Lecture 7.ppt viral disease bacterial disease laboratory animal medicine

viral disease bacterial disease laboratory animal medicine

1. LABORATORY ANIMAL MEDICINE

2. Introduction
Laboratory animals are animals used in the laboratory for
scientific researches e.g.
Rabbit, mouse, Rat, Guinea pigs, Hamsters, Girbils etc.
Lab animal medicine is more of prevention than curative.
It is easier to prevent diseases than to cure.
When not prevented, the diseases can kill a whole colony
of pets or research animals
Involves good management e.g. hygiene, good, balanced
diet, good and adequate housing(free from draught,
dampeness, direct sunlight and extreme temperatures.)

3. (a)INFECTIOUS MYXOMATOSIS:
Caused by a poxvirus.
Characterized by high mortality (40-100%). It occurs as
fibromas.
Enzootic in Eastern and Western United States, Europe, South
America and Australia.
The situation in Africa is still unknown.
Transmitted mechanically by
oMosquitoes and biting insects e.g. fleas
oDirect contact from the cotton tail to domestic rabbits where
the disease ranges from peracute, fatal to transitory and single
fibromas.

4. Clinical Signs
All ages are susceptible but younger ones (1 month – 1 year) are less
susceptible.
 Characterized by conjunctivitis with milky ocular discharges
listlessness, anorexia, fever (108
0
F).
In severe cases death may occur within 48 hours.
Survivors after this become progressively, depressed, develop rough
coat, edematous eyelids, nose, lips and ears giving rise to the
characteristic “big head”.
Edematous and inflamed vent in the male, the scrotum becomes
swollen.
Drooping ears due to edema.
Purulent nasal discharges and laboured respiration followed by coma
and death which usually occurs 1-2 weeks after the appearance of
clinical signs.

5. Diagnosis
oClinical signs, Virus isolation and serology
Treatment
o None
Control and prevention
oControl of vectors
oQuarantine of new animal in insect proof
quarters for 2 weeks.
oVaccinate animals with a live attenuated
myxomatosis virus vaccine.

6. BACTERIAL DISEASES
Common in domestic rabbits.
PASTEURELLOSIS
oSnuffles
oEnzootic pneumonia
oOtitis media
oGenital infection
oAbscesses
oConjunctivitis
oSepticaemis
oPyometra
oOrchitis

7. 1)Snuffles (Nasal catarrh)
Aetiology: Pasteurella multocida
Characterized by
Rhinitis, pneumonia, otitis media and conjunctivitis.
Used to describe rhinitis and paranasal sinusitis characterized by
serous, mucous or mucopurulent nasal discharges.
Usually complicated by such bacteria as Staph. aureus and
Bordetella bronchiseptica.
Symptomatic carriers may come down due to stress (change in
weather, pregnancy, concurrent diseases, experimentation)
Spread is by direct contact or through aerosol.

8. Clinical Signs
May be acute, subacute or chronic characterized by nasal
discharges which may be serous, mucous or mucopurulent.
Sick rabbits paw with the inside of the front legs causing matting
of the fur around that area, sneezing coughing are usual.
Snuffles is common at kindling period or during low resistance.
 Death may occur while recovered animals become carriers.
 
 Treatment
Penicillin and streptomycin, Sulphaquinoxaline, furazolidone may
be administered.

9. 2. ENZOOTIC PNEUMONIA
Aetiology P. multocida
Usually complicated by other bacteria like
oklebsiella pneumomae,
oBordetella bronchiseptica
oPneumococci.

10. Clinical signs
Starts with nasal infection, anorexia, fever
(40
0
C) dyspnea.
There may be diarrhea and weakness.
 Death may occur within 4 days.
 Some animals may die without showing
clinical signs.
Treatment
As for snuffles. Tetracyclines may be used.

11. OTITIS MEDIA
P. Multocida is the usual causative agent but
Staph spp and Bordetella spp may also be
found.
oTransmission is by
odirect contact,
oformites
respiratory route

12. Clinical signs:-
Torticollis. In severe cases the rabbis may not
be able to eat or drink resulting in weight loss
and dehydration. If the meninges are affected
incordination and other nervous signs may
occur.
Treatment
Tympanocentesis plus antibiotic (antibiotic
alone may not be effective).

13. GENITAL INFECTION
Caused mainly by P. multocida
complicated by other organisms.

Common in adults, more common in
does than in bucks.
Transmission is through coitus.

14. Clinical signs
oMay be acute or subacute inflammation of the reproductive
track.
oCauses pyometra in females characterized by mucoid vaginal
discharges.
oIt may also be purulent, thick yellowish-grey in colour.
oIn bilateral cases there is sterility but if only one horn is affected
there may be normal litter.
oIn the male a purulent penile discharge, orchitis also occurs.
Treatment
oAntibiotics which may be of little value. Ovariohysterectomy in
pets plus antibiotic.
Control
oCull all affected animals.
oRegularly examine the genitalia of breeding stock.
oBucks with low conception rate should be culled also females
that consistently fail to conceive.

15. ABSCESSES
P. multocida predisposed by wounds which may result from light
by males, scratches from other rabbits or sharp wire from the
cage.
Clinical signs
Subcut swelling, abscesses of internal organs which may result in
septicaemia and death.
Treatment
Lancing and draining antibiotic treatment both topically and
systemically.
Control
Eliminate affected animals, remove predisposing factors.

16. CONJUNCTIVITIS
oCaused by P. multocida, other organism may be incriminated.
Common in young ones than in adults but both are quite
susceptible.
Clinical signs
oSwollen eye lids gumed together by exudates.
oInflamed conjunctiva, mucoid later mucopurulent ocular
discharges. Affected animals rub the eyes with their front legs.
o Inflammation may become chronic with edema subsiding but
discharges continue resulting in epiphora.
oPathological overflow of tears on to the cheek.
Treatment
oPenicillin or chloramphenicol eye ointment.

17. SEPTICAEMIA
oCaused by P. multocida:- may be from other Pasteurella
infection.
Clinical signs
oMay not be detected as the animal dies suddenly but may
be noticed if other forms of pasteurellosis have been
incriminated.
Treatment
oUsually not practicable as animal dies suddenly.
Control:-
oAvoid infection by P. multocida, eliminate affected animal.
Prevent stress.

18. PARASITIC DISEASE
Coccidiosis
Major intestinal but self limiting disease of rabbit
Recovered animals become carriers.
There are two forms of the disease in rabbit, liver and
intestinal coccidiosis.
Liver form is caused by Eimeria stiedae
The intestinal form is caused by a variety of spp – E.
megna, E. irresidua, E. media, E perforans.
Nasal coccidiosis is due to contamination of mucous
membranes of the nose while practicing coprophagy.
Clinical signs
Older animals may be able to cope with the infection
but become carriers. The young ones succumb easily.

19. Hepatic coccidiosis:- There may be no clinical signs but
severe infection results in cachexia, abdominal
distension and death as a result of hepatic dysfunction.
Intestinal coccidiosis
Vary from inapparent to poor weight gain. May be acute
or chronic. Common signs are enteritis, diarrhea which
may be unformed stool or watery, catarrhal or bloody
fluid. In acute cases there is rapid weight loss severe
dehydration, polydipsia, anorexia but at times with
ravenous appetite. In some cases when young ones are
affected with virulent organisms e.g. E. irresidua or E
magna may die with no clinical signs.

20. Diagnosis is based on finding oocysts in the faeces but
there could be oocysts without clinical signs. In case
of sudden death oocysts may not be seen but all the
stages may be found in the intestinal mucosa.
Treatment
Sulphamerazine 0.02% in drinking water
Sulphaquinoxaline 0.05% in drinking water or 0.03% in
feed (for 2 weeks).
Control
Hygiene, eliminate carriers, screen incoming rabbits for
oocysts. Avoid contamination of food and water with
faeces. Separate the young ones from the adults.