Rabies is a viral disease that affects the central nervous system of mammals, including dogs. It is spread through the saliva of infected animals and is almost always fatal once symptoms appear. Rabies causes about 59,000 human deaths worldwide per year, with over 95% of cases caused by dog bites. So how obvious is rabies infection in dogs? There are some clear signs, but the disease can also be easy to miss in its early stages. This article will go over the timeline of rabies progression in dogs and what symptoms to look out for.
How is rabies transmitted?
The rabies virus is spread through the saliva of infected animals. Transmission usually occurs through a bite, where the virus is introduced into a wound. The virus travels from the wound site to the central nervous system, causing inflammation of the brain and spinal cord. Less common routes of transmission include:
– Saliva of an infected animal getting into an open wound or mucous membrane (eyes, mouth, nose)
– Inhalation of aerosolized rabies virus, such as in a cave with infected bats
– Transplantation of an infected organ
– Rarely, transmission from mother to baby during pregnancy
Dogs are most often infected through a bite from a wild animal, like a raccoon, skunk, bat or fox. The incubation period is typically 1-3 months, but can range from several days to years. During this time, the dog may appear normal but can still transmit the virus through its saliva.
Stage 1: The Prodromal Phase
The first phase of rabies symptoms in dogs is called the prodromal phase. It lasts for 2-3 days on average. Some subtle behavioral changes may be noticeable, including:
– Increase or decrease in appetite
– Fever
– Changes in temperament – unusual shyness, irritability, or aggressiveness
– Seeking solitude and hiding more than usual
These symptoms are very non-specific though and could be caused by many other more common illnesses. There are no visible physical symptoms yet. Owners may not think anything serious is wrong at this point.
Stage 2: The Excitatory Phase
After the prodromal phase comes the excitatory or “furious” phase. This lasts for 3-4 days. The signs become more distinctive:
– Hyperactivity and restlessness
– Jaws snapping with no apparent reason
– Disorientation
– Lack of fear
– Aggression and biting at real or imaginary objects
– Seizures
– Dilated pupils
The dog may attack suddenly with no provocation. There is also excessive salivation and drooling. These symptoms are caused by the virus inflaming the dog’s brain.
Stage 3: The Paralytic Phase
The final stage is the paralytic or “dumb” phase. It generally lasts 2-4 days until death. Symptoms include:
– Fever
– Paralysis of the lower jaw and muscles for swallowing
– Paralysis that spreads through the body
– Loss of consciousness
The paralysis is progressive. It starts in the face and jaw, making it difficult for the dog to swallow. The throat and esophagus are also affected. Rabid dogs appear to have something stuck in their throat because they cannot swallow their saliva. Owner may notice their dog bringing up saliva and not able to eat or drink.
As the virus spreads to the spinal cord and brainstem, rear leg paralysis, convulsions, and coma occurs due to brain dysfunction. Most dogs succumb to respiratory paralysis.
What major symptoms indicate rabies?
The most distinctive symptoms of rabies in dogs are:
– Unexplained behavioral changes – including sudden aggression, irritability, and biting. This is one of the earliest signs.
– Excessive drooling and salivation – Rabid dogs look like they have something caught in their throat because they cannot swallow their saliva.
– Attack of imaginary objects – Biting and snapping at the air. May also run into walls and furniture.
– Seizures and muscle spasms in the later stages.
– Progressive paralysis – Starting in the face and throat muscles and spreading through the body.
– Fever
– Death within 10 days of onset of symptoms.
If a dog is showing these neurological and behavioral changes, rabies should be highly suspected. Seek emergency veterinary care.
What tests confirm rabies?
There are two main tests used to diagnose rabies in dogs:
Fluorescent Antibody Test
This test looks for the rabies virus in a sample of the dog’s brain tissue. It is the gold standard for postmortem rabies confirmation. A brain sample is taken after the dog dies or is euthanized. The antibodies bind to any rabies antigen in the tissue and glow fluorescent when visualized under a microscope.
RT-PCR
RT-PCR (reverse transcription polymerase chain reaction) detects rabies virus RNA in a saliva or brain tissue sample from the dog. Results can be obtained within hours. This test is performed if a dog needs to be quarantined and observed for rabies development. However, early in the disease there may not yet be detectable virus shedding in the saliva.
Can rabies be cured?
There is no effective treatment for rabies once clinical signs appear. The disease has almost a 100% fatality rate. Even with intensive supportive care, dogs usually die within 7-10 days.
Euthanasia is typically recommended once the diagnosis is confirmed, both for the dog’s sake and to prevent further viral transmission.
However, if caught very early before symptoms develop, the disease may be preventable with prompt post-exposure prophylaxis. This consists of:
– Immediate washing of bite wounds with soap and water. This may help flush out some of the virus before it can enter the nervous system.
– A dose of rabies immune globulin injected at the bite site to neutralize any remaining virus
– 4-5 doses of rabies vaccine given over 2-4 weeks. The immune response generated can still fight the infection before it reaches the brain.
So the key is proactive prevention and early intervention after any suspicious bite from a potentially rabid animal. But once symptoms have started, curing rabies is virtually impossible. Supportive care to ease suffering may be given until a dog succumbs to the illness or is humanly euthanized.
Facts about Rabies
What animals get rabies?
The rabies virus can infect any mammal, though some species are more susceptible. In the US, wild animals most likely to carry rabies include:
– Raccoons
– Skunks
– Foxes
– Coyotes
– Bats
Unvaccinated domestic animals like dogs, cats, ferrets and livestock are also at risk if exposed to the virus.
How long does it take for symptoms to appear?
The incubation period before rabies symptoms appear is quite variable:
– Dogs – 2 weeks to 6 months after infection. Most commonly 1-3 months.
– Cats – 3 weeks to 3 months after infection.
– Livestock – 10 days to 8 weeks, averaging 20-60 days.
– Humans – A few days to >1 year, typically 1-3 months.
The initial bite may go unnoticed since it is not painful. This can delay association with rabies development later on. Any unexplained neurological symptoms in an animal that could have been exposed to rabies should be evaluated.
Is rabies treatable in humans?
Unlike for dogs and other animals, effective post-exposure prophylaxis is available for humans. The Milwaukee protocol for rabies treatment has allowed a small number of patients to recover even after symptoms began. This intensive protocol kept patients alive until the immune system could fight off the virus. However, it has still only been successful fewer than 10 times.
Preventive treatment is still key and has made dog-transmitted rabies rare in the US today. If someone is bitten by a rabid or possibly rabid animal, the CDC recommends:
– Immediately washing bite wounds with soap and water for at least 15 minutes.
– Getting rabies immune globulin and rabies vaccine shots. This is critical and can prevent the disease from progressing even days after exposure.
– Additional booster rabies shots are given over the next two weeks.
Conclusion
Rabies can be difficult to initially spot in dogs, with vague symptoms like fever and appetite changes. But most cases will rapidly progress to the classic manifestations of excess salivation, seizures, aggression and paralysis. Any sudden neurological or behavioral changes in a dog should be evaluated urgently for rabies. Though virtually 100% fatal once symptoms manifest, human rabies cases are rare in the US today thanks to effective post-exposure prophylaxis. Suspected rabid animal bites should always be treated immediately with thorough wound cleansing and vaccination to prevent disease in humans.