If you are struggling financially due to COVID-19 then please call us on 0344 557 0300 or visit our FAQS.

Animal Friends Blog


What Effects Can Parasites Have on Pets?

Animal Friends Pet Insurance

Different types of parasite can have varying effects on the host they feed off. Here are some of the most common types and how they impact pets.


Animals infested with hookworm suffer from blood loss, because the parasite sucks the blood of its host. This can be critical for young puppies unless a transfusion is carried out. Older pets may also lose weight and have diarrhoea. Anaemia, anorexia and lethargy are some of the other ways host animals can be affected.


Often there are no outward symptoms of roundworm. However, in the case of severe infestations the animal may experience vomiting or diarrhoea, and the condition of the coat could deteriorate. These symptoms are more commonly seen in infected puppies. Roundworms can also inhibit growth and give the host a pot belly. Dogs may cough if the roundworm finds its way into the lungs, and they can be present in vomit or faeces.


Again there are usually not many outward signs, but severe infections can cause bloody diarrhoea, anaemia and can also stunt the growth of young dogs. Whipworm can cause serious disease and even kill an animal if left untreated.


Often pets will show no signs of infection, but they may vomit or have diarrhoea, and excessive licking can cause irritation. Also, dogs may ‘scoot’ across the ground because of the irritation they are suffering from.


There are various symptoms of lungworm, which contribute to general cardiac and respiratory debilitation. These include coughing, diarrhoea, vomiting, tiring easily, weight loss and bleeding too much from small wounds, to name a few.

Fox lungworm

This type of parasite affects the respiratory system, so symptoms include coughing and problems breathing, as well as retching and nasal discharge.


Although not currently found in the UK, heartworm may be contracted abroad. It can cause high blood pressure, breathing problems, lethargy and heart failure. The host is also at risk of dying as a result.

Dirofilaria repens

These worms might live in visible swellings under the skin. Infected hosts may have itchy skin and dermatitis.

Spirocerca lupi

This type of worm isn’t found in the UK, but pets can contract it when travelling abroad. They may experience vomiting, regurgitation and difficulty swallowing. It can also cause cancer of the oesophagus and sudden death from the rupture of the aorta it lives in.


Ticks feed on blood, so puppies can suffer from anaemia in the case of severe infestations. They can also spread Lyme disease in the UK and Ireland, and Babesiosis or Ehrlichioisis in various other countries. There may also be reactions where the tick attaches to the skin.

Deer ticks

Deer ticks are said to be the primary carrier of Lyme disease, although they aren’t present in the UK. Signs can include depression, fever, swollen lymph nodes, swollen joints leading to lameness, loss of appetite and depression. Extreme effects can include kidney damage, disease of the heart and disease of the nervous system.

Ear mites

Signs of an ear mite infestation may be head shaking, constant scratching of the ears, neck or head, crusting or waxy residue, a strong smell, pus-filled discharge and irritation. However, many pets don’t show any signs at all.


The severity of the reaction caused by these mites varies between animals. If the infestation gets out of control, the pet can start to display signs of demodicosis, the symptoms of which include hair loss and patches of skin inflammation.

Sarcoptic mange mite

These parasites can live on one area of the body and then spread everywhere else. Affected areas can include the ear margin, groin, abdomen, elbows and hocks. The mites cause skin irritation, redness, itching, hair loss and also skin disease, leading on to bacterial infections. Signs to look out for are the scaling and wrinkling of the skin.

Notoedric mange mite

The effects of this parasite are very similar to the Sarcoptic mange mite, in that they cause redness, itching and irritation of the skin, as well as hair loss and skin disease. They can spread around the whole body from areas such as the ears, head and neck, and can also cause bacterial infections.

Biting lice

Severe itching resulting in skin damage, hair loss and inflammation are some of the symptoms of biting lice. They can also cause bacterial infections.


Fleas can affect animals by causing Flea Bite Dermatitis and Flea Allergy Dermatitis, which is an allergic reaction to flea saliva. Their bites can transmit other parasites, plus viral and bacterial disease.

Keep an eye out on our blog for more charity visits, product reviews and pet advice or head over to our Facebook page for updates on our latest campaigns and giveaways.

We have a range of pet insurance policies to suit your needs

Get a quote


Hello, fellow animal lovers! I’m Elena, and I take care of social media for Animal Friends Insurance. I’m here to share the latest on animal welfare, our charity work and pet care. I foster and adopt rabbits and have a rescue dog called Luna.

You may also like