Ask a vet online – ‘ Is too many wormer tablets bad for my dog?’

Question from Gillian Richards

I have a American bull dog and every couple of weeks as worms I have giving 1 dose wormer tablets but is to many wormer tablets bad for her or is their another wormer I could use to treat it many Thanx

Answer from Shanika Winters MRCVS, Online Vet

Hi Gillian and thank you for your question about worming your dog. I will start by discussing the common worms that affect dogs and then treatment options.

When we say a dog has worms we are usually talking about intestinal (gut) worms but we are now much more aware that worms can also affect the lungs and heart of dogs. Worms have a life cycle and this can include other species sometimes such as cats, foxes, sheep, slugs, snails and mosquitoes. The worms are a parasite, the animal it is living in is called the host, and if the worm as part of its life cycle has to pass through another animal then this animal is called an intermediate host.

Common worms affecting dogs include the round worm Toxocara canis, tapeworm Dipylidium caninum, whip worm Trichuris vulpis, hookworm Ancylostoma caninum, heart worm Dirofilaria immitis and the lung worm Angiostrongylus vasorum.

The life cycle of the round worm is as follows:

Worm eggs are eaten or licked up by the dog, these hatch in your dog’s stomach and develop into larvae.
Larvae pass into your dog’s blood, are carried to the lungs where they climb up the trachea (windpipe) and are coughed up and swallowed. These larvae then mature into adult worms. Larvae can also remain inside your pet in an encapsulated (protected stage) in different body tissues.

Adult female worms produce eggs which are then passed out in your dog’s faeces (poo). These eggs can then be eaten by your dog or other animals. Worm eggs can survive in the environment for a long time.
Round worms can be passed directly from pregnant bitches to the puppies both before and after birth.

How can you tell if your dog has worms?

Most healthy adult animals show little or no signs of having intestinal worms. Passing worms in the faeces, segments in the case of tape worms around your dog’s bottom which look like grains of rice, intermittent diarrhoea, vomit plus or minus worms, weakness and anaemia may be seen. Very young animals, those which are severely infected or with a weak immune system may show the more severe signs listed when infected with intestinal worms.
If there are no obvious signs of worms or we are trying to work out which exact type of worms your dog has then test can be carried out of faeces and blood samples from your dog.

How do we treat intestinal worms?

Most pregnant bitches are given several doses of an appropriate worm treatment throughout pregnancy and lactation (milk production). We advise regular worming of puppies from birth to 6 months of age. Puppies 6 months of age and adult dogs are advised to be routinely wormed three to four times a year.
It is safest to discuss which wormer to use with your vet to ensure it is safe for your dog, its life stage and that the correct dose is given. Worm treatments tend to kill the adult worms and larvae inside your dog, the encapsulated larvae are only killed by certain worm treatments. It is very easy for your dog to pick up worms soon after treatment from eggs in the environment, faeces and other animals.

Worm treatments:

The worm treatment drugs come in the form of tablets, pastes, granules and spot on preparations. The exact type you use should be decided after discussion with your vet especially in the case of recurrent infestations. It is always important to use the correct dose of a drug and one that is safe for your pet’s age and health status. Reasons a worm treatment may not appear to be working include: pet reacts badly to certain drugs, the worms they have are not being killed by the drug given, their immune system is weakened by other conditions or they are being exposed to a high level of worms.

Many combination drugs are available that treat different types of worms and some other parasites also. A list of drugs commonly found in worm treatments include, fenbendazole, praziquantel, milbemycin, pyrantel, moxidectin, selamectin and flubendazole.

In conclusion regular worming of your dog with a suitable drug is important for dogs of all ages, the exact drug used can be chosen after discussion with your vet based on your dogs needs. If worm infestation is recurrent then your vet may suggest performing tests to work out exactly which worms are present, helping to choose the best drug to use and an individual worming regime can be set. Worm treatment is a constant battle as re infestation occurs to easily. I hope this has helped you and that your dog’s worms are soon under control.

Shanika Winters MRCVS (online vet)

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