What are the symptoms of worms in dogs?

As a vet, I find that worms are one of the most unexpected and unsightly infections for pet owners to cope with. 

Whilst a mild worm infection is fairly harmless, leading to only mild discomfort to your dog, heavier worm burdens especially if left untreated can lead to serious illness. It's a well known fact that puppies, older dogs and dogs with weakened immune systems are especially vulnerable to damage that internal parasites may cause. 

However, don't despair, this article aims to help you recognize the signs and symptoms of worms in dogs. You can then make sure your pup receives prompt treatment for their infections, and reduce risks of transmission to other animals and in some cases, your family. 

What are worms in dogs?

Worms in dogs aren't like the worms you see in your garden, even though that's the mental picture a lot of us conjure. 

The worms you’ll see through dog ownership are parasites that live inside a dog’s body. The worms often live in the intestines, however some species will affect other organs such as the heart and lungs. The more organs affected, the worse the symptoms your dog will experience. 

Common types of worms found in dogs include roundworms, hookworms, tapeworms and heartworms. Each different type of these worms cause different symptoms because they have different life cycles.

Because of the nature of internal parasites such as worms many symptoms may not be present until the infestation is significant. Some of the commonly seen infestations of worms in dogs include:

• Roundworm - Roundworms live in the intestines of your dog. They look like spaghetti and can grow up to 15cm long. It's rare to be able to actually see them, unless your dog has a heavy infestation and vomits them up. It's important to be aware that round worms can infect people, a disease called Toxicocariasis (although this is a very rare occurrence)  
• Tapeworm - Tapeworm live in the small intestine. You can spot tape worm segments in your dog's stool as they often look like small grains of rice. 
  Lungworm - A parasite which can cause severe illness or death. Dogs catch this parasite by coming into contact with slugs or snails. Once infected the parasite travels round the body causing breathing difficulties, heart failure or seizures. 
• Heartworms - Another parasite which can affect your dogs respiratory system. Dogs catch heartworms exclusively from mosquito bites, so cases are generally reported in areas with large mosquito populations. 
• Hookworms - This worm feeds off the blood in your dog's intestines, which can lead to anemia. If you spot them in the stool, hookworms resemble very thin noodle strands approximately 1-2cm in length. 
  

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How do dogs get infected with worms? 

There are many ways dogs can become infected with worms, which is why prevention is so difficult, and infections so common without regular anti-parasiticide treatment.

Your dog can become infected with worms in their day to day lives through coming into contact with contaminated soil, which will likely happen on a daily basis if you exercise or walk them outside of your home. Other routes of infection include eating slugs, snails, frogs or infected meat.

Less commonly, but still an important way of transmission are through drinking water contaminated with worm eggs.

Puppies can even catch worms before they are born if their mothers are infected. After birth they can catch worms from their mother through contact, or through drinking their mothers milk. 

What are the symptoms of worms in dogs?

If your dog has become infected with worms, you may see the following symptoms:

Diarrhoea

One of the first noticeable signs of intestinal worms is diarrhoea in dogs. Diarrhoea can vary in intensity from loose stools through to watery hosepipe brown liquid. Diarrhoea comes in varying shades of brown, but may include mucous (a slimy yellow, white or grey material) or blood. Blood in the stool needs veterinary help.

Vomiting 

Dogs that have round worms may experience vomiting. Worms may even be visible in the vomit, appearing as long spaghetti like strands.

Weight loss

Your dog continues to enjoy their daily meals but may not gain any weight, and may even lose weight if they are infected with worms. This is because worms will consume the nutrients from your dog's intestines instead of it going to your dog. And so a dog will lose weight. This can be a very rapid decline in small puppies, so weighing your puppy weekly is an easy way to check for weight gain. 

Scooting

Tapeworms can trigger irritation around the anus. Therefore you may notice your dog dragging their bottom across the floor in a process known as “scooting”. If your dog is scooting, they will likely also lick around their bottom area- this is because there are often small rice-like segments attached to your dog's fur around the anus (indicating a tapeworm infection). 

Bloated Belly 

A swollen or bloated appearance to the belly especially in puppies is a sign of concern. It is a common sign of a round worm infestation, and can lead to problems including anemia, intestinal obstruction or intussusception if left untreated.

Poor coat condition

Worm infestations interfere with nutrient absorption. The lack of nutrients will then affect the quality of your dog's coat. Your dog's coat may appear dry, dull or even brittle. The coat hairs may shed easily or you may notice excessive shedding outside of normal shedding seasons.  

Coughing

Typically worm infestations occur in the digestive tract. Heartworms and lungworms can affect your dog's respiratory system causing symptoms such as persistent coughing, difficulty breathing and fatigue. 

Heartworm infections can become life threatening if left without treatment making prevention important in areas with high mosquito populations (hot weather areas such as USA and Australia).

Anaemia

Hookworms feed on the blood contained in the intestines. If left untreated the infection may cause significant blood loss and anaemia. Signs of anemia in dogs include pale white or pink gums, lethargy, collapse and rapid breathing.

How do I treat worms?

The good news is treating worms is incredibly easy if the infection is mild. Your vet will be able to prescribe medication to treat the worms, and success rates are incredibly high. It's important to use medication from your vet, rather than from pet stores or online sources as you need a product that treats all types of worms. It can be easy to think that the product you are buying from the pet shop treats all worms, but then your dog will still have an untreated worm infection, leading to more serious illness. 

Your veterinarian can provide in depth advice about preventing reinfection, such as regular anti-parasiticide treatments, how best to clean your home etc. They also know their local area very well, and will be able to suggest areas to avoid that would have higher risks of infections (such as contaminated ponds for example)

When treating your dog for worms, it's important to treat all cats and dogs in your household at the same time, and then regularly as advised by your veterinarian to prevent further illness. 

If your dog has more serious signs from worms such as anaemia, your vet will be able to assess them and provide treatment as appropriate. Most dogs will make a full recovery from even heavy worm infections, so try not to panic when you hear the diagnosis of a worm infection.

Summary

There are many tell-tale symptoms of worms, including diarrhoea, scooting and the most obvious of worms in the poo. Whilst it can be scary to think your dog is infected with parasites, know that the treatment of this condition is very simple, and success rates are very high. The most important thing to consider after treating your dog for a worm infection is preventing re-infection. This is through the regular use of de-worming medications prescribed by a qualified veterinarian.