may have drank from a puddle and gotton something..may be giardia or cociddiosis.
i would start by just giving him a peice of crushed garlic,wrap it in a peice of luchmeat.if he quits taking water you may need to look into it further.
this is from the merck vet book for giardia
Giardia infections in dogs and cats may be inapparent or may produce weight loss and chronic diarrhea or steatorrhea, which can be continual or intermittent, particularly in puppies and kittens. Clinical disease is also reported in calves. Feces usually are soft, poorly formed, pale, malodorous, contain mucus, and appear fatty. Watery diarrhea is unusual in uncomplicated cases, and blood is not present in feces; typical small-bowel diarrhea is more common. Occasionally vomiting occurs. Giardiasis must be differentiated from other causes of nutrient malassimilation (eg, exocrine pancreatic insufficiency [ Exocrine Pancreatic Insufficiency], intestinal malabsorption [ Malabsorption Syndromes]). Clinical laboratory findings usually are normal. Pathogenesis of Giardia spp infections is poorly understood. Gross intestinal lesions are seldom evident, although microscopic lesions, consisting of villous atrophy and cuboidal enterocytes, may be present. Laboratory studies have demonstrated malabsorption of nutrients, decreased quantities of intestinal disaccharides, increased enterocyte turnover, lymphocytic infiltration, and villous atrophy.
Back to top
Diagnosis:
The motile, piriform trophozoites (10-20 × 7-10 µm) are occasionally seen in saline smears of loose or watery feces. They should not be confused with trichomonads, which have a single rather than double nucleus, an undulating membrane, and no concave ventral surface. The oval cysts (9-15 × 7-10 µm) are best detected in feces concentrated by the zinc sulfate (specific gravity 1.18) flotation technique. Sodium chloride, sucrose, or sodium nitrate flotation media are too hypertonic and severely distort the cysts. Staining cysts with iodine aids identification. Because Giardia cysts are excreted intermittently, several fecal examinations should be performed if giardiasis is suspected; eg, 3 samples collected and examined over 3-5 days. About 70% of infected dogs can be identified with a single zinc sulfate flotation; 93% can be identified with 2. In dogs, duodenal aspiration for trophozoite detection is useful; however, in cats, Giardia spp are more prevalent in the mid to lower small intestine. An ELISA that detects Giardia antigen in the feces of dogs and cats is available, but field data on sensitivity and specificity are lacking.
Photographs
Giardia spp cysts
Giardia spp cysts
Back to top
Treatment:
No drugs are approved for treating giardiasis in animals. Fenbendazole (50 mg/kg/day) effectively removes Giardia cysts from the feces of dogs; no side effects are reported, and it is safe for pregnant and lactating animals. This dosage is approved for controlling and removing Toxocara canis , Trichuris vulpis , and Ancylostoma caninum in dogs. Recently, a combination product of praziquantel, pyrantel pamoate, and febantel decreased cyst excretion in infected dogs. Fenbendazole is not approved in cats, but may reduce clinical signs and cyst shedding at 50 mg/kg/day, PO, for 3-5 days. Albendazole is effective at 25 mg/kg, PO, bid for 2 days in dogs and for 5 days in cats, but should not be used in these animals because it has led to bone marrow suppression and is not approved for use in these species. Giardia- infected calves may be treated with albendazole or fenbendazole. Oral fenbendazole may also be an option in large animals and some birds. Metronidazole (25 mg/kg, PO, bid for 5-7 days) is ~65% effective in eliminating Giardia spp from infected dogs but may be associated with acute development of anorexia and vomiting, which may occasionally progress to pronounced generalized ataxia and vertical positional nystagmus. Metronidazole may be administered to cats at 10-25 mg/kg, PO, bid for 5 days. Furazolidone at 4 mg/kg, PO, bid for 7 days, is also effective in cats and small dogs, although diarrhea and vomiting are possible side effects; it is also suspected of teratogenicity. A killed vaccine, available for dogs and cats, reportedly reduces clinical signs and the number and duration of cysts shed into the environment.
Back to top
Control:
Giardia cysts are immediately infective when passed in the feces and survive in the environment. Cysts are a source of infection and reinfection for animals, particularly those in crowded conditions (eg, kennels and catteries). Prompt removal of feces from cages, runs, and yards limits environmental contamination. Cysts are inactivated by most quaternary ammonium compounds, household bleach (1:32 or 1:16 dilution), steam, and boiling water.
To increase the efficacy of disinfectants, solutions should be left for 5-20 min before being rinsed off kennel or run surfaces. Disinfection of grass yards or runs is impossible. These areas should be considered contaminated for at least a month after infected dogs last had access. Cysts are susceptible to desiccation, and areas should be allowed to dry thoroughly after cleaning. Cysts contaminating the hair of dogs and cats may be a source of reinfection. Shampooing and rinsing the animals well can help remove cysts from hair. The killed vaccines that are available for dogs and cats aid in disease prevention by decreasing or preventing cyst shedding.
Back to top
See Also
coccidiosis here
Many species of coccidia infect the intestinal tract of cats and dogs. All species appear to be host-specific. Cats have species of Isospora , Besnoitia , Toxoplasma , Hammondia , and Sarcocystis . Dogs have species of Isospora , Hammondia , and Sarcocystis . Neither dogs nor cats have Eimeria .
Hammondia has an obligatory 2-host life cycle with cats or dogs as final hosts and rodents or ruminants as intermediate hosts, respectively. Hammondia oocysts are indistinguishable from those of Toxoplasma and Besnoitia but are nonpathogenic in either host. See also besnoitiosis, Besnoitiosis: Introduction, sarcocystosis, Sarcocystosis: Introduction, and toxoplasmosis, Toxoplasmosis: Introduction.
The most common coccidia of cats and dogs are Isospora . Some Isospora spp of cats and dogs can facultatively infect other mammals and produce in various organs an encysted form that is infective for the cat or dog. Two species infect cats: I felis and I rivolta ; both can be identified easily by oocyst size and shape. Almost every cat eventually becomes infected with I felis . Four species infect dogs: I canis , I ohioensis , I burrowsi , and I neorivolta . In dogs, only I canis can be identified by the oocyst structure; the other 3 Isospora overlap in dimensions and can be differentiated only by endogenous developmental characteristics.
Clinical coccidiosis, although not common, has been reported in kittens and puppies. In kittens, it is seen primarily during weaning stress. The most common clinical signs in severe cases are diarrhea (sometimes bloody), weight loss, and dehydration. Usually, coccidiosis is associated with other infectious agents, immunosuppression, or stress.
Treatment may be unnecessary in cats because they usually spontaneously eliminate the infection. In clinically affected cats, trimethoprim-sulfa (30-60 mg/kg/day for 6 days) can be used.
In kennel conditions when the need for prophylaxis might be predicted, amprolium is said to be effective, although it is not approved for use in dogs. In severe cases, in addition to supportive fluid therapy, sulfonamides such as sulfadimethoxine (50 mg/kg the first day and 25 mg/kg/day for 2-3 wk thereafter) can be used. Sanitation is important, especially in catteries and kennels, or where large numbers of animals are housed. Feces should be removed frequently. Fecal contamination of feed and water should be prevented. Runs, cages, and utensils should be disinfected daily. Raw meat should not be fed. Insect control should be established.
link to the online vet book
http://www.merckvetmanual.com/mvm/index ... /21206.htm
good luck