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Rocky Mountain Spotted Fever, Tularemia and Ehrlichiosis can infect tick species which often attach themselves to dogs.
The ‘Hard Ticks’ (Ixodidae) are blood-suckers. They all moult twice during their life cycle. The three stages (larval, nymph and adult) either stay on the same individual host animal all the time, have two hosts or three. (Tick Biology). The adults drop off their final host and usually lay their eggs in the grass (or other vegetation). The eggs hatch and the larvae crawl up the stem to wait for a passing host. They cannot jump, so must wait for physical contact. Two species are of special interest to people who have dogs as pets. American Dog Tick. The American Dog Tick Dermatocentor variabilis is a ‘three-host’ Tick. The first two hosts are often small mammals (where they may be transferred to cats), and the third is usually a dog or a human being. It does not carry Lyme Disease, but is the most important vector in the Eastern USA for the equally serious human disease, Rocky Mountain Spotted Fever. This disease is ‘reportable’ and can be very dangerous if not treated early. Rocky Mountain Spotted Fever. Rocky Mountain Spotted Fever is caused by the bacterium Rickettsia rickettsii, and characterised by a fever , then rash, two or three weeks after having been bitten by the tick. At this stage the disease responds well to treatment. If left untreated it can become life-threatening. There is no vaccine currently available, so the best thing is to avoid being bitten! Next best is to remove ticks as soon as you notice them on you – usually effective because it takes several hours of tick attachment to get enough of their infected saliva into your bloodstream. Hunters Disease (or Rabbit Fever). Tularemia is the ‘proper’ name for this disease, first identified at Lake Tulare in California. It is caused by the bacterium Francisella tularensis which is one of the most infective bacteria known - 10 individual bacteria can cause an infection. Many Ticks can carry this disease (including the American Dog Tick), and it can also be transmitted in aerosol form. One man caught it while mowing his lawn in 2001, but it should be added that he ‘mowed’ a dead rabbit at the same time! Fortunately the bacterium is killed by half an hour of exposure to sunlight and does not ‘linger’ long. Germ Warfare. Tularemia was used by the USSR against the Germans at Stalingrad during WWII, and was studied intensively by the US in the 1950’s. There has been recent concern that it might be a ‘weapon of choice’ for terrorists, and the CDC has taken this threat seriously. Happily there will probably soon be a vaccine available. Kennel Tick. Also known as the Brown Dog Tick Rhipicephalus sanguineus; this is a brown tick of dogs – not a tick of brown dogs! It is responsible for the disease Ehrlichiosis in dogs. Like the American Dog Tick it is a Hard Tick with two moults, but in this case the tick attaches itself to one host only and remains there until fully adult. The adult females choose to lay their eggs in the ‘home’ of the host – hence the name ‘Kennel Fever’. This is a worldwide problem, and German Shepherd Dogs seem to be unusually susceptible to the disease. Like this? – see what else I have written.
The copyright of the article Ticks and dogs in Pet Care is owned by John Blatchford. Permission to republish Ticks and dogs in print or online must be granted by the author in writing.
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