Poultry Medicine: Infectious Disease Flashcards
Which drugs have no extralabel use in food-producing animal species?
How is colibacillosis diagnosed? What 6 postmortem findings are seen?
bacteriology –> E. coli
- air sacculitis and pneumonia
- enteritis
- septicemia
- synovitis, arthritis
- omphalitis
- coligranuloma formation
How is colibacillosis treated? Prevented?
antibiotics based on sensitivity - not typically recommended due to widespread resistance
- sanitation and disinfection
- biosecurity
What causes fowl cholera? Which poultry is most commonly infected? What acts as reservoirs?
Pasteurella multocida
young, mature free-range turkeys, chickens, ducks, and geese
chronically infected, asymptomatic carriers –> wild birds, cats, dogs, pigs, raccoons, insects
What signs are associated with acute fowl cholera?
- lethargy, poor condition
- anorexia
- mucoid discharge from nares/beak
- dyspnea
- cyanotic comb/wattle
- sudden death
What signs are associated with chronic fowl cholera?
- tracheal rales, dyspnea
- nasal/ocular d/c
- swelling of sinuses, wattles, leg or wing joints, foot pads, and sternal bursa
- toricollis
- decreased egg production
- stunted growth
How is fowl cholera diagnosed?
bacterial culture of oral/nasal mucus
What 4 postmortem findings are indicative of acute fowl cholera?
- general hyperemia with widespread petechial and ecchymotic hemorrhage, especially in the lungs, subserosa, and abdominal fat
- exudative pneumonia
- hydropericardium
- swollen liver with small, necrotic foci
What postmortem finding is indicative of chronic fowl cholera?
fibrinopurulent inflammation of respiratory tract, musculoskeletal system, and integument
What treatments are recommended for fowl cholera? How is it prevented?
- antibiotics - Sulfonamides decrease clinical signs and mortality
- acute form - prolonged IV antibiotics (10 days)
eliminate reservoir, good management practices, vaccine
What causes infectious coryza? What poultry are susceptible? How is it transmitted?
Avibacterium paragallinarum - highly contagious, acute respiratory disease with high morbidity and low mortality (secondary infections common!)
chickens of all ages - disease most severe in mature birds
direct through respiratory exudates or indirect through drinking water
What clinical signs are indicative of acute infectious coryza? Chronic?
- depression
- nasal discharge and sneezing - wiping exudate on wings/back
- conjunctivitis
- hyporexia, decreased water intake
- diarrhea
- stunted growth
- decreased egg production
dyspnea and facial edema
How is infectious coryza diagnosed? What postmortem findings are seen in acute and chronic cases?
swabs of exudate placed in commercial transport medium –> serology, culture, PCR (needs feeder bacteria to grow)
ACUTE - catarrhal (fibrinous rhinitis, conjunctivitis, sinusitis), SQ edema on face
CHRONIC - bronchopneumonia, air sacculitis
How can infectious coryza be prevented?
- IDEALLY - depopulation of infected/recovered flocks, cleaning and disinfecting, restocking 2-3 weeks
- vaccination
What causes Pullorum disease? How is it transmitted? What poultry is most commonly affected?
Salmonella pullorum –> almost eradicated, caused the formation of the National Poultry Improvement Plan
- vertically through infected hen through the egg
- horizontal
chicks and poults
What characteristic signs is seen in chicks with Pullorum disease?
chicks able to hatch are typically weak/depressed and have white diarrhea and dyspnea
- these chicks infect other birds in the flock
How is Pullorum disease treated? Prevented?
cull positive birds - antibiotics will not eliminate the pathogen
- careful sourcing of new birds from disease-free flocks
- good hygiene
What causes fowl typhoid? How is it transmitted?
Salmonella gallinarum
- vertical
- horizontal
- pests and fomites
What clinical signs are indicative of fowl typhoid in adults?
- depressed
- respiratory signs, dyspnea
- pale comb/watttle
- pyrexic
- weight loss
What 4 postmortem findings are indicative of fowl typhoid?
- septicemic
- catarrhal enteritis
- miliary necrosis of liver
- pericarditis
How is fowl typhoid treated? What is prognosis like?
- antimicrobials
- supportive therapy
- cull positive birds
fair - most survivors remain carriers
How is fowl typhoid prevented?
- good hygiene and biosecurity
- use serology and bacteriology to ID carriers
What is the most common cause of gangrenous dermatitis? What poultry is most commonly affected? How is it transmitted?
Clostridium perfringens
young, growing chicks - commonly secondary to immunosuppressive disease (prior infection with IBD)
fecla-oral
What are 2 classic signs of gangrenous dermatitis in poultry? What is seen on postmortem exam?
- legs/feet are hyperemic and swollen
- tissues of wing tip, medial thigh, and ventral wing become hyperemic and slough off
- dark, moist, edematous skin patches
- discoloration of underlying muscles
- swollen internal organs
How is gangrenous dermatitis treated? Prevented?
antibiotics or culling of infected birds to prevent spread (poor prognosis)
- good biosecurity and husbandry
- minimize stress
- control immunosuppressive disease
How is Mycoplasmosis transmitted?
- vertical
- horizontal - inhalation (direct), living vectors or fomites (indirect)
What causes chronic respiratory disease (CRD)? What poultry is most commonly affected?
Mycoplasma gallisepticum
chickens and turkey
What clinical signs are seen in cases of chronic respiratory disease of chickens and turkeys? What other complications are associated?
CHICKENS - air sacculitis (dyspnea)
TURKEYS - air sacculitis (dyspnea) + severe sinusitis
- poor hatchability - embryos with curled toes and dwarfism
- pericarditis
- perihepatitis
- peritonitis
What unique signs are associated with Mycoplasma synoviae infection?
- synovitis
- arthritis
- lameness
What poultry is most common affected by Mycoplasma meleagridis? How is it transmitted?
turkeys
vertical and horizontal –> present in bursa of Fabricius, phallus, oviduct, repro tract, and contaminated semen
What 4 clinical signs are associated with Mycoplasma meleagridis infection?
- air sacculitis
- decreased hatchability
- perosis, crooked neck, osteochondrodystrophy
- birds sick at time of hatching
How is Mycoplasmosis diagnosed? What 3 postmortem findings are indicative?
direct detection and ID on special media followed by biochemical differentiation, immunofluorescence, PCR, and antibody detection by serum plate agglutination, ELISA, and hemagglutination inhibition
- catarrhal - fibrinous rhinitis, sinusitis, tracheitis, bronchitis, air sacculitis
- pneumonia
- pericarditis, epicarditis with secondary E. coli infection
What treatment is recommended for Mycoplasmosis? What is prognosis like? How is it prevented?
antibiotics - Macrolides, Tetracyclines, Fluoroquinolones
good - nearly impossible to eliminate from a flock, recurrence common
provide optimal environment and nutrition + vaccine
What causes necrotic enteritis? What is it commonly secondary to?
Clostridium perfringens –> commensal in young growing broilers
- coccidiosis
- poor diet
- stress
- intestinal mucosal damage
What characteristic postmortem finding is seen with necrotic enteritis?
diphtheritic pseudomembrane in intestines with necrotic contents
How is necrotic enteritis treated? Prevented/
- fluid therapy
- trear underlying coccidiosis
- antimicrobials - Tylosin, Amoxicillin
coccidiosis control and good husbandry
What causes quail disease? How is it transmitted?
Clostridium colinum –> ulcerative enteritis
fecal-oral - exposure alone is unlikely to cause disease unless there is stress (coccidiosis, immunosuppression)
What are 2 characteristic clinical signs associated with quail disease? 3 postmortem findings?
sudden death of birds in good condition + diarrhea, dullness
- ulceration of intestine +/- pseudomembrane
- splenomegaly
- large areas of focal hepatonecrosis
How is quail disease treated? Prevented?
reduce stress, antibiotics
- control underlying factors - coccidia, immunosuppression
- good hygiene and biosecurity
What causes Newcastle disease? What poultry is susceptible? What acts as an asymptomatic natural reservoir?
Paramyxovirus
chickens and turkeys
waterfowl –> inhalation, fomite
What are the 3 forms of Newcastle disease? What clinical signs are associated?
LENTOGENIC - endemic, mild to severe respiratory signs in young birds
MESOGENIC - endemic, respiratory + CNS signs, drop in egg production, low mortality
VELOGENIC - REPORTABLE (exotic), severe respiratory signs, paralysis, diarrhea, short duration + rapid spread, acute high mortality
What should be considered with CNS and respiratory signs?
Newcastle disease
What 2 diagnostics are used for Newcastle disease? How is it treated?
- virual isolation - conjunctival, choanal, nasal, tracheal swabs
- hemagglutination inhibition test (serotype)
- VVND - depopulate (poor prognosis)
- other forms - supportive care +/- antibiotics (good prognosis)
What causes avian influenza? Which birds demonstrate clinical signs? Which are asymptomatic reservoirs?
Influenzavirus Type A
poultry and raptors - outbreaks common in autumn/winter, transmitted by respiratory secretions, feces, feathers, and fomites
waterfowl - latent + long-term shedding without clinical signs
What are the 2 forms of avian influenza? What signs are associated?
LOW PATHOGENIC - hyporexia, lethargy, dyspnea, conjunctivitis, sinusitis, wattle cyanosis, diarrhea, high morbidity and high mortality with recovery in 3 weeks without return to previous performance
HIGH PATHOGENIC - reportable AND zoonotic. sudden death, acute respiratory distress, wattle, comb, and leg cyanosis, coughing, sneezing, nasal d/c, swollen head, eyelids, comb, wattles, and hocks, ataxia
How is avian influenza diagnosed? What 3 postmortem findings are seen?
pharyngeal/cloacal swab –> PCR
- fibrinous inflammation of URT, air sacs, and sinuses
- laying birds can develop egg yolk coelomitis
- pancreatitis, nephritis, splenic hyperplasia, catarrhal enteritis
How is avian influenza treated? What is prognosis like?
- LPAI H5/H7 and HPAI are reportable - depopulation carried out by authorities
- other subtypes - supportive care, antimicrobials
good for LPAI, poor for HPAI
How is avian influenza prevented?
- improve hygiene
- separate poultry from waterfowl/other birds
- vaccine - flock specific for LPAI
What causes fowlpox? What poultry is most commonly affected? How is it transmitted?
Poxvirus
chickens and turkeys
- direct contact with abraded/injured skin with contaminated material
- mosquitoes - Culex, Aedes
What are the 2 forms of fowlpox?
- cutaneous (dry) - proliferative nodules on unfeathered parts of body, including eyelid margins
- fibrinoproliferative (wet) - necrotic lesions of URT and GIT
What are 2 options for diagnosing fowlpox? How is it treated? Prevented?
- cytology of impression smears - large IC inclusions
- viral isolation
supportive care +/- antibiotics
vaccine + mosquito control
What causes avian infectious bronchitis? How is it transmitted?
Coronavirus –> highly contagious, acute disease of (upper) respiratory tract of chickens of all ages - most severe in young birds, may also affect urogenital tract
inhalation (direct) or fomites (indirect) - low mortality, survivors are carriers for several months, recovered birds have lasting immunity
What clinical signs are indicative of infectious bronchitis?
- respiratory signs - dyspnea, sneezing, tracheal rales, nasal d/c
- conjunctivitis and swollen sinuses
- marked decreased in egg production - soft, wrinkled eggs with watery albumin and possible hemorrhage
- nephropathogenic –> wet droppings, PD, stunted growth, mortality
How is infectious bronchitis definitively diagnosed? What 4 postmortem signs are seen?
viral isolation (egg, tracheal ring culture) + detection of viral antigen (ELISA, rtPCR, rising antibody titers
- acute phase - catarrhal inflammation of trachea and bronchial tubes (+ nares/sinuses in chicks)
- foamy air sacs
- mucoid, yellow, caseous deposits of exudate
- kidney lesions - swollen, pale, tubules/ureters distended with urates
How is infectious bronchitis treated? Prevented?
no effective treatment - isolate affected birds + optimize ventilation and heat to young chicks + improve hygiene + moisten food + antibiotics
vaccine
What causes infectious bursal disease? What is it?
Birnavirus
Gumboro - acute, contagious disease of young chickens (3-6 weeks) that results in inflammation followed by atrophy of bursa of Fabricius, damaged B cells, and immunosuppression
How is subacute infectious bursal disease diagnosed? What is the characteristic postmortem finding?
serology + bursal histopath + PCR
bursa of Fabricius filled with pus or blood
How is infectious bursal disease treated? Prevented?
supportive care + antimicrobials
vaccination
What causes infectious laryngotracheitis? What poultry are most commonly affected? Asymptomatic?
Herpesvirus
adult chickens >3 months
turkeys and ducks
How is infectious laryngotracheitis transmitted? What are characteristic signs?
direct contact with infected birds or fomites
- marked inspiratory dyspnea with harsh lung sounds
- expectoration of blood-stained mucus
- drastic drop in egg production
- high morbidity, mortality can reach 50%
- sudden death caused by asphyxia or exhaustion from prolonged illness
- MILD = conjunctivitis, rhinitis, sinusitis, tracheitis
How is infectious laryngotracheitis diagnosed? What 3 postmortem findings are seen?
PCR or respiratory conjunctival exudates + ELISA or viral neutralization 7 days after infection
- clear mucus in trachea to severe hemorrhage/diphtheritic changes of larynx and trachea
- pneumonia, air sacculitis
- hemorrhagic cloacal inflammation
How is infectious laryngotracheitis prevented?
vaccination with attenuated live vaccine –> recommended in enemic regions to develop flocks into latently infected carriers
- may cause activation of already latent carriers into virulence
What causes Marek’s disease? How is it transmitted?
Herpesvirus –> younger chickens
inhalation - matures into a fully infective, enveloped form in the epithelium of feather follicles, long term carriers may not exhibit clinical signs
What kind of disease does Marek’s disease cause?
lymphoproliferative –> B and T cells experience cytolytic infection, causing transient/permanent immunosuppression and pleomorphic lymphoid infiltration of nerve trunks and/or organs
What clinical signs are associated with classic, acute, and chronic Marek’s disease?
CLASSIC - asymmetrical limb paralysis, pale visceral tumor development
ACUTE - death in young unvaccinated birds following 24-72 hours of depression and stupor
CHRONIC - immune suppression —> worsening of current disease due to lymphocyte impairment
What 3 additional lesions are associated with Marek’s disease?
- ocular lymphomatosis - lymphocytic infiltration of iris = grey discoloration, pupillary irregularity, and blindness
- cutaneous leukosis - lymphocytic feather follicle infiltration = alters cholesterol metabolism, resulting in atherosclerosis
- transient paralysis - vasogenic cerebral edema = flaccid paralysis of limbs/neck for 24-48 hours (persistent torticollis)
How is Marek’s disease diagnosed? What 2 postmortem lesions are characteristic?
histopath of classical lesions - neoplastic lymphocytes
- CLASSIC = multiple pale visceral tumors and swollen, discolored nerves
- CHRONIC = bursa of Fabricius atrophy, thymic atrophy
What causes lymphoid leukosis-sarcoma complex? What does it cause?
Retrovirus - chickens are natural host, most commonly layers 20-36 weeks of age
lymphoid tumor development, especially in bursa of Fabricius, liver, spleen, and kidneys –> fibrosarcoma, hemangiosarcoma, nephroblastoma, osteopetrosis tumors
What 2 clinical signs are indicative of lymphoid leukosis-sarcoma complex? What diagnostics are used?
- non-specific signs depending on organs affected with lymphoma
- subclinical infection can cause decreased egg production
virus isolation, ELISA, histology of several birds to differentiate from Mareks
What 5 postmortem lesions are seen in cases of lymphoid leukosis-sarcoma complex?
- variable anemia
- enlarged, red liver and spleen due to infiltrating lymphoblasts
- diffuse or nodular white tumors of liver, spleen, kidneys, eyes, or visceral surfaces of flat bones
- osteopetrosis –> thickened long bones
- tumor in bursa of Fabricius
How is lymphoid leukosis-sarcoma complex treated? Prevented?
cull affected birds
- eradication from breeding adults
- good hygiene
What lice most common infect poultry? What is their lifecycle like? Where are they most commonly found?
chewing lice
entirely on bird
found near the vent, head, and ventral wings of young birds
What are the 3 most common mites infecting poultry?
- common chicken/red mite (Dermanyssus gallinae) - feeds on bird at night and hides in cracks in coop during the day
- Northern fowl mite (Ornithonyssys sylviarum) - remains on bird
- scaly leg mite (Knemidocoptes mutans) - burrow in featherless skin
What flocks are most commonly affected by internal parasites?
backyard, hobby, and exhibition poultry
- few anthelminthic approved for poultry, extralabel use is common
What are the 4 most common intestinal parasites in poultry?
- ascarids - small intestines
- threadworm - Capillaria, crop and small intestine
- cecal worm - Hetarakis gallinarum, usually asymptomatic, vector of histomonas meleagridis
- tapeworms - heavy infestation causes emaciation
What causes coccidiosis in poultry? What clinical signs are seen?
Eimeria spp. –> rare in commercial poultry due to common use of coccidostats
- lethargy, poor growth
- mucoid/bloody diarrhea, dehydration
- reduced egg production
How is coccidiosis diagnosed? Treated? Prevented?
oocysts in feces
anticoccidials + supportive care
- coccidiostats
- sanitation, disinfection
- biosecurity
What causes histomoniasis in poultry? What are 3 method of transmission?
Histomonas meleagridis –> blackhead in turkeys (chickens appear resistant)
- direct from feces
- consumption of transport host - eathworm
- ingestion of infected cecal worm eggs - Heterakis, chickens act as reservoir
What clinical signs are seen with histomoniasis in poultry?
- sudden death
- anorexia
- PD
- depression, droopiness
- yellow feces/diarrhea
- cyanosis of face –> “blackface”
What 3 postmortem lesions are seen with histomoniasis?
- emaciation
- circular irregular depressed areas of liver
- caseous cecal core
What treatment is recommended for histomoniasis? How is it prevented?
no specific treatment - extralabel Metronidazole and Fenbendazole to control cecal worm
- control IH
- do not mix chickens and turkeys
- oregano-based supplements anecdotally used as a preventative
What causes trichomoniasis? How is it transmitted?
Trichomonas gallinae –> canker, frounce –> takes advantage of oral, esophageal, or crop mucosa damage
- spread by wild birds - pigeons
- shared water sources
What clinical signs is characteristic of trichomoniasis? Postmortem signs?
yellow button oral lesions (cankers) cause inappetence and weight loss
caseous lesion in the oral cavity
How is trichomoniasis treated? Prevented?
extralabel Metronidazole
- good sanitation and biosecurity
- minimize interaction with wild bird populations
What are the 2 most common fungal infections in poultry? How are they treated?
ASPERGILLOSIS - ubiquitous and opportunistic, more common in young birds with yellow/grey nodules in respiratory tract –> treatment not commonly persued, good sanitation/disinfection
CANDIDIASIS (albicans) - sour crop, thrush, ubiquitous and opportunistic, white plaques in oropharynx and thickening of crop mucosa –> crop wash, probiotics, antifungals, good sanitation, avoid excessive use of antimicrobials
What causes botulism? What poultry is especially suspected? What clinical signs are associated?
Clostridium botulinum toxin from decaying matter, shallow alkaline ponds, and maggots
ducks
- depression
- loose, ruffled feathers
- ataxia
- flaccid paralysis –> limberneck
How is botulism diagnosed? Is treatment commonly persued? How is it prevented?
- clinical signs + lack of postmortem findings
- toxin bioassay
no - once clinical signs are observed, treatment is of little value
sanitation/disinfection + remove dead/decaying matter
