I joined MSD animal health to facilitate a recent webinar on all things ticks and milk drop in dairy herds.
They had two expert speakers on the webinar.
My view on ticks is they are increasingly causing issues on farms. They are vectors for disease, meaning they can potentially spread disease.
It’s not just animals as many people will be aware that ticks can spread diseases to people as well. Lyme’s disease is a tick-borne disease that many people would have heard being discussed in the last number of years;
Tick-borne diseases can be tricky to diagnose and with a limited number of products to control ticks available.
With Tick-borne diseases, it can be difficult sometimes to make a diagnosis on clinical signs alone. Both speakers advocated the need for diagnostics when working up any potential issues where ticks were suspected.
We must also not underestimate the impact of ticks causing immunosuppression in our herds.
The main tick-borne diseases discussed were
Tick-Borne fever (Anaplasmosis)
The first speaker was vet Tom Strydam who is a global expert in tick-borne diseases in livestock
For me some of the key take away points were
- There are three stages in the tick lifecycle, nymph, larvae, and adult. The main tick in Ireland affecting cattle is Ixodes Ricinus.
- The adult female can lay 2000 eggs
- All stages of these ticks can potentially spread diseases like Redwater
- The tick can be active from early March until November. They like moist shaded conditions and don’t like dry hot weather.
- Where you have red and fallow deer on a farm your risk of tick-borne diseases may be higher
- When temperatures hit 7-10 degrees Celsius ticks can become active
- A Recent Irish study showed <1.0% of ticks infected with Babesiosis and up to 23% of ticks infected with anaplasmosis (TBF)
- Redwater causes fever (>40 degrees Celsius), blood loss, reddened urine, diarrhea, and jaundice. Animals may start with a pipe steam diarrhea but can become constipated as the disease progresses. Many of these clinical cases will require blood transfusions.
- Redwater has a mortality rate of about 10% in infected animals.
- Animals can develop resistance to the infection, with animals under 1 year of age showing minimal symptoms
- To have the disease you will need infected ticks on the farm.
- We want to have exposure for all young stock before one year of age so immunity develops to babesiosis.
- Naive animals older than a year are most at risk from Redwater.
- In Ireland, the licensed treatment is Imidocarb which has a withdrawal of 213 days for meat and 21 days for milk
- He also spoke about Tick-borne fever or anaplasmosis, which can show mild symptoms in herds with fever, milk drop, and weakness. Some of these animals may present with mild respiratory symptoms also
- He gave a useful tip when applying ectoparasiticides or pour on. He said apply dose on either side of the spine in cattle. So split the recommended dose and apply it to both sides of the back. Half the dose on either side of the spine. Also, apply a small amount (couple of mls) of product to the tail swish (end of the tail) to allow the spread by the swishing of the tail.
The next speaker was vet John Gilmore from farmlabs in Co Roscommon he spoke about Tick-borne fever and milk drop.
- The key point was to never make assumptions about disease and tick-borne diseases
- The tick-borne disease may contribute to immunosuppression and other disease issues
- He gave an example of one of his clients in his vet practice. They had tick-borne fever TBF which caused lots of other issues because of the immunosuppression in the herd.
- His lab run a milk drop screening profile looking at a number of diseases that may be contributing to milk drop
- TBF (tick borne fever) can cause milk drop, fever, respiratory symptoms, and lower leg swelling oedema
- It may cause abortion also and has a higher prevalence in younger animals like heifers
- They currently carry out a unique test for the organism using PCR. This tests for the DNA of the organism and is very accurate.
- Animals will be positive for at least three weeks after infection with TBF
- 20% of samples tested for TBF are positive in the lab, indicating there is a widespread prevalence in herds potentially. He said it is a disease that must be considered in milk drop along with the other common infectious agents.
- Grazing management is important in tick management. Get younger animals exposed early in their lives. Avoid rough grazing and use electric fences to keep cattle away from ditches (more likely tick habitats)
- Risk when buying in any stock who has no exposure to ticks previously. Farms with ticks should look to rear their own replacements
- Q fever is another tick-borne disease but john said we need more research into its role on the impact of fertility on Irish farms. They have not yet found the organism on any aborted samples sent into the labs. We need more research on the prevalence and the role of this disease in Irish herds.
- He referenced a 2010 study which looked at bulk milk antibodies for Q fever that found 38% of bulk samples tested were positive and on serum (blood) the prevalence was under 2%
- He also said that TBF can also be involved in cases of milk drop where other viral and bacterial respiratory diseases are isolated
- The big issues in milk drop with infectious diseases are still common viruses, bacteria, and parasites.
- With respiratory disease in cows, for fresh cases, it can be useful to carry out nasal swabs. This allows for more strategic vaccination once a diagnosis is made.
- We can test blood also for antibodies to viruses and bacteria.
- Where you see milk drop don’t make assumptions and investigate with your vet
- Tick-borne fever is one of the most common tick-borne diseases and may be underdiagnosed with milk drop
- From now on lungworm becomes a very strong differential in herds with milk drop
This is just a short summary of some of the key points I noted during the meeting. For more information on diagnostic testing work with your own vet on what test and when?
Happy safe farming