Biliary
Urgent Treatment Needed

Biliary is a tick-borne disease that primarily occurs in young dogs, although dogs of all ages can be affected and accounts for approximately 10% of the number of cases presented to veterinary practitioners across South Africa.

Babesia canis rossi, the dominant babesia species found in South Africa, is transmitted by the yellow dog tick (Haemaphysalis ellepticca, previously known as H. leachi) and is very virulent (has an extreme ability to cause severe disease).  This condition can be classified as either complicated or uncomplicated and many factors can cause the patient to be classified as a severe or complicated case, including cerebral babesiosis (babesiosis with neurological signs that cannot be attributed to any other cause). 

Complicated biliary is considered common by 26% of veterinary practitioners across South Africa. Among admitted biliary cases, 10 - 12% die and 2 - 3% are euthanised and mortality rates (number of deaths) for cerebral biliary cases reached more than 80% according a survey by Corlett in 2000.

Cerebral babesiosis can either result from sludging of red blood cells infected with biliary parasites in the capillaries (minute blood vessels) of the brain, or matabolic abnormalities.  The sludging of parasitised red blood cells within brain capillaries may be due to the effects of Soluble Parasite Antigents (SPA's).  SPA's are toxic substances that are released by the infected parasites during their life cycle.  SPA's induce coating of both infected and uninfected red blood cells with fibrinogen-like protein.  These proteins cause the red blood cells to become sticky, and the red blood cells then agglutinate (adhere, as with glue).  The SPA's also activate several complement systems within the dog's body, resulting in the release of vasoactive mediators into the blood circulation, leading to vasodilation (dilation of blood vessels) and hypotension (abnormally low blood pressure).  All these changes favor local proliferation of biliary parasites.

Nervous signs including inco-ordination, hindquarter paresis (slight or partial paralysis), muscle tremors, nystagmus (uncontrollable and rapid movement of the eyeball in any direction), anisocoria (ineuqlity of the pupils of the eye), intermittent loss of consciousness, seizures, coma, aggression, paddling and crying, and opisthotonus (a tetanic spasm in which the body is bent backwards).

In cases of cerebral babesiosis, parasites may not necessarily be seen on blood smears, but are present in brain capillaries.

Lesions are most commonly seen in the grey matter of the brain.  Haemorrhage (bleeding) and infarction (area of dying tissue) are commonly seen.

The prognosis is usually poor.

Attempts will be aimed at limiting further cerebral damage and will include the use of drugs to decrease cerebral oxygen consumption and decrease the cerebral swelling, sedation, oxygen supplementation, avoiding increasing cerebral pressure.

An integrated control strategy involving tick control in the environment, tick control on the dog and now vaccination is an option too.  Contact your local veterinarian for more information on a complete biliary control strategy.

Veterinary articles supplied by Dr S Strydom and published with kind permission of DIA Publishing - publishers of KUSA Dogs in Africa Magazine

Dr Sunelle Strydom qualified as a veterinarian in 2004 at the Faculty of Veterinary Science, University of Pretoria. She has a passion for writing and the sharing of knowledge to promote animal health and welfare. She has written several articles for KUSA Dogs in Africa as well as for Vra vir Faffa on the Landbouweekblad website at www.landbou.com