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Gastrointestinal parasites are commonly seen in reptiles brought into a veterinary hospital, particularly in imported and wild caught specimens. Reptiles can serve as both definitive and intermediate hosts for several species of parasites. However, the ones which cause the most concern to veterinarians are nematodes, trematodes, cestodes, and protozoans, for whom lizards are definitive hosts, leading to shedding of the parasites through the gastrointestinal tract.
Endoparasites
- Protozoa: amoeba, coccidia, flagellates (Hexamita, Trichomonads, Giardia and Leptomonas), ciliates.
- Metazoan parasites: nematodes, cestodes
Nematodes are frequently encountered during routine fecal examinations . The most common parasites is the pinworm (e.g., oxyurids) which are usually nonpathogenic. However, heavy burdens may lead to clinical disease. Furthermore, oxyurids have a direct life cycle and can reach high numbers within the colon, particularly in herbibvorous iguanids, putting the lizard at high risk for impaction.
Clinical signs
Clinical signs of amoebiasis include anorexia, pica, prolapse, regurgitation, wasting, dehydration, constipation, weight loss, and lethargy. However as the parasite colonizes the animal's organs, such as the liver and kidney, it may cause necrosis and abscess formation.
Diagnosis
Routine faecal examinations and worming should be part of a standard quarantine procedure or part of regular examinations.
Prevention
Quarantine, correct husbandry, and preventive medicine (e.g. regular faecal testing).
Treatment
Any parasite found in captive reptiles should be treated, especially those with direct life cycles, since the stress of captivity can weaken the immune system. Poor husbandry facilitates the build up of direct cycle parasites and parasitised lizards have a shorter life span and tend to be more susceptible to disease.
Flagellates
- Metronidazole PO, repeat in 2 weeks
Coccidia
- Sulphadiazine, sulphamerazine, sulphamethazine PO daily for 21 days, recheck faeces in 3 weeks
- Trimethoprim/sulphamerazine daily for 2 doses, then every second day for 3 weeks, recheck faeces in 3 weeks
Nematodes
- Ivermectin PO or SC, repeat in 2 weeks
- Oxfendazole PO
- Fenbendazole PO, repeat fortnightly until negative faecal examination
- Levamisole ICo, repeat in 2 weeks
Cestodes
- Praziquantel IM once