STEPS IN TORTOISE PARASITOLOGY

Tortoises housed inside and, in particular, those passing through the pet trade can easily build up high levels of parasites.

Transmission

Eggs and cysts are passed in the faeces, which the tortoise spreads around its enclosure on its feet. This material can contaminate food sources and infect all tortoises in the group. Tortoises that have access to a particulate substrate can be even harder to manage, and those given access to the same patch of ground every summer (“garden” tortoises) can have a problem that will never go away. In these cases, it is critically important to ensure the tortoise is as free of parasites as possible, prior to going outside.

Identification methods

The first step in dealing with this problem is to correctly identify what infections are present and if they require treatment. At the University of Edinburgh, we commonly use two methods to rule out high parasite levels.

First, a wet preparation is performed from a freshly voided faecal sample. A very small amount of faeces is mixed with warmed saline and smeared on to a slide. It is immediately examined for eggs, cysts and any motility. If the sample has cooled, it can be gently warmed by sitting the slide on a preheated coin.

A secondary test is the faecal flotation, which is easy and quick to run. A variety of flotation liquids can be used, but saline flotations are probably the most commonly used in our practice. A saturated saline solution is mixed with a small amount of faeces, and shaken to break up the faeces. This mixture is then passed through a tea strainer to remove any solid material, and the remaining liquid is placed in a small container. Saturated saline is added until the container is full, and a cover slip is then applied. After 10 minutes, the cover slip is removed and placed on a glass slide for examination.

A third method to consider is a concentration technique, which requires overnight processing. However, this increases the time involved and may be less practical in a busy practice.

Common parasites

These include a number of nematodes, mainly ascarids and oxyurids. All the species are sensitive to benzimidazoles. They can be treated with oral fenbendazole (25mg/kg daily) over a three-day period.

Common species include Tachygonetria,which is an oxyurid with a characteristic egg. Heavy levels can lead to anorexia and impactions with ascarids.

Protozoa are also very common in chelonians. Typical species include Balantidium coli (potential zoonoses) and Nyctotherus. Generally, these do not require treatment, but can be present in higher numbers in sick tortoises. Given the zoonotic potential, treatment may be required with, for example, metronidazole.

Hygiene and worming

Environmental control is equally important, because if the tortoise is infected then so is its environment. Good hygiene is critical, and removal of all bedding and contents is important, along with a thorough cleaning of the environment.

Regular and complete removal of all faecal material is important to control these infections. Any food should be kept in one place and removed quickly if not eaten immediately. Otherwise, the tortoise will walk through this material and re-infect itself when it eats more food.

Long-term hygiene maintenance is important. After treatment, it is worth retesting the tortoise to see if the infection has been effectively controlled. The vet should wait three days after completing treatment before re-evaluating the faeces, as tortoises have a slow transit time and if checked too early may produce positive results.

Many owners routinely “worm” their tortoises themselves or come to the vet to request it. Agents such as fenbendazole have side effects if given in high doses and reptiles have died from fenbendazole toxicity. I discourage owners from routine treatment wherever possible, instead preferring routine testing with appropriate treatment as an alternative.

The exotic animal service at the University of Edinburgh is surveying owners of chelonians to identify incidence and any predisposing factors that may influence parasite levels. Visit www.dickvetexotics.com to download the questionnaire for clients.