DISEASES OF RESPIRATORY SYSTEM
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Disease of nasal cavities and
sinuses
Nasal myiasis
Nasal bot, head bot, head grub
Definition:
It is a chronic rhinitis and sinusitis of sheep
characterized by persistent annoyance and
mucopurulent discharge and is caused by
invading maggots. This disease presents in all
sheep-producing countries and maintains high
incidence in flocks.
Occurrence:
• This disease occurs in all breeds, sexes and
ages of deep.
• In warm countries both adult and larval phases
of the disease persist throughout all seasons,
but in temperate zones, adult flies emerge, mate
and oviposit only during summer and myiasis
continues throughout the cold seasons.
Etiology
• Oestrus ovis is the prevalent fly cause nasal
myiasis.
• Both the adult insects and their larvae attack
sheep.
Pathogenesis
1.
2.
3.
4.
Mated female deposit 500 larvae on the nostrils of
sheep.
The first larval stages enter the nasal cavity and feed
on the mucus and desquamated cells. Then first larval
stages molt into second larval stages.
The second larval stages pass into the frontal and
maxillary sinuses where they grow into third stage
larvae mature larvae.
After 2-10 months, the mature larvae return to the
nostrils and are sneezed to the exterior. They enter
the soil and pupate through a period of 27 to 36 days.
Pathogenesis (cont’)
1.
2.
3.
4.
Adult females deposit larvae throughout the summer
in temperate zones and throughout most seasons in
hot zones
the movement of numerous maggots in the nasal
cavities, paranasal sinuses annoy the hosts, and
animal’s feeding.
In the sinuses, the larvae produce allergic and
inflammatory reactions. These changes cause
discomfort and interrupt the animal’s feeding.
Some larvae wander along the trachea into the lungs
producing fatal reactions.
Oestrus ovis life cycle
Larvae within nasal sinus
Clinical signs:
1. Sheep attacked by ovipositing flies stamp with their
feet, shake their heads, sneeze, and blow and ram
their noses against the ground or other sheep.
2. In some cases, these acts traumatize and infect the
nostrils.
3. The animals also seek cool areas such damp shade
where the flies do not frequent.
Clinical signs (cont’)
4. During the time the larvae occupy the nose and
sinuses, affected sheep may hold their heads
towards the ground and persistently discharge
mucopurulent exudate from the nostrils.
5. Breathing may be difficult due to swollen nasal
membranes and plugged nostrils.
6. The morbidity may reach 80% of a flock, but
mortality is nil. The course of adult fly attack
periodically extends through the summer and the
rhinitis and sinusitis continue up to 10 months.
Oestrus ovis in nostrils of sheep
Mucopurelent nasal discharge in
sheep bot
Diagnosis:
• Restlessness behavior of sheep during hot-mid
–days and observation of the fly.
• Chronic nasal discharge and finding of larvae in
sinuses confirm myiasis.
Treatment
•Important
• Sheep should be treated for nasal myiasis during
autumn as larvae are small. Killing of mature larvae in
the sinuses may result in severe reaction in the sinus
membranes.
• Either of the following compounds and dosage rates are
highly effective.
• Rafoxinide administered orally at dose rate of 7.5 mg/kg, B.wt
• Ivermectin at the rate of 50 ug/kg B.wt Ivomic, Iveen,
Ivomax, uvemic, avimic.
Pharyngitis
• Definition
Inflammation of pharyngeal mucosa characterized
clinically by coughing and painful difficult
swallowing
Etiology
1.
2.
3.
4.
Pharyngeal trauma usually results from aggressive use of
equipment used to administer oral medication (e.g., balling
guns, dose syringes, oral speculums, and stomach tubes).
Injuries may result in the formation of discrete abscesses
or extensive and diffuse cellulitis, both of which can
interfere with swallowing and possibly lead to respiratory
difficulty or distress.
Bacteria commonly isolated after an incident of pharyngeal
trauma include Actinomyces, Pasteurella multocida,
Pasteurella haemolytica, and Fusobacterium.
Corynebacterium pseudotuberculosis, the causative agent
of caseous lymphadenitis in sheep and goats may localize
in the regional lymph nodes of the head, especially the
pharyngeal lymph nodes.
Clinical Signs
• Sheep with pharyngitis have a normal desire to
eat and drink but may have difficulty swallowing.
• Coughing.
• Respiratory distress in pharyngeal abscess.
Diagnosis
• Case history
• Clinical signs
• Endoscopic examination
Treatment
• Antimicrobial: antibiotics (oxytetracyclines,
gentamycin, streptomycin) or sulphonamides.
• Anti-inflammatory: corticosteroids such as
dexamthazone or NSAID such as diclofenac.
• Surgical drainage of abscesses.
Laryngitis
• Definition:
an inflammation of the mucosa or cartilages of the
larynx, leading to coughing
Etiology:
• May result from upper respiratory tract infection
• Direct irritation from inhalation of dust, smoke, or
irritating gas; foreign bodies; or the trauma of
intubation, excess vocalization,
• Injury from roping or restraint devices.
• Bacteria: Laryngitis may accompany
Fusobacterium necrophorum or
Corynebacterium pyogenes infections in sheep.
Clinical Signs
• A cough is the principal sign of laryngitis when edema is
slight and the deeper tissues of the larynx are not
involved. It is harsh, dry, and short at first, but becomes
soft and moist later and may be very painful. It can be
induced by pressure on the larynx, exposure to cold or
dusty air, swallowing coarse food or cold water.
• Stridor may result from swelling and reduced motion of
the arytenoid cartilages.
• Halitosis (bad breath) and difficult, noisy breathing may
be evident, and the animal may stand with its head
lowered and mouth open.
• Fever in infectious causes.
Diagnosis
• Case history
• Clinical signs
• Endoscopic examination (laryngoscope).
Treatment
1. Corticosteroids should be administered to reduce the
obstructive effect of the inflammatory swellings.
2. Concurrent administration of NSAID (Declofenac 1
mg/kg BW IV) and systemic antibiotics is also
necessary.
3. Administration of diuretic drugs, eg, furosemide, may
be indicated for resolution of laryngeal edema if
present.
Questions