Dog Parasites

Dog parasites are organisms that lives on or in a dog and gets its food from or at the expense of the dog.

There are two main categories of parasites in dogs which are internal and external. Internal parasites live inside the body, can be transferred in various ways and can affect several organs. External parasites live on the body of the host and produce an infestation.

Internal parasites examples:

  • Heartworms
  • Hookworms
  • Ringworms
  • Roundworms
  • Tapeworms
  • Whipworms
  • Coccidia, Giardia and Spirochetes (non-worm parasites)

External parasites examples:

  • Fleas
  • Ticks
  • Lice
  • Mites

Parasites take many forms, but they all have one thing in common: sooner or later their presence will almost always have an impact on your pet’s health or comfort. They can cause anything from mild irritation to serious illnesses. Some parasites are zoonotic meaning it can be transmitted from animal to human.

Symptoms will vary depending on the parasite and where it lives. Most internal parasites will not show symptoms until the infestation has become severe whereas external parasites are more obvious.

Symptoms of internal parasites:

  • Diarrhoea (with or without blood/mucous)
  • Vomiting
  • Weight loss
  • Loss of appetite
  • Decrease activity
  • Distended abdomen (pot-bellied appearance)
  • Scooting
  • Worms or segments visible in the faeces
  • Coughing
  • Difficulty breathing

Symptoms of external parasites:

  • Excessive scratching
  • Excessive chewing
  • Red/inflamed skin
  • Hair loss
  • Dry coat
  • Scaly appearance to fur
  • Fleas or flea dirt
  • Restless behaviour
  • Crusting and discolouration of the skin

How to prevent dog parasites:

  • Medicate- There is a wide availability of preventative medications that can help ensure your pet avoids having parasites hibernating in or on them. Some medications are more complicated than others, so it is always best to ask your vet for their recommendations specific to your pet but also to the parasite.
  • Monitor- Annual screening tests are available at your vets if required. Watch out for any behavioural changes in your pet. Monitoring your pet’s food and water intake is a good indication to alert you to a potential problem.
  • Maintain- A clean environment is crucial for your pet. Ensure the bedding, food/water bowls, coats, etc are all cleaned regularly. Keep them away from rubbish, dead animals, or other dogs on the walk that may be infected. Ensure you remove any waste from the animal at least once a week to avoid contamination.

Diagnosis and treatment:

There is no single medication that can treat and prevent all parasites. However, it is important that you seek veterinary advice if you suspect your pet has any parasites on or in them. They can then help you identify the parasite and find the most effective treatment for your dog. Faecal testing can detect most parasites, but some other such as heartworm require a blood test. In severe cases of internal or external parasites dehydration, anaemia and secondary infections can occur. In this case, your vet will treat any additional symptoms alongside the course of medication to kill the parasite.

Internal Dog Parasites:

Heartworms- These enter the dog’s bloodstream from the bite of an infected mosquito. The worms mature in the dog’s heart and clog it up. Inflammation in the dog’s arterial wall disrupts blood flow making the heart have to work harder. Once the blood flow slows sufficiently, the infested dog may develop a mild, persistent cough, suffer from a lack of appetite, and may become fatigued after only mild exercise. The end result can be heart failure. The vets will look for these typical symptoms but most dogs harbouring this parasite don’t have symptoms when screening tests are being done for detection. These tests are usually done during routine veterinary check-ups and the test is so sensitive that it can detect a single worm in a dog’s body. Timing is very important as the test can only detect adult heartworms. Treat worm is expensive and must be administered by a vet. In rare cases, surgery may be required to remove the worms. Fortunately, there are many effective options for heartworm prevention including daily/monthly tablets, chewable and monthly topicals.

Intestinal Dog Parasites:

Hookworms- These live inside a dog’s digestive system and can be contracted in 3 different ways. The hookworms can burrow into the skin, adult dogs can swallow the parasites eggs, or puppies can contract it from their mothers when nursing. Hookworm live in soil and can be ingested when the dog perform routine self-cleaning. After attaching to the lining of the intestinal wall, hookworm feeds on the dog’s blood. the blood loss can have serious effects, especially on puppies. The vet can detect hookworms by examining a stool sample under a microscope. The infection can be prevented by keeping a dog’s environment clean. Diarrhoea and weight loss are common symptoms of infection.

Ringworm- This is actually a fungus and not a worm. Due to their still-developing immune system, puppies that are less than a year old are more susceptible to ringworm. Adult dogs that are malnourished, stressed or whose immune system is weaker are also at risk. The ringworm fungus is easily transmitted, and an infected dog will develop lesions on his head, ears, paws, and forelimbs. The lesions cause circular bald spots which sometimes look red in the centre. Treatment depends on the severity of the infection. In mild cases, vets typically prescribe a medicated shampoo or ointment to kill the fungus. In severe cases, the animal may need oral medications in addition to clipping the fur.

Roundworm- These are extremely common and again, puppies are most at risk, but it can affect other dogs and even children. They look like white, firm, rounded strips of spaghetti about 1-3 inches long. Your vet will look for signs of roundworm in the stool sample. Some of the symptoms to look out for are coughing, vomiting, diarrhoea, and malnourishment.

Tapeworm- These are ingested by your dog via a host harbouring a tapeworm egg, this is usually an adult flea. You will know if your dog has got tapeworm because you will see segments of the worms (they look like grains of rice) around the anus or in the stool of your pet. It will also cause your dog to lose weight and have occasional diarrhoea. Your vet will administer medication, which is highly effective, by injection or orally. The best preventative against tapeworm I to keep your dog free of fleas and away from rubbish/dead animals.

Whipworm- These are acquired by licking or sniffing contaminated ground. An adult whipworm is only about 1-3 inches long and resembles a very small piece of thread. Whipworms live in the dog’s large intestine, but unlike other parasitic worms, they are very difficult to spot in a stool sample. One sign that can be seen if a stool has a mucus covering, usually at the tip. The dog will also show signs of weight loss. An infected dog will need to be treated with a de-wormer.

Coccidia and Spirochetes- These are invasive, non-worm parasites that live in a dog’s intestinal tract. What makes them particularly dangerous is that can infect a dog before he actually appears sick. It may not be clear that the dog is carrying these parasites until stress or another immunity-comprising factor arises. Coccidia are single-celled and found more frequently in puppies, where they may acquire it through their litter mates or mother. Older dogs are also susceptible to coccidia. Spirochetes can live in the bloodstream as well as in the intestine and can cause Lyme Disease, syphilis, and other serious diseases. Transmission of these parasites can come from infected soil, water, faeces, other animals, etc.

External Dog Parasites:

Fleas- These are tiny wingless insects that feed on mammals, including dogs. These pests will transform eggs into larvae, then into pupae and then finally into reproducing, blood-sucking adults. Some dogs that have fleabites respond to them in an extremely negative way and will bite/scratch themselves raw. Other dogs are not affected as much and do not seem to respond to the fleabites with the same intensity. If you see any evidence of fleas on your dog, its essential to get rid of them as quickly as possible before the population grows. Dark fleas can be visible and are about the size of sesame seeds which scurry around on the skin. Look closely at sparsely haired places. When live ones are not observed, a more accurate way is to part the fur in several places and look for tiny black specks about the size of poppy seeds. These specks are flea faeces, composed of digested blood. If you are not sure whether is it ‘flea’ dirt or only normal dirt, place a damp piece of white tissue and leave it for a minute or so. After that time, a small red spot will become apparent if its flea faeces as the blood rehydrates and diffuses into the tissue.

Ticks- These can cause a number of serious illnesses such as Lyme disease, Ehrlichiosis and Rocky Mountain Spotted Fever. Early detection and removal of the ticks is crucial to avoid any other complications. There are over 800 species of ticks worldwide and they all feed on the blood of mammals, birds, and reptiles. Annual screening by your vet for tick disease is mandatory. There are broad-spectrum antibiotics that are effective for tick-borne diseases. Check your dog for ticks daily and if you see one remove it immediately. The best way to do this is to numb the tick with rubbing alcohol or petroleum jelly and then pull it off with tweezers. Once removed, kill the tick by putting it in a container of alcohol. You then must treat your dog with a medication, dip, spray or powder as recommended by you vet to prevent an infestation.

Lice and mites- These are microscopic organisms that feed on your dog’s skin and cause itching, hair loss and infection. Generally speaking, lice and mites are two different species, but they function and behave in a very similar way. Note that dog lice and humans’ lice are different species as dog lice need dog blood and human lice need human blood. While humans may occasionally be bitten by dog lice, they will not get an infestation. Lice live in a dog’s hair and can be killed with an insecticide used for ticks or fleas. Various kinds of mites inhabit different areas of the dog, and the problems they cause are generally know as mange. Demodectic mange causes hair loss around the forehead, eyes, muzzle, and forepaws. A tell-tale sign that your dog may have mites is if they shake their head and scratch their ears. Scabies affects humans as well as dogs and is caused when mites burrow into the dog’s skin. Scabies usually affects the ears, elbows, legs, and face. There is also a mite that causes ‘walking dandruff’ on a dog’s head, back and neck. This mite also causes itchy red spots on humans. All mites should be diagnosed by a skin scraping done by a veterinarian.

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