Dairy calf pneumonia: Effective treatment depends on early and accurate diagnosis

Abstract

Dairy calf pneumonia is one of the most economically important diseases of calves. A delayed diagnosis could result endemic herd problem, prolonged use of antibiotics, high recurrence rate, pulmonary abscessation and ear infections. The key for effective control is the early detection of pneumonia and the accurate diagnosis of the etiologic factor. For the early detection, a respiratory disease score was assigned based on rectal temperature, character of nasal discharge, eye discharge or ear appearance, and presence of a cough. Each clinical sign has a point scale from 0 (normal) to 4 (severe). The respiratory disease score is the sum of points from the 4 categories of clinical signs, with increasing values representing progressive severity. The scoring system results in a minimum score of 0 and a maximum score of 12. Calves with score 5 or higher, having at least 2 clinical signs of respiratory disease, are considered sick and have to be treated. For the accurate diagnosis of the etiological agent the best tool in a live calf is bronchoalveolar lavage (BAL) fluid collection. Sampling of severely affected animals should be avoided. New acute cases are ideal. BAL is performed in sedated calves using a sterilized, flexible catheter with a 5-cc balloon cuff. The fresh BAL fluid sample is processed within 2 hours of collection or refrigerated until analysis. Part of the sample is used for microbiology and the remaining is submitted for cytology. BAL fluid that yields homogenous (>106 CFU/ml) bacterial or positive Mycoplasma bovis culture is considered abnormal. A disproportionate lowering of macrophages (<61%) or elevation of neutrophils (>39%) provides evidence of an inflammatory response with or without a positive culture. The ideal antibiotic selection would be based on the antibiotic susceptibility pattern of lung pathogens after BAL fluid culture.Pneumonija kod teladi je jedna od ekonomski najvaznijih bolesti goveda. Zakasnela dijagnoza mogla bi da izazove endemski problem kod stada, da rezultira u prolongiranoj upotrebi antibiotika, visokom stepenu ponovnog javljanja, pulmonarnim abcesima i infekcijama uha. Kljuc za efikasnu kontrolu je rana detekcija pneumonije i precizna dijagnoza etioloskog faktora. U cilju ranog otkrivanja bolesti, odredjeno je bodovanje respiratorne bolesti na osnovu rektalne temperature, karaktera nazalnog iscedka, iscedka iz oka ili izgleda uha, kao i prisustva kaslja. Svaki klinicki znak ima skalu bodova od 0 (normalno) do 4 (tesko). Bodovanje respiratorne bolesti predstavlja zbir bodova za 4 kategorije klinickih znakova, tako sto povecane vrednosti predstavljaju progresivno ozbiljnije stanje. Bodovni sistem moze dati minimalni rezultat od 0 bodova ili maksimalni rezultat od 12 bodova. Telad bodovana sa 5 ili vise, kod kojih je prisutno najmanje dva klinicka znaka respiratorne bolesti, smatraju se bolesnim i treba da dobiju terapiju. Najbolje sredstvo za preciznu dijagnozu etioloskog agensa kod zivih taladi je sakupljanje tecnosti bronhoalveolarnom lavazom (BAL). Treba izbegavati uzimanje uzoraka od tesko obolelih zivotinja. Idealni su novi akutni slucajevi. BAL se vrsi kod sedirane teladi koristeci sterilizovan i fleksibilan kateter sa vazdusnim jastucetom od 5 kubnih centimetara. Svezi uzorak BAL tecnosti se obradjuje u roku od 2 sata od sakupljanja ili ostavlja u frizideru dok se ne pristupi analizi. Deo uzorka se koristi za mikrobioloska ispitivanja a ostatak za citoloska ispitivanja. Rezultat se smatra abnormalnim kada BAL tecnost pokaze homogenu (>106 CFU/ml) bakterijsku ili pozitivnu kulturu Mycoplasma bovis. Disproporcionalno smanjenje makrofaga (<61%) ili povecanje neutrofila (>39%) pruza dokaze o postojanju inflamatornog odgovora sa ili bez pozitivne kulture. Idealna antibiotska selekcija bila bi bazirana na antibiogramu za plucne patogene na osnovu kulture BAL tecnosti.