Biliary (Babesia Canis)

Babesia canis is one of the two common diseases caused by blood parasites, and transmitted by ticks to dogs and cats.

The Babesia canis parasite causes a disease similar to malaria in humans. This is the classic tick bite fever, biliary fever, bosluiskoors or babesiosis. The parasites enter the bloodstream in the saliva of an infected tick and then invade the red blood cells. They proliferate within a red blood cell and cause it to rupture when they exit, looking for a new host cell. If a large number of cells rupture whilst in circulation, the red pigment in the blood cells is excreted in the urine, causing a red discolouration , so that owners think that their dog is urinating blood.

Not all patients are affected in this way. In some cases the infected red blood cells are identified by the spleen and liver and are removed from the circulatory system before they rupture. The infected cells and parasites are destroyed in these organs and the pigment is converted to bile. These dogs may show jaundice, a yellow colouration of the skin, eyes and gums.

The most common early symptom of biliary is that a dog is a bit depressed, will not eat and has a fever (T>39°C). If presented to the veterinarian early these dogs only require an injection to kill the parasite and will usually be back to normal within 24 hours. The diagnosis is made by examining a blood-smear under a microscope to look for the parasite and by checking the blood count.

Once the patient becomes anaemic and has pale gums, the disease is more advanced. Just as in malaria, biliary in dogs can present as a severe, complicated disease and some dogs rapidly develop kidney failure, lung failure, cerebral biliary with severe seizures, blood clotting changes and excessive red blood cell destruction due to an over stimulated immune system.

Our protocol for patients with advanced biliary varies with the support required. It is common for these patients to be hospitalised in our high care ward for up to a week. They require blood transfusions to replace the ruptured red blood cells. The babesia parasite is killed with an injection of berenil, a drug also used to treat biliary in cattle. The damage caused by the parasites can persist, as the body now has to deal with all the fragmented red blood cells in circulation as well as the internal content of the cells - all of which cause inflammation. In severe cases it is this severe inflammation of the patient that causes most complications and not the anaemia. In these patients blood vessels become leaky and blood pressure is low. They need intravenous fluids and tube feeding, as well as kidney and liver support. Their blood pressure needs constant monitoring and their blood values need to be frequently checked, to make sure they are getting the correct combination of fluids intravenously.

Tick control is the only form of prevention. Dips, sprays, collars and spot-on treatments are all effective but must be used strictly according to manufacturers’ instructions for the best results. Some preparations are effective against only ticks or fleas and others are effective against both. Dips are generally cheaper than other treatments but weekly dipping is required, whereas spot-ons are more expensive, but only a monthly application is usually required.
NB. Cats are very sensitive to poisons and dips and only a few products are safe for use in cats. If the label doesn’t say ‘for cats’, then don’t use it.