Dog Owner's Home Veterinary Handbook.pdf - Mr. Walnuts

360 •DOG OWNER’S HOME VETERINARY HANDBOOK
Dogs who recover may exhibit a posttraumatic syndrome that can include
seizures, behavior changes, head tilt, and blindness.
Brain Diseases
ENCEPHALITIS (BRAIN INFECTION)
Encephalitis is an inflammation of the brain. Symptoms include fever, depression,
behavior and personality changes (especially aggression), uncoordinated
gait, seizures, stupor, and coma.
Canine distemper is the most common cause of encephalitis in dogs. Signs
develop two to three weeks after the onset of the disease. Other causes of viral
encephalitis include rabies, pseudorabies, and herpesvirus. Rabies is a very
serious disease, but with present-day vaccination programs the disease is not
common among domesticated animals. Canine herpesvirus produces an
encephalitis in puppies younger than 2 weeks of age.
Bacterial encephalitis is caused by organisms that enter the brain via the
circulatory system, such as bacterial endocarditis, or by direct extension from
an infected sinus, nasal passage, or an abscess in the head or neck. Migrating
foreign bodies such as porcupine quills or grass awns may get into the central
nervous system. Fungal brain infections (caused by cryptococcosis, blastomycosis,
or histoplasmosis) are rare causes of encephalitis, as are protozoan infections.
Tick-borne rickettsial diseases, notably Rocky Mountain spotted fever
and canine ehrlichiosis, are infrequent causes. These diseases may also
involve the spinal cord.
Postvaccination encephalitis is rare with modern vaccines. It was most
likely to occur when modified live virus distemper vaccine was administered
at the same time as modified live parvovirus vaccine in puppies less than 6 to
8 weeks old. This is not usually seen with current vaccines and vaccination
schedules.
Lead encephalitis is seen primarily in young dogs who chew on materials
that contain lead, such as paint and drywall, especially in older buildings.
Lead alters brain metabolism and causes inflammation and swelling. Central
nervous system signs are often preceded by vomiting, diarrhea, or constipation.
The diagnosis is confirmed by an elevated blood lead level.
Meningitis is an infection of the surface of the brain and spinal canal. It is
caused by infected bite wounds about the head and neck and bacterial infections
that travel to the brain from the sinuses, nasal passages, or middle ears.
Aseptic meningitis is a nonbacterial disease of unknown cause. It affects
large-breed dogs 4 to 24 months of age.
The diagnosis of encephalitis or meningitis is based on analysis of cerebrospinal
fluid obtained by spinal tap. Serologic tests may identify the cause of
the inflammation.