Chickens

History

·    What type of birds, e.g. meat or egg layers?

·    What aged birds affected?

·    How many of flock?

·    What clinical signs seen?

·    Any other clinical signs seen?

o  Egg drop? Reduction in egg quality? ND, infectious bronchitis

o  Nervous signs? – ND, AI

o  Scour? – ND, AI, infectious bronchitis

·    Vaccination protocol? – for infectious bronchitis, ND

·    What is the management like - stocking density? Access to feed/water? Ventilation

·    Recent management/diet changes?

·    Still eating/drinking? – decreased appetite = avian rhinotracheitis

·    Any deaths? – ND, AI, infectious bronchitis

Clinical signs

·    Snicking (cant cough), sneezing

·    Ruffled feathers

·    Huddling

·    Ocular/nasal discharge – avian rhinotracheitis

·    Blepharospasm

·    Conjunctivitis – avian rhinotracheitis

·    Sinusitis - Mycoplasma gallisepticum

·    Head shaking, swollen heads – ART

·    Reproductive signs, e.g. egg drop, decr. egg quality – ND, infectious bronchitis, infectious laryngotracheitis, Mycoplasma gallisepticum

·    Tail bob = increased respiratory effort

Investigations

Clinical examination of affected birds/selection of birds:

·    Wattle/comb colour – pale = anaemic, cyanotic = AI

·    Indentation below eye = infraorbital sinus – swelling?

·    Respiratory distress – avian rhinotracheitis

·    Feather quality – ruffled?

·    Any discharge? – avian rhinotracheitis

·    BCS – weight loss = AI

·    Look at dead birds – torticollosis = ND

Further investigations:

·    If cannot rule out ND or AI (respiratory signs + neuro signs, scour, egg drop, deaths) – contact APHA

·    PM examination of any dead birds

o  Tracheitis – infectious bronchitis, avian rhinotracheitis, Mycoplasma gallisepticum

o  Airsacculitis – infectious bronchitis, Mycoplasma gallisepticum

o  Heart – myocardial necrosis = AI

o  Haemorrhage in proventriculus – ND

o  Swollen kidneys – infectious bronchitis

·    Blood sample – brachial vein, DO NOT FREEZE

·    Culture – bacterial causes

·    Serology (ELISA) – assess efficacy of vaccination (infectious bronchitis, avian rhinotracheitis)

·    Tracheal/cloacal swabs for PCR – viral causes (infectious bronchitis, AI)

Prevention

·    Reduce stocking density to reduce stress

·    Vaccination – via drinking water, spray, intra-ocular, in ovo

Causes

Viral:

·    Newcastle disease – egg drop, scour, neuro signs, sudden death

·    Avian influenza – scour, swollen/cyanotic wattles, neuro signs, sudden death

·    Infectious bronchitis – scour, egg drop

·    Avian rhinotracheitis – nasal/ocular discharge, conjunctivitis

·    Infectious larynotracheitis – egg drop, periocular swelling

Bacterial:

·    Mycoplasma gallisepticum – egg drop

Parasitic:

·    Gapeworm (nematode, lives in trachea, Y-shaped)

o  Treatment: albendazole

Newcastle disease

·    Avian paramyxovirus 1 – NOTIFIABLE – contact APHA

·    Transmission: aerosol (from secretions/excretions), remains on carcasses for few weeks

·    Clinical signs:

o  Sudden death

o  Respiratory signs – snicking, sneezing, swollen heads

o  GI signs - scour

o  Neurological signs – torticollosis, wing paralysis, depression, opisthotonus

o  Reproductive signs – egg drop, soft shelled eggs, concentric rings on shell

·    Diagnosis

o  PM examination – haemorrhage in proventriculus, lesions in respiratory tract

o  Haemagglutination test to detect virus in allantoic fluid (eggs), then PCR

·    Control: improve biosecurity, cull confirmed cases, vaccination

Avian influenza

·    NOTIFIABLE – contact APHA

·    Clinical signs

o  Sudden death

o  Respiratory signs – sneezing, snicking

o  Nervous signs – depressed

o  GI signs – scour, anorexia/weight loss

o  Oedema

o  Swollen wattles, cyanosis

·    Diagnosis

o  PM exam – myocardial necrosis

o  Tracheal, cloacal, oropharyngeal swabs for PCR to detect virus

·    Control: if confirmed, cull positives, 3km protective zone, 10km surveillance zone (movement restriction)

·    Current issue: now endemic, causing massive losses

Infectious bronchitis

·    Coronavirus

·    Clinical signs:

o  Respiratory signs – sneezing, snicking

o  Reproductive signs – egg drop

o  GI signs – scour

o  Mortality

o  Huddling

·    Diagnosis:

o  Serology (ELISA)

o  Tracheal/cloacal swab for PCR

o  PM examination – tracheitis, swollen kidneys, airsacculitis

·    Treatment: oxytetracycline (in water for 5d), booster vaccine 6w later (via spray or drinking water)

·    Prevention: live vaccination

Avian rhinotracheitis

·    Coronavirus

·    Clinical signs

o  Respiratory signs – ocular/nasal discharge, conjunctivitis, sneezing, snicking, face/head swelling, dyspnoea, sinusitis

o  Decreased appetite

·    Diagnosis:

o  PM exam – serous rhinitis, tracheitis, pus in bronchi

History questions

·    What time of year/season?

·    How many animals affected?

·    Have they seen any bullying/hierarchial behaviours?

·    Other clinical signs, e.g. itching, pain

·    Eating/drinking normally?

Causes

·    Primary skin/hair disease

o  Parasites: red mite, lice (cause itching and feather plucking in large numbers)

o  Cutaneous Marek’s disease

·    Other underlying disease

o  Pain ® feather plucking

o  Malnutrition

o  Dermatitis

·    Behavioural – bullying behaviour, brooding patch, mating behaviorus

·    Normal moulting – starts in autumn, works head to tail

Parasite

·    Dermanyssus gallinae

Life cycle

·    Mites live off bird, in the hutch

·    Come onto bird at night to drink blood

Clinical signs

·    Weight loss/BCS loss

·    Egg drop

·    Anaemia – pale wattles

·    Death

What birds?

·    Pheasants

·    Partridges

Housing

·    Remain in brood huts first 7w of life

o  Issues: poorer biosecurity and hygiene, no parent stock so gameskeeper needs to brood them, access to feed and water instantly (yolk sac provides nutrition only 3-4d)

·    Release pens at 7w – introduce bird to wild environment gradually

Common issues

First week of life:

·    Yolk sac infection

o  Clinical signs: emaciation, large pale smelly yolk sac, death

o  Diagnosis: bacteriology from swab of liver/heart (not yolk sac as contaminated)

·    Starve outs and non-starters

o  Death within 4-7d

o  Yolk sac regressed normally, bird underweight

§ Starve outs – no ingesta in gizzard

§ Non-starters – food in gizzard (attempted to eat)

·    Viral enteritis

o  Clinical signs: sudden death at 4-10d, yellow frothy droppings (due to typhilitis), dehydrated, pyrexic, ruffled feathers

o  Diagnosis: typhalitis on PM

·    Salmonellosis

Aged 2-7 weeks:

·    Protozoa

o  Motile - spironucleosis, trichomoniasis, non-motile – coccidiosis (Eimeria)

§ Clinical signs: watery D+, dehydration, weight loss, lethargy, depression, death

§ Diagnosis: PM exam, microscopy of intestinal scrapes (asap after death if motile sp.)

§ Treatment: tetracyclines, toltrazuril for coccidiosis

o  Histomoniasis – Histomonas meleagridis

§ Diagnosis: PM examnecrotising black circular lesions with white rings on liver

§ Treatment: fenbendazole to prevent transmission

·    Bacterial enteritis

o  Clostridium colinum – dx via histopathology

o  Sacina – dx via PCR

History

·    DLWG? Any change/reduction? – reduced DLWG/FCR = Eimeria 

·    Feed conversion rate?

·    Water consumption? Any change?

·    Egg production? Egg drop? – egg drop = brachyspira

·    Mortality levels? – sudden death = clostridial enteritis, high mortality = salmonella, Eimeria

·    Appearance of scour? – yellow, frothy = Brachyspira, green = salmonella

·    Vaccination protocol?

·    Any recent changes in management/diet?

·    How many birds affected? What age? – young = salmonella

·    What other clinical signs seen?

o  Weight loss? – Eimeria

o  Respiratory signs? – infectious bronchitis

o  Huddling? – clostridial enteritis

o  Depressed/dull? – clostridial enteritis, infectious bursal disease

Investigations

Clinical exam of affected birds:

·    Look at scour/back end – white caked vents salmonella

·    Comb/wattle colour – pale/anaemic = salmonella, infectious bursal disease

·    Hydration status – dehydrated = Eimeria

Further investigations:

·    PM exam

o  Intestinal necrosis – clostridial enteritis, infectious bronchitis

o  Enlarged kidneys – infectious bronchitis

o  Hepatomegaly – salmonella

·    Impression smears for microscopy – Eimeria

·    Faecal sample for PCR – Brachyspira, Eimeria, infectious bronchitis, infectious bursal disease

·    ELISA – salmonella

Treatment

·    General supportive treatment – improve bedding management

·    Clostridial enteritis – 3d oral amoxicillin

·    Brachyspira – tylosin or tilmicosin

·    Coccidiosis – toltrazuril

Causes

·    Protozoal

o  Spironucleosis

o  Trichomoniasis

o  Eimeria

·    Bacterial

o  Clostridium perfringens

o  Brachspira (gram -ve)

o  Salmonella

·    Viral

o  Infectious bronchitis

o  Infectious bursal disease (Gumboro disease)

o  Avian influenza, Newcastle disease – NOTIFIABLE – contact APHA

Risk factors

·    Poor litter management – incorrect substrate/depth, incorrect ventilation, leaks from drinkers, poor temperature control

·    Poor quality protein sources ® reduced digestion ® increased pH ® increased chance of bacterial scour

Prevention

·    Correct litter management: absorbent, biodegradable, comfortable, dry

·    Enzyme supplementation to enhance protein digestion

·    Prebiotics – selectively encourage commensal bacterial growth

·    Vaccination for coccidiosis (but expensive, and still can see CS)

·    Good biosecurity

·    Coccidiostats for Eimeria (chemical or antimicrobial)

·    Vaccination for infectious bronchitis, infectious bursal disease

BCS

·    Assess by feeling keel bone ventrally

Infectious causes

·    Eimeria – also see scour, high mortality rates, dehydration

·    Avian influenza – also see scour, respiratory signs, cyanotic/swollen wattles, neurological signs, sudden death

Non-infectious causes

·    Wet litter

History

·    How many birds affected?

·    How long been going on for?

·    Any previous history of egg drop?

·    Any reduction in egg quality?

·    Any other clinical signs?

o  Respiratory signs? – ND, AI, infectious bronchitis

o  Neurological signs? – ND, AI

o  GI signs? – ND, AI, Mycoplasma gallisepticum, yellow frothy scour = brachyspira

Investigation

·    Full clinical exam of affected birds

·    Look at eggs – soft shells, concentric rings = ND

Further investigations:

·    If suspect ND/AI – NOTIFIABLE – contact APHA

·    Tracheal/cloacal swabs for PCR – viral causes (infectious bronchitis, AI)

·    PM exam – proventricular haemorrhage = ND, tracheitis = infectious bronchitis

·    Faecal sample for PCR – infectious bronchitis, Brachyspira

Non-infectious causes

·    Seasonality

·    Broody hens

·    Geriatric stock

·    Poor nutrition

·    Environmental stress

Infectious causes

Viral disease:

·    Infectious bronchitis – most common

·    Newcastle disease

·    Avian influenza

·    Infectious laryngotracheitis

Bacterial disease:

·    Mycoplasma gallisepticum

·    Infectious coryza

·    Brachyspira

Parasitic disease:

Egg drop syndrome

·    Main transmission route – vertical transmission through eggs

·    Pathogen – adenovirus

Disease development

·    Normal ovulation – but oviduct doesn’t engulf ova ® foreign body inflammatory reaction occurs

·    Can have ascending infection (from contaminated cloaca), translocation (from respiratory system or intestines)

Clinical signs

·    Lethargy

·    Egg drop/stops laying

·    Upright posture

·    Weight gain with reduced appetite

·    Dirty around vent

Treatment

·    Drain ascities (can do cytology and culture)

·    NSAIDs – withdraw eggs for 7d

·    Antibiotics based on C+S

History

·    How long been going on for?

·    Known nutritional deficiencies?

·    Recent management/diet changes?

·    Any neurological signs?

Investigations

·    Examine birds

o  Unilateral lameness? -

o  Bilateral lameness? – rickets, tibial dyschondroplasia

o  Recumbent? – difficulty rising = femoral head necrosis, sitting on hocks = spondylolisthesis, osteomyelitis of thoracic spine

o  Swollen joints? – femoral head necrosis, hock infections, tibial dyschondroplasia

o  Normal walking? – uncomfortable walking = rickets, tibial dyschondroplasia, severe lameness = femoral head necrosis, hopping lame = tendon rupture

·    Look at feet – pododermatitis

·    PM exam

o  Pliable, bendy bones – rickets

o  Pus in joints – hock infections

o  Thickening of gastrocneumius tendon – tendon rupture

o  Spinal abscesses/deformities – spondylolisthesis, osteomyelitis of thoracic spine

Causes

·    Rickets (lack of vitamin D3 ® lack of bone mineralisation

·    Femoral head necrosis (due to immunosuppression, e.g. Marek’s disease, or bacterial infection, e.g. Staphylococcus aureus)

·    Hock infections (Staphylococcus aureus, E. coli, Mycoplasma synoviae)

·    Tendon rupture (rapid growth and insufficient exercise)

·    Tibial dyschondroplasia (thickening of growth plate of tibiotarsal bone, absent blood supply ® cartilage fails to calcify)

·    Osteomyelitis of thoracic spine

·    Spondylolisthesis (kinky back)

·    Newcastle disease – can cause neurological/lameness signs

Prevention 

·    Rickets – ensure adequate vitamin D3 in diet so mineralisation occurs properly

·    Ensure feeding correctly so correct DLWG

·    Allow sufficient space for exercise

·    Vaccination

History

·    How many birds affected?

·    How long been going on for?

·    Other clinical signs?

o  Respiratory signs? – ND, AI

o  Egg drop? – ND, AI

o  Scour? – ND, AI

o  Deaths?

o  Weight loss? – Marek’s disease

Newcastle disease

·    NOTIFIABLE – contact APHA

·    Avian paramyxovirus

·    Clinical signs:

o  Respiratory signs

o  Neurological signs – depression, ataxia, prostration, opisthotonos, mortality, egg drop

·    Diagnosis

o  PM exam – proventricular haemorrhage, lesions of respiratory tract

·    Prevention – vaccination

Avian influenza

·    NOTIFIABLE – contact APHA

·    Clinical signs:

o  Anorexia

o  Sudden death

o  Respiratory signs

o  Neurological signs

o  Scour

·    Diagnosis

o  Tracheal, cloacal, oropharyngeal swabs for PCR

Marek’s disease

·    Herpes virus

·    Clinical signs:

o  Lameness, leg/wing paralysis

o  Weight loss

o  Eye changes

o  Tumours – skin/feathers

·    Diagnosis:

o  Clinical signs

o  PM exam – tumours on liver, spleen, kidney, lung, gonads

·    No treatment