Equine Health Update February 2017 Issue - Page 28

EQUINE | Equine Disease Update

EQUINE | Equine Disease Update

gins in the proximal small intestine and subsequently spreads to the colonic epithelial cells , leading to blunting of the intestinal villi and subsequent villous atrophy . Loss of epithelial cells results in malabsorption and maldigestion of nutrients and acute diarrhea . Following a short incubation period of 48-72 hours , adult horses develop fever , anorexia , and depression . Changes in fecal character , ranging from soft-formed stools to watery consistency , and colic are seen in less than 20 % of affected horses . A small number of horses develop acute neurologic signs due to hyperammonemia , which may manifest as severe depression , head pressing , ataxia , proprioceptive deficits , recumbency , nystagmus , and seizure .
Common hematological abnormalities are leucopenia due to neutropenia and / or lymphopenia . ECoV infection generally resolves within 1-4 days with supportive care consisting of the administration of antiinflammatory drugs and oral or intravenous fluids . Fatalities have been associated with septicemia , endotoxemia as well as metabolic abnormalities leading to encephalopathy ( hyperammonemia ). Historically , the detection of ECoV has relied on either electron microscopy , antigen-capture ELISA , or viral isolation from the feces . All of these detection modalities lack sensitivity , especially if Equine Coronavirus – An Emerging Enteric Virus of Adult Horses viral particles are not present in sufficient numbers . Quantitative polymerase chain reaction ( PCR ) assay for the detection of ECoV nucleic acid has supplanted many conventional virological assays , mainly due to its short turn-around-time , high throughput capability and increased analytical sensitivity and specificity . The overall agreement between clinical status and PCR results for ECoV is over 90 %, making fecal PCR the diagnostic tool of choice . Infected horses can shed ECoV up to 14 days . Due to the fecal-oral transmission route and the highly infectious nature of ECoV , commonsense biosecurity protocols should be instituted during an outbreak of ECoV . ECoV PCR positive horses ( clinical or subclinical ) should always be isolated from the rest of the equine population to decrease the exposure risk and environmental contamination . Potentially exposed horses should not be moved until their definitive infection status has been determined . For isolation purposes , use an empty barn or an isolation unit . In a barn situation , close one end of the barn and use it as isolation area . Caretakers and owners should wear gloves , protective clothing ( coveralls or disposable gowns ), and dedicated footwear . Good hand hygiene should be instituted ( faucet with warm / cold water or hand sanitizer ). Barrier nursing techniques should be established in the form of footbath or mats in front of the isolation unit and each stall . This will minimize the spread of pathogens from stalls to clean areas . It is very important to control traffic and minimize contact of affected horses with the general public . Hygiene should be maximized by regular cleaning and disinfecting . Contact : Nicola Pusterla , DVM , PhD , Diplomate ACVIM npusterla @ ucdavis . edu ( 530 ) 752-1360 Department of Medicine and Epidemiology , School of Veterinary Medicine UC Davis , California
Screwworm Myiasis
Myiasis is the infestation of vertebrate animals by larvae ( maggots ) of any species of fly . Some fly species are specialized to use amphibian , reptilian , or avian hosts , but most usually infest mammals . In horses , the typical and most widespread of such parasites are species of internal bot flies ( Gasterophilus spp .), but many other maggots ( e . g . blow flies and / or flesh flies ) may facultatively infest equines externally . Although none of these typically poses a serious threat to hosts , screwworms are a separate and often dire exception . Unlike the others , the New World screwworm , Cochliomyia hominivorax , is a specialized native blow fly and obligate parasite whose maggots voraciously feed only on living tissues of warm-blooded animals .
28 • Equine Health Update •