Giardia is a parasite that can infect the intestines of cats, dogs or humans. Left unchecked it causes giariasis, which can weaken a cat's immune system. Complications from giardia are rare, however, because the condition is relatively straightforward to treat.
Becoming Infected With Giardia
The Cornell University College of Veterinary Medicine estimates that giardia occurs in fewer than 5 percent of cats. The likelihood of catching the disease is higher in environments with dense cat populations, such as catteries or animal shelters. Giardia are one-celled organisms that infect a cat's small intestines. Infection usually occurs by ingesting the giardia cysts of another infected animal, such as a littermate or a neighbor carrier cat. When the cyst enters a cat's intestine, it transforms into a trophozoite, an organism that attaches itself to the intestinal wall to feed. Trophozoites divide to reproduce themselves; some transform into the cystic form the cat originally ingested. The transformed cysts are passed in the cat's stool. Another animal can then become infected by eating or even sniffing the poo, or by drinking water contaminated by it. Kittens have a greater tendency to shed more cysts in their stool than older cats. Males and females are equally likely to pick up the cysts, and no particular breed is more vulnerable to giardia infection than any other. Cats less than 1 year old have a higher infection rate.
Symptoms & Diagnosis
Cats with giardiasis often don't show signs of infection. Symptoms include weight loss despite a healthy appetite, vomiting, excessive gas and diarrhea. Diarrhea is the most common sign of infection; it tends to be liquid, light-colored and strongly odorous. The diarrhea may be intermittent and occasionally contain blood. Other symptoms include stool with excess mucus or a decline in normal activity. Diagnosis requires several stool samples. The cysts aren't always present in a cat's feces, so several samples over the course of a few days may be necessary. If the antigens aren't present in the sample yet your vet still suspects giardia infection, special tests can detect the parasite's presence.
Treating Giardia Infection
The popular treatment is metronidazole, which can be difficult to administer because of its bitter tablet form. Some vets can compound the medicine into a flavored medicine to mask the bitterness.The treatment period tends to be short, approximately five to seven days. Fenbendazole is another option sometimes used with metronidazole if a cat continues experiencing diarrhea. If the cat is severely dehydrated, other supportive therapy may be necessary. Pregnant cats and those with certain disorders shouldn't take metronidazole; if you suspect your cat is infected with giardia, make sure you share her medical history with your vet. The prognosis for a cat with giardiasis is good in the majority of cases. Geriatric or debilitated cats, or those with compromised immune systems such as cats with feline leukemia virus, have an increased risk for complications from giardia infection, including death.
Preventing Giardia Infection
Since the parasite can be transmitted through water, it's important to make sure no stagnant water stands in areas where your cat spends time -- the parasites flourish in such areas. Ensuring the environment is clean and decontaminated will also help prevent recurrence of infection. In situations where there are multiple cats, proper sanitation is vital to prevent cross contamination. This means making sure all fecal matter is removed from cages and common areas. Bathing a previously infected cat before introducing her into an uncontaminated environment is also recommended because it will prevent shedding of contaminated cysts from her coat.
Cats don't develop an immunity to giardia, so it's possible for them to become reinfected. There is a vaccine available for the parasite, however it's rarely recommended because the condition responds well to treatment and has minor consequences. The VetInfo website states it's acceptable to give your cat metronidazole on a regular basis, as it can prevent the formation giardia without side effects. However, you should consult your vet to determine appropriate dosage. If your cat is one of the rare ones that becomes infected, treat her as recommended by your vet and be sure to keep her and the environment she spends time in sanitary. Cleanliness is your best defense against the disease.