Multisystemic viral diseases of dogs Flashcards
(80 cards)
1
Q
Canine Parvovirus -2 (CPV-2)
A
most severe of the canine enteric diseases
family Parvoviridae, genus parvovirus
2
Q
strains of CPV-2
A
4 strains
CPV-2, CPV-2a, CPV-2b, CPV-2c
CPV-2b and 2c are currently circulating
3
Q
transmission of CPV-2
A
fecal-oral
infected dogs shed 10^9 CPU/gm in feces
susceptible dogs need only 10^3 CPU to get infected
4
Q
how long do dogs shed CPV-2?
A
10 days
5
Q
what is the most common type of infection of CPV-2
A
subclinical infection in >75%
6
Q
Age susceptibility to CPV-2
A
originally, all dogs were susceptible regardless of age
now, mostly seen in 2-6 month old puppies (<1%
7
Q
Breed susceptibility to CPV-2
A
susceptible breeds: rottweilers, Dobermans, german shepherds, golden retrievers, Alaskan sled dogs
resistant breed: beagles
8
Q
incubation period of CPV-2
A
1 week
9
Q
What is CPV-2 antigenically similar to
A
more similar to Feline Panleukopenia virus than CPV-1
10
Q
clinical signs of CPV-2
A
either myocarditis (uncommon) or enteritis
11
Q
presenting signs of CPV-2 enteritis
A
vomiting with sudden acute diarrhea (foul smelling feces)
feces often bloody or frankly hemorrhagic
mostly puppies <12 weeks
dogs die or recover quickly
leukopenia present
12
Q
Presenting signs of CPV-2 myocarditis
A
not common
seen in 4-8 week old puppies
sudden death (heart failure)
13
Q
pathogenesis of CPV-2
A
primary site of replication is in oropharynx and lymphoid tissue
viremia seen after 2-3 days, virus spreads and infects FAST GROWING CELLS (intestinal epithelium, lymphocytes, and actively dividing myocytes)
in intestine, virus infects and causes necrosis of crypt cells of ileum and jejunum… also causes necrosis of lymphocytes in PEYERS PATCHES
myocardial infection with heart failure seen in young 4-8 week old puppies with no circulating maternal Ab (heart lesions occur during first 2 weeks of life)
14
Q
Diagnosis of CPV-2
A
History (sudden onset diarrhea, distinct smell, bloody, V)
Clin Path (LEUKOPENIA)
Pathological Lesions
- dehydration, hemorrhagic enteritis (hose-like) of SI, mucosal petechial, necrotic Peyer’s Patches
- histopath: ballooned crypts with necrosis of crypt cells, shortened villi, and IN inclusions in crypt cell of ileum and jejunum
Detection of viral Ag
- FA test and immunohistochemistry using viral specific Mab
- CITE test (IDEXX) is most important diagnostic test for diagnosing CPV-2 in dogs (ELISA)… fecal ELISA
Detection of virus/viral nucleic acid
-PCR
Detection of circulating Ab
-serology on paired samples (acute and convalescent) to detect seroconversion`
15
Q
control of CPV-2
A
fluid replacement, control acidosis and vomiting
broad spectrum antibiotics
16
Q
Prevention of CPV-2
A
vaccine is available- both MLV and inactivated
17
Q
puppies with no maternal antibodies to CPV-2
A
or titer <5
susceptible to both infection with CPV-2 AND susceptible to CPV-2 in the MLV vaccine (can be properly immunized with MLV)
18
Q
Puppies with high levels of maternal Ab (>80 titer)
A
are resistant to infection or vaccination with MLV (cannot respond to vaccination due to neutralization)
19
Q
puppies with maternal Ab titers between 5 and 80
A
can become infected with virulent CPV-2 but CANNOT be immunized with MLv virus
20
Q
When do puppies become susceptible to infection with CPV-2?
A
when titers drop below 80
21
Q
when do puppies become uniformly susceptible to CPV-2 infection?
A
when titer drops below 40
22
Q
When do puppies allow successful vaccination?
A
when titer drops below 5
23
Q
What is the “window period” for CPV-2?
A
the period during which puppies can become infected but not immunized… titer between 40 and 5
24
Q
how should puppies be vaccinated?
A
starting at 6-8 weeks, and repeatedly vaccinated every 2-3 weeks until they are 18 weeks old
25
Canine Parvovirus-1 Infection
AVIRULENT virus of dogs ("Minute virus of canine")
26
is CPV-1 similar to CPV-2
they are antigenically distinct
27
what does infection with CPV-1 cause?
asymptomatic disease which results in seroconversion
mild diarrhea in pups 5-21 days old... poor growing pups ("fading pups")
can cause abortions in bitches
28
Canine Distemper virus synonyms
hard pad disease
29
Where has canine distemper recently been seen and gained notoriety?
African lions
| 1/3 of infected lions developed neuro disease (seizures)
30
canine distemper family and genus and classification
family Paramyxoviridae, genus morbillivirus
large enveloped virus with ssRNA and helical nucleocapsid (envelope has fusion and hemagglutination protein)
31
what proteins are in the envelope of distemper?
fusion and hemagglutination protein
32
What is distemper antigencally related to?
measles and rinderpest virus
33
What species does Distemper infect?
```
wild and domestic dogs
RACCOONS
Mink
skunk
seals
cat
lions, tiger, cheetah
ferret
```
34
how is distemper transmitted?
aerosol droplets, very contagious
| also by contact with mucous membranes or urine/feces
35
Does distemper survive in environment well?
NO
| easily inactivated by disinfectants
36
are recovered dogs carriers of distemper?
NO
37
what animal is important for maintenance of virus in circulation?
raccoons and other wild animals
38
clinical signs of Distemper
signs depend on age and immune status of dog and virulence of virus
39
what percentage of distemper infections are subclinical?
50%
40
mild infections of Distemper
ocular/nasal discharge, fever, cough (indistinguishable from other respiratory infections)
leukopenia (lymphopenia) common early in disease
41
severe infections of distemper
respiratory signs predominate
- mucopurulent nasal and ocular discharges, lung infection with moist productive cough, pneumonia
- can also have GI signs (V, D)
usually ends in death
42
what causes the GI signs of distemper virus?
usually a result of secondary bacterial infection with salmonella
43
CNS signs of distemper: when, what?
CNS signs seen late during or after respiratory signs... can be seen after the dog seemingly recovers from a mild respiratory disease
seizures, ataxia, myoclonus, chorea (twitching), ascending paralysis
44
what is the result of CNS signs of distemper?
either rdeath or recovery with permanent residual CNS signs
45
Other signs of Distemper (3)
1) Hyperkeratosis of foot pads (Hard Pad Disease)
- after they recover... these dogs more likely will develop CNS signs
2) teeth deformities (enamel hypoplasia) in young pups
3) Hypertrophic Osteodystrophy (aka metaphyseal osteopathy)
- seen with systemic CDV and following vaccination with MLV vaccine of CDV
46
Encephalitis caused by Distemper
"Old dog Encephalitis"
rare condition- ataxia, head pressing, pacing, uncoordination
no history of distemper
no infectious CDV seen in brain, but FA on CNS tissue is positive for CDV
47
raccoon CDV
same signs as canine
nasal/ocular discharge
respiratory signs, cough
fever
vomiting, diarrhea, dehydration, weakness
CNS signs- most noticeable... wander aimlessly, not scared of humans, seizures, sudden aggression
hyperkeratosis of foot pads
48
pathogenesis of Distemper
virus enters oropharynx, replicates in tissue macrophages
carried by these macs to tonsils and bronchial LN (replicates in macs, DC, and lymphocytes)
viremia follows virus replication in leukocytes
virus then spreads and infects cells in many different organs (pantropic virus)-epithelial cells of respiratory and GI tracts, skin, and glial cells and neurons of CNS
Skin and CNS infection occur late infection process... if immune response is quick, these do not get infected
secondary bacterial infection also important in pathogenesis of CDV- exacerbates pneumonia and diarrhea
49
what does the disease outcome of distemper dependent on?
speed of immune response/neutralizing Ab
if antibodies are developed by 9 days and high titers by 14 days, the animal clears the infection and recovers
if antibodies are not made by 9 days, virus disseminates to all organs and animal will die
if intermediate immune response (delayed until 14 days to produce Ab or no increase in titers between 9 and 14 days), virus infects CNS and epithelial tissue... CDV can be cleared from lymphoid tissues but persists in neurons and epithelia... can cause CNS signs and hyperkeratosis
50
Diagnosis of CDV
History (unvaccinated young dog, respiratory disease, nasal and ocular discharge, seizures)
Clin path
- leukopenia with absolute LYMPHOPENIA
- exam of buffy coat smear or cytology of conjunctiva/respi epithelium shows low number of inclusions in leukocytes, neutrophils, and monocytes (will light up when FA test is performed)
- CSF exam in dogs with neuro signs- increased protein and lymphocytes in CSF
Pahology
-at necropsy: resp and GI tracts affected (interstitial pneumonia, secondary bacterial infection)
-histopath: IN and IC eosinophilic inclusions in astrocytes, resp, GI, and bladder epithelial cells
~lymphoid depletion in all lymphoid tissue
~demyelination and lymphocytic inflammation within cerebrum, cerebellum, and brain stem
~non-suppurative meningoencephalitis
RT-PCR
FA and IHC are important tests for diagnosing CDV Ag
-submit spleen, tonsils, LN, lungs, duodenum, brain
high IgM titers during acute infection
IgG Ab seen with maternal Ab, vaccination, prior infection, or recent infection
51
Treatment of Distemper
supportive care, non-specific treatment
Vitamin C, Vitamin A
anticonvulsants
antibiotics
52
Vaccine for Distemper
MLV for best vaccine protection... but post vaccine complications with MLV (encephalitis in young pups)
a recombinant canarypox vaccine containing F and H protein is available for dogs and zoo animals ***Can immunize pups in the presence of maternal antibodies
1 dose of MLV can provide protection in colostrum-deprived pups of any age
pups can consume colostrum- immunized until 12-14 weeks (vaccinate these pups from 8 weeks until 16 weeks)
yearly re-vaccination is recommended
53
measles vaccination for distemper
MLV measles was used to immunize pups and cause self-limiting non-contagious infection... can be used in the face of maternal Ab
no we use recombinant vaccine instead
54
Canine Adenovirus-1 synonyms
Infectious Canine Hepatitis
Rubarth's disease
fox encephalitis
55
canine Adenovirus-1 family, classification
family Adenoviridae
non-enveloped, ds DNA virus
icosahedral symmetry (12 fibers)
resistant virus in environment
56
CAV-1 disease
causes hepatitis with basophilic IN inclusions in hepatocytes`
57
age range susceptible to CAV-1
younger dogs
most infections are subclinical and do not result in disease
58
what is the source of virus for CAV-1?
infected and recovered animals (recovered animals can excrete virus for months in URINE)
59
how do recovered animals excrete CAV-1?
urine
60
transmission and incubation period of CAV-1
transmission is by direct contact- mucosal contact with urine or fomites
incubation period 1 week
61
Forms of clinical disease of CAV-1
1) inapparent form (most infections)
- mild subclinical disease
2) mild respiratory form
- pharyngitis, laryngitis, tonsillitis (more common with CAV-2)
3) Acute (hepatitis) form (rare)
- sudden onset disease, fever, vomiting, thirst
- diarrhea (dark feces from hemorrhage)
- pale mucus membranes with petechial
- icterus
4) Ocular form "Blue Eye"
- seen in 25% of dogs that recover from CAV-1
- transient corneal opacity caused by edema of cornea as a consequence of uveitis (hypersensitivity type III)
- can also be seen in 1-2% of dogs 8-10 days after vaccination with MLV vaccine
5) encephalitic form
- very common in foxes, up to 20% of foxes
- seizures, aimless wandering
62
pathogenesis of CAV-1
virus multiplies in oropharynx/tonsils, then invades lymphatics with resultant viremia
CAV-1 infects vascular endothelial cells and disseminates throughout body causing necrosis of endothelial cells of blood vessels and hepatocytes
leads to consumptive coagulopathy (DIC), petechial, ecchymosis
damage to hepatocytes in acute hepatic necrosis with typical IN inclusions in hepatocytes
when Ab appear (7 days), immune complexes are formed, deposited in kidneys and EYE (results in kerato-uveitis/type III), causing "blue eye"
63
Diagnosis of CAV-1
Clin path (marked neutropenia and lymphopenia... thrombocytopenia, elevated Liver enzymes)
pathology
- at necropsy: swollen liver with markedly swollen hemorrhagic gallbladder, petechial
- at histopath: basophilic IN inclusion bodies in endothelial cells and hepatocytes
PCR id's viral DNA in blood
FA and IHC are BY FAR the most important tests for diagnosis (viral Ag)
64
can dogs become re-infected after they recover from CAV-1
no, dogs that survive infection develop strong lifelong immunity and are protected
65
Prevention of CAV-1
maternal Ab transfer will protect pups until 12 weeks
vaccinate with CAV-2****- CAV-2 is antigenically related to CAV-1, so it is the vaccine of choice... CAV-2 MLV also has not been associated with blue eye
66
Canine Herpesvirus-1
causes acute highly lethal generalized infection in young puppies < 2 weeks
67
who gets canine herpesvirus-1?
high percentage of bitches and male dogs are latent carriers in sacral ganglia (50% carriers)
puppies < 2 weeks are the ones affected-lethal
68
what is canine herpesvirus-1?
only 1 serotype of canine herpesvirus
alpha-herpesvirus
69
how is herpesvirus transmitted in adult dogs?
venereally
pups infected from birth via infected vaginal mucosa from dam
70
clinical signs of canince herpesvirus in adult dogs
in adults, lesions are rare (can occur during stress/oestrus... lesions on vulva, vagina, penis--> vesicles/ulcers)
71
clinical signs of canine herpesvirus in puppies
in pups less than 2 weeks old, acute highly lethal generalized infection
- puppies infected from birth via contact with infected vaginal mucosa
- virus spreads hematogenously resulting in disseminated fatal infection
- soft greenish stool, labored breathing, abd pain, death in 24-48 hrs
72
how does the virus spread in body
hematogenously
73
does herpesvirus cause fever?
NO
74
pathogenesis of herpesvirus
upon recrudesce from sacral ganglia, CHV-1 replicates on genital mucosa, transmitted venereally
if bitch is seropositive at time of whelping, she passes anti-CHV-1 Ab to pups via colostrum and pups are protected against the DISEASE
if bitch is seronegative at time of whelping, pups will have no protection and will develop disease
**this is only relevant to bitches whelping for the first time... pups from subsequent litters do not develop disseminated fatal from of CHV-1
75
Diagnosis of herpesvirus
history (genital lesions, non-febrile acute disease with mortality within 2 days in <2 week pups)
pathology
- at necropsy: lesions are characteristic (can make diagnosis on gross lesions)- disseminated focal necrosis and hemorrhage in all organs, especially kidneys and liver. Kidneys appear mottled- disseminated ecchymotic hemorrhage
- histopath: foci of necrosis and hemorrhage in liver, kidney, lung with IN inclusions
virus isolation in tissue culture cells
PCR to id virus DNA
FA detection of viral Ag
detection of circulating Ab
-dogs will develop neutralizing Ab measured by VNT
76
what type of dams is this disease seen in?
bad bitches that whelp for the first time
poor mothering ability
-disease is rarely observed in the same bitch at subsequent whelpings
77
do neutralizing antibodies prevent recrudescence of virus from nerve cells?
no
78
do maternal antibodies prevent infection?
NO- maternal Ab prevent disease, puppies can still be infected
-if a pup is infected at birth but protected by maternal Ab, virus can latently infect nerve cells of the pup without the pup mounting an immune response--> when pup becomes an adult, it can recrudesce and not have Ab to protect the infected pups (if the dog is whelping). Subsequent pups are then susceptible to disease... after this first episode, bitch will mount solid immune response and protect subsequent litters
79
treatment of canine herpesvirus
increasing body temp to 103* will increase survival
~bad bitches will leave pups unattended and not provide the warmth necessary for treatment
hyperimmune serum can be used on surviving pups in the litter
80
is there a canine herpesvirus-1 vaccine?
no
