The most common external parasite in this area is the soft tick, Ornithodoros sp. Of the family Argasidae. This tick is also common to wild desert tortoises. Your tortoises may remain free of these ticks but you should be on the look out and know what to do if you see them. They may be found on any part of the skin but are most common in the seams between the large plates of the shell. This is where the shell produces new material which is easy for the tick to penetrate with its mouth parts, reach the capillaries and feed. A meal will last many weeks so most ticks found on the shell are at rest, not feeding.
The ticks that may be found on dogs is a hard tick, a different family from the soft ticks. Soft ticks appear quite different from the hard tick and their backs are, indeed, soft. Unless the soft tick has just fed, the body is flat, and the upper surface appears wrinkled. An average adult is about 1/4″ long. The minute chigger stage may be hard to see unless it moves or has fed recently, in which case, the red from the blood meal shows through its skin. As the tick grows, the skin becomes a dull, grey brown color.
Look for ticks to be resting under any thin film of dust that collects in the seams or on top of the rear and front marginal scutes (those around the edges of the carapace). Gently, blow off the dust and you may find several of different sizes resting together. Do frequent tick-checks and remove them as soon as you find them.
To remove the ticks you can use an old soft toothbrush and a bucket reserved only for ticks. Keep several inches of water with some liquid detergent bleach in the bucket. This will kill the ticks. Put the bucket and brush where they will be handy but not in reach of small children or pets. Carefully brush off ticks into the bucket. Keep the brush dry or the ticks will stick to it. Because most ticks will be resting and not attached, gentle brushing will do the job. If a tick is feeding, particularly on the skin, you may have to pick it up with tweezers or your fingers using just enough pressure to hold the tick. Special liquids, or heat is not necessary and can be harmful.
Once ticks become established in your yard it is very difficult to eliminate them. Ticks live and breed by the hundreds in tortoise burrows. One seldom sees them walking about. Effective fumigation of the entire length of the burrow is necessary to eliminate them and requires the use of chemicals too dangerous for anyone but a specialist. Most commercial exterminators may not be qualified to handle the fumigants. During the procedure, the burrow has to be made airtight and kept sealed for several hours. Preventing re infestation is difficult. If a tortoise enters a tick-free burrow carrying one female tick with fertile eggs or two immature ticks (male and female)it is just a matter of time and you are back where you started.
Can you keep ticks off tortoises by using pesticide sprays and powders on the tortoise’s skin and shell, if the burrows contain ticks?
Possibly. There are a number of pesticides that can be purchased easily. Their toxicity to tortoises is not really known. Because repeated application seems to be necessary the cumulative effect on the tortoise may be detrimental. Check with your tortoise vet. Do not apply these near your pets’ drinking water or on the lawn where tortoises feed. If the infestation in your tortoise’s burrow is severe don’t expect to rid your tortoise of ticks by these applications. An alternative tick deterrents that can be applied to the shell and may work for you is a mixture of ground mint and lemon juice. This would be applied after ticks are removed from the skin and shell.
What effect do these soft ticks have on the tortoise?
Considering that the ticks feed infrequently the amount of blood lost is probably not debilitating. Secondary infection does not seem to occur at the places where ticks have pierced the skin. The usual concern about ticks is whether or not they transmit diseases to us, and our pets.
Several species of the genus Ornithodoros are known to transmit Relapsing Fever (otherwise known as TBRF). According to the Nevada State Health Division, Bureau of Disease Control and Intervention Service, from 1989 until 2005 in Clark County there was one reported case of relapsing fever in 1991 and two reported cases in 1989. During the same period, there were seven reported cases in Washoe Co., four in Douglas Co, and two in Nye Co. Lyme disease does occur locally but appears to be carried only by the deer tick and dog tick, both are hard ticks.
It is not known if any diseases that affect tortoises are passed to them via the tick. The possibility that the mycoplasma that causes Upper Respiratory Tract Disease (URTD)in tortoises may be transferred by the tick has yet to be investigated. Although wild rodents are known to act as a reservoir for soft ticks, none of the local veterinarians with whom we spoke had ever seen soft ticks on any of the mammals that they have treated.
When you handle a tortoise with ticks check your hands and arms afterwards and keep your legs and feet out of the way when you brush the ticks off the shell into the bucket. Wash your hands when you finish with your tick-checks. With reasonable care you should not have to worry.
Pregnant women should not handle tortoises with ticks.
TBRF can cause complications in pregnancy and pregnant women should not handle ticks. Cases in Africa, specifically in refugee camps, have been observed with pregnant women to cause abortions, but these have been identified as co-morbidity causes associated with malnourishment. Abortion should not be a concern with the strains of Borrelia in the Mojave (and assuming that no woman in NV, CA, AZ or UT would be suffering from this degree of malnutrition), but we want to be as careful as possible and therefore recommend that pregnant women do not handle tortoises with ticks.
What specific harm does this tick pose to household pets?
Dogs, cats, birds primarily. Dogs have been noted to manifest clinical signs when manually infected with TBRF, but they don’t always display these signs. Dogs (and cats) can be treated with tetracyclines and clinical signs usually clear up. Although, little is known about how TBRF may affect birds, chickens have been documented to be infected and it was implicated in the death of a spotted owl.
Should I be worried if my tortoise has ticks?
Overall, no. The tick doesn’t seem to cause the desert tortoise any visible medical issues, and the issues associated with human or pet bites can be treated with simple antibiotics or a veterinarian visit.
If you see ticks on your tortoise, remove them using methods noted above and be watchful for future occurrences. Remember that it isn’t necessarily the tortoise that will bring the tick into the burrow, but the burrow is most likely the place where ticks will nest. Please contact us if you have any questions concerning soft bodied ticks.