Helminthic therapy for pets

There has been some discussion in the Helminthic Therapy Support group about the possible use of this therapy in pets, especially cats and dogs, and there is evidence that helminth products can produce immunomodulatory effects in dogs. [1]

The deworming of animals can have similar adverse consequences to those seen in humans. For example it has been suggested that the routine deworming of dogs may be contributing to allergies, inflammation and autoimmune disease in these animals, in the same way that the loss of helminths has led to these conditions in humans.

I just want to caution everyone that unless you have seen an infestation of worm eggs or larvae on a slide done from a fecal float and your dogs are presenting with symptoms of a worm infestation, please - do NOT just routinely worm you dogs. Believe it or not, routine worming is being found to cause auto-immune deficiencies and diseases in our pets! (Link expired)

The use of anthelmintic treatments in dogs has also resulted in the appearance of a multidrug-resistant strain of the canine hookworm, A. caninum, [2] and, in horses, the removal of adult cyathostomins has led to an altered faecal microbiota and the promotion of an inflammatory phenotype.

... we have observed significant indications of changes in the equine gut microbiome associated with anthelmintic treatment. These changes were associated with an inflammatory response and could be an indication of the immunoregulatory effects of cyathostomins either directly or through manipulation of bacterial microbiota. [3]

The following comment is from a member of the Helminthic Therapy Support group on Facebook.

So many people with the breed of horse that we own have problems with obesity, insulin resistance, allergies, laminitis (inflammation under the hoof wall), etc. We don’t have those issues as much if at all in many of our horses, despite raising them in conditions that horse people claim will cause all of the health issues above. We also almost never chemically deworm our horses, even the young ones. When I do fecal counts on them, they still have worms shedding eggs, so I think they have naturally found a balance with their parasites.

Obviously, this is a topic that pet owners will want to discuss with their veterinarian/veterinary surgeon but, even when it is decided to worm a pet periodically, it is still possible for it to benefit from the immune modulation provided by therapeutic helminths. For example, dogs can be given worming medicine just before they are due to receive a fresh dose of a therapeutic helminth. This way, they and their owners will be protected against the possibility of a disease caused by pathogenic worms, but there will only be a minimal break in the benefits afforded by whichever symbiotic helminth is being used.

Best currently available species

Hymenolepis diminuta cysticercoids (HDC)

When someone asked whether H. diminuta cysticercoids (HDC) might be safe to give to a 6 week old kitten to prevent it developing allergies, etc., an expert in the use of HDC in humans suggested that this species would indeed be safe for a kitten, and pointed out that HD normally lives in insects and that cats often catch and eat insects without ill effects. HDC can be purchased from several of the helminth providers and are easy to grow at home.

I have been giving my dogs HDC for months now and they are distinctly less chewing on themselves. One in particular that used to whine loudly while chewing her feet is much much better -- about 95%. I have been growing my own beetles and I just give them each one beetle per week, wrapped in butter. [4] [5] (And the following update, one year later.) My dogs seem to be cured of their itch. They haven't had any HDC for months but no symptom at all. [6]

I started our 11 year old Labrador, Zeb, on HDC about 12 months ago to try and see if they could help with arthritic back legs, which was causing a very obvious decrease in strength and mobility. While it is difficult to judge exact response, Zeb's mobility and back leg strength has definitely stabilized - a big change from the very fast deterioration we were observing 12 months ago. While we recognize that Zeb is getting very old for his breed, we are hoping that the HDC will continue to make his last years more comfortable and enjoyable. 12 months ago it seemed very likely that he would be unable to support his own weight within a very short period and this would be the factor that would shorten his life - but we are now hopeful that Zeb will be able to continue running around the woods and shores for the rest of his life. [7]

Trichuris suis ova (TSO)

During toxicity studies carried out on TSO, this organisms was tested in mice, rats, rabbits, dogs and monkeys, with no problems being recorded. [8]

I’ve had success treating my newly adopted cat with TSO.

She had constant diarrhea that was not the result of parasites (we tested her poo). I tried several different types of foods and nothing was helping.

She also had something called Esonophilic Plaques. Excess esonophils were being deposited in scabby itchy spots in the skin on her back legs. (this was diagnosed by a vet btw. I initially thought it might be mange but this is a disease cats can get apparently.) She was constantly stopping and licking/biting her legs to the point where she had good sized bald spots on the backs of her legs and seemed pretty uncomfortable.

I was assured by the TSO provider that it was safe for animals and they have other customers that give it to their pets. And she definitely seemed like a good candidate. I had some dewormer on hand for her just in case but never needed it.

I had to guess with dosing. She weighed 7 lbs when I started so I gave her 0.2 ml TSO (from a bottle of 2500 ova) at the beginning of May. I mixed it in a Churu treat. I take TSO weekly myself so it was easier for me to keep her on a weekly schedule instead of bi weekly and give her a dose at the same time I took mine. She is at 0.35 ml TSO weekly now.

I’m pleased to report that her diarrhea has completely cleared up and her plaques are almost totally gone. The bald spots are gone as well. She still had one very small scabby spot I felt today but each time I check for plaques there is less and less.

She is active and playful, her eyes are bright, her coat is shiny, and she has gained a pound. She also seems really happy. I’m so pleased it worked. [9]

Alternative species with some disadvantages

Four further species of helminth have been suggested as possibly having therapeutic value in pets, but each has disadvantages.

Necator americanus (NA)

N. americanus (NA) may be suitable for use in dogs. [10]

… if you want to try anything readily available you could try NA. It's pretty good adapted to dogs as well. [11]

However, caution is recommended when considering administration of NA to dogs. NA is closely related to the dog hookworm [12], so should feel sufficiently at home inside a dog to mature, mate and produce eggs that would be passed in the animal's feces. Infective larvae could potentially result from even a small amount of infected dog feces left on soil or grass during warmer months. These larvae could infect other animals, and even humans.

Dipylidium caninum

Dipylidium caninum (also called the flea tapeworm, double-pored tapeworm or cucumber tapeworm) may be suitable for dogs and cats

I suggest the cucumber tapeworm (Dipylidium caninum). It seems harmless and can colonize both cats and dogs. If you can convince a vet to collect some fleas from a colonized animal then you could feed them to your cat. [13]

D. caninum can, rarely, infect human pet-owners, and especially young children. [14] According to Wikipedia, most infections in humans are asymptomatic, but can result in any of the following symptoms: mild diarrhea, abdominal colic, anorexia, restlessness, constipation, rectal itching, and pain due to emerging proglottids through the anal cavity. [15]

Trichuris vulpis

Trichuris vulpis may be appropriate for dogs. [16] However, the risk is quite high that dogs treated with TV ova will shed eggs wherever they defecate, potentially leading to unintended infection in other pets. [17]

Uncinaria stenocephala

Uncinaria stenocephala known in the UK as the northern hookworm, this is the most common canine hookworm in cooler regions, such as Canada and the northern parts of the US. Also known to infect cats, U. stenocephala may be a possible therapeutic species for cats and dogs, [18] but it can also be transmitted to humans.

Sources of mutualistic helminths

Suppliers of TSO, HDC and NA can be found on the following page.

Helminth providers