I am not a vet and have limited knowledge of infectious diseases. If in doubt, you should consult your vet or get a second oppinion from another vet.
Canine Ehrlichiosis is an infection transmitted by ticks that can cause severe damage in dogs. Much like HIV, C. Ehlichia "hide" from the immune system and cannot be cured without antibiotics.
For canine ehrlichiosis, tetracycline (22 mg/kg given every eight hours) or doxycycline (5 mg/kg every twelve hours) administered for four weeks is the recognized treatment. Most dogs recover from the acute and subclinical phases when treated with doxycycline or other tetracyclines at appropriate dosages for an adequate period of
This study of 62 dogs infected with Ehrlichiosis reports that:
Antibody titers generally remain positive for 3 to 9 months after therapy and may remain elevated for up to 31 months. [...] The persistence of serum antibody titers does not reflect the presence of a CMI response or clearance of the organism. Clinical recovery and amelioration of laboratory parameters often precede declines in serologic titers. However, the presence of persistently elevated antibody titers could imply the presence of the organism with concurrent stimulation of immune system, suggesting failure to completely eliminate the infection. For this reason, whether the length of medical therapy should be based upon clinicopathologic signs or on serologic titers is still not clear.
In short: it may take a long time to completely cure the dog and vets cannot say for sure when the animal is completely free of pathogens.
Add to that a predisposition for other diseases that may infect your dog due to the weakened immune system:
In this study, there were also a number of concurrent diseases that may be associated with ehrlichiosis as either a direct result of the E. canis infection or secondary to immunosuppression. These include DIC, sepsis, pneumonia, hemolytic anemia, uveitis, cutaneous pythiosis, mycotic pleuritis, and disseminated phaecomycosis.
The response to therapy in this study was variable, yet the majority of deaths were presumably caused by unrelated disease processes. However, it is important to note that 18% of the mortality rate was presumed to be secondary to ehrlichiosis.
I would suggest being very considerate of your dog's health for at least several months. Don't put her under physical stress and avoid places like dog parks where she might catch more illnesses. Only after she recovered fully from the infection should you think about more tests and diagnoses.
During the acute phase of Ehrlichiosis, changes in the composition of the blood may seem like leukemia but return to normal later.
This presentation states:
Granular lymphocytosis can occur occasionally during the acute phase
and lead to a misdiagnosis of lymphocytic leukemia.
And this article "Lymphoid Leukemia in Dogs" by VetFolio states: (emphasis mine)
The diagnosis of ALL [acute lymphoblastic leukemia] or CLL [chronic lymphocytic leukemia] in dogs is straightforward in advanced cases with extremely high lymphocyte counts. However, in less severe cases with solely marrow involvement or mild to moderate lymphocytosis, the diagnosis can be quite challenging, and associated nonspecific clinical signs and mild hematologic abnormalities may be difficult to interpret. Lymphoid leukemias must be differentiated from other diseases, such as lymphoma, AML, and chronic ehrlichiosis. Lymphoma and AML are the two most common rule-outs for ALL, whereas chronic ehrlichiosis more closely resembles CLL. Because therapeutic protocols and prognoses vary tremendously not only between the differential diseases that mimic lymphoid leukemia but also between subtypes of the disorder itself, an accurate diagnosis must be made when possible.
To sum it up:
- You must treat your dog for Canine Ehrlichiosis.
- You must continue the treatment for 4 weeks, even if your dog seems to recover much faster.
- It is useless to test your dog for leukemia now. On the contrary, the stress of the procedure might be harmfull in the weakened state your dog is currently in.