VTS257

1. CHICKENS

2. COMPANION CHICKENS
 Value of bird is often sentimental
 Make interesting pets
 Supply eggs
 Eat insects including ticks

3. WHAT IS A CHICKEN
 A chicken is a bird with some unusual
features
1. comb- red appendage on top of the head
2. Wattles- two red appendages under the chin
- There are many breed variations on the
comb and wattles
- Both of these will bleed, sometimes
profusely, if damaged

4. FLIGHT
 Domestic chickens have for the most part,
lost the ability to fly
 Large meat breeds can jump and may flap
there wings to reach a low branch
 Lighter breeds can fly short distances,
especially bantams
 The feet and shanks are covered with scales

5.  Respiration rate- roosters 18-21 times a
minute and hens 31-37 times a minute when
not stressed
 Heart beat- 286 beats per minute in roosters
and 312 in hens when not stressed
 Digestion- 2 ½ to 25 hours to pass through,
depending on fullness of digestive tract when
feed is ingested

6.  Body temperature- 107 degrees
 The beak does not contain teeth
 Mastication occurs in the gizzard, chickens
swallow grit if free range to assist in
digestion. Commercial flocks are fed a very
fine meal so grit is not essential
 13 air sacs assist in respiration

7. LIFESPAN
 Relatively short life spans
 Pets can live 10-15 years
 Commercial layers are replaced at 18
months of age ( they start laying at 6 months)

8. EXTERNAL CHICKEN ANATOMY

9. CHICKEN DIGESTIVE SYSTEM

10. WELLNESS EXAM
 Potential for zoonotic disease such as
chlamydiosis and salmonellosis
 Focus on overall body mass, behavior and
general condition of the integument ( ie: skin,
plumage, nails, beak and comb)
 Observe for mentation, activity level,
normal/abnormal
 Systemically ill birds weak or neurologic

11. WELLNESS EXAM
 Examine eyes, ears, throat, pectoral muscles
and abdomen
 Common disorders such as parasitism cause
a decreased pectoral mass or prominent keel
 Reproductive disorders such as egg
peritonitis may cause increased abdominal
mass
 Ask about egg laying frequency, hardness or
softness of shell, number of eggs, dystocia

12. WELLNESS EXAM
 Examine the skin
 Look for cleanliness
 Feather appearance
 Ectoparasites
 Paleness of comb or wattle
 Appearance of feet and legs

13. COMMON PROBLEMS
 Trauma
- Feather plucking, skin very thin, easily
damaged
- Fracture, open or closed,
- due to pneumatic bones, don’t flush as they
communicate with respiratory system
- Tremendous weight-bearing ratio of a
chicken’s leg make proper orthopedic
technique necessary

14. HEAD AND NECK
When examining this region of the bird, one should observe a red,
non-flaccid comb, free of scabs. The bird should hold the head
high, indicative of good muscle tone, and be free from swelling.

15. EYES
The eyes of a healthy bird should be clear; bright and round;
and opened wide. The pupil margin should be round with well-
defined margins. The eyes should not be cloudy and should be
free of any discharge.

16. NOSTRILS AND BEAK
The external nares (nostrils) should be clear
and free of any discharge, crust, and
scratches. The beak should be smooth, free
of cracks, and the tips should come to a
point. Suspicion should be raised if there
are any scratches in the beak, cracks, or
the tips do not meet.

17. FEATHERS AND VENT
 Evaluation of the feathers is important, as it may reveal parasitic
infection or evidence of foul play in the flock. On examination, the
feathers should lay flat against the body and be well preen. Lift up the
feathers and check the base of the feather shaft. This area should be
clear and free from parasites. Part the feathers to check for lice and
mites. Lice may lay their eggs at the base of the feather shaft, appearing
as white clumps. The feathers in the tail and vent region should also be
clean and free from any fecal material as white build-up or pasty vents
may be indicative of an intestinal disease.

18. FEET
 The scales on the feet should be smooth and closely adhered to each
other and straight. Upturned scales may be the result of a scaly leg mite
infestation. The bottoms of the feet should also be free from scratches,
swelling, scabs or ulcerations. The top left picture demonstrates
elongated nails that need trimming. The bottom left picture demonstrates
the beginning stages of bumblefoot as evidenced by the scabbing.

19. COMMON POULTRY DISEASES
 There are many poultry diseases
 These are a few of the most common ones
encountered in backyard flocks

20. FOWL POX
 Common in backyard flocks
 Also known as “chicken pox”, “bird pox”,
“avian diptheria”

21. FOWL POX
Symptoms
 Lesions are “warts” on unfeathered areas of
the body
 Egg production drops
 Skin raw and may be bleeding
 Respiratory distress
 Respiratory congestion

22. FOWL POX
 Treatment
- No treatment
- Slow spreading in the flock
- Prevent by vaccination

23. INFECTIOUS CORYZA
 Also called “cold” or “roup”
 Extremely common among backyard flocks

24. INFECTIOUS CORYZA
Symptoms
 A foul smell, very distinctive ( like parvovirus
in dogs)
 Discharge from nasal cavity and eyes
 Difficulty breathing
 Mild to severe diarrhea
 Harsh sounds when breathing

25. INFECTIOUS CORYZA
 Treatment
- Antibacterial medications ( no antibiotics are
approved for egg layers)
- Some antibiotics can be administered
through the water

26. MAREK’S
 Herpes virus infection of chickens and rarely
turkeys
 New highly virulent strains have become a
problem since the 1990’s

27. MAREK’S DISEASE MANIFESTATIONS
1. neurological- infiltrates the CNS and PNS
leading to floppy broiler syndrome, paralysis
of legs and wings, eye lesions
2. Visceral- tumors in heart, ovary, testes,
lungs and muscles
3. Cutaneous- tumors of feather follicles

28. MAREK’S DISEASE
 Route of infection- usually
- Highly contagious
- Spread by infective feather follicle dander,
fomites, etc
- Infected birds remain viremic for life
- Vertical transmission not considered
important

29. MAREK’S DISEASE
 The virus
- Survives at room temp for up to 65 weeks
- Resistant to some disinfectants such as
quaternary ammonium and phenol
- Inactivated when frozen and thawed

30. MAREK’S DISEASE
 Signs
- Paralysis of legs, wings and neck
- Loss of weight
- Grey iris or irregular pupil
- Vision impairment
- Skin around feather follicles raised and rough
looking

31. MAREK’S DISEASE
 Post- mortem lesions
- grey/white neoplastic lesions of liver, spleen,
kidney, lung, gonads, heart and skeletal
muscle
- Thickening of nerve trunks

32. MAREK’S DISEASE
 Diagnosis
- History
- Clinical signs
- lesions,
- Age affected
- Morbidity 10-50%, mortality 100%
- DDX: botulism, thiamine deficiency, vitamin D
deficiency, Ca/P deficiency ( esp at start of
lay)

33. MAREK’S DISEASE
 Treatment: none
 Prevention: hygiene, all in all out, vaccination

34. MYCOPLASMA GALLISEPTICUM
CHRONIC RESPIRATORY DISEASE
 Slow onset, chronic respiratory disease
 In adult birds, infection rate can be high but
morbidity may be minimal and mortality
varies

35. M. GALLISEPTICUM
ROUTE OF INFECTION
 through conjunctiva or upper respiratory tract
 Incubation period 6-10 days
 Transmission may be transovarian, or by
direct contact with exudates, aerosols,
airborne dust and feathers or to a lesser
extent, fomites
 Recovered birds may remain infected for life
and stress may cause recurrence of signs

36. M. GALLISEPTICUM
 Infectious agent
- Only survives days in environment
- Prolonged survival in egg yolk and amniotic
fluid
- Survival on hair and feathers

37. M. GALLISEPTICUM
 Signs:
- coughing, nasal, ocular discharge
- Poor productivity, slow growth
- Leg problems, stunting
- Inappetance
- Reduced hatchability, chick viability
- Occassional encephalopathy and abnormal
feathers

38. M. GALLISEPTICUM
 Post mortem lesions
- Airsacculitis
- Pericarditis
- Perihepatitis
- Inflammation of nasal passages, sinuses,
trachea and bronchi
- Occassional arthritis, tenosynovitis

39. M. GALLISEPTICUM
 Diagnosis
- lesions, serology, isolation of organism
- Serology- serum agglutination is standard
screening test
- Suspect flocks retested in 2-3 weeks
- DDX: Infectious Coryza, Aspergillosis, Vit A
deficiency

40. M. GALLISEPTICUM
 Treatment
- tylosin, tetracyclines, fluoroquinolones
- Reduce dust and secondary infections
 Prevention
- Eradication
- Purchase of uninfected chicks, all-in/all-out
production
- Serological monitoring

41. EGG PERITONITIS
 Taylor put picture here

42. EGG PERITONITIS
 Causes
- After prolapse or when yolk goes into
abdominal cavity instead of out the oviduct
- Often occurs after some viral diseases which
damage the reproductive tract
- A ruptured intestine can also cause this
problem

43. EGG PERITONITIS
 Diagnosis and treratment
- Penguin stance or just swollen around the
abdomen
- May have a blue comb and/or diarrhea
- Post mortem shows inflamed abdomen with
putrid yolk odor
- Some birds have been treated with
antibiotics and withdrawal of fluid

44. COCCIDIOSIS
 Caused by a protozoan type parasite
 Lives and multiplies in intestinal tract and
causes tissue damage
 Interferes with food digestion and nutrient
absorption causing dehydration and blood
loss
 Tissue damage can lead to secondary
bacterial disease
 Marek’s disease can decrease immunity to
coccidiosis

45. COCCIDIOSIS
 Eimeria is the coccidia that affects poultry
 There are many species that are important in
different types of poultry

46. COCCIDIOSIS
 signs
- None to bloody droppings, watery diarrhea,
weight loss, paleness, ruffled feathers, huddling,
depression
- Affected birds don’t eat, high pitched cry
- All ages, usually resolves around 6-8 weeks of
age
- Most susceptible between 3-5 weeks
- Many times the disease is subclinical

47. COCCIDIOSIS
 Diagnosis
- necropsy: red or white speckled lesions on
intestines and cecum, thickened intestinal
wall
- History, clinical signs, fecal flotation
 Transmission
- Oocysts are shed in feces
- Warm wet litter
- Oocysts can survive up to 4 years

48. COCCIDIOSIS
 Prevention
- Good sanitation and litter management
- Avoid wet conditions
- Change litter after each brood, clean houses
and discard litter
- Anticoccidial medications in poultry feed
 Treatment- to control an outbreak, sulfa
drugs, make sure withdrawals are adhered to

49. COMMON EXTERNAL PARASITES
 Poultry lice
 Poultry mites
 Scaly leg mites

50. POULTRY LICE
 Tiny, wingless, 6 legged, flat bodied
 Lay eggs on feathers, especially at base
 Do not suck blood, they feed on dry skin
scales, feathers and scabs
 Entire life cycle on host bird, primarily
feathers
 Host specific, cannot be transferred to
humans

51. POULTRY LICE
 Fall and winter are the most common times
for lice infestation
 Inspect ventral region of bird for live lice or
nits
 Infected birds look moth eaten, dull or
roughened

52.  Taylor insert lice egg slide

53. POULTRY MITES
 Two major types of mites
1. Northern fowl mite
2. Red roost mite ( chicken mite)

54. NORTHERN FOWL MITE
 Most common external parasite in poultry
especially in cool climates
 Sucks blood
 Primarily remains on host entire life cycle
 Can live off host bird for 2-3 weeks
 Mites are small, black/brown, 8 legs, spread
through bird to bird contact

55. RED ROOST MITE
CHICKEN MITE
 Primarily a warm weather pest
 Suck blood from birds at night, hide in cracks
and crevices of house during the day
 Resemble the Northern Fowl Mite

56. SPREAD OF MITES
 Life cycle can be as little as 10 days
 Can be transferred between flocks, crates,
clothing and wild birds
 Can live in environment for short periods
 Diagnosis- inspect bird and house

57. FLOCK SYMPTOMS OF MITES
 Decreased egg production
 Decrease weight gain, increased disease
susceptibility, decreased food intake
 Treatment
- Sanitation and cleanliness
- Sevin dust bath for individual birds in small flock
- Repeat treatment in two weeks
- Prevent by quarantining new stock for 2 weeks
at least

58. COMPARISON CHART
 Taylor insert table 1

59. SCALY LEG MITE
KNEMIDOCOPTES MUTANS
 Taylor insert picture

60. SCALY LEG MITE
 Causes scales on legs to thicken and appear
raised/protruding outward, rather than flat
 Causes
- Live under scales on feet and legs, entire life
cycle on the host
- Spread by contact with other birds
- Irritation of the skin raises the scales

61. SCALY LEG MITE
 Treatment
- Petroleum jelly rubbed on legs every few
days suffocates the mites and they die, also
softens the skin
- Can take up to 10 days to get rid of the mites
- Ivermectin can also be prescribed to treat the
mites

62. COMMON PARASITES OF BACKYARD FLOCKS
 Hair worms - Found in the crop, oesophagus,
proventriculus and intestine.
 Round Worms - Found in the birds digestive system.
 Gizzard Worm - Found in the gizzard, mainly in
geese.
 Tape Worms - Fairly uncommon, found in the
intestine.
 Gape Worm - Found in the trachea and lungs.
 Caecal Worms - Cause little damage but transmit
blackhead to Turkeys. Found in the cecum.