Ovine pneumonic pasturellosis--a clinical, pathological and therapeutic study.
Bronchopneumonia caused by Pasturella multocida or Mannheimia haemolytica or combination of both has a cranioventral lung distribution and affects sheep and goats of all ages worldwide where complicated secondary pasturella infections are precipitated by primary viral respiratory infections (Aiello 2012). These common inhabitants of tonsils, nasopharynx and proximal digestive tract of apparently healthy animals, following exposure to environmental and managemental stressors, precipitate diseases including ovine pneumonia, septicaemia in lambs, ovine enzootic pneumonia (Radostitites et al., 2009; James et al., 201 3). Pasturella pneumonia and septicaemia (<25%) precipitated by altered immunity consequent to various stressors and climatic attributes with significant morbidity and mortality among ovines (Kumar et al., 2004, Kumar, 2005, Latif et al., 2012).
Materials and Methods
Five hundred and twenty one sheep and lamb carcasses in age group of 3 months to 4 years, referred within 12-24 hrs after death for postmortem examination constituted the basis of study. Comprehensive history, feeding practices, disease status, clinical picture, therapeutic protocols and response to treatment were recorded by examination of flocks and collecting data from concerned Veterinarians while considering the contributing factors like age, sex and season, climatic and managemental factors.
Impression smears from cut sections of lungs, liver and heart blood smears were methanol fixed and stained with Giemsa and Grams stain. Sterile heart blood swabs and lung tissue swabs from fresh carcasses were collected. Sections of selected specimens were sent to Veterinary Biological Research Institute (VBRI), Hyderabad for histopathological analysis.
Heart blood and lung tissue swabs from twenty two animals, positive for bipolar organisms on impression smears were incubated in sterile tryptose soya broth for 24 hours at 37[degress]C and streaked over blood and Mackonkey agar. General appearance of colonies (morphology, size, color, consistency) were noted, typical colonies were stained using gram's staining, examined under light microscope, inoculated over Simmons citrate agar, Triple Sugar Iron agar and subjected to MR-VP test as per Quinn et al. (1994).
The isolates were subjected to Antibiotic sensitivity test using antibiotics commonly used by Veterinarians with antibiotic sensitivity discs as per Bauer et al. (1966). Control of infection was managed by Ceftriaxone with Tazobactum (5mg/ kg I/M), Tylosin (10mg/kg BID I/M) and Flunixin meglumine (2mg/kg I/M). Atrophine sulphate (0.6 mg/kg), Bromohexedine tablets 2mg BID), Multivitamin and Mineral bolus (Nutrisacc (a) bolus) and Probiotics (Ecotas (b)) are included to manage respiratory symptoms and as adjuvant to treatment.
Results and Discussions Selection of animals
Of the 521 ovine post mortems conducted 248 (47%) were lambs, 3-8 months of age and 273 (52.3%) were adults sheep, mostly ewes, all belonging to small to medium sized flocks of 40-100 animals. They were migratory in their habitat, fed exclusively on grazing without any supplementation and with limited access to drinking water. 99 lambs (39.9%) and 89 adults (32.6%) were found to be affected by pneumonia, septicaemia and their organ impression smears were found positive for bipolar stained organisms.
Animals were exposed to environmental stress, had no housing facility and had to walk for long distances for grazing. The mean ambient temperature was 18-46[degrees]C, rainfall was 1063 mm with increasing trend towards deficit to scanty rainfall and dwindling pastures. Most of the animals were underweight with mean adult weight of 17.4 kg and lamb weight of 3.2 kg. The body condition score was average to poor ranging from 2-2.5/5 with carcass yield of 30-40%. All animals of flocks were reported to be dewormed two to three times a year and were vaccinated against Enterotoxemia, PPR, sheep pox with history of inconsistent foot and mouth vaccination.
The disease occurred in all ages and both sexes. However lambs in first few months of age, weaned lambs and middle aged ones appears to be more affected. Stressors like early weaning, inadequate access to colostrum, transportation, lack of housing facility, sudden change in weather are found to be precipitating factors. Majority of animals had moderate Strongyle ova infestation and anaemic changes in blood smear which increase susceptability to infection. Selection of ram lambs prior to their weaning age and procurement of ram lambs from different sources were significant contributory factors for clinical infections. Highest incidence in lambs was recorded during September-November and lambs born during October-November succumbed significantly due to pneumonia than those born in March-April. In adults, the incidence is highest during December-February (Table 2). The climate between August to February tends to be humid becoming gradually dry and cold with chilly winds. Susceptible lambs exposed to such weather are affected earlier and adults who initially resisted the cold humid weather affected at the height of winter. The period of birth had significant effects on lamb losses due to pneumonia in all age groups while the season of birth had a significant influence on mortality to 3 months of age (Ajoy et al., 2005) (Fig. 1).
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Sudden deaths in absence of premonitory signs, pyrexia (104-106F), anorexia, depression, respiratory distress while at rest, dyspnoea, slight frothing at mouth, occulonasal discharges etc. are observed.Septicaemic changes like fever, listlessness, poor apatite, recumbency and death were prominent in young lambs <2 months. Adult sheep showed more prolonged course of respiratory symptoms and may survive for 2-4 days. Arthritis and nervous symptoms like circling and convulsions were also observed. Recovered animals failed to gain weight, suffer from comorbidities like parasitism and anaemia, can become shedders and became early cullers.
Post mortem findings
Out of 521 post-mortem examinations, 185 animals showed gross lesions suggesting pneumo septicaemia of which 102 (41.6%) were lambs and 83 (32.2%) are adults. Their tissue impression smears esp. lungs and heart blood smears contained large number of bipolar organisms. Both septicemic and pneumonic lesions were comingled and former are prominent in younger lambs (3-4months) and pneumonic changes are conspicuous among adult carcases.
The general condition of carcases showing prominent septicemic lesions are fair to poor, congested conjunctival membranes, subcutaneous echymotic haemorrhages over neck and thorax, hemorrhagic trachitis with blood stained froth were important lesions. Liver was congested with focal to discrete necrotic areas. Tonsillar and pharyngeal lymph nodes are oedematous and there were necrotic lesions of oesophagus and pharynx.
The lungs were oedematous, with patchy to diffuse areas of consolidation, grey hepatisation especially involving apical, cardiac and diaphragmatic lobes. Fibrino purulent necrotic lesions over pulmonary surface with pluratic adhesions, pluracy and cardiomegaly and pulmonary abscesses in recovered and ill thrift cases well circumscribed hemorrhagic areas with sanguineous mucopurulent discharges oozing from bronchi and bronchioles. HPE revealed thickening of intra-alveolar septa, alveolar oedema, necrosis, with areas infiltrated by polymorphs and mononuclear cells. The lesions are in agreement with Odugbo et al., 2006 and Radostitis et al., 2009 (Fig. 2-6).
Bacteriological studies and Antibiotic sensitivity test
Bacterial isolates were gram negative coco bacilli with bipolar staining, dew drop, mucoid and non haemolytic colonies, no growth on Mac Konkey agar, negative for MR-VP test on Cimmons citrate agar and identified as Pasturella sp. (OIE Manual, 2004). Antibiotic sensitivity pattern of bacterial isolates (Table 3) indicated highest sensitivity to Ceftriaxone (92%), Chloramphenicol (88%) Cefotaxime (80%), Ciprofloxacin (72%). Despite diverse in site of origins, isolates exhibited uniformity in sensitivity pattern. Ragab et al. (2015) recorded Erythromycin, Rifampicin, Ciprofloxacin and Chloramphenicol while Marru et al. (2012) reported Chloramphenicol, Tetracycline, Sulfamethaxazole as sensitive antibiotics for ovine pasturellosis. In the present study, there is a trend of increasing resistance to Cotrimethaxazole, Doxycyclin, Tetracycline, Gentamicin and Streptomicin. The practice of indiscriminate and erratic use of antimicrobial drugs probably led to development of antibiotic resistance (Table 3).
Therapeutic management of Pasturella pneumosepticemia is complex with inconsistent outcome. The strategy is a combination of an specific antibiotic and an NSAID supported by correctors of mechanical and secretory disorders of lungs. Treatment comprised of Ceftriaxone with Tazobactum (Intacef Tazo (a), 5mg/kg), Tylosin tartrate (Tysin (c) 10mg/kg BID) and Flunixin meglumine (Unizif (a), 2mg/kg) intramuscularly for five days. As the bacteria play a crucial role in pathologic cascade, the antibiotic must be administered as soon as possible with observance of earliest symptoms like anorexia and pyrexia. As the involvement of mycoplasma is suspected, Tylosine tartarate is also injected. Flunixin Meglumine, a cyclooxygenase inhibitor was selected for its anti inflammatory, analgesic and endotoxin neutralization to effectively manage fever, anorexia and dyspnoea.
Bromohexadine hydrochloride, a mucolytic expectorant was given orally @ 1 mg orally BID for 5-7 consecutive days for its secretolytic and secretomotoric effects in bronchial tract area which facilitates expectoration and eases respiratory distress (Dariusz et al., 2012). Atropine sulphate, an anticholinergic drug (parasympatholytic) is given @ 0.06 mg/kg b.wt. subcutaneously once daily for 3 days to reduce bronchial and salivary mucus secretion.
Despite intensive therapy about 50% of acute clinical cases with hyperpyrexia and respiratory distress and septicemic symptoms could be saved. This treatment is very effective for sub acute cases with moderate fever, dysponea, cough where the animals are alert and able to walk. A biannual formalin inactivated Pasturella multocida vaccine is recommended prior to risk season. Vaccines incorporating antigenically similar, iron-regulated proteins, which confer cross-protection against all sero types of bacteria are proven to be effective in control of the disease and has a primary course of two injections 4-6 week apart followed by an annual booster 4-6 week before lambing are recommended (Aiello, 2012).
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(a)--Brand of Cargill Animal Health, Benguluru
(b)--Brand of Intas Animal Health, Ahmedabad
(c)--Brand of Vet India, Hyderabad
K.V. Ramakrishna (1), B. Yoganand and Ch. Sudharani Choudhury
Animal Disease Diagnostic Laboratory Department of Animal Husbandry Eluru
West Godavari--534001 (Andhra Pradesh)
(1.) Assistant Director and Corresponding author. E-mail: firstname.lastname@example.org
Table 1: Details of ovine post mortems (PMS) conducted Year Number of PMS conducted Lambs Adults Total 2010-11 48 94 142 2011-12 23 63 86 2012-13 62 38 100 2013-14 71 22 93 2014-15 44 56 100 Total 248 273 521 Year Animals found positive Lambs Adults Total % 2010-11 20 25 45 31.7 2011-12 7 22 29 33.7 2012-13 24 9 33 33.0 2013-14 27 5 32 34.4 2014-15 21 28 49 49.0 Total 99 89 188 36.4 Table 2: Season wise incidence of pasturellosis in sheep Sept-Nov Lamb Adult Total Lamb Adult Mar-May 60 67 127 16 (26.6%) 25 (37.3%) Jun-Aug 42 67 109 23 (21.0%) 18(26.8%) Sept-Nov 85 38 123 38 (33.3%) 8 (23.5%) Dec-Feb 68 94 162 25 (16.2%) 32 (35.5%) 255 266 521 102 (41.6%) 83 (32.2%) Sept-Nov Total % Mar-May 41 32.28 Jun-Aug 41 38.00 Sept-Nov 46 37.40 Dec-Feb 57 35.19 185 35.51 Table 3: Antibiotic sensitivity pattern of Pasturella sp. in sheep Antimicrobial Concen- tration Sensitive % (ug) Amoxycillin 30 13/25 52 Amikacin 30 14/25 56 Ceftriaxone 30 23/25 92 Cephotaxime 30 20/25 80 Ciprofloxacin 5 18/25 72 Chloramphenicol 30 22/25 88 Co-trimoxazole 25 5/25 20 Doxycyclin 30 6/25 24 Enrofloxacin 10 19/25 76 Gentamicin 120 15/25 52 Kanamycin 30 15/25 52 Streptomycin 300 9/25 36 Tetracycline 30 10/25 40 Fig. 1: Seasonal incidence pattern of Pasturella pneumosepticemia in sheep. March-May 32.28 June-Aug 38 Sept-Nov 37.4 Dec-Feb 35.19 Note: Table made from line graph.
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|Title Annotation:||Clinical Article|
|Author:||Ramakrishna, K.V.; Yoganand, B.; Choudhury, Ch. Sudharani|
|Date:||Jul 1, 2015|
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