Symptoms of Canine Rabies: What to Look Out For

Rabies is a zoonotic disease caused by the rabies virus, primarily affecting the central nervous system. It leads to acute, progressive, and irreversible fatal encephalomyelitis, characterized by a particularly striking hydrophobia, hence the alternate names hydrophobia and rabies.

Puppies under one year of age play a crucial role in the virus's transmission. The disease is primarily transmitted through the bite of an infected animal, but can also occur through the animal's licking of mucous membranes, wounds, or scratches. Rabiesinfected animals carry a high viral load in their saliva, making them contagious 3 to 5 days before the onset of symptoms.

Rabies is generally sporadic and does not exhibit a clear seasonal pattern, although it tends to be more prevalent during spring and autumn. After infection, humans may experience anxiety, a feeling of constriction in the throat, difficulty swallowing, and rapid breathing. In the later stages, symptoms include hydrophobia, aversion to wind, and abnormal secretion of saliva, leading to a rapid deterioration in health and ultimately respiratory and circulatory failure.

The incubation period for rabies varies, with the shortest being 5 days and the longest extending to several months or even up to a year. Clinically, there are two main forms: the excitatory (or rabid) type and the paralytic type. Approximately 80% of dogs exhibit the excitatory type. Initially, dogs may become excited, aggressive, and exhibit strange behaviors. After about 7 days, they enter the paralytic phase, gradually becoming paralyzed, and ultimately succumb to respiratory failure. The paralytic type begins in a paralyzed state and typically results in death 3 to 6 days after onset, with minimal aggression towards humans or other animals.

Following natural infection, the course of the disease usually lasts 6 to 8 days, with some cases extending to 10 days. The excitatory phase is typically divided into three stages: the prodromal stage, the excitement stage, and the paralytic stage.

During the prodromal stage, dogs may appear listless, sensitive to sounds and light, and often hide in dark places. They may drool, wag their tails, have weak hindquarters, exhibit atypical eating habits, and show a strong desire to bite at inanimate objects. The throat may become partially paralyzed, and they may exhibit a fear of water, an increased sexual desire, and may change their behavior, showing tendencies to flee or avoid humans.

The excitement stage, or rabid phase, is marked by increased aggression, with dogs running for long distances, sometimes up to 10 kilometers, and biting humans or any animals they encounter along the way. Hydrophobia is a hallmark symptom, with dogs experiencing severe throat spasms upon seeing water, drinking, or even hearing running water. Fear of wind is also common, with spasms in the throat triggered by light, sound, touch, or any breeze. Dogs may also exhibit excessive salivation, red eyes, and may bite their tails or limbs.

As the disease progresses into the paralytic stage, dogs may have a drooping lower jaw, tongue sticking out, increased salivation, and paralysis of the hindquarters and limbs. Eventually, they may lie down and die due to respiratory failure.

Pseudorabies has an incubation period of 3 to 6 days, with some cases extending to 10 days. Initially, dogs may appear disinterested in the world, followed by restlessness, loss of appetite, but increased thirst. They may sit hunched over, with intermittent fever and vomiting. The wound site may become itchy, and dogs may scratch and lick the area. In a few hours, large, ulcerous sores may appear, with surrounding tissue swelling and deep lesions. Some dogs may exhibit symptoms similar to rabies, such as biting and tearing at objects, but they do not attack humans or other animals. Early in the disease, dogs may show signs of throat paralysis, drooling, and difficulty swallowing. Pupils may be unevenly sized, and most dogs will exhibit intermittent twitching in the muscles of the head and neck, as well as the lips. Difficulty breathing is common, and dogs often die within 24 to 36 hours.

Dogs with symptoms such as disinterest, depression, and hydrophobia should be considered suspect for rabies. A preliminary diagnosis can be made based on a history of exposure to infected animals, but laboratory diagnosis is necessary for confirmation.