Final answer:
When a pet tests positive for heartworms or tick-borne diseases, additional diagnostic tests are necessary to confirm the diagnosis due to the possibility of false positives. After confirmation, treatment should start immediately, and the pet owner should be informed about the diagnosis and treatment options.
Step-by-step explanation:
If a pet tests positive for heartworms and/or tick-borne diseases, the correct action would be C) Additional diagnostic tests are required. Given the risk of false positives and the complexities in diagnosing these conditions, it is essential to confirm the diagnosis with further testing, such as an immunoblot or a Western blot test, especially if the initial tests are indeterminate or positive. After confirmation, treatment should begin promptly because early treatment for conditions like heartworm, which can result in significant health issues, and tick-borne diseases, such as Lyme disease, is crucial.
For heartworm, which is caused by the parasite Dirofilaria, a preventive treatment is available, and for dogs with an active infection, the condition may range from non-existent in mild cases to severe symptoms as the disease progresses. Treating tick-borne diseases such as Lyme disease generally involves antibiotics, since these are bacterial infections. It's important to inform the pet parent of the initial test results and the need for further confirmation and potential treatment plans.