Final answer:
The immediate diagnostic test indicated for a 3-week-old kitten in status epilepticus with the mentioned symptoms is blood glucose levels, which is crucial to identify and treat potential hypoglycemia. Follow-up diagnostics may include a complete blood count and a biochemistry panel to check for other causes.
Step-by-step explanation:
A 3-week-old kitten presenting with status epilepticus, subsequent limpness, pale mucous membranes, salivation, and a temperature of 97.8 degrees F likely requires immediate diagnostic attention. With a successfully placed 24 g IV catheter, the priority would typically be to check the kitten's blood glucose levels as hypoglycemia is a common and treatable cause of seizures in kittens. Due to the urgency of the situation and the clinical signs being potentially life-threatening, other immediate diagnostics might include a complete blood count (CBC) and biochemistry panel to assess for other metabolic disturbances or infections that could be contributing to the kitten's condition.
Additional diagnostics might require more advanced imaging such as an MRI or CT scan; however, these are often not the first line of diagnostics in an emergency setting due to time constraints and the need to stabilize the patient quickly. Also, given the age and fragile state of the kitten, less invasive measures are preferred initially.