Canine
Erlichiosis In South Africa
Compiled by Dr. S. Engelbrecht BVSC MRCVS from Wilgers Animal Hospital***
Most
dog owners know about billiary fever by now and that there is no vaccine against
it and that the only defense we have against it is topical applications with a
residual effect against ticks. Few owners however are ware of another relatively
common tick borne disease known as tickbite fever caused by Ehrlichia Canis.
How
does a dog look with Canine Ehrlichiosis?
A
dog with this disease often appears to be completely normal especially during
the early and sub clinical stages of the disease and then only becomes ill
during the chronic stage of the disease when it may be too late. It is for this
reason that it has been coined as the silent killer by some clinicians. Not all
dogs develop the chronic severe stage of the disease. Clinical signs most
commonly described include depression, lethargy, not eating, fever, enlarged
lymph nodes of the whole body, and bleeding. The latter would include blood
spots on the abdomen and inside the ears, as well as bleeding from orifices like
the nose. This is because all blood cells are affected by the parasite but
especially the blood platelets are affected. The dog's body sometimes tries to
defend itself from this invader but unfortunately this makes matters worse as it
does a lot of damage to the body's own cells. We call this an immune-mediated
effect. This can lead to all sorts of problems including poly-arthritis,
inflammation of the muscles, eye problems for example retinal detachment and
kidney problems.
How
do vets diagnose Canine Ehrlichiosis?
When
your dog is presented with the above signs, your vet will check for enlarged
lymph nodes as well as signs of bleeding. A blood smear can be used to look for
parasites as well as evaluate the relative amount of platelets and different
type of white blood cells in the blood. Unfortunately detection of the parasite
in monocytes (a type of white blood cell) is rare (only in 4% of cases), and
thus one cannot base one's diagnosis on this alone. Thus even if one does not
find any parasites in the monocytes, but there is very few platelets and a lot
of monocytes; and the dogs lymph nodes is enlarged, then that is enough reason
to treat for canine ehrlichiosis. There is a commercial test available namely
the idexx snaptest but this is not available routinely in most practices in
South Africa at this point in time, and is also relatively expensive.
How
do vets treat this disease?
Ehrlichia
parasites are sensitive to doxycycline and there is often a marked improvement
in the dog within 2-3 days. However, this does not mean one should stop
treatment. The Doxycycline course should be at least 3 weeks long @ a dose of
10mg/kg bodyweight once daily. Treatment with the injectable drug imidocarb
diproprionate is sometimes also used to treat especially when babesia
co-infection is suspected. Together with this one should treat supportively for
immunemediated problems
What
can the owner do to help?
As in most diseases prevention
is better than cure and the only viable option for this is topical application
of an acaroids like Frontline or Advent on a regular basis. It is advised to do
this monthly but in problem areas 3 weekly applications is advisable. It is also
important to apply these products correctly, so make sure from your vet that you
do it correctly. The above measurements are
not a 100% fail safe but will help reduce the likelihood of contracting
the disease significantly. When your dog is diagnosed with the disease it is
important to finish the full course of doxycycline that your vet prescribes even
if it is longer than the 3 week period prescribed here.
***Reference: Proceedings of 2006 Small Animal World
Congress from the lecture – “Canine Ehrlichiosis - A Silent Killer”
by Dr. Gad Baneth, DVM, PhD, Dipl. ECVCP
