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What is Tick Allergy?

As noted above, a bite from these blood-sucking parasites can carry diseases like Rocky Mountain spotted fever, additional forms of tick typhus, anaplasmosis and Lyme Disease to numerous species of mammals, including horses, dogs and humans.  In these species of mammals, these diseases can have devastating effects and even cause the death of the host. 

Tick allergy in horses is defined as the reaction which results from the bite of a blood-sucking parasitic insect commonly known as a tick. The tick bites are capable of carrying serious illnesses to its victims.

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Symptoms of Tick Allergy in Horses

There are various types of ticks which are known to attack horses in different areas of the country.  All types are blood-sucking organisms and are able to transmit some pretty serious diseases to their victims.  Here are some of the outward symptoms you may see:

  • Small raised lumps that are itchy
  • Lumps may appear abraded and oozy
  • Lumps and swollen areas appear across the skin of the horse, sometimes occurring gradually or can appear rapidly
  • Equine will become agitated 
  • Fever
  • Lower limb swelling
  • Depression
  • Reluctance to move
  • Occasional staggering
  • Decreased appetite


There are basically four categories of types of ticks, though within each category exists many other species of tick.  The four basic categories are:

  • Wood ticks
  • Dog ticks
  • Deer ticks
  • Spinose ear ticks

Ticks can be found across the United States in general, with some being partial to particular areas of the country.  Here is a list of types of ticks which are most commonly found and the diseases/conditions they are known to carry or cause:

  • American Dog Tick - Carries Piroplasmosis (Babesiosis), Spotted Fever, Tularemia
  • Brown Dog Tick - Carries Equine Granulocytic Anaplasmosis (Ehrlichiosis)
  • Deer (or Blacklegged) Tick - Carries Lyme Disease, Equine Granulocytic Anaplasmosis, Piroplasmosis
  • Gulf Coast Tick - Carries Heartwater, African Theileriosis
  • Lone Star Tick - Carries Lyme Disease, Spotted Fever, Equine Granulocytic Anaplasmosis
  • Pacific Coast Tick - Carries Colorado Tick Fever, Tick Paralysis
  • Rocky Mountain Wood Tick - Carries Rickettsia, Colorado Tick Fever, Tularemia, Tick Paralysis
  • Spinose Ear Tick - Causes significant irritation, rubbing and loss of hair
  • Tropical Horse Tick - Carries Piroplasmosis
  • Western Blacklegged Tick - Carries Lyme Disease, Equine Granulocytic Anaplasmosis
  • Winter (Moose) Tick - Responsible for emaciation and anemia

Causes of Tick Allergy in Horses

Ticks are basically large blood-sucking mites and, as such, have the dubious honor of being able to transmit an incredible number of infectious organisms to their victims.  In fact, in this particular arena, the tick is second only to the mosquitos in terms of infectious potential for public health risk as well as animal health risks.  Some of the organisms transmitted can infect humans without causing any problems with animals while others will wreak havoc on animals without potential harm to humans and still others which will be problematic to both. Ticks infect their victims in this way:

  • Tick bites and secretes toxins through its saliva
  • Transmitting infectious organisms into skin wounds which are open for secondary bacterial infection
  • Screwworm infestations
  • Some of these organisms lead to anemia and death of the victim

Of all of the above listed diseases known to be carried and transmitted by ticks, Equine Granulocytic Anaplasmosis is the most serious and the most commonly found in horses, with Lyme Disease coming in second.

Diagnosis of Tick Allergy in Horses

When you note any of the above symptoms, be sure to get your veterinary professional involved as soon as possible.  Also, when feeding and grooming your equine, if you suspect ticks, remove them in an appropriate manner and seek medical attention as soon as possible.  When your vet sees your horse, he will need your complete history which should include pasturing habits and frequency, feeding regimen, symptoms noted and the duration of those symptoms as well as the presence of ticks found on your horse.  

He will do a physical examination and will likely need some blood work and perhaps tissue samples for lab evaluation.  He will be looking at the CBC panel to show blood values reflective of any possible bacterial infection or other evidence of immune system involvement.  Often, a response to treatment (medications) is the best way to confirm diagnosis.  Once the vet has the blood work results which he has ordered, an appropriate treatment plan will be developed and initiated.

Treatment of Tick Allergy in Horses

Treatment for tick bites usually will begin with treatment of the symptoms and clinical signs found in the vet’s examination.  He will need to address things like fever, pain, and swelling with appropriate medical techniques.  Generally, the antibacterial medication of choice is oxytetracycline intravenously if possible, but the oral route is also an option (using doxycycline instead of oxytetracycline) though it is a little less effective.  The treatment regimen of antibiotic medications will likely require administration of the chosen drug for 1 to 2 weeks, depending on the horse’s condition and the medication/route opted. The symptoms and clinical signs for both Lyme Disease, the less often diagnosed tick-borne disease, and Equine Granulocytic Anaplasmosis, the more often diagnosed tick-borne disease, are similar to each other as well as many other maladies known to afflict horses, a definitive diagnosis may not be certain unless certain antibodies are found in the blood work.  

Regardless, many vets will treat with tetracycline or doxycycline if a bacterial infection is apparent (regardless of the source of the bacterial infection) and improvement will generally be noted in the afflicted animal.  Once the animal is treated for the bacterial infection, recommendations will likely be given for application of preparations which will reduce the opportunity for ticks to attach themselves to their victims, thereby providing another level of control and prevention.

Recovery of Tick Allergy in Horses

Not all ticks carry these diseases and not all horses will respond allergically to their bites.  That being said, an important thing to know is that, many times, the untreated horse who contracts these diseases from tick bites do resolve and get better in about 2 to 4 weeks and suffer no long term effects.  This is, by no means, a reason not to carefully examine your equine herd regularly for ticks and to appropriately remove them immediately when discovered.  Some horses are simply more sensitive to the toxins in the bites of ticks than others, with the Equine Granulocytic Anaplasmosis being the the disease to more often afflict horses.  

It is also important to remember that, while many of the diseases normally carried by ticks may not be problematic for the equine species, this is not necessarily the case for humans and other animal species also known to suffer from these diseases.  Ticks are a problem pretty much everywhere for everyone, man and beast, and we all need to be more aware of their presence and be proactive in prevention and protection measures for our animals and those humans we love.

Tick Allergy Questions and Advice from Veterinary Professionals

20 Years
Moderate condition
0 found helpful
Moderate condition

Has Symptoms


My 20 year old horse has a severe tick allergy. She gets a large lump and if you pick at it- it appears like a puncture wound would. My vet has examined her and said that due to her living in MN where we have ticks- there’s not much we can do. Anyone else have a horse with a sever tick allergy and something I can do to help her? She does not seem bothered by the bites or sore- they just look terrible to me!

I have a very sensitive skinned mare. I noticed a large bump under her hind leg last night, after further inspection noticed a tick in there. I pulled the tick out and noticed a puncture type hole, as you also noticed on yours. I cleaned it out well and let her be for the night. I checked her this AM and noticed it had seeped out a tiny bit of yellow and bloody gooky stuff from the hole. Also cleaned that out and cleaned the area, put some swat around the area to prevent the bugs from irritating it (fingers crossed) I had to get to work so we’ll see how it looks today when I get home. I have never had any of my guys have a reaction from a tick bite like this before so I’m hoping she heals herself!

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Maddison’s county ( maddie )
New forest
21 Years
Moderate condition
0 found helpful
Moderate condition

Has Symptoms

Hard swell
Hard swell and is lame

My horse as had a tick in its lower flank. we’ve removed the tick and she now has a hard swelling and is lame. Could you tell me what to do as I am unsure and worried about her.
Please get in touch ASAP.

Dr. Callum Turner, DVM
Dr. Callum Turner, DVM
3320 Recommendations
There may be an allergic reaction to the saliva from the tick or depending on your location it may be the start of a tick borne disease; you could try using an antihistamine, you should call your Veterinarian as they may be able to prescribe something instead of using over the counter medications if you have an existing patient doctor relationship. Regards Dr Callum Turner DVM

Does anyone have any info on hair loss after a tick bite please? Many thanks

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Mild condition
1 found helpful
Mild condition

Has Symptoms

Minor swelling
Hard flat swelling

Does swelling indicate infection/disease? Or is it simply an allergic reaction to the tick bite? My gelding had a tick on the underside of his neck and I didn't realize until I'd already gone over it a few times with my curry. I noticed something that felt lodged, and lifted up the hair to find legs. It was very small and white; I doubt it had been there long. I removed the tick and disinfected the area with iodine. He now had mottled-looking swelling around the area of the bite, but it is not much. Just enough to make me question it. He shows no other symptoms, other than being itchy, but je is always itchy under his neck along his throat, so thisbis not unusual.He rode beautifully, and has no outward symptoms other than the minor swelling. The swellings themselves are hard, and almost like when you scratch yourself and it swells up a bit.

Dr. Callum Turner, DVM
Dr. Callum Turner, DVM
3320 Recommendations
Swelling may be just due to an inflammatory response to the tick bite; however, I would call your Veterinarian to ask about tick borne diseases in your area as in some geographical locations tick may be the vector for some diseases which may infect horses so it is always best to be proactive as some of these diseases will have an incubation time before clinical symptoms present. Regards Dr Callum Turner DVM

Anyone gave any info on hair loss after a tick bite? Many thanks

My horse suffers from allergic reaction to tick bites every spring. Less reactive as the season progresses. He gets extremely itchy, hard, raised bumps that ooze a clear sticky liquid. He frequently gets bit between his back legs and on inner thighs. Occasionally right on his sheath which then fills with fluid, hot to the touch. I hose him down twice a day which seems to help, give him Benedryl twice daily and apply a topical to the bites (contains clay, zinc, charcoal and shea butter) which offers temporary relief. My aim is to keep the ticks from biting in the first place. Any suggestions?

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