10. Rabies in dogs & cats

What is the causative agent of rabies?

Rabies lyssavirus

Is rabies zoonotic?

Yes

Is rabies a WOAH listed disease?

Yes

What are the main reservoirs for rabies?

Carnivores

• Sylvatic cycle (foxes, bats, racoons)

• Urban cycle (stray dogs)

How is rabies transmitted?

Saliva from biting animals

Where is the rabies virus found in an infected animal?

Nervous tissue, salivary glands, saliva, cerebrospinal fluid

How does the rabies virus travel to the CNS?

Via acetylcholine receptors in the neuromuscular junction, then along peripheral nerves

How does the rabies virus travel from the CNS to the salivary glands?

Neuron axons

What are the two main forms of rabies?

Furious form and dumb/paralytic form

During the first course of replication of rabies, where is the virus found?

Limbic system → furious form

During the second course of replication of rabies, where is the virus found?

Brain cortex → dumb form

What is the incubation period of rabies?

Depends on the location of the bite e.g. neck vs leg. 2 weeks to 3 months (or years)

What are the initial signs of rabies?

Restlessness, anorexia, or an increased appetite, vomiting, slight fever, dilation of the pupils, hyperreactivity to stimuli & excessive salivation.

These signs usually last for 2 to 5 days, & may be followed by either the paralytic or furious form.

What are the three stages of the furious form of rabies?

1. Prodromal stage → lasts 2-3 days: sudden change in temperament, rise in temperature, dilation of pupils, loss of corneal reflex.

2. Manifestation/Excitation stage/ Fury → lasts 3 days: restlessness, wandering, drooling & attacks of animals, people or objects, teeth broken & mouth is lacerated. Tries to catch imaginary objects, swallow foreign objects, change of voice, sensitive to pain, hypersalivation (drooling). Wild animals often lose their fear of humans.

3. Paralytic stage: rapid ataxia, convulsions, paralysis, & then death

What are some clinical signs of the dumb/paralytic form of rabies?

Progressive paralysis, lethargy, muscle tremors, paralysis of hindquarters, paralyzed throat, masseter, tongue, respiratory paralysis → death

What are some differential diagnoses for rabies?

Aujeszky’s disease, Canine distemper, Japanese encephalitis, E. coli meningitis, Brucellosis, Listeriosis, brain tumour, liver/kidney disease

How is rabies diagnosed?

FAT (fluorescent antibody test), immunohistochemistry, ELISA (Ag), RT-PCR, histology (Negri bodies, perivascular cuffing)

What is the gold standard diagnostic test for rabies?

FAT (fluorescent antibody test)

What may be seen in a post mortem examination of an animal with rabies?

Brain will be oedematous and darker (hyperaemia & petechiae) in colour

What are the days, after being bitten, to test an animal for rabies?

1, 5, 14

What are treatment options for rabies?

Euthanasia, isolation, re-vaccination

What is the treatment for rabies once clinical signs appear?

Euthanasia

How is rabies prevented?

Vaccination (inactivated); core in Slovakia; over 3 months old; booster: annual (cats), every 3 years (dogs)

Oral marker vaccine for wild animals (SAD Bern strain)

What is the minimum antibody concentration required before travelling to a rabies free area?

0.5 IU/ml

If a dog comes into the clinic and has bitten someone, what is the procedure?

• Vet: protect yourself! Gloves, glasses, proper restraint

• Human: clean wound and give anti-serum

• Dog:

  • Euthanasia

  • Unknown vaccine history: Isolate for 6 months + give vaccine 1 month before end

  • Vaccinated: vaccinate on day 1 + isolate for 45 days