Our Archives: worms

Looking for something in particular? Check our categories!

Worms and How To Kill Them: Dog and Cat Tapeworms

Hopefully every pet owner knows that they must regularly ‘worm’ their pets. But did you know that “worm” is a very broad category referring to hundreds of different parasites that can live inside your pet’s gastrointestinal tract? Today we will be discussing one specific group – tapeworms. We will talk about tapeworm biology and the different species of dog and cat tapeworms. Also how you can treat and prevent tapeworm infection in your pets.

No Comments

Worm Tales 3: Lungworms

We know of some great animal journeys.

We can watch them on TV. So many weird and wonderful animals pass through so many strange places on Earth. Salmon migrate by leaping upriver; crabs scuttle over the ground; locusts swarm; grazing herds wander; whales go miles and miles using echolocation. But the journey that I’m going to marvel at today takes place on a much smaller scale. And that’s the journey of a parasite we know as Lungworm.
No Comments

Worm Tales Part 2: Nematodes

Nematodes are the most abundant animals on Earth (according the Encyclopaedia Britannica)   Trees have them; soil has them; the insides of animals have them..... And so, of course, do people and their pets.   But what exactly is a nematode? Nematodes are Roundworms. These are round worms, as their name suggests: earthworms are the obvious example. The Encyclopaedia Britannica describes roundworms as being ‘the most abundant animals on Earth’; they have an opening at each end, and soil, tissue and dirt travel through them, getting smaller as the worm breaks this matter down and removes some useful nutrients. It is an important part of the decay process.   And how do nematodes affect me? They help to shape our landscapes and support the food chain. Without nematodes, our world would look completely different......
No Comments

Worm Tales, part 1 – Canine Tapeworms

Our planet has a wealth of habitats. There are the icy poles; there are equatorial rainforests. There are peat bogs and tundra, mountain and desert, city and moor. Life, however, has developed ways of surviving in almost every nook and cranny, whatever the temperature, light intensity, moisture levels or hazards in that environment. The animal's body is another collection of environments with differing levels of harshness, that support small forms of life.
2 Comments

Do I really need to worm my horse?

horse-473093_1280

Endoparasites;  the gut-wrenching villains that terrorise our horses from their tums to their bums, but how big an issue are they for the average horse? Which worms do we need to be aware of? Is wormer resistance really that big an issue? So many questions, so many drug names.

What is a worm?

A worm, or an endoparasite, is an organism that lives inside of your horse, to your horse's detriment. We have all seen the adverts for ‘good bacteria'; this is known as a synergistic relationship, where both host and occupier benefit. With parasites, only the parasite gains.

  1. Cyathostomes. Why did the cyathostome always get what he wanted? Because he was so encystant… Excuse my awful jokes; it’s been a long day. Cyathostomes are a type of nematode, or round worm, known as small encysted redworm.  The adults, when in the large intestine, produce eggs that the horse will excrete onto their pastures; the eggs then hatch, and the larvae are eaten by the horse. It is also the larvae that are capable of encysting (hiding) in the walls of the large intestine. So the saying really is true, don't eat where you… These nasty critters can encyst in the mucosal lining of the large intestine of horses; the larvae are capable of ‘hypobiosis’; they stay in a state of arrested development (a bit like hibernation).  It is when they emerge that they can cause potentially fatal damage and diarrhoea, known as larval cyathostomosis.
  2. Strongyles (large redworms). These nematodes are detrimental to your horse in a different way than their smaller namesakes. Eggs in the pasture have a moult phase, referred to as Larval stage 1, L1, and moult to form, logically, L2. The L3 are consumed by an unwitting grazer; it is the L4 stage that migrate from the gut to the arterial supply of the intestine (the cranial mesenteric artery if you are curious). This can cause a compromised blood supply to the large intestine with inflammation of the arteries known as verminous arteritis, and can cause the dreaded colic.
  3. Parascaris Equorum (ascarids); another nematode. Are you the owner of a young horse? This one is for you (sorry!).  Thankfully, our equid amigos develop a resistance to these worms; however, young-stock in the 6 month – 2-year old bracket are highly susceptible. The eggs are passed out in excrement, and moult to L1 and then L2; unlike large redworms, it is the second larval stage that is ingested. They, too, have a damaging migratory pathway; from the intestines, they migrate through the liver and moult to L3, before progressing to the lungs.  From here, they can be coughed up, swallowed, and moult to L4 and then adulthood in the small intestine before starting the whole cycle again. Liver and lungs may be damaged, but impacted colic from a heavy worm burden, along with ill-thrift and a pot-belly, are common signs.
  4. Dictyocaulus arnfieldi (lungworm) is another nematode. To my horror, it is donkeys that are particularly affected by lungworm, and carry it, as the life cycle is not actually completed in the horse.  These larvae are ingested, and burrow out of the intestinal wall into the bloodstream, where they penetrate the lungs. They will cause reactive changes in the respiratory system, such as coughing, increased mucus production and irritation of the bronchi. Chronic pneumonia, secondary infections and pulmonary oedema (fluid on the lungs) may be other features in heavy burdens.
  5. Anoplocephala (tapeworms); a cestode, not a nematode. It requires an intermediate host to develop to a larva from an egg, and it finds a host in the oribatid (harvest) mite. When the horse eats the mite with the parasite, the adult tapeworms can then settle in the caecum (the huge fermentation chamber of the horse gut) and small intestine. Tapeworms pose a real threat to your horse by associations with spasmodic colic; it can cause food impaction and intussusception, when the colon ‘telescopes’, folding in on itself. Inception may be about a dream within a dream, so think of intussusception as a colon within a colon.
Other parasites include Oxyurius equi (pinworms, causing itching and irritation around the anus) and Gasterophilus (bots; actually a fly larva, and not known to cause many problems despite settling in the stomach).

What can we do about worms?

I have been on many yards with rigid worming routines as a means of prevention as much as treatment: this is called interval dosing. Is it necessary? If I had to fall in a strict ‘yes’ or ‘no’ camp, I would be in the latter. Wormers, known as "anthelmintics", are becoming less efficacious; that is to say, anthelminthic resistance is becoming a real problem. The more that worms are exposed to wormers, the more the wormer becomes a selection pressure; some worms will have innate features which allow them to survive despite these chemicals specifically designed to kill them – pesky mutants. The more that we use wormers when we may not need to, the stronger this selection pressure is; we kill the worms which are susceptible to the wormers, allowing the few worms which can survive to reproduce in an environment with less competition. Thus, new wormers need to be developed all the time; a laborious and long task. How can we slow or stop this resistance developing? By being responsible owners and avoiding ‘over-worming’ - saving our horses and wallets in the process! Moving away from wormers, we need to look to management. As we can see in the life-cycles, it is the output of eggs in faeces that are responsible for providing a suitable environment for parasites. Poo-picking fields is one of our biggest weapons in the battle of the bugs; deploy it often! Quarantining new horses prior to turn-out can help to minimise worms on a busy yard; moxidectin and praziquantel can be used 24 hours prior to turn-out. What wormers are available? There are macrocyclic lactones (ivermectin and moxidectin), tetrahydropyrimidines (pyrantel) and benzimidazoles (fenbendazoles) and pyrazinoisoquinolines (praziquantel). We must treat with what is most efficacious for the type of worm, and also only when it is needed. Faecal egg counts (FECs) give a picture of what worm eggs are being put out in your horse’s faeces; when the FEC exceeds 200 eggs per gram, it may be justification for worming. If that sounds a lot, we need to get our heads around the fact that horses will always have worms; whilst this is not a pleasant idea, unfortunately our horses will never have a totally worm-free body, and we shouldn’t strive for that in our worming regimes. Further to this, we want to keep a certain worm population ‘in refugia’; this means we want to keep some worms unexposed to wormers, because then we are not selecting for worms resistant to the wormers. It is only when worm burdens get too high and will damage our horses’ well-beings that we should use wormers. FECs can reduce the selection pressure that help those resistant worms to thrive, as well as being a cost-effective means of targeting the individual horses who need it most.

Is there an ideal worming regime?

Perhaps not. FECs will not give an accurate representation of encysted populations, and are not deemed specific enough for tapeworm counts. Fecal egg flotation or ELISA (enzyme-linked immunosorbent assay) blood tests can be used for tapeworms, but are more expensive. Furthermore, an ELISA detects the antigen (the immune response to a parasite) level, thus the burden may appear high as antibodies are still circulating against the old burden, even if the worms are now dead. However, there are means of interval dosing that do not require administration of a wormer, regardless of whether the horse needs it. We must focus on what burdens are of concern and when… SPRING: Performing a faecal egg count (FEC) for strongyles; ivermectin or single dose pyrantel can be utilised if there are over 200 eggs per gram. Stronglyes were previously a huge concern for causing colic, but thanks to ivermectin, they have become less of a menace, hence the need to protect the efficacy of this wormer by responsible use. Additionally, treatment for tapeworms in the form of praziquantel or double dose pyrantel may be used in spring. SUMMER: FEC for Strongyles and treatment when the FEC indicates, again with ivermectin or pyrantel. AUTUMN: we must treat for any encysted cyathostomes. Remember the larval cyathostomosis? Commonly these larvae will encyst, and emergence can occur in late winter/early spring. Treatment of a heavy burden is advisable; a five day course of fenbendazole, or a single dose of moxidectin are licensed for encysted cyathostomes. However, a large amount of dead worms and a huge inflammatory reaction can spell out a disaster in the form of colic, so if there's a heavy burden your vet may recommend using the older (and less potent) but "gentler" course of fenbendazole first, and then following up with moxidectin 4-6 weeks later to "mop up" any survivors. Tapeworms can be treated with praziquantel or double dose pyrantel again at this time of year. WINTER: The same treatment (or not!) for strongyles when indicated; if bot flies were a problem over the summer, ivermectin or moxidectin will kill the larvae in the stomach. From all of us here from VetHelpDirect, we hope your horses have a wonderfully worm-free year ahead! There is nothing so good for the inside of a man as the outside of a horse. ~John Lubbock
No Comments

Zoonotic diseases – what could you catch from your pet?

Zoonosis is any disease that can pass from animal to human. Although most are easily treated, some of them can be serious and even fatal. Below are several zoonotic diseases that can be passed from dogs and cats, sometimes via other organisms that use the dog and cat as their host.

Toxocariasis

These are the roundworms of the dog and cat (and other species). They can be transferred to humans via their eggs which are left in soil after infected animals have defecated. Children are more predisposed to ingesting the eggs as they might play in the soil and not wash their hands. Adults can also ingest the eggs from eating raw vegetables that have not been washed properly.

If the infection is heavy or repeated, it can cause the disease ‘visceral larva migrans’. This is when the worm larvae move through the body and causing swelling to the major organs and affecting the central nervous system. High-temperature, coughing even pneumonia are various symptoms. The disease is also known to cause ‘ocular larva migrans’ when the worm larvae enter the eye causing inflammation and even blindness.

Once this disease has been diagnosed it is treatable by medication from a doctor.

Dermatophytosis

More commonly known as ringworm this highly infectious disease, affects cats and dogs, it is not a worm at all, but a fungal disease. It can be transferred from animals to humans by skin to skin contact. It can also be spread by contaminated clothing, grooming brushes and other items that have come into contact with the animal.

The disease is characterised in cats and dogs by circular, raised and dry lesions that are normally crusty and cause hair loss. The disease often starts on the head and feet areas, but can spread across the body if left untreated. In cats ringworm is often difficult to detect as it sometimes causes only very mild symptoms. In humans the infected areas are often red rings with scaly edges.

Ringworm can be treated both in animals and humans with the correct medication, however full recovery can be prolonged.

Sarcoptic mange

This is caused by a mite known as sarcoptes scabei canis and is found predominantly on dogs, a different, but closely related mite causes scabies in humans. A similar condition is caused in cats by the mite Notoedes cati. In animals sarcoptic mange causes fur loss and intense itching, where in extreme cases animals can bleed by prolonged scratching, the sarcoptic mange mite that infests dogs can infest humans, however in most cases the mite will quickly die off as they cannot complete their life cycle.

 Leptospirosis

This is a bacterial disease that is carried through the body of the infected animal (in companion animals this is normally dogs) and excreted in the urine. Dogs can pick up the disease by wading through, sniffing or drinking contaminated water where rats have been. Humans can contract this disease with direct contact of the animal’s infected urine.

In dogs the disease can cause vomiting, high-temperature, dehydration, shivering and muscle weakness. In advanced stages it can also cause chronic kidney failure, causing death.

In humans common symptoms are like influenza, however severely infected people can get intense headaches, muscle weakness, high-temperature, vomiting and diarrhoea and meningitis. The infection can go on to produce jaundice and kidney failure. In humans the condition is known as Weil’s disease.

Although there is a vaccine for dogs, there is no vaccine for humans. In some cases people are known to have come into contact with leptospirosis are put on antibiotics by their doctor as a precaution. Toxoplasmosis

This is a parasitic disease carried by cats. It can be transferred to humans by contaminated soil which carries the parasite after the cat has defecated in the area. The soil may be on poorly washed garden produce, much the same as Toxocariasis can be contracted. It can also be transferred to humans by poor hygiene after cleaning cat litter trays.

In cats there are very non-specific symptoms of toxoplasmosis, they might display a lack of appetite, vomiting or diarrhoea, high-temperature, lethargy and weight loss. These symptoms can be attributed to many other cat illnesses. In humans the symptoms are usually mild but people may display a prolonged high-temperature. The main issue with toxoplasmosis is for pregnant women. Should women that are carrying unborn children contract the condition, it can result in miscarriage or severe disease in the new-born child.

Rabies

Although this condition in the UK is very rare, it is not unknown. With the stringent guidelines of the pet passport scheme and quarantine, animals are highly unlikely to carry the disease in the UK.

The disease itself is an acute viral infection that affects the central nervous system. Affected animals normally show behavioural changes, in further stages they can start to drool, become excited then aggressive, attacking people and other animals. Convulsions and paralysis normally follow, before death.

If a human contracts the disease through a dog or cat bite, it is invariably fatal. After the initial bite, a high-temperature followed by headache and nausea are common. Mood changes such as apprehension or excitability come before paralysis, fear of water and delirium. A respiratory paralysis is often the final cause of death. Other Zoonoses Of course it is not just cats and dogs that carry diseases that can be passed to humans. Other species such as birds, goats and cattle can also carry diseases which can, if severe and left untreated, cause death. Reptiles and tropical fish are known to carry salmonella which can make humans very ill and even be fatal. Scientists are constantly monitoring infection and trying to develop treatments for new strains of zoonotic diseases for example avian bird flu, CJD and others. There are numerous zoonotic diseases in the UK (and there are more carried by cats and dogs than are listed above). Despite this, by the use of proper vaccination (in the case of leptospirosis, regular boosters as well), parasitic treatments, stringent hygiene and common sense, risks to human health from animals can be minimised.

David Kalcher RVN, DipCW(CTJT), A1

If you have any worries about your pet, please make an appointment with your vet, or try our Symptom Guide.

No Comments