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Dogs: Internal and External Deworming

4 minutes
If you notice your dog scratching you might wonder if they might have some kind of internal or external parasite and which kind of deworming treatment you should apply. 
Dogs: Internal and External Deworming
Last update: 27 December, 2022

When you get or adopt a dog it’s important to vaccinate it and do internal and external deworming. This will not only maintain the health of your pet, but also the health of everyone else around them.

Keep in mind that your dog’s health could impact your own health as many of these parasites can adapt to living in human organisms. Blood is blood. Therefore, taking care of your furry friend means taking care of yourself too.

Puppies need deworming before their first vaccination. That is, between their first 20 and 30 days of life.

Puppies need internal and external deworming

The best person to give us advice on how to deworm our puppy is a veterinarian. If it’s still breastfeeding, the doctor will recommend a special solution just for newborn dogs.

At the time of the vaccination, dogs should be free of parasites. It’s recommended that they get a deworming treatment about seven days before their first vaccine.

When they reach six months of age, you should start a deworming schedule to plan the subsequent treatments. Needless to say, you should stick to it.

For example, if yours is an outdoor dog or often exposed to other animals, then you should deworm it once or twice every two months.

When your dog spends a lot of time indoors or doesn’t have too much contact with other animals, the time lapse between treatments can extend to three or four months.

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In addition to fleas and ticks, dogs could also pick up internal parasites that you wouldn’t easily notice.

There are many sources of internal parasites such as sniffing the ground, playing with infected objects, through breast milk, through infected dogs, etc. Intestinal worms are an example of internal parasites.

Internal and external deworming methods

  • Purge dewormers come in many forms including granules that you can add to your dog’s food, pills, chewing tablets, and liquid suspensions. These are for treating internal parasites such as roundworms, flukes, and tapeworms.

Also, there are systems for external parasitic diseases.

  • There are deworming collars available. These contain active ingredients capable of eliminating fleas, ticks, and other parasites off your pet. Depending on the brand, they can last from two to eight months. You’ll have to renew them after that period.
  • Pipettes or ampoules. These contain a liquid that’s applied to the back of our dog’s neck. It lasts for up to one month –this varies among brands. After that time, you may repeat the treatment. There are special pipettes for two-month-old puppies and older.
  • Spraying the dogs with an antiparasitic solution can also eliminate fleas and ticks temporarily, although it only works for a few days. You may repeat the treatment as often as you have to.
  • Flea shampoos. With these, you may wash your pet as often as you wish. Note that, its effect is temporary. Shampoos only kill fleas and ticks that your dog may already have but they don’t work as a preventive measure.

Internal parasites

There are no obvious, clear symptoms that a dog might have parasites but they may, in fact, be carrying several types of intestinal parasites. These could cause serious damage to their intestines, kidneys, and liver.

Not only that, but you should take into account that such internal parasites can also affect people who live in the same household as the dog. Children are particularly vulnerable to them.

Among the symptoms that could be explained by parasites are:

  • Digestive problems that include unexplained constipation, diarrhea, bloating and flatulence
  • Skin problems such as unexplained rashes, eczema, hives, and itching
  • Muscle and joint pain
  • Fatigue, even after plenty of sleep

Proper deworming

For deworming to work, it’s important that the antiparasitic active ingredient or product is effective with both adult worms and their larvae. This is the only way to prevent said parasites from reproducing.


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Some dogs may experience negative side effects, especially if they were treated for severe parasite infestations. Also, diarrhea and vomiting are among the most frequent side effects of deworming.

If you or anyone else overdose your dog with antiparasitic drugs or products, the animal should be taken to the veterinarian as soon as possible. Overdose symptoms include, but aren’t limited to: drooling, weakness, tremors, wobble, head pressure, and paralysis.

This text is provided for informational purposes only and does not replace consultation with a professional. If in doubt, consult your specialist.