Endoparasites, some of which are commonly known as worms, can affect all animals.
They most commonly affect the gut (roundworms and tapeworms), and the lungs (lungworms), but often their effects manifest as syndromes affecting other parts of the body.
For instance, whilst gut worms can cause digestive upsets such as reduced appetite and diarrhoea, farmers often report “ill thrift”, “poor growth rates”, or “poor fleeces” as the main signs in their lambs.
Worm burdens can interact with several other factors, such as decreased nutrient absorption, increased risk of fly strike (in sheep), and decreased immunity, to lead on to many more problems.
Worms can be a problem at any time of the year, but traditionally our freezing winters would kill them off and no life-stage would be able to overwinter on pasture.
Unfortunately, in recent years, we haven’t had prolonged cold spells, and last year we found that worm egg levels in faecal samples from lambs peaked in November and December.
Many farmers were caught out by this and, unfortunately, treating with de-worming products at that time of year has the added complication of meat withdrawal periods in lambs that are soon to be slaughtered.
The overwintering of worm eggs on pasture is also a major issue as this allows hatching as soon as we have a warm spell in the spring and this can affect young lambs before any immunity develops.
Because the clinical signs of worms can overlap with other diseases, we rarely prescribe worming products without doing worm egg counts.
These can be performed quickly, often while you wait, at the surgery, using 3g of faeces mixed from at least five different animals from the group.
The worm egg levels have to be above a certain level to warrant treatment as young animals require some exposure to develop immunity, and resistance to wormers is such a real issue.
We know there are farms in the practice area with worms that are resistant to all three of the traditional wormer groups.
It is important to maintain the action of the two newer groups of wormers (for sheep) for the future.
As well as worm egg counting to try reduce the development of resistance, we also advise tactics such as leaving 10 percent of the group – healthy-looking lambs are chosen – untreated each time, treating new arrivals whilst in quarantine, rotating which type of wormer is used, and monitoring trace element levels to try to prevent decreased immunity.
Over the last 11 years since I graduated, wormer use has decreased significantly, but we like to think that they have been used more effectively based on worm egg counts, rather than “my father always wormed lambs on June 1 so that’s what I always do”.
We now have much more knowledge about how resistance to wormers develops, but on many farms there’s still a long way to go in terms of keeping today’s lambs healthy without compromising future lambs’ health by harbouring resistant worms.
Alnorthumbria Vets is a mixed practice that treats all species of domestic animals, and a few wild ones.
Within the practice, the vets have developed special interests so there are separate teams of vets dedicated to the care of farm animals, horses and small animals, such as dogs, cats and other small pets.
There are nine centres across Northumberland, from Wooler in the north to Ponteland in the south.
There is ongoing investment in the training and development of vets, nurses and support staff, and the practice has been approved by the Royal College as a Veterinary Nurse Training Practice.