Regular testing for equine tapeworm in horses and donkeys with the Equisal Saliva Test and Bespoke FEC Kits can increase the effectiveness of anthelmintic treatments, reduce the risk of parasite resistance and promote the long-term health of your horses and donkeys.
Overtreatment Increases Parasite Resistance
Treatment with equine de-worming medicines, known as anthelmintics (AH), effectively controls the vast majority of intestinal parasitic worms (helminths). However, the ready availability of these same medicines has lead to their overuse as a quick and easy substitute for veterinary testing and livery stable hygiene.
Tolerance to AH drug treatments in parasitic worm populations ranges from ‘highly susceptible’ to ‘highly resistant’. Overexposure to AH treatment might kill the vast majority of parasites, but the more resistant worms – though initially fewer in number – may still survive and multiply.
Without competition from the more susceptible worms, the fewer highly resistant survivors thrive, breed and pass on their drug-resistance to the next generation. The outcome is that overmedication reduces the effectiveness of each AH treatment until no useful treatment option remains.
Stronger and Stronger Doses Are Not The Answer
Increasing anthelmintic resistance (AHR) means that even stronger doses of AH medicines are needed next treatment. Continued over-treatment with the same AH medicine again and again only strengthens the resistance of the surviving tapeworms.
Eventually, the treatment becomes ineffective or, worse still, only effective in a dose so strong as to risk a dangerously adverse reaction from the horse itself. Changing the drug of choice may only begin a further round of acquired resistance ending in yet another ineffective treatment.
Strategies To Avoid Acquired Drug Resistance
Constantly changing the AH regime means that the few survivors of one treatment are less likely to survive a second, different, treatment before further resistance develops. With twice-yearly laboratory testing and good stable hygiene, unnecessary and ineffective treatment can be avoided.
With no new anthelmintic treatment on the horizon, the future relies on changes in the behaviour of owners and keepers. New strategies to counter increasing drug resistance in digestive tract parasites include regular monitoring and treating medically only when necessary.
Testing before treating not only helps prevent the development of drug-resistant tapeworms, it reduces the cost of wasteful over-treatment. The British Horse Society recommends a planned timetable of spring and autumn testing with medication, only when justified by the test results.
Good Hygiene Is Key to Equine Health
The need to resort to new treatment strategies is, perhaps, an indication that previous parasite reduction regimes have not been effectively applied. A report by UK-VET EQUINE (2009), circulated by The Horse Trust identifies the key risk factors in the spread of AHR, including:
– Poor manure collection and cleaning regimes.
– Poor pasture and paddock management.
– Frequently changing and high density horse populations.
– Grazing of younger, more vulnerable horses with older animals.
– Lack of effective quarantine measures.
UK-VET EQUINE recommended a range of effective strategies to reduce these risk factors:
– Collection of faecal material at least twice weekly.
– Rest and rotation of pasture – especially on stud farms.
– An awareness that parasites can overwinter on pasture.
– An awareness that worm larvae can migrate into pasture from contaminated field edges.
Types of Equine Intestinal Worm Infections
Horses and donkeys are at risk of infection and reinfection from a range of intestinal parasitic worms collectively known as Helminths. These worms fall broadly into three groups classified by veterinary laboratories as flukes (trematodes), tapeworms (cestodes) and roundworms (nematodes).
Animal charity Blue Cross warns that animals kept in poor, overstocked or unhygienic conditions are vulnerable to serious illness caused by five subtypes of intestinal parasitic worm:
Large Redworms (strongyles). Living in the horse’s intestine, they cause a swollen abdomen, internal bleeding, colic, weight loss and diarrhoea.
Small Redworms (cyathostomins). Feed on the intestinal tissue, these worms burrow into the gut wall to lie dormant through winter months emerging in early spring to cause weight loss, loss of condition, distended abdomen, colic and diarrhoea.
Roundworms (ascarids). Growing up to 40cm long, roundworms exploit the immature immune systems of foals under four years to cause inflammation and obstruction resulting in poor growth, lethargy, coughing, weight loss, loss of condition, distension and colic.
Tapeworms (anoplocephela). Tapeworms attach to the gut wall at the junction of the small intestine and large intestine causing impaction, colic, weight loss and even physical damage.
Tapeworm infestation is a particular problem for horse and donkey keepers because tapeworm eggs are too small for detection by routine centrifugation and McMaster slide FEC methodology.
Assessing The Worm Burden: Faecal Egg Counting
Equipped with a veterinary microscope, flotation solutions and a McMaster counting slide , the tell-tale eggs of most intestinal worms can be separated from horse faecal material. Faecal egg counts can accurately estimate the degree of any worm burden.
The tale-tale eggs of equine tapeworm are too small as to be accurately recovered and counted using the tried and tested methods of centrifugation and McMaster faecal egg counting. Detection of equine tapeworm infestation requires a new and innovative veterinary test.
Simple Saliva-Swab Test for Tapeworm in Horses
EquiSal Tapeworm Saliva Testing Kit for Horses is an Enzyme Linked Immunosorbant Assay test known as ELISA. The Equisal ELISA test searches out any antibodies produced by a horse’s immune system in response to tapeworm infection.
The EquiSal Tapeworm test works like an antibody blood test but uses saliva which horse
owners can collect themselves using a specially designed mouth swab as shown in this video . The swab is then simply packed in the preservative provided in the kit and posted to the laboratory in the freepost bag provided.
How Good Is The Equisal Saliva Tapeworm Test?
In a 2016 large-scale stables trial of Equisal, only 22% of the 749 horse tested were found to require veterinary treatment. This means that 78% – 583 horses – might have been unnecessarily and expensively treated if Equisal testing had not been carried out.
The economics of Equisal testing speak for themselves. Targetted treatment is not only economical, it also reduces the frightening prospect of runaway drug resistance resulting in debilitating and potentially lethal equine tapeworm infections.
To Treat or Not to Treat – That is The Question
The only 100% accurate way to measure a horse’s tapeworm burden would be count the number of worms within the horse’s intestines. In validation studies, the EquiSal Tapeworm test only misreported horses as tapeworm free when fewer than 20 tapeworms were present.
Parasitologists consider horses and donkeys showing fewer than 20 tapeworms to have a non-pathogenic medical condition. This means that these tests confirm the EquiSal Tapeworm Test as a success in identifying all pathologically significant tapeworm burdens.
Vets and stable owner can find all their technical questions about Equisal Testing answered in detail here, on Vetlab’s EquiSal Tapeworm FAQs page.
