Worm Advice

Health Risks to Pets

Common belief suggests a parasite can just bite and cause itching. Many do, but there is so much more to it than that. These culprits are nasty and cause a lot of discomfort for your pet, as you might have noticed from the symptoms chapter.

Parasites not only cause a bunch of unwanted symptoms, but further potentially more serious problems such as infections and diseases. Parasites, especially ones that feed on blood, can carry all kinds of disease, with some ending in fatality if not addressed by a vet.

Let’s take a look at some of the more specific health risks and conditions parasites can cause for pets and which parasites cause them:

Lyme’s disease

Lyme’s disease is the most widespread disease transmitted by ticks. It is not well-known to occur in cats, but is more likely to affect dogs due to their likelihood of exploring and being exposed to vegetation where ticks are present. It can also being transmitted to humans.

Lyme’s disease inflames joints and causes mobility problems such as lameness. Your pet will experience lameness on and off, with swelling and pain in the joint. Their gait will appear stiff and they may have trouble breathing.

Other symptoms include depression and poor appetite. It can become much more serious than this, however, and problems with the nervous system, heart and kidneys can occur. When the kidneys begin to fail, the pet may experience diarrhoea, vomiting, a loss in weight, changes to how frequently they urinate and an accumulation of fluid in the abdominal area and limbs.

It’s extremely important you see the vet so they can conduct proper tests and provide suitable treatment for your pet, which will be something along the lines of prescribed antibiotics, tick removal (unless you removed the ticks yourself) and care and management advice.

Bacterial infections

There are a number of bacterial infections parasites can cause – the infections can either be caused directly from the parasite, or as a secondary infection connected with the symptoms the parasite causes, e.g. when a cat or dog can’t stop scratching away at itchy skin and ends up causing open wounds from their claws or teeth where bacteria can then enter.

These infections may need cleaning out, dressing or other treatment and it’s best to go to the vet – not only for treatment of the parasite, but to treat the infection to prevent it from getting much worse.


Many parasites cause blood-loss anaemia because of their need to feed on your pet’s blood to survive. Anaemia kicks in when your pet is infested with high levels of parasites, and/or has been for a long period of time. When your pet has anaemia from parasites, this is an indication that it is out of control and immediately needs treatment.

You can spot anaemia by checking your pet’s mucous membranes – the lips and gums will appear pale in colour. If this is the case, go to the vets.

Flea bite or flea allergy dermatitis

This kind of dermatitis occurs when your dog or cat has a skin-based allergic reaction or hypersensitivity to flea saliva when bitten. It can cause intense itching, skin inflammation, crispy or weeping sores or ‘hot spots’, fur loss, red bumps and pain, which can come on even when the amount of fleas present on the pet are relatively few.

When flea allergy dermatitis is really bad the skin can appear to thicken and become darker in colour. The condition can become worse by your pet’s own reaction to the skin irritation where bacterial and yeast infections can develop. You might also notice an odour.

Your vet will need to be contacted to recommend the best flea removal treatment and prescribe medication for the skin troubles.

Haemobartonellosis / Hemotrophic mycoplasmosis / Feline infectious anaemia

A blood infection caused by bacterial parasites called mycoplasma where they infect the red blood cells of the cat or dog. It can go undetected and not even show signs of anaemia, unless your pet has had their spleen taken out at some point.

If symptoms do show they will be along the lines of poor appetite, listlessness, pale lips and gums and both male and female animals becoming infertile.

Mycoplasma bacteria is usually contracted via fleas or ticks infesting the animal after previously feeding off the blood of an infected host or by two animal’s bodily fluids exchanging.

A vet will require various tests to make a diagnosis and treatment normally consists of antibiotics, but more rigorous treatments and therapies, such as steroids, fluid therapy or transfusions, may be required depending on the severity.

Tick-borne disease from other countries: Rocky Mountain Spotted Fever, Babesiosis, Ehrlichioisis, Hepatozoonosis, Anaplasmosis, etc.


These diseases are caused by specific ticks that are most common in North American countries such as the United States or Canada. These are a risk if you and your pet have travelled or relocated to these countries.

General symptoms include lethargy, poor appetite, vomiting, poor energy levels, weakness, weight loss, abnormal gait and stiffness, lameness, pain, depression, discharge from nose and eyes, bruising, etc.

If you have travelled abroad and your pet displays symptoms such as these, go to your vet so they can conduct tests, diagnose exactly what the problem is and then give suitable treatment.

Aural haematoma

Aural haematoma occurs as a secondary problem caused by the pet’s reaction to ear mites. When your pet shakes their head and scratch at their ears repeatedly they may end causing trauma. With aural haematomas the blood vessels in the ear rupture and blood begins to accumulate and make the ear flap swell with it.

Symptoms involve excessive head shaking and scratching followed by a swollen ear, pain, ear disfigurement (usually when left untreated or chronic) and the affected ear flopping.

The ear mites will need treatment to prevent the problem reoccurring, and then the aural haematoma can be treated. It has potential to go by itself, but scarring and other unwanted issues can occur, so it’s best to go to the vet who may opt to perform minor surgery on the ear flap.



This disease can be present in both cats and dogs. The condition in cats is also called cat scratch disease and this can affect humans, too.

Bartonellosis is caused by infectious bacteria called Bartonella which can be transferred over to a pet by lice, ticks or fleas. Dogs that hunt on a regular basis are most susceptible to bartonellosis as the environment has higher concentrations of these parasites.

Symptoms may include diarrhoea, vomiting, fever, inflamed nose, inflamed eye, swollen lymph nodes, lameness, seizures, arthritis, discharge from the nose, inflammation of internal organs (e.g. brain, spleen, liver or heart) and coughing.

Your vet will be able to make a formal diagnosis and advise the best treatments. Antibiotics will usually be prescribed according to the individual symptoms.


Toxoplasmosis affects both humans and animals. It’s a parasitic infection involving toxoplasma gondii and is considered a common disease. It is most common in cats where the parasite’s life cycle finalises in the intestines and is then excreted out where it is able to be contracted by others.

Symptoms include lethargy, seizures, depression, poor coordination, problems breathing, weakness, paralysis, loss in weight, poor appetite, diarrhoea, vomiting, pain, jaundice, neurological problems, trembling, inflammation in the eyes or tonsils and fever.

A vet will need to examine your pet, especially as severe cases are considered emergency situations. Therapies and medications will be given including any urgent treatments and hospitalisation for emergency cases.


This infection and parasite of neosporosis is known to be similar to toxoplasmosis – the parasite is similar in look and the infection causes similar symptoms. The difference is neospora caninum can cause more intense problems in a pet’s muscles and the nervous system. Neosporosis involves tissue and cells of the animal dying off from being infected with neospora caninum parasites.

Symptoms involve stiffness of rear legs, paralysis, tremors, seizures, changes in behavioural patterns, muscle weakness, dermatitis, blindness and problems swallowing. Paralysis can lead to vital muscles being affected which can lead to fatality.

Diagnosis is rigorous to examine all symptoms and rule out other possible causes. Medications are prescribed in milder cases, but more advanced levels of the disease where serious paralysis has occurred will not be as treatable and can lead to decline and death.


Giardiasis is an infection located in the intestines and involves a parasite called giardia. This parasite is well-known to be present in the gut of human beings.

Giardiasis involves diarrhoea in varying textures – runny, foamy, or slimy, accompanied sometimes with mucous and a pungent, powerful smell. Overall, diarrhoea that is different from regular kinds.

Your vet will try and score out any other possibilities before making a diagnosis and treatment is prescribed drugs, unless the pet has become very unwell and needs supervision.

Coccidiosis / coccidia


An infection caused by a parasite called coccidium able to infect both cats and dogs. It normally involves diarrhoea that is watery and contains mucous. It can become bloody if the infection is advanced. Weakness may also be present and your pet may become less and less able to control the diarrhoea.

Late or no treatment will cause harm to the intestinal tract, so be sure to go to the vet if you notice these symptoms. They will conduct an examination and prescribe your pet medication designed to kill any parasites. Treatment for any dehydration caused by excessive diarrhoea may also be needed. More severely ill pets will need supervision.


This is a bacterial infection caused by spirochetes – parasites that take the form of spirals. The parasite burrows through the skin and gets into the animal’s bloodstream. This way it can get around the whole body, even in major organs. Humans can get this infection, too.

Their system can naturally get rid of most of the parasite, but many factors can leave traces behind, including pets with compromised immune systems such as the very old or very young. The spirochete – known as leptospira spirochete – can be left behind in organs such as the liver or kidneys, causing them harm.

Signs of Leptospirosis include fever, stiffness, weakness, quivering, poor appetite, depression, changes to drinking and elimination habits, vomiting, diarrhoea, discharge from genitals, specks on the gums, jaundice, coughing, problems breathing, swellings and dehydration.

After careful examination, the vet will hospitalise badly infected cases and provide therapies and medications to remedy symptoms as well as antibiotics to clear infection.

Breathing conditions

Parasites can cause an array of breathing conditions and respiratory tract infections, such as severe coughing, fluid build-up, general difficulty with breathing, pneumonia, emphysema, breathlessness or shortness of breath and bronchitis to name a few.

Out of all the parasites known to threaten animals, parasitic worms are the most likely culprit behind breathing problems as they work internally, with heartworm and lungworm residing in pulmonary arteries, heart and lung airways. Most other parasitic worms reside in the small or large intestines. Additionally, mites are able to live in the respiratory system of your pets.

Go to the vets as soon as possible if you notice any difficulty with breathing, coughing, wheezing, choking or retching, wheezing, nasal discharge, noisy breathing or changes in the pet’s behaviour. They will then diagnose and treat any parasites present as well as any secondary respiratory problems that still remain after parasite removal.



Yes, it’s not just humans that can get allergies! Pets do, too. What’s more, dogs and cats can get parasite allergies, which can make an uncomfortable infestation just that bit more irritating for your beloved pet.

Pets can be hypersensitive to the bite of a parasite. In this case, flea allergies are the most well-known. Flea bite allergies usually involve dermatitis – known as flea bite dermatitis or ‘hot spots’ – mentioned earlier in this same chapter. Pets can get very similar conditions, such as skin mite dermatitis.

Mite allergies present themselves with itching, scratching around the paws and facial areas of the body, inflamed skin, redness, rashes, scaly skin and further complications, particularly for cats – they can progress to eosinophilic granuloma complex which exhibits lesions, scratching, chin acne, inflammation, and a problem occurring in the paw pads named plasma cell pododermatitis. Ear infections and ear inflammation is also possible.

You’ll need to make some changes around the house and ensure the allergies are diagnosed by your vet so medication to manage it and ease the symptoms can be given.

Sudden death

Not a disease or medical problem as such, but the biggest risk of all when a pet has parasites. Though some parasites cause problems that are minor or non-fatal, others can lead to death if severe and/or left untreated. So, it’s always important to get pets treated for parasites and to recognise and act on any unusual symptoms quickly.

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