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Roundworm in Cats & Dogs



A large percentage of puppies and kittens are born with microscopically small roundworm, or ascarid larvae in their tissues.




The larvae is introduced to the developing puppy or kitten in the mother's uterus. This occurs via migration through the mother's tissues.


The mother's milk is also a route by which the Roundworm larvae can also be transferred to the nursing puppy or kitten. The larvae then migrate to the intestinal tract where they develop and can grow up to five inches in length. The larvae then start shedding eggs and try to remain in the small intestine of the puppy or kitten.


The eggs that the adult worms lay are then passed in the faeces of the puppy/kitten, these can now reinfest the animal or other dogs and cats if the eggs in the faeces are eaten.


When the worm eggs hatch, larvae are released internally to migrate to the animal's lungs where the larvae are coughed up, swallowed, and continue their lifecycle developing into adults in the small intestine.  


Clinical signs & Treatment


Female roundworms can produce 200,000 eggs per day. These eggs are protected by a hard shell, which enables them to exist in soil for a number of years.


Puppies and kittens with roundworms infections in the intestines often have a pot-bellied appearance and poor growth. The worms may be visible in vomit or faeces. If an large infestation is left untreated, they can cause death by intestinal blockage.


Roundworms do not just affect young puppies or kittens, they can infest adult dogs and cats, too.  The larvae can encyst in body tissue of adult dogs and cats and remain dormant for long periods of time.  


Dormat roundworms in female cats and dogs can activate during the last stages of pregnancy to infest the puppies and kittens.


Worming the mother has no effect on the encysted larvae in the body tissues and cannot prevent the worms from infecting the foetus.


Almost all wormers work only on the adult parasites in the intestinal tract.






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