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Ticks and your horse

Ticks are small, blood sucking parasites of mammals. This can include horses, dogs, cats and humans. They are increasingly common in the UK. The three most common species of tick are: Ixodes ricinus (sheep or deer tick); Ixodes hexagonus (hedgehog tick); Dermacentor reticulatus (marsh tick). Ticks vary in colour from red-brown to black. Before feeding they are small (<0.5mm) but once engorged, they have a larger, rounded shape.

This article was written by a FirstVet vet

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Tick activity and risk periods

Ticks cannot jump or fly, but crawl onboard to take a blood meal when a host passes by. Once they have fed, they detach from the host and drop to the ground to lay eggs or moult. Ticks are most prevalent in rural areas of woodland, grassland and moorland, such as, the Highlands of Scotland, Exmoor, the Lake District and the New Forest. The highest number of ticks can be found in areas with high livestock density, including water troughs, feeding areas and around trees.

Ticks are more active from April to November but they can remain active in temperatures as low as 3.5 degrees celsius. Therefore, although tick bites are most common from Spring to Autumn, it is important to take a precautionary preventative approach all year round.

Tick bites themselves rarely cause a problem. In very large numbers they may cause anaemia or challenge the immune system, but this is very unlikely in horses. However, ticks can transmit a variety of potentially dangerous diseases, including Lyme Disease, Babesiosis, Anaplasmosis, Bartonellosis, Q-fever and Louping ill virus.


Lyme Disease

Lyme Disease is a tick-borne infection caused by the bacterium Borrelia burgdorferi. It is a serious chronic inflammatory disease that affects many body systems. Humans and other animals, including horses, can be affected by Lyme Disease. The vast majority of ticks will not transmit the disease. However, it cannot pass from one infected animal to another without the help of ticks. Lyme Disease is a growing concern and owners should be aware of the dangers that ticks can pose and remove them quickly to minimise the risks. Infection typically occurs after the tick has been attached to the horse for around 24 hours.


Signs of a tick bite (days to weeks)

  • An infection around the tick bite area (80% of cases)
  • Further skin infections, remote from the tick bite site

Signs of Lyme’s disease (weeks to months)

  • Most infected horses do not show obvious clinical signs
  • Lameness: sore joints lead to a stiff gait and/or recurrent lameness affecting different legs
  • Lethargy
  • Low-grade fever
  • Hypersensitivity and muscle tenderness
  • Neurological dysfunction
  • Inflammation in the eyes


Diagnosis of Lyme Disease

Diagnosis in horses is difficult because lameness, caused by other musculoskeletal injuries, is common. In addition, subclinical exposure is common, so a positive blood test result only indicates exposure to Borrelia burgdorferi, and does not confirm an active infection.


How to help prevent tick bites and associated diseases in your horse

  • If possible, avoid taking your horse to areas where there are high populations of ticks, particularly during peak tick activity in the Spring and Autumn.
  • A licensed vaccine for Lyme Disease is not available in horses in the UK.
  • Therefore, tick control is a very important component of management: use insecticides and tick repellents for your horse, and, if necessary, environment/pasture management.
  • Consider having tick predators, such as chickens, to help you manage the tick population.
  • If you find a tick on your horse, use a tick fork to remove it. Tick Twister have a useful video to demonstrate how to use their tick fork. When a tick bites, it inserts its mouth parts through the skin by twisting, therefore a tick must be twisted out of the skin to remove it safely.
  • DO NOT apply Vaseline, chemicals, or freeze/burn a tick, as this will stimulate it to regurgitate it’s saliva and stomach contents, increasing the risk of infection.
  • Please note - once removed, ticks should be killed (not by crushing) or sent in a crush-proof container to Public Health England for identification. This information is used to identify potential tick-borne diseases that may pass to animals or humans. A submission form can be found here.
  • Lyme Disease UK has handy tips for protecting yourself and your pets from contracting the illness.


Treatment of tick bites and Lyme Disease

If your horse is bitten by a tick, or a tick is dislodged by accident and the mouth parts remain in the skin, the area should be monitored closely for signs of infection. A localised skin reaction may occur, which can take several weeks to fully resolve.

As a bacterial infection, the treatment for Lyme Disease is an intensive and prolonged course of antibiotics. Kidney function is closely monitored before, during and after treatment. Sometimes, despite the appropriate tests being performed, a definitive diagnosis of Lyme Disease cannot be made and your vet may recommend treating your horse presumptively. Unfortunately, despite apparently successful treatment, clinical signs may recur.


When to see your physical veterinarian

  • If you notice any of the clinical signs of Lyme Disease above.

Please note that any human health concerns should be addressed by your GP.


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