Download Lecture 1

CANINE DISTEMPER
INTRODUCTION
Canine distemper is a highly infectious
disease of canidae.
It is characterized multisystem involvement
 Gastrointestinal,
 Respiratory system,
 Neurological signs
 Hyperkeratosis on the nose and footpad.
The mortality rate in affected animals is high.
Aetiology:o It is an RNA enveloped virus. A paramyxovirus of the Genus
Moribilivirus measuring 150 – 300nm in diameter but ranges
between 110-550nm. All strains of CDV are antigenically similar
and are indistinguishable by cross-protection and crossneutralisation tests.
o Antigenically related to the measles and rinderpest viruses and
highly contagious can spread by air, or mechanical means.
o Very delicate in the dry form and easily destroyed by the
environmental factors such as heat, UV light, humidity and visible
light.
o Susceptible to pH 4.4, ether and bile salts sensitive.
o Virus is easily destroyed in the stomach and the small intestine.
Epizootiology
o Affects about 95% of unvaccinated urban
dogs but only a few show clinical signs.
o Only about 50% of those showing clinical
signs manifest the typical signs of canine
distemper
o About 50% of those showing clinical signs die
i.e. there is high mortality rate.
o Suckling pups may be born infected especially
if the mother is infected.
Transmission:o
By inhalation (aerosol) during coughing or
sneezing.
o
Indirect transmission is rare because the
virus outside the body is very labile.
PATHOGENESIS AND PATHOLOGY
o Following infection, initial multiplication takes place in the
tonsils, cervical and bronchial lymph nodes.
o Virus is then phagocytosed by macrophages along the nasal
passages and pharynx and transported through nasal and
pharyngeal epithelium into the sub-epithelial lymphoid deposits
of the tonsil.
o Virus enters the blood stream directly or spreads along the
chain of lymph nodes in the cervical region.
PATHOGENESIS AND PATHOLOGY (CONTD.)
o Virus reaching the lower respiratory tract is
carried by macrophages to the bronchial lymph
nodes.
o Whatever route, there is viraemia which can
be detected in two days after inhalation.
o The virus present in the monoclear cells and
neutrophil is then transported to various target
organs where it produces pathological changes.
Clinical signs:The disease is multisystemic and it can affect:
o The Alimentary system
o The respiratory system
o The eye
o The skin
o The nervous system
The Alimentary System
Reduced appetite
Vomiting
Diarrhea and excessive
Hypoplasia of the enamel (If this disease
occurs while the puppy is teething) exposing
the brown coloured dentine. This is referred
to as “distemper teeth”.
Respiratory system
Coughing (Initially soft but later, harsh and
accompanied by expectoration of mucus). The
owner may think of bone in the throat.
Nose is dry with serous fluid coming from the
nostrils earlier in the disease.
Nasal discharge becomes thicker and copious
becoming mucopurulent or purulent.
Respiratory system (contd.)
Ĭ There is sneezing.
Ĭ Rhinarium becomes hyperkeratotic (cracked or
pitted).
Ĭ Auscultation and percussion of the chest reveal
harsh bronchial or bronchovesicular inspiration
over the whole thorax.
Ĭ Bacterial pneumonia is a complication.
Eye:The conjunctivae are congested with
purulent discharge (small or copious) which
becomes crusted at the inner canthus.
 Thick pus may adhere to the cornea and can
be difficult to remove.
There may be ulcerative keratitis.
Skin:• On the skin of the abdomen are distemper pustules
– discrete circular yellow – green pustules about 5mm
in diameter – termed “impetigo”
Hard PAD
• Hyperkeratosis is a common feature but not in all
cases. The pads are usually warm and tender initially.
The hyperkeratotic part may extend into the sensitive
tissue thus making the dog lame
• When the pads are very hard they make distinctive
noise – “hard pad”.
Nervous system:o About 50% of the cases develop fits later in the disease
and when it occurs, it is the hysterical form, animal
looks frightened, run around wildly yelping.
o Rapid twitching of lips and eyelids, champing jaw
movements and salivation for a few seconds.
o In some cases full blown epileptiform fits consisting of
falling over, violent mouth champing spasm with
profuse salivation.
The limbs make purposeless
movements.
o There also chorea, paralysis and incoordination clonic
encephalitis and cranial nerve involvement in some
cases.
Diagnosis:• Clinical Signs such as Hyperkeratosis, CNS
signs like fits, epilepsy, paralysis,
conjunctivitis, respiratory signs, diarrhea
and the prolonged illness.
• FAT on the buffy coat of blood samples.
• Inoculation of tissue culture with buffy
coat layer for viral isolation,
• Neutralization test (paired sera)
• Histopathology of tissues
Treatment:• No specific cure but symptomatic. Confine the
animal to rest, clean the nose, systemic antibiotic
for pneumonia and diarrhea diarrhea – give lean
meat and bread diet and also give kaolin.
• For fits and whining, administer phenobarbitone.
• Leave animal in undisturbed.
• Vitamins – injection preferable
• Good quality food.
Prevention
• In boarding kennels and hospitals. Discharge as
many as possible segregate affected animals and
incontact animals should be given a booster
vaccination.
• Wash kennel with 0.3% quaternary ammonium (0.3%
“Roccal”).
• Rest the kennel.
• Heat the room to kill the remaining virus.
• Prognosis depends on the stage of the disease and
the system affected. Prognosis is bad for those with
fits but they can recover from paralysis grave
prognosis in severe diarrhea and pneumonia and
continuous fever with weight loss.
Prophylaxis:• Vaccination – Distemper vaccine combined
with leptospira, hepatitis parvo and
parainfluenza.
• Puppies get 3% of maternal Hb in – utero
while 80% of the dam is obtained from the
colostrums. Abs (passive) wane at 12 weeks of
age, so puppies should be vaccinated.