Ever worry about what your pet could be contracting when he/she stops and drinks out of a pond or other stagnant body of water? Many water-borne parasites can cause clinical signs that are anywhere from mild to severe. The most common parasites include, but are not limited to:
Giardia: Giardia is a protozoan that can live for a long time in stagnant water. It causes diarrhea, which is often watery but not bloody. It can be hard to detect on a regular fecal float at your vet, and often further testing is required. It is shed intermittently in the feces, making detection that much harder. The most common treatments are fenbendazole and metronidazole. There is a vaccine for giardia that does not prevent the infection, but does prevent shedding of the protozoan — making it useful in kennel-type situations. Is it transmittable to humans? Yes, humans can be affected by drinking contaminated water.
Coccidia: Coccidia is a single-celled organism that is transmitted by the fecal-oral route, meaning that it is passed in the stool of the host and ingested by another host. The most common form of Coccidia Isospora is species-specific and therefore is not cross-transmitted. Coccidia causes watery, voluminous diarrhea, with or without blood. It is easily passed to young animals with weaker immune systems but rarely affects adults. It is usually detected on a fecal flotation, but a very small amount of Coccidia can cause an infection, so it can be missed on a fecal flotation. Coccidia is commonly treated with Albon or sulfa drugs. Can it be passed to humans? The most common form is species-specific, but humans can contract the Coccidia toxoplasma from cats, which can be a risk for pregnant women.
Leptospira: Leptospira is a spirochete bacteria that affects dogs and rarely cats. It thrives in warm, stagnant water such as a marsh or muddy area and is usually shed in the urine of wildlife or rodents. It initially causes a fever; then the fever subsides, and the clinical signs progress to liver damage and kidney failure. Leptospira can be detected by a blood test. Many dogs are vaccinated for Lepto as part of their annual checkup. The vaccine is specific for certain serovars or strains of Lepto, so it is still possible to contract Lepto after being vaccinated. The treatment for Leptospira is supportive care and antibiotics, but the prognosis is poor.
Campylobacter: Campylobacter is a bacteria often found in water contaminated with feces. It mostly affects puppies less than 6 months of age, and rarely affects cats. It is often isolated from the GI tract of normal adult dogs, but can overwhelm the system in puppies, causing a high fever and watery, mucoid or bloody diarrhea. The diagnosis is made on a fecal wet mount. Animals that are positive for campylobacter and have an associated high fever are treated with antibiotics.
Cryptosporidia: Cryptosporidia is a protozoa affecting both cats and puppies usually less than 6 months old. It is usually found in water contaminated with feces. It causes watery diarrhea, weight loss, bloating, gas and nausea. It is hard to detect on routine fecal flotation, and usually is detected by sending a fecal out to a lab that uses special flotation solution. The clinical signs are usually self-limiting and rarely require treatment other than a bland diet for three days. If the diarrhea is severe, occasionally IV fluids and supportive care are required.
The majority of the water-borne parasites cause diarrhea, which is treatable in a healthy animals. An immuno-compromised or otherwise debilitated animal might have more severe clinical signs. Among water-borne parasites, Leptosporidia carries the poorest prognosis if it advances to liver and or kidney failure. The best prevention is to make sure your dog is vaccinated, to carry fresh water for your dog, and to try to discourage them from drinking from stagnant water.
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