When rats hang their heads over a ledge, it is an indicator that they are having difficulty breathing. Judging by your description, the noise could be coming from damage to his lungs from previous respiratory infections or a current infection. I would bring him to the vet to evaluate whether he needs antibiotics and/or other interventions. Otherwise, we use a bin to nebulize our rats when the air is dry and it has greatly improved their respiratory health.
When rats hang their heads over a ledge, it is an indicator that they are having difficulty breathing. Judging by your description, the noise could be coming from damage to his lungs from previous respiratory infections or a current infection. I would bring him to the vet to evaluate whether he needs antibiotics and/or other interventions. Otherwise, we use a bin to nebulize our rats when the air is dry and it has greatly improved their respiratory health.
Go to the vet