Faculty of Veterinary Medicine and Animal Science Department of Clinical Sciences Complications to strangles in horses presented at referral hostpitals Anna Katarina Sjöblom Degree Project 30 credits within the Veterinary Medicine Programme ISSN 1652-8697 Examensarbete 2014:54 Uppsala 2014 Complications to strangles in horses presented at referral hospitals Komplikationer till kvarka hos hästar inkommande till remitterande hästsjukhus Anna Katarina Sjöblom Supervisor: Professor John Pringle, Department of Clinical Sciences Examiner: Miia Riihimäki, Department of Clinical Sciences Degree Project in Veterinary Medicine Credits: 30 hec Level: Second cycle, A2E Course code: EX0736 Place of publication: Uppsala Year of publication: 2014 Number of part of series: Examensarbete 2014:54 ISSN: 1652-8697 Online publication: http://stud.epsilon.slu.se Key words: Stangles, equine, horses, complication Streptococcus equi subsp. equi Nyckelord: Kvarka, häst, komplikationer, Streptococcus equi subsp. equi Sveriges lantbruksuniversitet Swedish University of Agricultural Sciences Faculty of Veterinary Medicine and Animal Science Department of Clinical Sciences SAMMANFATTNING Kvarka är en smittsam luftvägssjukdom som drabbar hästar. Kvarka orsakas av bakterien Streptococcus equi supsp. equi. Den klassiska symptombilden är feber, näsflöde (24-48 timmar efter feber) först tunt och klart sekret sedan mer tjockt samt svullna lymfknutor och svårigheter att svälja. De svullna lymfknutorna kan bilda abscesser som sedan kan spricka upp med varutträde. Det är de unga hästarna som visar kraftigast symptom och de äldre hästarna mildare. Bakterien sprids både direkt och indirekt och utsöndring av bakterier börjar 24-48 timmar efter första febertoppen. Inkubationstiden är 3-14 dagar och det är när utsöndringen av bakterien börjar som provtagning kan ske. Nässvabbsprov, nässköljsprov och provtagning av purulent exsudat och analys via odling och PCR används. Symtomlösa smittbärare som intermittent utsöndrar bakterier från luftsäckarna är en trolig smittspridare. Kvarka kan efter infektionens utbrott leda till olika följdsjukdomar. Dessa kan vara allvarliga och leda till stora djurlidanden. De mest omskrivna komplikationerna är lunginflammation, kastad kvarka, anasarka (purpura hemorrhagica) och myosit. I denna retrospektiva studie ingick 69 hästar remitterade till hästsjukhus på Universitetsdjursjukhuset SLU samt Regionhästsjukhuset Helsingborg. Av dessa drabbades fyra hästar av ovannämda komplikationer. De vanligaste symptomen var feber och dysfagi. De vanligaste komplikationerna var svullna retropharyngeallymfknutor och purulent exsudat i luftsäckarna. Det fanns en korrelation mellan svullen pharynx och dysfagi och feber. Det fanns även en korrelation mellan svullna retropharyngeallymfknutor, näsflöde och dyspné. Fem av hästarna avlivades varav tre på grund av ekonomiska skäl, en i djurskyddssynpunkt och en självdog på kliniken. En sjätte häst dog hemma, uppgifter om orsak saknas. 32 hästägare kontaktades per telefon för uppföljande kontakt om hur hästens sjukdom utvecklats efter hemgång. Av dessa hade 27 hästar tillfrisknat och fyra hade avlivats. SUMMARY Strangles is a highly contagious disease in horses. Strangles is caused by the bacteria Streptococcus equi subsp. equi. Common clinical signs are fever, nasal discharge (24-48 h after onset of fever), swollen lymph nodes and problems swallowing. The swollen lymph nodes may form abscesses that may erupt. Younger horses suffer from more severe clinical signs than older horses. The bacterium is spread within 24-48 hours after the first onset of fever and is transmitted either direct or indirect. The incubation time is 3-14 days and when transmission of the bacteria begins samples can be taken. The diagnosis of strangles is based on clinical symptoms and laboratory findings like culture, PCR and/or serology. But culture of nasal swabs, nasal washes and aspirated pus from abscesses remains the gold standard. Asymptomatic carriers that intermittently shed the bacteria are a source of transmission. Strangles may lead to several complications. These are severe and cause loss in animal welfare. Pneumonia, bastard strangles, purpura hemorrhagica and myositis are the most mentioned common complicatiations in the literature. In this retrospective study included 69 horses referred to two equine hospitals. Four of them developed the above-mentioned complications. The most common presenting clinical signs were fever and dysphagia. The most common clomplications were swollen retoropharyngal lymph nodes and purulent discharge in the guttural pouch. There was a correlation between swollen pharynx and dysphagia and fever. There was also a correlation between swollen retropharyngal lymphnodes and nasal discharge and dyspnea. Five of the horses were euthanized, of which three were because of economic reasons, one because of animal welfare and one died by natural causes at the hospital. A 6th horse died at home and no cause of death was recorded. 32 owners were contacted by telephone for a follow-up. 27 horses recovered fully and four horses were euthanized. Complication ratesand case fatality in horses referred for care of strangles in Sweden appeared similar to what was reported in field cases, with the exception that no diagnosis of myositis was observed in these horses. CONTENTS INTRODUCTION ................................................................................................................................................ 1 MATERIALS AND METHODS ......................................................................................................................... 1 LITERATURE REVIEW ..................................................................................................................................... 2 ETIOLOGY ........................................................................................................................................................................... 2 PATHOGENESIS.................................................................................................................................................................. 3 CLINICAL SIGNS ................................................................................................................................................................. 3 The guttural pouches...................................................................................................................................................... 4 DIAGNOSIS ......................................................................................................................................................................... 4 Hematology and other diagnosis .............................................................................................................................. 5 VACCINATION .................................................................................................................................................................... 5 EPIDEMIOLOGY .................................................................................................................................................................. 5 Immunity .............................................................................................................................................................................. 6 DETECTION OF CARRIERS ................................................................................................................................................ 7 Treatment of carriers ..................................................................................................................................................... 7 TREATMENT ...................................................................................................................................................................... 8 HOW TO MANAGE AN OUTBREAK OF STRANGLES ........................................................................................................ 8 COMPLICATIONS................................................................................................................................................................ 9 Pneumonia ........................................................................................................................................................................... 9 Bastard stangles – metastatic spread .................................................................................................................... 9 Purpura hemorrhagica ................................................................................................................................................10 Myositis ...............................................................................................................................................................................11 Agalactia ............................................................................................................................................................................12 Other complications ......................................................................................................................................................12 RESULTS ........................................................................................................................................................... 12 HORSES AT REFERRAL HOSPITAL ................................................................................................................................