What every South African dog owner should know

As the weather warms up, so does the risk of one of the most serious diseases South African dogs face. Biliary, also called tick bite fever, is caused by a blood parasite passed on by ticks, and vets consider it one of the most important canine diseases in the country.

What causes it

Biliary is caused by tiny Babesia parasites that invade and destroy red blood cells. Two species occur in South Africa, and they are very different.

The one behind almost all serious cases is Babesia rossi. It is unique to this part of the world: it has been found only in sub-Saharan Africa, so international advice about biliary, which usually focuses on other species, doesn’t always apply here. In a study of 150 sick dogs at an Eastern Cape state clinic in 2021, B. rossi was found in 149 of them. It is carried by the yellow dog tick, Haemaphysalis elliptica, and black-backed jackals act as natural hosts.

B. rossi is also the most dangerous of the dog Babesia species, causing severe destruction of red blood cells and sometimes brain complications that resemble a severe form of human malaria. Complications such as kidney failure and fluid on the lungs are seen commonly by South African vets, and death can occur in more than 10% of cases.

The second species, Babesia vogeli, is spread by the brown dog tick and is the least harmful of the group, usually causing only mild fever and anaemia.

When to worry

Cases peak in summer. The gap between a tick bite and the first signs of illness can be as short as two weeks, so a dog may fall ill well after you’ve forgotten about any tick.

Signs can include fever, pale gums, anaemia, jaundice, and red urine, which can lead to weakness and difficulty breathing. Lethargy, fever and pale gums are the most common early signs, so a dog that is suddenly flat and off his food in tick season should see a vet the same day. Some infected dogs show no signs at all.

Diagnosis is quick: vets typically confirm it by examining a stained blood smear. Treatment involves antiparasitic drugs, often with blood transfusions and supportive care. Treatment should only follow a confirmed diagnosis, so don’t be tempted to medicate at home.

Are cases rising or falling?

The honest answer is that nobody has published recent national figures. The last large study, covering records from 44 veterinary hospitals and 2.6 million dog visits, found the rate of biliary treatment fell by 72% between 2011 and 2016, with Gauteng, the Free State and Mpumalanga recording the most treatments.

The researchers noted that a newer class of tick-control products, the isoxazolines (given as monthly or longer-acting chews), arrived in South Africa in 2014, and the steepest drop came afterwards, though their data cannot prove the products caused it. That study is now a decade old, and tick numbers and case loads can vary considerably from one area and one season to the next. Anecdotally, many vets describe an increase in biliary in their practice in recent years due to the changing weather patterns. What hasn’t changed is how serious the disease is when a dog does get it.

Why prevention works

There is a useful window of opportunity. An infected tick usually needs to be attached for more than 24 hours before it transmits the parasite, so killing ticks quickly can stop infection before it starts. In practice:

• Keep tick control continuous, not seasonal. Year-round control is widely recommended in South Africa, and gaps between doses are when dogs are exposed.
• Check your dog after walks, especially around the ears, neck, armpits and between the toes, and remove any ticks promptly.
• Ask your vet which product suits your dog, your area and your lifestyle. Products differ in how they work and how long they last.
• Never use dog tick products on cats. Some can be lethal to them.

Biliary remains a serious disease, but it is also one of the most preventable. Consistent tick control, quick action when your dog seems off colour, and a vet who knows your area are your best defences this summer.