is evident in everdayhorse management. Worms and other parasites have a significant ongoingeffect on growth and production. Skin conditions, be they contagious ornot, are a familiar form of equine disease and a regular reason why horsescannot be ridden.

In attempting to make these subjects understandable to the lay person,therefore, it is necessary in this book to begin at the practical base. Forexample, common names, like `redworm' and lungworm' , are used inconjunction with the generic names, Strongylus and Dictyocaulus. Forcorrectness, however, the generic names will be used in parentheses insection headings, but every effort is made to enable the reader to gain theinformation he or she requires without being overcome by the technicalnomenclature which is vital to the scientist/veterinarian.

Similarly, in discussing the effects of parasite infection, it is notintended to delve into the complexities of equine pathology. Yet it shouldbe understood that pathology means the study of diseases, or, more prop-erly, the study of the changes in body tissues that result from disease.Thus, a worm is not just an undesirable resident of the digestive system;it may damage the lining to the bowel, it may migrate through other tis-sues, causing damage to remote organs. It may also interfere withdigestion, preventing the absorption of food elements from the bowel;this may lead to weight loss, stunted growth, and improper developmentof the horse's skeleton. Pathology therefore is a vital part of our discourse

2 Parasites and Skin Diseases

here; anyone who has an interest in horses and responsibility for theirwelfare will be better for an understanding of pathology, and more able tounderstand the wider practical effects of a given disease.

This book is, then, organised in a way that should make most sense tosuch a reader. It is not the way in which parasites and skin diseases aredealt with in professional literature, but that need not be of concern. Anyreader who digests the contents of this book and wants more informationmight well be ready to tackle the complexities of specialist professionaltexts. In order to help the reader with the more technical terms, a glossaryis included at the end of the book.

A parasite is a living organism that lives upon or within another livingorganism from whence it ekes its existence. Its affect on the host variesbut may occur directly through invasion of tissues, or through the inges-tion of blood as the redworm does. Mange mites live on surface cells,some even burrowing within the skin. Some parasites live within thebowel, in the lumen (centre of the tract) unattached, obtaining their foodfrom the bowel contents.

Parasites that exist within the animal are called endoparasites. Thosethat live on the skin are called ectoparasites.

The animal that supports the parasite is referred to as the host. In thisbook, the host in all cases is the horse and we will at times distinguishbetween the influence parasites have on horses at different stages ofgrowth.

In the main we are dealing with helminth parasites among which arethe common worms (divided into nematodes, cestodes and trematodes) ofthe horse's bowel and arthropod parasites (ticks, mites, lice and flies).

Many parasites are what is known as 'host-specific', meaning theyconfine themselves to a single species. Others are not and can be found indifferent animals. It is evident that a worm which is common to cattle,sheep and horses would therefore have a special significance where eachof these species were grazed on the same piece of land.

Each parasite has a specific location within a host where it is mostcommonly found – called a predilection site – and which may play a partin the technical naming of the parasite. Needless to say parasitic infesta-tion may cause interference with the horse's body defences and thus pavethe way for secondary infection with bacteria and viruses. A further prob-lem (associated mainly with ectoparasites) is the ability of some parasitesto transmit disease (e.g. encephalitis virus and swamp fever, transmittedby biting flies and mosquitoes; human malaria is a protozoan disease,transmitted by mosquitoes).

Introduction 3

Other factors which may influence disease are the age of the host andphysical condition, also matters like season, climate, geographic location,and so on. Internal worm burdens have a more insidious effect in cold,wet conditions and external parasites may irritate most in warmerweather.

Climatic factors also dictate the manner in which parasites survive out-side the host. Most endoparasites lay eggs which pass onto pasture in thefaeces. These may hatch into larvae which are ingested by the next host.The capacity of larvae to survive externally is influenced by heat andcold, the quality of the pasture, exposure to sunlight, and so on. Becauseof this life cycle, horses which are stabled are less likely to encounter par-asites than when kept at grass. However, parasitic risk is not completelyeliminated by stabling, and stable hygiene is important in preventingspread of disease.

Of course, very few infections are caused by a single parasite. The typeand number involved may vary, and there may be external and internalparasites occurring at the same time. This, naturally, will influence theeffect on the host. The most important aspect of all this is the daily influ-ence parasites have on management. What are the risks of your horsebeing affected by diseases which are not altogether evident on the sur-face? How can you recognise a worm infection? What is the life cycle?What is the prevention? What is the treatment?

Horses, being animals which are kept for pleasure, not food, sufferbecause research on their diseases is often deemed uneconomical. Wemust rely therefore to some extent on information from other sources, likeresearch into cattle and sheep diseases. Yet this does not reduce the valueof the information as long as it is understood that principles applying toparasitic infection in general may be diluted in certain circumstancesbecause of the nature of the horse. The horse owner is, of course, moreinterested in bone development, or diseases of bone that may ensue fromnutritional problems. He or she is also interested in weight gain, in thefull, normal physical development of an athletic animal; of its ability toperform, to stand up to training and to carry weight. But our primaryinterest must be in the soundness of our horses, not weight gain per se.We simply wish for the animal to reach its natural potential without duehindrance.

Skin diseases are also complex and have a variety of causes besides exter-

nal parasites. For example, modern medicine recognises such diverse

causes as infection, diet, contact with irritant or allergenic substances,

allergies, hereditary and auto-immune disease. Each of these are dealt

4 Parasites and Skin Diseases

with in some detail in this book, hopefully thus making it easier for thereader to understand and recognise the different expressions of skin dis-ease. There is a great deal that horse owners themselves can do tominimise the problems related to them.

In a book combining these two subjects, parasites and skin diseases, it isinevitable that there might be some duplication or variation from an idealline. For example, the botfly parasitises the horse's stomach in its larvalstages; the warble fly, when it affects horses, is most significant when adeveloping larva appears under the skin of the back. In this book, both areincluded with other conditions caused by flies, and are therefore treatedas external parasites. The reader should not suffer on that account.

Glossary

skin graze, as with rope burn, grazed kneecavity filled with pusinfestation with ticks or mitesskin condition marked by pustulesinherited absence of pigment in hair, skin and eyessubstance capable of causing allergyhypersensitivity to an antigen

skin inflammation caused by allergy

hives, of allergic originhair lossfocal patches of alopecialowered red blood cells and/or haemoglobindilatation of blood vessel wallcondition marked by painless swellings under the skin andmucous membraneschronic dry coatring-shaped or circular lesionhead appendage of arthropodchemical that inhibits or kills bacteriabody defence, produced by lymphocyte cellscauses antibody production (virus, bacterium, etc.)inhibits or destroys organismshereditary absence of skin (as epitheliogenesis imperfecta)family that includes arachnids and insectscyst containing porridge-like exudateear lesion, raised and circumscribed, said to be form ofpapillomatosis

abrasionabscessacariasisacnealbinismallergenallergyallergic

dermatitisallergic

urticariaalopeciaalopecia areataanaemiaaneurysmangioedema

anhidrosisannular lesionantennaantibioticantibodyantigenantisepticaplasia cutisarthropodatheromaaural plaque

196 Parasites and Skin Diseases

autoantibodyautogenous

autoimmunebasal cell tumourBasidiobolus

haptosporusbiopsyblowfly strikebullabullous

pemphigoidburnbursa

antibody against animal's own tissuesderived from same animal; autogenous vaccine is producedfrom organisms taken from an affected animalantibodies produced against own tissuesrare, benign tumour of skin

cause of fungal skin diseasesample from living tissue for diagnostic purposesinvasion of skin by blowfly larvaelarge blister

autoimmune skin diseasetissue injury resulting from heat, cold, chemicals, etc.fluid-filled sac often between bone and tendon/muscle (falsebursa – forms on the knee, etc., as a result of injury; spinousbursitis – fistulous withers)

calcinosiscircumscripta localised nodule of calcium

callus local thickening of skin due to friction, etc.Candida fungal organism that may be associated with diseaseCanadian

horsepox pustular skin diseasecellulitis inflammatory reaction spreading beneath the skincercaria larval stage of liver flukeCestoda class to which tapeworms belongchemotherapy treatment by chemical substances or drugsCoccidia protozoan cause of enteric diseasecoital exanthema viral venereal diseasecolic pain of abdominal origincollagen structural protein of white fibres of skin, etc.complement a body defensive substancecongenital a mark or condition present at birthConidiobolus

coronatus fungal infection of nasal cavities.crust dried skin exudatecryosurgery surgery by freezing, either with dry ice (liquid nitrogen) or

carbon dioxidecutaneous

habronemiasis see habronemiasiscutis the skincytology diagnostic examination of cellsdecubital ulcer skin ulcer due to lying downdepigmentation loss of colour from skindermatology study of skin disease

Glossary 197

Dermatophilusdermatophytedermisdermoid cystdorsal shieldeczemaelectrosurgeryembolusemollientendocrinologyeosinophileosinophilic

granulomaepidermal

collaretteepidermisepitheliogenesis

imperfectaerosionerythemaerythema

multiformeerythrodermaEVAexcoriationexfoliateexfoliative

dermatitisexudatefibromafibrosarcomafissurefistulafolliculitisfomes (fomites)furunculosisgangrene

granulomaguard hairshabronemiasis

bacterial cause of rain scald and greasy heelorganism that causes fungal infection of skinskin area between epidermis and fat layershereditary lesion often seen on skinplate or scutum on hard ticksinflammation of the outer skin layersurgery by use of an electric currentclot in blood, blocking artery (usually part of thrombus)agent that soothes irritationstudy of hormonesa type of white blood cell

subcutaneous nodules containing eosinophils

circular epidermal lesionouter layer of skin

see aplasia cutisa shallow surface skin lesionredness of skin

immune complex disease with annular lesionsredness of skin over wide areaequine viral arteritissuperficial graze, as from scratchingto shed

increased skin scalingdischarge like pus or serumbenign fibrous tissue tumourmalignant fibrous tissue tumourskin crackopen skin tract, possibly from deep infectioninflammation of hair folliclesinanimate object capable of spreading infectionskin boilsdeath of body tissue with invasion by saprophytic bacteria (drygangrene occurs with arterial damage at peripheral sites, suchas the ear; gas gangrene infection caused by anerobicorganisms; moist gangrene caused by loss of blood supply,as in torsion)tumour-like mass of granulation tissuelong hairs of body coatdisease caused by Habronema species (also called summer

198 Parasites and Skin Diseases

sores, bursatii, swamp cancer, kunkers, esponja and granulardermatitis)subcutaneous swelling consisting of bloodbenign tumour of blood vesselsparasitic wormgenetically transmitted traithairy statemicroscopic study of tissuemicroscopic study of abnormal tissuefungal infection with primary focus in lungs (also cause ofepizootic lymphangitis, pseudoglanders or African farcy)a benign disease caused by a poxvirus.excessive sweating, often seen after prostaglandin injectionhypertrophy of skin horny layerhirsutismsubcutis

reduction in normal pigmentationalopecia

increased skin pigmentation

study of immune diseases

therapy designed to aid or stimulate immunityhardening of skindisease caused by microorganisms or internal parasitesparasitic disease of the skintissue reaction to insult or infectionclass of arthropodswithin the skin

local tissue loss on ears, etc., a symptom of ergot poisoningprotein of epidermis, etc.kills larvae

haematomahaemangiomahelminthhereditaryhirsutismhistologyhistopathologyhistoplasmosis

horsepoxhyperhydrosishyperkeratosishypertrichosishypodermishypo-

pigmentationhypotrichosishyper-

pigmentationimmuno-

pathologyimmuno-

therapyindurationinfectioninfestationinflammationInsectaintradermalischaemic

necrosiskeratinlarvicidalleiomyosarcoma malignant tumour of smooth musclelesionleukodermaleukotrichialichenificationlipomalymphocytelymphoedemalymphoma

pathological tissuedepigmentation after injury, etc.whitening of hair after injurythickening and folding of the skina benign tumour of fata white blood celloedema due to lymphatic obstructiontumour of lymphoid tissue

Glossary 199

macrophagemaculemangemast cellmastocytomamelanomamelanosarcomametacercariametastasismicrofilariaMicrosporummiracidiummolloscum

contagiosummonocytemycetomamycosismyiasisnecrosisNematodaneoplasianeoplasmneurofibromaneutrophilnodulenodular

necrobiosisoedemaotoscopepanniculitispapillomatosispapuleparasiteparesispatchpemphigus

foliaceusphaeohypomy-

cosisphotodermatitisphoto-

sensitisationplaquepolydypsia

scavenger cell of tissueskin spotdisease caused by mitesbody defensive cellmast cell tumourtumour common in grey horsesmalignant melanomalarval stage of liver flukespread of disease from one organ to anotherlarval stage of worms like Onchocerca and Setariafungus causing ringwormlarval stage of liver fluke

skin disease caused by a poxvirusa white blood cellsubcutaneous bacterial or fungal growthdisease caused by fungibody invasion by fly larvaeprocess of cell deathroundworm classgrowth formationnew growth, usually refers to tumourbenign tumour of peripheral nervea white blood cellsolid lump of skin

multiple nodules of skin in horsefluid accumulation under skin or in body cavityinstrument for ear examinationinflammatory condition of subcutaneous fatrefers to multiple wart growthsmall elevation of skinorganism that lives on anotherpartial paralysis, often of hind legsdefined skin lesion

general scaling disease

diffuse fungal dermatitiscondition of skin due to sunlight exposure

acquired reaction of skin to sunlightlarge patchabnormal thirst

200 Parasites and Skin Diseases

polyphagiapolyuriapredilection siteproboscisprognosisProtozoaproud fleshpruritispustulepyodermarediareservoir host

resistanceringwormsarcoidscalescarschirrous cordsclerosisseborrhoeasebumsensitivityserpiginous

lesionserumsinussitfastsporotrichosissquamous cell

carcinomaSt John's wortstranglesstratumstratum corneumsubcutissubcutaneous

emphysemasweet itch

abnormal hungerexcessive urinationsituation parasite lives in/on bodysucking mouthpart of insectlikely disease outcomesingle-cell family of organisms (includes Coccidia)exuberant wound granulationitchinesspimple filled with puspurulent skin diseaselarval stage of liver flukeanimal that acts as source of infection for others, usually withoutshowing signs of diseaseability to withstand disease, or druga fungal infection of skinskin tumourskin flakerepaired (skin) after woundenlargement of spermatic cord after castrationhardening from inflammationincrease of sebum production with scaling and crustsoily product of sebaceous glandsopen to disease, or organism susceptible to drug

having wavy outlinefluid part of blood after clottingcavity, as in paranasal sinus, or open discharging tractsore on withers caused by saddlefungal skin disease

malignant tumour of skin/mucous membrane junctiona plant cause of photodermatitisa bacterial disease marked by abscess formationlayerouter layer of the skinlayer beneath the skin

air or gas under skinskin disease due to fly bites (also called Queensland itch,dhobie itch, Kasen, summer eczema)

sweat glandadenoma benign tumour of sweat gland

tardive late, inherited trait appearing after birthtetanus bacterial disease caused by Clostridium tetani

Glossary 201

thermo-regulation regulation of body temperature

thrombus clot within vessel, may include worm larvaetitre serum level measured against specific entity, like a virustopical application of drug, etc., to local skin areatoxin a poisonTrematoda parasitic family that includes flukeTrichophyton fungal cause of skin diseasetrypanosomiasis protozoan disease caused by Trypanosoma speciestumefaction a skin swellingtumour a mass or swelling, synonymous with neoplasmthermal injury burn (including firing marks, cryosurgery)ulcer a lesion that penetrates the skin (or other tissues)ulcerative

lymphangitis bacterial infection of lymphatics in lower limbsunilateral papular

dermatitis papules that appear on one side only of horse, cause unknownurticaria hivesvellus hairs smaller hairs of body coatvesicle small blistervibrissae sensory hairs or whiskersvitiligo local loss of skin pigmentwart papillomawheal urticarial lesionzoonosis disease transmitted from animal to manzygomycosis fungal skin disease

Index

abdominal worm 47-9abrasion 99abscess 145absorption (of food) 9acariasis 136acne 147Actinobacillus mallei 148Actinomyces 148actinomycotic mycetoma

148Aedes 48, 119aflatoxin 163African horse sickness 114albinism 182allergen 154allergic reaction 12allergy 154-8

tests 97alopecia 185

areata 187A mblyomma 136AMTRA (Animal Medicines

Training RegulatoryAuthority) 78

amyloidosis 177anaemia 10aneurysm 13, 21, 24angioedema 158anhidrosis 177Anopheles 119Anoplocephala 8, 59, 68Anoplocephala magna 56-8

Anoplocephala perfoliaita56

Anoplura 110, 128anorexia 8antibody 154antifungals 86antigen 154Apis mellifera 121aplasia cutis 182Arachnida 131, 140A rgasidae 136-7arsenic 163arsenical poisoning 163ascarids 34-8, 82, 83Aspergillus 152Aspergillus flavus 163aural plaque 173, 179

Babesia caballi 65bacterial disease 141basal cell tumours 167bees 122beetles (Coleoptera) 110benzimidazole drugs 67, 75,

85benzyl benzoate 85biopsies 97black hair follicular

dysplasia 182blowfly 120boils 144, 145Boophilus 136

botfly 121-5bots 18, 76, 81, 84, 121-5bowel damage 11Brachycera 110Brucella abortus 180bugs 110burns 107

Calliphora 112Calliphoridae 112Canadian horsepox 147Candida albicans 152cannon keratosis 189carbon disulphide 80cavalryman's itch 133cellulitis 146Ceratopogonidae 113cercariae 61, 62, 64Cestoda 18, 56chiggers 135Chorioptes 131, 134Chorioptes equi 134chorioptic mange 134Chrysomya 112, 121Chrysomya bezziana 112Chrysops 119Claviceps purpurea 164climatic conditions 14, 15Clostridium tetani 102Coccidia 18, 65Cochliomyia 121Cochliomyia hominivorax

112

204 Parasites and Skin Diseases

Coleoptera 110collagenolytic granuloma

(equine eosinophilicgranuloma, or EEG) 178

complement fixation test 98congenital disease 182constipation 13contact dermatitis 161contusions 99corticosteroids 117Corynebacterium

pseudotuberculosis 146,147

coughing 34coumaphos 85Culex 48, 119Culicoides 113-17, 156, 159Culicoides nubeculosus 45,

114, 116Culicoides pulicaris 114Culicoides robertsi 114curly coat 182cutaneous asthenia 182

habronemiasis 52muscle 93onchocerciasis 75vasculitis 189

cyathostomes 25, 67, 68, 70,72, 74

Cyathostomum 25, 69, 80,82, 88

Cyclorrhapha 110cypermethrin 85cytology 97, 180

Damalinia equi 128dead tissue 104deer fly 110, 119demodectic mange 136Demodex 131Demodex equi 136dentigerous cysts 182Dermacentor 65, 136

nitens 136, 137Dermanyssus 136Dermatobia hominis 112Dermatophagoides 156Dermatophilus 142

Dermatophilus congolensis117, 141

dermis 92diarrhoea 13dichlorophene 59dichlorvos 80Dicrocoelium dendriticum

60Dictyocaulus 68Dictyocaulus arnfieldi 5, 32,

34Dictyophora 110Diptera 110discoid lupus erythematosus

187diseases of external ear 169dosing 74, 78dourine 66drainage 64Draschia 52, 68Draschia megastoma 52, 54,

118dressings 103drugs resistance 67dung beetles 55

ear disease 179Echidnophaga 131Echinoccus granulosus 60ectoparasites 17, 109Eimeria leuckarti 65emboli 13, 21embolic colic 21, 24encysted cyathostomes 26,

68, 70endoparasites 6enilconazole 87epidermis 92epitheliogenesis imperfecta

182equine coital exanthema

(ECE) (horse pox) 173,192

equine encephalomyelitis119

equine eosinophilicgranuloma (EEG) 168

equine infectious anaemia

(EIA) 117, 119equine protozoan

myeloencephalitis 66equine viral arteritis (EVA)

193ergot 164ergot poisoning 169erosion 97erythema multiforme 188erythroderma 107examination of faeces 88-9eyeworm 20, 49-52

face flyfaecal

egg count 75samples 89

faeces, examinationof 88-9

farcy 148Fasciola 6, 60-4, 68, 69Fasciola gigantica 61Fasciola hepatica 60Fasciola magna 61febantel (Bayverm) 80fenhendazole (Panacur) 74,

80fibroblastic sarcoids 173,

174fibromas 167fibromatosis 168fibrosarcoma 168filling in the legs 180-1first-aid 102fistula 145fistulous withers 180fleas 109, 110, 131, 140flies 110-27flotation solution 90-1fluke 18, 56, 60-4fly screens 116fly worry 110foaling-heat scoursfolliculitis 144fomites 148forage mite 131, 136functions of skin 96fungal disease 141

Index 205

fungi 155, 157furunculosis 145

Gasterophilus 68Gasterophilus

haemorrhoidalis 122, 123Gasterophilus intestinalis

122, 123Gasterophilus nasalis 122,

123generalised steatitis 177girth galls 191-2glanders 148gnat 110goiter 186Gonglyonema 20, 54, 68Gongylonema pulchrum 54granulation tissue 106granuloma 147greasy heel 142griseofulvin 86gullet worm 54-6

Habronema 20, 52, 54, 68,82, 117

Habronema microstoma 52Habronema muscae 52, 118haemangioendothelioma 168haemangioma 168haemangiosarcoma 168Haemaphysalis longicornis

137haematomas 181Haematopinus asini 128Haematopota 119hair 95hairworm 38-41haloxon (Multiwurma) 81hard ticks 136harrowing 73harvest mite 131, 135, 136Hemiptera 110hereditary disease 182heterogonic larvae 29Hippobosca equina 119hippoboscids 119hirsutism 185homogonic larvae 29

honey bee 121hormonal disease 185horn fly 118horse fly 110, 118horse pox 192horse roundworm 8, 34-8host specificity 5house fly 118Hyalomma anatolicum 137Hydrotoea irritans 118Hymenoptera 121Hypericum perfoliatum 164Hypoderma bovis 68, 125hypothyroidism 186

immune disease 186immunity 12immunotherapy 158, 191infective larvae 19, 22, 31,

40, 70Insecta 18, 56, 110, 140insecticides 85intensification 76iodine poisoning 165,ivermectin (Eqvalan) 74, 81Ixodes 136Ixodes holocyclus 138,Ixodes ricinus 137,Ixodidae 136

keratinization disorders 189keratoma 168Klosiella equi 65

laboratory analysis 88lacerations 99lactation 16large redworm 20-5large strongyles 20-5, 68,

69, 70, 80, 81, 82, 83leishmaniasis 191leukoderma 182leukotrichia 185levamisole 82lice 86, 109, 110, 127-131,

140Limnaea truncatula 60linear keratosis 189

lipoma 169liposarcoma 169liver fluke 6, 60-4, 76, 77,

83Lucilia 112, 120lungworm 5, 19, 32-4, 82lupus erythematosus 187lymphangitis 189-90lymphosarcoma 169

malignant melanoma 171Mallophaga 110, 128mange 132-5Margaropus 136marita 62mast-cell tumours 170mebendazole (Telmin) 82Medicines (Veterinary

Drugs Pharmacy andMerchants' List) Order(1992) 78

Medicines Act (1968) 78melanoma 167, 170-1mercury poisoning 165metacercariae 62microfilariae 45, 47microscope 90Microsporum 86, 148, 151,

152Microsporum gypseum 149midges 113migrating larvae 21, 32, 35miracidium 61, 62, 64mites 109, 131-6, 140mixed grazing 73mixed infections 16mixed sarcoids 173-4molluscum contagiosum 192mosquitoes 48, 110, 119-20motor oil 165moulds 155, 157mud fever 117, 142, 143Musca 118Musca autumnalis 49, 118,Musca domestica 118,myiasis 52-3, 112myxoma 170myxosarcoma 170

206 Parasites and Skin Diseases

natamycin 87neck threadworm 44-7Nematocera 110Nematoda 18Neotrombicula 131, 135Nilverm 82Nocardia 148nodular panniculitis 190Notoedres 131

occult sarcoid 173, 175oedema 13Onchocerca 20, 44-7, 68,

82, 159, 182Onchocerca cervicalis 44-7,

114Onchocerca reticulata 46open wound 104oribatid mite 57-8otitis externa 179Otobius 136, 140Otobius megnini 137Otodectes 131oxfendazole (Systamex,

Synanthic) 82oxibendazole 83oxyclozanide (Zanil) 83Oxyuris 18, 41-4, 68, 69,

76, 77, 80, 81, 82, 83, 84,182

Oxyuris equi (pinworm) 18,41-4

pain 12-13papillomas 171papillomatosis 171Paranoplocephala

mamillana 59Parascaris 7, 8, 11, 20,

34-8, 68, 76, 77, 84Parascaris equorum 7,

34-8, 68pasture contamination 70pediculosis 128pemphigoid 187pemphigus foliaceus 169,

187pentachlorophenol 165

permethrin 86Phlebotomus 191photosensitisation 164piebaldism 185pigment disorders 182Pilobolus 34pinworm 18, 41, 44, 75, 77piperazine 75, 83piperonyl butoxide 86piroplasmosis 65plug feeders 24, 27, 41PML (Pharmacists and

Merchants List Category)78

poisons 163Polestes humitis 121poll evil 191pollen 41-4, 154, 155, 157predilection site 7prepatent period 22, 26, 32,

36, 45productivity 16proglottid 56-7Protozoa 18, 56, 64-6protozoan skin disease 191proud flesh 102, 106Psoroptes 131Psoroptes cuniculi 133Psoroptes equi 133psoroptic mange 133puncture wounds 99purpura haemorrhagica 179pyrantel embonate

(Strongoid-P) 74, 83pyrethrum 86

quantity of parasite 6Queensland itch 114

rain scald 117, 141red poultry mite 136rediae 62redworm 20-8reproduction 16Rhinoestrus purpureus 112Rhipicephalus 136Rhodococcus equi 145, 146,ringworm 86, 148-52

roaches 110roundworm 8, 18, 19, 34-8Royal Pharmaceutical

Society (AnimalMedicines Division) 78

saddlegalls 127, 191sores 191-2

Saddlers List 78sandfliessarcoids 167, 173-6Sarcoptes 131, 133Sarcoptes scabei var equi

132sarcoptic mange 132schwannoma 177screw-worm 120seasonal influences 15, 76sebaceous gland 94sebaceous gland tumour 177seborrhea 192sebum 94selenium toxicity 166Senecio jacoboea 164Setaria 47-8, 68, 117, 119Setaria equina 47signs of infestation 13Simulium 119Siphonaptera 110sitfast 181skin 92-4

repair 99scrapings 97tuberculosis 148

small redworm 25-8small strongyles 25-8, 68,

69, 80, 81, 82, 83spinose ear tick 137sporocyst 62sporotrichosis 153sporulation 65squamous cell carcinoma

(SCC) 176St John's wort 164stable fly 117stable hygiene 72, 77Staphylococcus 144

Index 207

stomach worm 52-4Stomoxys calcitrans 117strangles 145stratum corneum 92stratum germinativum 92strawberry birthmark 185Streptococcus equi 144, 145,

178Streptococcus

zooepidemicus 144strongyles 20-8Strongyloides 20, 69, 76, 80,

81, 82, 83, 84Strongyloides westeri 30,

31, 75Strongylus 27Strongylus edentatus 20, 22,Strongylus equinus 20, 22,

23Strongylus vulgaris 20, 21,

22, 23subcutis 93Suitably Qualified Persons

(SQP) 78summer dermatitis 114summer sores 52sweat 94

sweat gland tumour 177sweat glands 94sweet itch 86, 113-17, 156

Tabanus 118Taenia hydatigena 60,Taenia multiceps 60tapeworm 8, 18, 56-60, 74,

75, 76, 83, 84Thelazia 20, 49-52, 68, 118Thelazia lacrymalis 49thiabendazole 75, 83threadworm 28-32, 46ticks 109, 136-40topping (pasture) 73Trematoda 18, 56trematodes 60trichlorfon 84Trichophyton 86, 151, 152Trichophyton equinum 148Trichostrongylus 68, 69, 82Trichostrongylus axei

38-40, 41, 74, 77Trypanosoma equiperdum

66trypanosomiasis 119tsetse fly 119

tumours of pituitary gland185

tumours of skin 167Tunga 131Tyrophagus 131, 136

ulcerative lymphangitis 146unilateral papular dermatosis

190urticaria 158

Venezuelan equineencephalitis 114

verrucous sarcoid 173, 175vesicular stomatitis 193viral disease 192viral papular dermatitis

193vitiligo 185

warble fly 125-7warts 167, 171-3wasp 121worm control 67worming 77

calendar 84wounds 99