Definition
An acute infectious disease, fatal in the majority of cases, viral polioencephalitis of warm-blooded animals, including humans

Etiology
Rabies is produced by an ultramicroscopic virus. Rabies virus a single-stranded RNA virus, genus Lyssavirus, family Rhabdoviridae. Rabies is a characteristically is confined to one species in a given geographic area. This virus is found to be the most virulent when taken from the central nervous system (brain and cord), less so form the peripheral nerves, salivary another glands and their secretions.

Species

• All warm-blooded animals, including dogs, cats, and humans
• U.S four strains endemic within fox, raccoon, skunk, and bat populations, all four strains can be transmitted to dogs and cats.

Geographic Distribution

• Worldwide
• Exceptions British Isles, Australia, New Zealand, Hawaii, Japan, and parts of Scandinavia
• Species adapted strains specific geographic distributions within endemic countries

Natural infection
Rabies is produced in practically all cases by the victim being bitten animal, introduction the virulent saliva into the wound, to come in contact with the nerves, muscles, or subcutaneous tissues. Rarely are cases produced by infectious agent being licked from wounds, or from contact with lesions on the skin.

Pathogenesis
Transmission is almost always by introduction of virus-laden saliva into the tissues, usually by the bite of a rabid animal. Virus may be present in the saliva or via mucous membranes and transmitted by an infected animal several days before onset of clinical signs. After the virus reaches the central nervous system to produce irritation on certain group of cell, it is distributed to different parts of body. It reaches the saliva glands, which favors the development of the virus, increasing the secretion of the glands and then is further disseminated trough the saliva.
The period of incubation of rabies is both prolonged and variable. The period of incubation in cats is usually shorter than in dog. Investigation has shown that the virus may be present in the saliva form seven to nine day previous time that symptoms are first shown.

Clinical Sign
General Comments

• Quite variable; atypical presentation is the rule rather than the exception.
• Three progressive stages of disease prodromal; furious; and paralytic

Historical Findings

• Change in attitude solitude; apprehension, nervousness, anxiety; unusual shyness or aggressiveness
• Erratic behavior biting or snapping; licking or chewing at sight of wound; biting at cage; wandering and roaming; excitability; irritability; viciousness
• Disorientation
• Muscular incoordination; seizures; paralysis
• Change in tone of bark
• Excess salivation or frothing

Physical Examination Findings

• All or some of the historical findings
• Mandibular and laryngeal paralysis, with dropped jaw
• Inability to swallow
• Hypersalivation
• Fever

Pathologic Findings

• Gross changes—generally absent, despite dramatic neurologic disease
• Histopathologic changes—acute to chronic polioencephalitis; gradual increase in the severity of the nonsuppurative inflammatory process in the CNS as disease progresses; large neurons within the brain may contain the classic intracytoplasmic inclusions (Negri bodies).

Diagnostic Procedures
Clinical diagnose is difficult, especially in location where rabies in uncommon. In the early stages, rabies can easily be confused with other diseases or with normal aggressive tendencies.
• CSF
minimal increased protein and leukocyte counts may be seen.
• DFA test of nervous tissue
rapid and sensitive test; collect brain, head, or entire body of a small animal that has died or has been euthanized; chill sample immediately; submit to a state-approved laboratory for rabies diagnosis.
• DFA test of dermal tissue
skin biopsy of the sensory vibrissae of the maxillary area, including deeper subcutaneous hair follicles

Diferential Diagnosis

• Canine distemper
• Any neurologic disease—brain tumor; viral encephalitis
• Head wound—identify lesions from wound
• Laryngeal paralysis
• Choking
• Pseudorabies virus infection

Treatment

• No treatment
• Once the diagnosis is certain, euthanasia is indicated.
• Patient monitoring
• All suspected rabies patients should be securely isolated and monitored for any development of mood change, attitude change, or clinical signs that might suggest the diagnosis.
• An apparently healthy dog or cat that bites or scratches a person should be monitored for a period of 10 days; if no signs of illness occur in the animal within 10 days, the person has had no exposure to the virus; dogs and cats do not shed the virus for more than 3 days before development of clinical disease.
• An unvaccinated dog or cat that is bitten or exposed to a known rabid an Rabies
• imal must be quarantined for up to 6 months or according to local or state regulations.

Preventive
Vaccines (dogs and cats) all dogs and cats with any potential exposure to wildlife or other dogs vaccinate after 12 weeks of age and 12 months later and then every 3 years using a vaccine approved for 3 years; use only inactivated vaccines for cats.