Horrors of the tick and flea season PDF Print E-mail
News - Rubrieke
Monday, 21 September 2009 14:36
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In this column veterinarian Dr Liesel van der Merwe provides practical assistance for common problems in companion animals. She is a specialist physician at the Onderstepoort animal teaching hospital and a senior lecturer in the section of small animal medicine. Send your questions to This e-mail address is being protected from spambots. You need JavaScript enabled to view it


Dr Liesel van der Merwe

Spring has sprung and the ticks will no doubt soon abound; not that they even go north for the winter these days. First let us clarify the terminology used. At least two different blood parasites are transmitted by ticks to dogs and cats.

Babesia canis parasite causes a disease similar to malaria in humans. This is the classical 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 while in circulation, the red pigment in the blood cells is excreted in the urine, causing a red discolouration, which makes owners think that their dog is urinating blood.

Not all patients go this route; 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. These cells and parasites are destroyed in these organs and the pigment is converted to bile. These dogs may show jaundice.

The most common early symptom of biliary is a dog that is a bit depressed, will not eat and has a fever (T>39°C). If presented to the veterinarian early, the dog just requires an injection to kill the parasite and he will be back to normal within 24 hours.

The diagnosis is made by examining a bloodsmear under a microscope and checking the blood count. Once the patient becomes anaemic and has pale gums, the disease is more advanced and a blood transfusion and other supportive treatments may be required.

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. Ehrlichia canis is another parasite transmitted by ticks and causes tickbite fever, ‘bosluisbytkoors’ or ehrlichiosis in dogs. This is a more subtle disease and is the same as tick-bite fever in humans. Symptoms include fever, enlarged glands, cloudiness in the eyes, light sensitivity and painful joints; basically very similar to flu symptoms.

If left untreated, it becomes asymptomatic for a long period, but targets the bone marrow, eventually causing total destruction, a fatal consequence to infection. This disease is not easily diagnosed and special laboratory tests need to be requested. Your veterinarian will often place your dog on a course of antibiotics, doxycline, if the disease is suspected. Improvement is usually rapid.

Cats living on the coast get biliary. The tick which transmits feline babesiosis does not occur in the highveld. Cats also get a disease called Mycoplasma from ticks. This usually only causes anaemia if the cat is immuno-suppressed and we suggest testing for feline leukaemia and immunodeficiency viruses.

Tick control is the only form of prevention. Dips, sprays, collars and spot-on treatments are all effective, but must be strictly used according to manufacturers’ instructions for the best result. Some preparations are just effective against either ticks or fleas, and others against both. Dips are generally cheaper but require weekly dipping. The spot-ons are more expensive, but a monthly application is generally required. 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.

 

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