OFA Cardiac Number. The OFA Cardiac test is designed to determine whether your dog has a heart murmur. A heart murmur occurs when there is a disruption to the normal flow of blood through the heart. This disruption to the blood flow causes turbulence, which a good vet can hear during an exam. The two most common causes of heart murmurs are severe anemia or valve problems in the heart. In the case of valve failure, some of the blood in the dog's heart flows the wrong way through the heart, which can result in blood that hasn't been oxygenated mixing with oxygenated blood, and vice versa. Blood flowing the wrong way can eventually lead to congestive heart failure, which can be fatal. Congestive heart failure may be a gradual process that can include chronic coughing, labored breathing, or a blue color in the gums and tongue. The OFA Cardiac Number on your dog's certificate will be in this format: AS-CA12/28M/C-T. The following table shows how to interpret this number. AS = Breed Abbreviation (Australian Shepherd, in this example) CA = Test type (Cardiac) 12 = Certificate Number 28 = Dog's Age in Months M = Dog's Gender C = Examiner (C=Cardiologist, S=Specialist, G=General Vet) T = The dog has a permanent ID, such as a tattoo or microchip Notice the Cardiac Number itself doesn't provide information about the results of the exam. The results appear on the report, and may include: Normal - no murmur detected. Grade 1 - a very soft murmur barely detected. Grade 2 - Indicates a soft murmur readily evident. Grade 3 - Indicates a moderately intense murmur. Grade 4 - Indicates a loud murmur. Grade 5 - Indicates a loud murmur with a palpable precordial thrill, which is an abnormal pulse that can be physically felt during the examination. Grade 6- Indicates a loud murmur with a palpable precordial thrill that is audible even when the stethoscope is lifted from the thoracic wall. The purpose of the OFA's cardiac testing is to maintain a database of dogs' cardiac results. Dogs with a normal or Grade 1 result may enter into breeding programs, but dogs with a Grade 2 murmur or above should not be bred due to the risk of passing on congenital heart disease. General veterinarians, specialists, and cardiologists can all diagnose a murmur, although specialists and cardiologists are likely to be more skilled at detecting a murmur early in young puppies.