Can you tell me in one glance that it has rabies?

The classic 'mad dog' stage is only a later symptom, before that develops the first phase after infection usually lasts for 2-3 days in dogs. Apprehension, nervousness, anxiety, solitude, and a fever may be noted. Friendly animals may become shy or irritable and may snap, whereas, aggressive animals may become affectionate and docile. or infected dog sometimes may not show any signs or symptoms at all until the disease progresses to the Furious stage.
So it may not be very obvious in the early stages of the disease that a dog is infected.

Signs that should be obvious and clearly unusual include: losing their fear of humans (becoming overly friendly), showing signs of depression and hiding, signs of partial paralysis such as abnormal facial expressions, drooping head, sagging jaw, or paralyzed hind limbs. other symptoms include: extreme excitement or aggression, gnawing and biting their own limbs, attacking stationary objects and/or other animals,

Seizures, diluted pupils, foaming at the mouth, erratic behavior, appearance of choking, drooping of the lower jaw, and paralysis of jaw, throat, and chewing muscles are probably what you would expect on first glance.

Hope this helps!

Probably not when you there are so many other diseases that mimic symptoms-Remember poisoning from chemical can resemble symptoms of rabies

Furious Form:
This is the classic “mad-dog syndrome,” although it may be seen in all species. there is rarely evidence of paralysis during this stage. The animal becomes irritable and, with the slightest provocation, may viciously and aggressively use its teeth, claws, horns, or hooves. The posture and expression is one of alertness and anxiety, with pupils dilated. Noise invites attack. such animals lose caution and fear of other animals. Carnivores with this form of rabies frequently roam extensively, attacking other animals, including people, and any moving object. they commonly swallow foreign objects, eg, feces, straw, sticks, and stones. Rabid dogs may chew the wire and frame of their cages, breaking their teeth, and will follow a hand moved in front of the cage, attempting to bite. Young pups can seek human companionship and are overly playful, but bite even when petted, usually becoming vicious in a few hours. Rabid skunks may seek out and attack litters of puppies or kittens. Rabid domestic cats and bobcats can attack suddenly, biting and scratching viciously. As the disease progresses, muscular incoordination and seizures are common. Death results from progressive paralysis

Paralytic Form:
This is first manifest by paralysis of the throat and masseter muscles, often with profuse salivation and inability to swallow. Dropping of the lower jaw is common in dogs. Owners frequently examine the mouth of dogs and livestock searching for a foreign body or administer medication with their bare hands, thereby exposing themselves to rabies. These animals may not be vicious and rarely attempt to bite. The paralysis progresses rapidly to all parts of the body, and coma and death follow in a few hours.

Species Variations:
Cattle with furious rabies can be dangerous, attacking and pursuing humans and other animals. Lactation ceases abruptly in dairy cattle. The usual placid expression is replaced by one of alertness. The eyes and ears follow sounds and movement. A common clinical sign is a characteristic abnormal bellowing, which may continue intermittently until shortly before death.
Horses and mules frequently show evidence of distress and extreme agitation. These signs, especially when accompanied by rolling, may be interpreted as evidence of colic. As in other species, horses may bite or strike viciously and, because of their size and strength, become unmanageable in a few hours. People have been killed outright by such animals. These animals frequently suffer self-inflicted wounds.

Rabid foxes and coyotes often invade yards or even houses, attacking dogs and people. The abnormal behavior that can occur is demonstrated by the fox that attacks a porcupine; finding a fox with porcupine quills can, in most cases, support a diagnosis of rabies.
Rabid raccoons and skunks typically show no fear of humans and are ataxic, frequently aggressive, and active during the day, despite their often crepuscular nature. In urban areas, they may attack domestic pets.

In general, rabies should be suspected in terrestrial wildlife acting abnormally. The same is true of bats that can be seen flying in the daytime, resting on the ground, attacking people or other animals, or fighting.

Rodents and lagomorphs rarely constitute a risk for rabies exposure. however, each incident must be evaluated individually. Reports of laboratory-confirmed rabies in woodchucks are not uncommon in association with the raccoon rabies epizootic in the eastern USA.

Diagnosis:
Clinical diagnosis is difficult, especially in areas where rabies is uncommon and should not be relied on when making public health decisions. In the early stages, rabies can easily be confused with other diseases or with normal aggressive tendencies. Therefore, when rabies is suspected and definitive diagnosis is required, laboratory confirmation is indicated. Suspect animals should be euthanized and the head removed for laboratory shipment.

Rabies testing should be done by a qualified laboratory, designated by the local or state health department in accordance with established national standardized protocols for rabies testing. Immunofluorescence microscopy on fresh brain tissue, which allows direct visual observation of a specific antigen-antibody reaction, is the test of choice. when properly used, it can establish a highly specific diagnosis within a few hours. Brain tissues examined must include medulla oblongata and cerebellum (and should be preserved by refrigeration with wet ice or cold packs). The mouse inoculation test or tissue culture techniques using mouse neuroblastoma cells may be used for indeterminate fluorescent antibody results, but it is no longer in common use in the USA.

I would bring it to the vet if you see any of the following :

fever ,lethargy ,loss of appetite,changes in behavior ,tone of bark change, extremely mean and aggressive, totally uncontrollable ,break it own teeth by biting objects ,constant growling ,biting ,dilated pupils ,restless ,disorientation ,seizures, choking ,dropping of the lower jaw ,unable to swallow any food ,foaming at the mouth ,paralysis of jaw, throat and chewing muscles

GL, and best wishes!

most states require dogs to be vaccinated; which if your dog isn't hopefully this will encourage you to do so.

for the first few days / weeks (maybe months i'm not sure), depending on where they got bit, they will appear normal.
but when the signs do eventually come, the first answer is correct.

i suggest skimming this
animalhospitals-usa.com/dogs/…

Act crazy, weird look in their eyes foaming at the mouth…