OATHALL VETERINARY GROUP LTD 

30 Oathall Road

Haywards Heath 

West Sussex

RH16 3EQ

01444 440224

enquiries@oathall-vets.co.uk 

 

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What is Babesia?

Babesia is a type of parasite called a protozoa, that attacks red blood cells causing anaemia. There are species that can affect humans, dogs, and other mammals worldwide. Babesia canis is the species that typically affects dogs in continental Europe, although other species do exist.

How is this parasite spread?

It is spread by infected ticks mainly of the species Dermacentor reticulatus (marsh tick)  which is present in continental Europe. Since the introduction of the Pet Travel Scheme, dogs in the UK that have travelled abroad have been diagnosed with increasing frequency. It was thought the tick responsible was not present in the UK, but in recent years clusters of cases have occured in dogs that have never left the UK. Outbreaks have occured around Essex and its surroundings. It is unsure if these clusters are connected or if, as predicted by some experts, D reticulatus is spreading. There is a theory yet to be proven that wildlife such as deer or foxes may establish new disease reservoirs.

Babesiosis can affect dogs of all ages, although disease mostly occurs in young dogs. Female ticks feed on the host for a week, leaving the host before disease develops. Once inside the bloodstream the parasites invade red blood cells and multiply. Signs usually appear after 10-21 days. Infected dogs can then also infect uninfected ticks.

What are the symptoms?

The symptoms vary depending on the age of the dog, and if there are any other underlying issues affecting the immune system. Symptoms may be mild or absent. Signs may include pale gums, depression, weakness, rapid breathing, lack of appetite and red urine. On examination they may have a high temperature and fast heart rate. We don’t fully understand the cause of the anemia, but it’s thought that the parasite causes the red blood cells to rupture (haemolyse). There may also be a poor response by the bone marrow in replacing these lost red blood cells, compounding the anaemia. There seems little correlation between number of parasites and severity of signs.

In some cases the dog’s own immune system also destroys red blood cells (immune mediated haemolytic anaemia) and platelets (cells that form clots when needed), causing a severe form of disease. Complications such as liver and kidney damage may then occur. Yellowing of the skin and gums may be seen.

How is it diagnosed?

Blood samples show anaemia (reduced red blood cell numbers). Some larger, immature red blood cells are often found in the circulation. Reduced numbers of platelets is often another finding. There are many causes of anaemia, so linking the anaemia with the babesia parasite requires further work. Sometimes we can see the parasites on stained blood smears.

In more chronic cases, parasites may not be as obvious. Blood tests looking for antibodies to the parasite can be done. These tests only show that the dog has met the parasite in the past, not that it is currently there. However a positive result alongside a history, and physical examination findings is suspicious. In dogs that have never left the UK, a positive result  would provide good evidence of current infection. Blood tests to look for Babesia DNA have recently been developed, and may be more accurate.

The liver is involved in breakdown of red blood cells and may be affected as it tries to keep up with demand of all the ruptured red blood cells. Liver damage may be seen on blood screening. The kidneys may also be damaged by this process. Red urine also evidences an increase of red blood cell breakdown products.

Can it be treated?

In order to treat the anaemia we need to kill the parasite using an antiprotozoal drug. The main one we use is called Imidocarb, given by injections two weeks apart. This drug is only licensed in cattle but a 100% safe and efficacious treatment with a license is not available. Treated dogs may be affected for life as it is difficult to completely cure the disease despite easing signs. Immunosuppression or infection with other diseases may cause the disease to recur.

Patients with mild or moderate anaemia may only require anti-parasitic medications but very anaemic animals, or those with complications, will require additional treatments.

Approximately 85% to 90% of canine patients worldwide survive the illness. Dogs developing complications can however have a poor prognosis.

Can I do anything to prevent this disease?

If you travel with your pet, tick prevention is essential. Speak to one of our vets about the options. There are also many other diseases that need to be considered when travelling abroad, so it is essential to be prepared and to prevent what you can. While in the UK, tick prevention is advisable to prevent this and other tick transmitted diseases.

A tick must feed on the host for at least three days to transmit this parasite so removing – or using a product to kill – any ticks quickly can prevent this disease.

Identification of tick-infested areas and avoidance is best. However, other wild mammals will still face exposure and potentially move infected ticks over distances.

Dog owners can send ticks to Public Health England for identification. For details on how to do this go to https://www.gov.uk/guidance/tick-surveillance-scheme , or the Big Tick Project http://www.bristol.ac.uk/news/2016/march/big-tick-project-2016.html.

Significant research will be required, looking at the UK outbreaks, before further advice can be given. For now it is best to be safe, especially if you live in or around the county of Essex, or visit the area. Use tick prevention, check your dog for ticks after a walk, and avoid known tick infested areas. In 2012, the requirement for tick treatment prior to entry into the UK of pets travelling from Europe was removed. More research is needed to see if this has affected the rate of tick-borne diseases in the UK.

If you think your dog might be affected, give us a call right away.