An anthelmintic, or de-wormer, is a drug that is used to treat parasites. Anthelmintic resistance is when anthelmintics become ineffective in treating parasites. Anthelmintic resistance is a serious and increasing threat to the health and welfare of all animals. Find out more about anthelmintic resistance in working animals, the causes of anthelmintic resistance, and how global animal welfare charity SPANA is controlling parasites in the face of anthelmintic resistance.
The Impact of Parasites and Drug Resistance on Working Animals
Parasites are a constant threat to working animals. They live in the gut or on the skin of animals. If there are too many parasites in a working animal, identified by a high faecal egg count, the parasites can drain animals of the nutrients they need. Intestinal parasites can also cause inflammation of the gut or secondary problems like colic. Working animals suffering from too many intestinal parasites can experience symptoms including weight loss, a rough coat, diarrhoea and fatigue.
If left untreated, the number of parasites in the environment will also increase, placing other vulnerable working animals at risk. It’s therefore important that working animals receive the appropriate anti-parasite treatment when needed.
However, anthelmintic resistance is a serious and increasing problem. Parasites are surviving anthelmintic treatments and passing on their ability to survive to their offspring. Left unchecked, this could lead to existing anthelmintics becoming ineffective, which could have serious consequences for animal health and welfare.
Causes of resistance in working animals
One of the major causes of anthelmintic resistance is the misuse of anthelmintic drugs. Misuse includes administering the wrong dosages, using the wrong drug, using the same drug repeatedly, re-administering treatments too quickly after a previous treatment, or failing to follow the drug manufacturer’s instructions. This is why it is so important that anthelmintics are prescribed and administered by a veterinary professional.
The biology of parasites is also an important factor. The parasitic worms may have genetic mutations, which means they are not susceptible to the anthelmintics being used. These genes can be passed on when they reproduce, increasing the population of worms that are resistant
Another cause is the movement of animals. If an animal hosting drug-resistant parasites moves into an area where anthelmintic resistance is not common, they could pass them on to other animals and therefore cause resistance in a new area.
How to control parasites in the face of anthelmintic resistance
When a working animal thought to be suffering from parasites is brought to a SPANA veterinary centre or mobile clinic, our vets will examine the animal and test a sample of their faeces for the presence of parasites. This test is called a faecal egg count. If the working animal is suffering from a high faecal egg count, our vets will administer a dewormer.
It is really important that the correct dose is used. By only deworming animals with a high egg count, we can reduce environmental contamination and allow some worms to still live in the gut of animals who have not been exposed to the drugs and hopefully will not have developed resistant genes.
In more serious cases, animals may also be administered vitamins or supplementary feed to boost their general health and ensure they are eating well. Their owner will be advised to give their animal lots of water and a good supply of nutritious feed. The team may also provide guidance on pasture management to help control parasites, including ensuring faeces are removed where the animals are grazing and reducing the number of animals grazing in the same area. You can read the story of how our vets in Tunisia helped a mule called Nahid beat parasites.
One of SPANA’s goals outlined in our charity’s 2023–27 strategy is that the world of working animals thrives and grows sustainably, as part of the nexus of animals, people and the environment. SPANA follows an overriding approach of ‘Do No Harm’, be that to the environment, people or the working animals we are here to support.
Our vet teams are acutely aware of the issues that can arise from the overuse of anthelmintics. That’s why we’re committed to having a responsible, strategic approach to deworming, decreasing parasite burdens by improving husbandry and environmental management, and running community training sessions where owners learn the consequences of parasitic infestations, how to recognise them and how to take preventative steps. Sadly, one-third of all the working animals our vets encounter have parasites. Thanks to our supporters, we can relieve working animals of the terrible suffering caused by parasites while also controlling anthelmintic resistance. With your help, we can provide treatment for internal or external parasites, help test, detect and monitor parasites in working animals, and run community training sessions where working animal owners are equipped with the knowledge to combat the threat of parasites, ensuring future generations can better protect their animals. If you’re interested in supporting SPANA, learn how you can get involved.