Aujeszky's Disease in Dogs: Fatal Outcome and Clinical Features
Aujeszky's disease, also known as pseudorabies, is a viral infection caused by Suid herpesvirus 1 (SHV-1). While pigs are the natural reservoir and can survive the infection, dogs face a much grimmer prognosis. If you're concerned about the risks this disease poses to dogs, it's important to understand how it affects them, how transmission occurs, what clinical signs to watch for, and why prevention is so crucial.
How Do Dogs Contract Aujeszky's Disease?
Dogs usually become infected by ingesting raw pork or offal from infected swine or wild boar. Sometimes, contact with contaminated environments—such as grass or soil where infected pigs have been—can also transmit the virus. Importantly, dog-to-dog transmission does not occur, so outbreaks among dogs are linked directly to exposure to infected swine rather than spread between canines.
Incubation Period and Onset of Symptoms
The incubation period in dogs typically ranges from 2 to 10 days. Once symptoms begin, they progress rapidly. The clinical course is acute and devastating, often leaving little time for intervention.
Clinical Signs in Dogs
- Sudden behavioral changes (restlessness or aggression)
- Seizures and loss of coordination
- Muscle tremors
- Excessive salivation
- Severe localized itching (pruritus), especially on the head and face—often called "mad itch"
- Jaw and pharyngeal paralysis
- Howling or vocalization
- Vomiting and diarrhea
- Respiratory distress
The intense pruritus leads many affected dogs to self-mutilate in attempts to relieve the sensation. Neurological involvement progresses swiftly; most dogs die within 24 to 48 hours after symptoms appear.
Disease Progression and Pathology
The virus attacks the central nervous system as well as peripheral ganglia. Pathological findings in naturally or experimentally infected dogs include:
- Nonsuppurative ganglioneuritis (inflammation of nerve clusters)
- Brainstem encephalitis (brain inflammation)
- Myocardial necrosis and hemorrhage (heart tissue damage)
- Pulmonary edema (fluid accumulation in lungs)
- Lymphoid depletion (immune tissue loss)
Cardiac troponin-I levels rise when there's heart muscle injury, which can explain respiratory distress seen in some cases.
No Treatment or Vaccine for Dogs
No specific antiviral treatment or vaccine exists for dogs. Supportive care may be attempted but is mainly palliative—focused on easing suffering rather than curing the disease. The rapid progression means most affected animals succumb before any meaningful intervention can take place.
Diagnosis: Fast but Often Postmortem
- A veterinarian will consider clinical history and symptoms—especially sudden neurological decline with intense pruritus.
- PCR testing can detect viral DNA; other methods include virus isolation, histopathology (looking for characteristic inclusion bodies), immunohistochemistry, and serological assays (mainly used in pigs).
Differential diagnosis includes rabies, canine distemper, and poisoning. Due to the speed of deterioration, postmortem diagnosis is common.
Epidemiology: Where Is the Risk Highest?
- Pig populations—both domestic and wild—serve as reservoirs for SHV-1.
- The virus remains viable for days outside a host—in grass, soil, feed—which increases risk for hunting dogs or those living near pig farms.
Sporadic infection occurs in non-swine species but is almost always lethal when it does. Hunting dogs are particularly at risk due to their likelihood of encountering wild boar meat or carcasses during hunts.
Prevention Strategies for Dog Owners
- Avoid feeding raw pork or offal from pigs or wild boar.
- If you work with pigs or hunt with your dog, maintain strict biosecurity practices—including decontaminating animals after potential exposure.
If a dog has had contact with potentially infected swine or wild boar meat—even if only environmental contamination—monitor closely for sudden behavioral changes or neurological signs. Immediate veterinary attention is essential but rarely alters the outcome due to the rapid progression of disease.
The Broader Picture: Control Measures in Swine Populations
- Pigs are vaccinated using gene-deleted live vaccines that allow differentiation between vaccinated and naturally infected animals via diagnostic tests.
This vaccination strategy helps prevent outbreaks among swine herds—and indirectly protects other mammals by reducing viral shedding into the environment. Surveillance among wild boar populations remains critical since they maintain sylvatic cycles of infection that can spill over into domestic animals like hunting dogs.
