Infectious diseases of the GI tract in dogs and cats (Proceedings)

Protozoans

• Giardia

• Coccidia

• Cryptosporidia

• Toxoplasma

• Trichomonia

Giardia lamblia

• protozoal infection

• watery, mucoid diarrhea

• may be asymptomatic

• affects young more than older

• small bowel or large bowel

• chronic diarrhea

• pet store, puppy mill, kennel or cattery situation

• Zoonosis!

Giardia

• Diagnosis:

o fresh fecal direct smears

o zinc sulfate fecal flotation

o fecal ELISA test

o duodenal aspirates

o trophozoites, cysts

• Treatment

o fenbendazole (Panacur)

o metronidazole (Flagyl)

o new vaccine GiardiaVax

Coccidia

• Cystoisospora spp.

• young kittens and puppies

• diarrhea with mucous and blood streaks

• weakness, dehydration, cachexia

• Diagnosis:

o oocysts on direct smear or

o fecal flotation

• Treatment:

o Albon, trimethoprim/sulfa, Marquis paste (ponazuril, Bayer ®)

Cryptosporidia

• Cryptosporidium parvum

• young dogs < 6 months

• cats – any age

• diarrhea, may be asymptomatic in cats

• Zoonosis

Toxoplasmosis

• Cat is definitive host

• Zoonotic

• many intermediate hosts (humans)

• shed infective oocytes

• transplacental transmission

Trichomoniasis

• Tritrichomonas foetus/suis

• Cats

• Large bowel diarrhea ± blood/mucus

• Diagnosis: direct fecal with saline, resembles Giardia, PCR(?)

Prototheca

• Rare cause of GI disease in the dog

• Hemorrhagic diarrhea

• Systemic signs – respiratory, etc.

• Diagnosis is by biopsy of tissue

• Treatment is not usually effective

• Prognosis is poor

Bacterial

• Enteropathogenic bacteria that are invasive to the intestinal mucosa or produce an endotoxic substance

• Salmonella, Campylobacter, Clostridium, E.coli

Salmonellosis

• gram-negative motile rods

• asymptomatic carriers common

• can cause significant disease

• young, stressed or immunosuppressed animals

• dogs and cats

Salmonella spp.

Gastroenteritis:

• acute onset of watery diarrhea, possibly hemorrhagic

Endotoxemia/septicemia

• pyrexia, anorexia, dehydration, neutropenia

• bacterial translocation from gut

Cats – milder signs: pyrexia, leukocytosis, conjunctivitis "songbird fever"

Salmonellosis

• Fecal-oral transmission, contaminated food source; ZOONOTIC!

• Diagnosis

o fecal culture (special media),

o blood culture (septicemia)

• Treatment

o IV fluids, NPO, supportive care, antibiotics controversial due to creation of a carrier state (enrofloxacin, TMS, chloramphenicol)

• Prognosis:

o usually good, septicemia guarded Campylobacter jejuni/ upsaliensis

Campylobacter jejuni/ upsaliensis

• gram negative curved rods

• young animal, recently kenneled, immunosuppressed

• dogs and cats

• usually asymptomatic in healthy animals

• acute onset of mild mucoid diarrhea, rarely hemorrhagic

• vomiting, pyrexia, tenesmus and anorexia

• concurrent infections: giardia, salm., parvo, etc. causes more severe disease

Campylobacter spp.

• Zoonotic potential

• Diagnosis:

o fecal cytology – slender seagull-shaped bacteria,

o culture- fragile, hard to grow

• Treatment:

o *erythromycin, *enrofloxacin,

o tylosin, chloramphenicol

• Prognosis:

o good

Clostridium

Clostridium perfringes, C.difficile - bacillus and enterotoxin

• normal flora in dogs

• dog kennels, hospital kennels

• acute mucoid or hemorrhagic diarrhea

• chronic intermittant large bowel diarrhea

• primary disease or secondary invader

Clostridium perfringes

• Diagnosis:

o measure enterotoxin in feces Elisa or latex agglutination test

o identify the endospores on fecal smear (safety pin shaped spores)

o *Identification of enterotoxin or endospores does not prove a primary disease process

• Treatment:

o -mild cases of watery diarrhea respond to supportive care (fluids, bland diet)

o -severe cases or chronic cases- ampicillin, metronidazole (Flagyl)

o -high fiber diets - soluble fiber, psyllium for prevention (increases colonic fatty acids)

E. coli

• gram negative rod

• normal flora; pathogenic strains

• not a lot known in dogs and cats

• produce toxin, enteroadherant

• acute or chronic diarrhea

• enteroadherant causes profound malabsorption

• isolation with special assays required but doesn't prove infection

Pythium

• Gastric, small and large intestinal pyogranulomatis lesions

• Usually history of hunting dog exposed to stagnant lakes (louisiana, oklahoma, arkansas, mississippi)

• Clinical signs are chronic with vomiting, diarrhea, severe weight loss after months of infection

• Diagnosis is by serology (IFA) or biopsy of the intestinal lesions

• Treatment is Itraconazole and Terbinafin, surgical resection

• Prognosis is poor with only 20% response to treatment. Large intestinal lesions can often be resected completely

Histoplasmosis

• Fungal disease found in the gulfcoast and northeastern states

• Intestinal lesions usually found in dogs although occasionally occurs in cats

• Clinical signs are vomiting, chronic diarrhea, weight loss

• Diagnosis may be made with a rectal swab and cytological exam if large intestine affected

• Tissue biopsy needed for small intestinal lesions

• Treatment with Itraconazole can be curative but usually the patient improves but needs long-term treatment and remains a chronic infection

• Prognosis is guarded