Rabies is a viral disease that affects the central nervous system of mammals, including dogs, and is almost always fatal once clinical signs appear. Transmitted primarily through the saliva of infected animals, this zoonotic disease presents a public health concern globally. Understanding rabies testing methods in dogs is important for disease control and prevention.
Diagnosing an Active Rabies Infection
The only definitive method to diagnose an active rabies infection in a dog involves a post-mortem examination of brain tissue. No approved test can confirm rabies in a living animal because the virus primarily targets the central nervous system, making it detectable only in brain tissue.
The standard diagnostic procedure is the direct fluorescent antibody (DFA) test. This test involves collecting brain tissue samples (e.g., brain stem, cerebellum) from the deceased animal. These tissues are examined under a fluorescence microscope for rabies virus antigens. The DFA test is highly sensitive (96-99% accurate) and provides reliable results within hours.
Testing for Rabies Antibodies
Testing for rabies antibodies, often called a rabies titer test, serves a different purpose than diagnosing an active infection. Tests like the Fluorescent Antibody Virus Neutralization (FAVN) or Rapid Fluorescent Focus Inhibition Test (RFFIT) measure rabies virus-neutralizing antibodies in a dog’s blood. A positive result indicates an adequate immune response after vaccination, not an active infection.
The primary application for rabies antibody titer tests is for international pet travel, especially to rabies-free countries requiring proof of immunity. A blood sample is drawn from the living dog and sent to an approved laboratory. A titer level of 0.5 International Units per milliliter (IU/mL) or higher indicates protective immunity.
Procedures After a Potential Rabies Exposure
Immediate action is necessary if a dog is bitten by or exposed to an animal suspected of having rabies. Initial steps include thoroughly washing the wound with soap and running water for at least 10 minutes to help reduce the viral load. Following this, immediate veterinary attention is advised to assess the wound and determine the appropriate course of action based on the dog’s vaccination status.
For a vaccinated dog, the recommendation is to administer an immediate rabies booster vaccine, ideally within 96 hours of exposure. The dog should then be kept under the owner’s supervision and observed for a period of 45 days for any signs of illness. This protocol helps ensure protection, as rabies infection in currently vaccinated animals is rare.
When an unvaccinated dog is exposed to a confirmed or suspected rabid animal, the protocols become much stricter. Euthanasia is often recommended to prevent potential disease development and spread. If an owner declines euthanasia, the dog typically undergoes a strict quarantine for a period of four months. This quarantine usually involves immediate vaccination upon entry and confinement in a secure facility, often at the owner’s expense, to prevent any further exposure to people or other animals.