January Newsletter 2023

placenta where an infected dam will almost inevitably infect
her unborn calf.
Reproductive losses are from reabsorption, abortion, stillbirth
and weak calves depending on the age of the affected foetus.
Many surveys have shown that most herds have at least one
positive animal and in some cases up to half the animals are
affected, although this is a worst case.
There are 2 main routes of infection
1. Infection of the unborn calf via its dam….most
common route of infection for a calf.
2. Cattle eating feed contaminated with infected dog
faeces.…less common route of infection but an
important mechanism for the introduction into the
herd.
Dogs are largely unaffected by the disease, remaining well
even when infected. They become infected through eating
raw meat or other infected material, maybe raw food waste or
cleansings from the calving yard. The infected dog may or may
not be yours. Many farms are crossed by public footpaths used
by dog walkers. The role of foxes is unknown and they may be
involved, no one is sure. The infected dog excretes infectious
oocytes for a period of time after infection until it becomes
immune. It then stops shedding. It is not known how many
times a dog can be infected but it is probably more than once.
Control of Neospora is easier than Johnes and involves only 3
main aspects:
1. Identify affected cows and don’t keep their heifer
calves for breeding. Previous heifer calves from
affected animals are probably affected and they also
should not be used to breed replacements for the
herd. Affected heifers often have some reproductive
problem.
2. Avoid dog faeces contaminating cattle feed.
3. Avoid dogs becoming infected by only feeding cooked
meat and avoiding scavenging of cleansings.
The good news is that cows rarely infect each other, even at
calving, apart from the dam to daughter infection within the
womb. A Neospora positive bull is no risk to the herd.
Again CHECS offers detailed disease control options.
Whilst the control of Neospora is much easier and the results
seen much more quickly than for Johnes, it still remains the
case that it is difficult to justify retaining a positive cow or
heifer for breeding purposes if the heifer calves are intended
to be kept for breeding themselves.
As with Johnes disease, Neospora infected animals produce
clean embryos. Again, Tyndale Vets are able to house these
infected animals and produce disease free embryos to return
to you to maintain and advance your herd genetics.
No bull works harder for the farmer, the plate and the planet 45