Parasite control in kittens requires knowledge of the pathogens involved and the capabilities of the different products for
controlling the parasites of interest. This article will review the parasites and their mode of transmission to kittens. It
will then examine the various products available for parasite control in kittens. Also, it will look at kittens as potential
sources of agents of zoonotic importance. Finally, it will examine various means of ensuring that kittens are protected from
Adult female earmite, Otodectes cynotisaption, can be directly acquired by kittens from their mother.
Kittens acquire only a few internal parasites from the queen directly. The only common internal parasite that is acquired
from the queen after birth is the common feline roundworm Toxocara cati, which is transmitted to the kittens in the milk.
It is unclear when the kittens will first shed eggs in their feces after transmammary infection, but it seems that the first
eggs would be shed no earlier than one month after birth. Kittens can acquire congenital toxoplasmosis from the queen, but
it appears that this is most likely if the queen is infected for the first time while pregnant. Congenitally infected kittens
appear to develop disease but do not appear to shed any significant number of oocysts. The relatively rare intestinal fluke,
Alaria marcianae, can infect kittens via the milk of the queen, but these infections are seldom life threatening, and eggs
in cat feces pose little risk to owners because an intermediate host is required in the life cycle of this parasite. There
is neither transmammary nor transplacental infection of kittens with the feline hookworms, Ancylostoma tubaeforme and Ancylostoma
braziliense; thus, hookworms do not pose the same risk to kittens that Ancylostoma caninum poses to puppies.
Fleas can cause severe anemia and death in kittens, so it is essential that they be protected from these parasites.
There are a number of ectoparasites that kittens can acquire by direct contact with the queen as she cares for them. These
include: fleas (Ctenocephalides felis), lice (Felicola subrostratus), ear mites (Otodectes cynotis), mange mites (Notoedres
cati), and the fur mites (Cheyletiella blakei and Lynxacarus radovskyi). Thus, kittens, when nursing, are at risk on becoming
infested with some of the insect and arachnid pathogens that are present on the queen. Only two of these pathogens are common
in cats, fleas and ear mites, so the risk of kittens acquiring infections with these other pathogens is rather rare. Also,
with the exception of fleas, these pathogens are typically not life threatening to kittens. Fleas on the other hand, can cause
severe anemia and death in kittens, so it is essential that they be protected from these parasites. It is also believed that
flea feces are the source by which cats are infected with the cat-scratch fever agent, Bartonella henselae; thus, this is
another reason to keep cats free of fleas.
Table 1: Antiparasitic products for cats and their label claims
Direct transfer to kittens via feces can occur with respect to a few parasitic pathogens. Queens shedding Giardia felis or
Cryptosporidium felis in their stools can directly infect young nursing kittens. In a similar fashion, they can infect kittens
with intestinal trichomonads. The only helminth that would be directly infectious to kittens is the stomach worm Ollulanus
tricuspis, which is transmitted in feces or vomitus; but fortunately, Ollulanus tricuspis is only relatively rare in cats.
Other risk factors
There are a number of fecal stages passed by queens that are capable of developing in the environment rather rapidly and infecting
kittens soon after birth. The most common of these pathogens would be the coccidians, Isospora felis and Isospora rivolta,
which can cause disease in neonatal kittens. Infective stages of these parasites could appear in the feces of cats as soon
as a week after birth. Also, the other roundworm that infects cats, Toxascaris leonina, has an egg that rapidly develops to
the infective stage, and it can often infect cats while they are still quite young, although it will take about two months
before eggs would appear in the feces of the kittens. If hookworm eggs are shed by the queen into a warm moist soil environment
around the kitten, infective-stage larvae could develop and be a source of neonatal infection in kittens. Kittens could contaminate
the environment with hookworm eggs as soon as two weeks after birth, but more likely not until they were about 4 to 6 weeks
old. (They would need to move about in the contaminated soil to get infected, and it would take two weeks for the worms to
Table 2: Age of first administration of antiparasiticides labeled for cats
There are two parasites that can be important in kittens and which infect cats through arthropod vectors. The flea tapeworm,
Dipylidium caninum, infects kittens if they ingest infected fleas. The kittens can shed segments within three weeks of having
eaten the flea, and it is possible that large numbers of these tapeworms could cause impaction of the small intestine. Kittens
also can be infected with heartworms by mosquito bites, but it is unclear how often this is an important disease in very young
Eggs of Toxocara cati. Kittens need to be protected against roundworms and other parasites to avoid serious medical problems.
Treatment and control
The products that control parasites in cats only are effective against a very few of the parasites previously listed. Infections
with giardiasis, coccidiosis, cryptosporidiosis and toxoplasmosis will be treated using various off-label combinations of
products or through the use of various palliatives for the signs of infection. Similarly, the rare nematode or trematode infection
will be treated only when diagnosed. Control programs have to be targeted at the common parasites. Thus, the available products
labeled for parasite control in cats treat or control infections with roundworms, hookworms, heartworm, tapeworms, fleas and
ear mites (Table 1, p. 14). Frontline® Plus provides broad-spectrum protection against ticks and protects against adult fleas
and also has effects against the developing larval stages of fleas. Advantage™ protects cats against adult fleas. These products
differ as to the time they can be first administered to kittens (Table 2), and it should be noted that one of the most common
products for treating hookworms and roundworms in kittens, pyrantel pamoate, does not appear on the list of labeled products
for cats. Thus, the standard of treating kittens with Nemex or Strongid T (at 20 mg pyrantel pamoate per Kg of body weight),
is an off-label use of both products.