Clinical Signs

It has been estimated that 70% of Canine Distemper Virus (CDV) infections in dogs are subclinical or very mild (6). However, severe disease, with or without involvement of the central nervous system may occur. Note that signs may increase in severity during disease progression. After the initial fever, signs vary considerably, depending on the strain of the virus and the individual immunity (1,2). Neurological involvement is often responsible for the death of the patient at a mortality rate of 50% (6). CDV is often exacerbated by secondary bacterial infections as the dog has become immunocompromised (1,2). The course of the disease is 10 days but onset may be delayed several weeks to months (1). Specific signs of CDV infection are listed below.

Initial Signs
                          Transient fever 3-6 days post infection                    
                           Leucopenia (1,6) (decreased white blood cell count)
Possibly anorexia (1)

                    Later Signs
2nd fever lasts for 1 wk often accompanied by (1,6)
Serous nasal discharge (watery)
Mucopurulent ocular discharge
         1: Nasal Discharge

Gastrointestinal Signs (1,2)
Loss of appetite

Respiratory signs (1,2)
Laboured Breathing
Rhinitis (inflammation of nasal cavity)
Nasal Discharge

         2: Keratoconjunctivitis

Optical Signs (2,6):
Keratoconjunctivitis, conjunctivitis, 
chorioretinitis (inflammation of the eye)
Retinal Lesions
Optic neuritis (inflammation of the optic nerve)

Neurological Signs (1,2,6):
Ataxia (muscle incoordination)
Hyperesthesia (increased sensitivity to sensory stimuli)
Cervical rigidity indicates meningeal involvement
                           Acute encephalomyelitis (inflammation of brain and spinal cord)
3. Seizure                                                                                     Localized muscle twitching (myoclonus, chorea, flexor spasm)
                                                                                Hyperkinesis in leg/face
          Paresis/Paralysis in hindlimbs or all limbs
Seizures characterized by “chewing gum” motions and salivation

Associated Chronic Conditions (1,2,6):pup
Enamel hypoplasia (the death of cells that make tooth enamel resulting in unenamled teeth subsequent to infection).Hyperkeratosis (hardening) of nasal and foot pad epitheliumChronic Distemper Encephalitis or Old Dog Encephalitis (ODE):ataxia, head pressing, and hypermetria. The development of these signs is progressive and is precipitated by persistant inflammation related to distemper infection. In utero infection is rare and may result in: spontaneous abortion, persistently infected puppies or normal puppies that die within 4-6 weeks (2). Note, this may occur in dogs with no prior history of the disease. Dogs with this form of the disease are not considered to be infectious.                                                                                                                                                                                                  4. Enamel Hypoplasia                       5. Perisently Infected Puppy