Infectious diseases of dogs

Question 1

What is the causative agent of Rubarth’s disease

Answer 1

Canine adenovirus 1

Question 2

Infectious canine hepatitis virus characteristics

Answer 2

= from canine adenovirus 1
Non enveloped dsDNA; survives well in environment

Question 3

How does infection with canine adenovirus 1 work

Answer 3

Mainly puppies before vaccination

Naso/oropharyngeal infection; penetrates epithelium –> lymphatic spread to hepatocytes/kidney/spleen/eye

Question 4

Clinical signs of canine infectious hepatitis

Answer 4

Lethargy, anorexia, abdominal pain, hepatomegaly, jaundice, vomiting, haematemesis/chezia
May see BLUE EYE in first week of infection

Question 5

Pathological findings with infectious canine hepatitis PM

Answer 5

Protein rich fluid in peritoneum, swollen pale liver, ecchymotic haemorrhages on serosa

Histologically: hepatocytes have owl eye includion bodies, necrosis in liver

+ blue eye = antibody-antigen response; POSITIVE sign for recovery

Can get dissemination into brain

Question 6

Canine distemper virus

Answer 6

= enveloped RNS virus; causes multisystem disease
Paramyxovirus

Get infection of URT lymphoid tissue, spread via lymphatics –> viraemia
THEN affects respiratry, GI, CNS and skin

Question 7

What are the signs of classical distemper

Answer 7

Prexia, anorexa, conjunctiviity, oculo-nasal diacharge, cough, leukopenia

Question 8

What is chronic distemper

Answer 8

Where a good immune response is mounted

See ocular signs
CNS effects; progressive ataxia, paralysis
Hyperkeratotic epithelial tissue = HARD PAD
Enamel hypoplasia if while developing dentition

Question 9

Which virus is responsible for ‘hard pad’ due to proliferation of epithelial tissue

Answer 9

Distemper virus; chornic form

Question 10

What viruses are covered by DHPPi vaccination

Answer 10

Distemper virus
Hepatitis; via canine adenovirus
Parainfluenza virus
Parvovirus

Question 11

Canine parovirus

Answer 11

= non-enveloped ssDNA virus; stable in environment
Seen esp in puppies

Faeco-oral transmission; get replication in oropharyngeal lymphoid tissue -> viraemia -> infects rapidly dividing cells

Question 12

Clinical signs of canine parvovirus

Answer 12

Fever, lethargy, abdominal pain, emesis
THEN profuse haemorrhagic diarrhoea

IF neonates/in utero infections: can get myocarditis; see death or congestive heart failure

Question 13

What strains does the L4 vaccine contain

Answer 13

L icterohaemorrhagiae, L canicola, L grippotyphosa, L australis

Question 14

What do leptospira pathogens look like

Answer 14

= thin, spiral, motile bacteria

Question 15

How does leptospira infection work

Answer 15

Urine contact; organisms penetrate abraded skin or intact MMs
–> Rapid multiplication in blood stream
–> Spread to kidneys and liver

Release haemolysin toxin; so see intravascular haemolysis and icterus
+ petechial haemorrhages from bacteraemia

Question 16

Where is the reservoir of lectospira in the host

Answer 16

Proximal convoluted tubules

Question 17

What blood parameters give leptospira suspicion

Answer 17

Thrombocytopenia, raised liver and kidney parameters
Normal blood glucose BUT GLUCOSE IN URINE

Question 18

Treatment of leptospira

Answer 18

Doxycycline
Ampicillin/penicillin

Question 19

Pathology seen with leptospira infection

Answer 19

Icterus, enlarged liver and spleen, ecchymotic haemorhages

On histology: dissociation of hepatocytes so don’t see portal triads etc; relative lack f inflammation

Question 20

Which dogs are especially at risk of leptospirosis

Answer 20

Male, large breed, entire dogs with wildlife access i.e outdoor

Question 21

What are the infectious agents in kennel cough

Answer 21

Bordetella bronchiseptica
Canine parainfluenza virus

Also: CDV, CAV-2, CHV-1

Question 22

Clinical signs of infectious canine tracheobronchitis

Answer 22

Dry hacking cough, pharyngeal retch, serous nasal discharge

Often think there is ‘something in their throat’

Question 23

Difference in how herpes viruses affect dogs and cats

Answer 23

In dogs, virus can become systemic

Question 24

What class of herpesvirus affects dogs

Answer 24

Alpha
e.g CHV-1

Question 25

Causative agent in tetanus

Answer 25

Clostridium tetani = gram +ve spore forming anaerobe

Question 26

Clinical signs of tetanus

Answer 26

Stiff gait, dorsally curved tail, erect ears, difficulty standing or lying

Question 27

Pathogenesis of tetanus

Answer 27

Spores enter penetrating wounds and convert to vegetative state; start making toxins which ascend nerves and prevent release of inhibitory neurotransmitters by interneurons -> Get spastic paralysis See signs 3-18 days after wound contamination

Question 28

What causes Lyme disease and what are the signs in dogs

Answer 28

Spirochaete B burgdorferi; spread by Ixodes ricinis ticks Dogs mainly asymptomatic

Question 29

If in doubt in dogs what are we treating bacterial infections with

Answer 29

doxycycline

Question 30

How does angiostrongylus vasorum infection in dogs work

Answer 30

Adults live in pulmonary arteries; get coughing and activation of coagulation system COMBINATION: RESPIRATORY SIGNS AND ABNORMAL BLEEDING

Question 31

Treatment for angiostrongylus vasorum in dogs

Answer 31

Fenbendazole Could use advocate (moxidectin)

Question 32

What type of virus causes rabies

Answer 32

Enveloped RNA virus = lyssavirus

Question 33

What genotype is classical rabies vs bat rabies

Answer 33

Classical = 1 Bat rabies = 2-7

Question 34

Diagnosis of rabies

Answer 34

Fluorescent antibody staining of the brain used to be used but false -ves real-time PCR best

Question 35

Pathogenesis of rabies

Answer 35

Inoculation via bite wound; migration to the CNS via nerves, CNS multiplication then viral dissemination Furious form: excitement pyrexia, aggression Dumb form: timid, affectionate, dysphagia Both progress to paralysis and death Other sign - hydrophobia due to pain on swallowing; so saliva drools out

Question 36

What is the minimum age a puppy can be given. rabies vaccination

Answer 36

12 weeks; then takes 3 weeks before effective enough to import puppy

Question 37

Survival of rabies virus

Answer 37

Can surivive in deep freezing BUT readily inactivated by disinfectants

Question 38

Histopath of rabies

Answer 38

No gross lesions On histopath see non-suppurative polioencephalomyelitis Negri bodies = intra-cytoplasmic inclusinos