Which of the following is a common cause of swollen cervical lymph nodes in dogs?

Swollen cervical lymph nodes in dogs are often a response to infections, with bacterial infections being a prevalent cause. When bacteria invade the body, the immune system activates and lymph nodes that filter lymph fluid can become enlarged as they produce more lymphocytes to fight the infection. This process leads to inflammation and swelling in the cervical region, where many lymph nodes are located.

While viral infections can also cause lymphadenopathy, bacterial infections are more directly associated with the significant swelling of lymph nodes due to the immune response to bacterial pathogens. Allergic reactions may lead to some level of lymphadenopathy, but they typically do not cause the same degree of swelling in lymph nodes as infections do. Malnutrition generally does not directly cause swollen lymph nodes, though it can affect the overall immune response, making infections more likely, which in turn could lead to swollen lymph nodes. Therefore, bacterial infections are the most common and direct cause of swollen cervical lymph nodes in dogs.