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June 2018 - Equine Skin Tumors

Pose your questions concerning equine skin tumors for expert, Dr. Elizabeth Carr from Michigan State University, during the month of June.

Click here to read this month's questions and answers.

Poor Performance

  1. My 10-year-old Quarter horse mare had a luxated or subluxated patella, which was put back by my veterinarian. She has been on stall rest for 3 months. She is using it a bit more although drags the leg from the side to underneath herself at times. Her leg is slightly turned out. Is there something more I could be doing for her? Exercises?

    (View Answer)

    It is likely that your horse has an upward fixation of the patella rather than a true luxation. If this occurred for the first time when she was ten, you should start with a detailed clinical workup to try and determine the cause. You say that she drags the leg, but it is unclear if she is lame. I would probably start with local anesthesia of all three joints associated with the stifle to see if that alters her gait. Radiographs and ultrasonography may be beneficial in determining if there is any injury to the patellar ligaments or the patella itself. If she is dragging the leg, I would also be concerned about possible meniscal or cruciate ligament damage in the stifle joint. Diagnostic imaging would be useful in assessing those structures as well. I would not recommend any treatment or exercise until a more accurate diagnosis is obtained.

    In cases of idiopathic upward fixation of the patella, local injection around the medial and middle patellar ligaments sometimes is helpful. There are also several surgical procedures aimed at shortening the ligament (or cutting it) that may alleviate that condition. If there is meniscal, cruciate ligament or patellar injury, there may be either surgical or medical treatment options: arthroscopy, shock wave therapy, platelet rich plasma, other joint injections. Again, however, you must try to get a more definitive diagnosis first. Brian MacNamara, DVM, MRCVS, New Bolton Center, University of Pennsylvania, College of Veterinary Medicine

  2. Our 7-year-old grey pony is suddenly uncontrollably itching, rubbing herself raw on her belly, girth area, sides, chest and spots on her face especially her jaw line. The horses have been on nightly turnout all summer and this is the first time she has had anything like this. The horses stand in a fly controlled barn under fans all day until dark and turned out until 9 o'clock the next morning. The other horses are fine. I have done nightly turnout in years past and never had a problem like this. They also get sprayed every day before going out at night and flax added to the diet. 

    (View Answer)

    From your description, it sounds as if your pony has developed a hypersensitivity to insect bites. It is unlikely related to the flax seed, although feed allergies occasionally occur. You might try some management changes to see if it can be controlled. A full fly sheet and mask plus liberal administration of an insect repellent may be effective. If not, you should schedule an examination with your veterinarian. He/she will be able to examine your pony to rule out other medical conditions. They may prescribe an antihistamine to control the reaction if they feel that insect bite hypersensitivity is the culprit. Alternatively, you could leave the pony in at night until the insect season is finished. Brian MacNamara, DVM, MRCVS, New Bolton Center, University of Pennsylvania, College of Veterinary Medicine

  3. My Arabian gelding, has suffered for years from internal heat in all 4 hooves, which has caused him to be short-strided and "ouchy". I can feel the heat with my hand, and he acts uncomfortable, but at least 3 vets have said it's not founder and that it's "normal". But it isn't. The horse is in pain. I feed him only timothy pellets and grass hay...and suspect I may have overfed him in the past. Do you have any idea what might be causing this heat? It is often located at the coronet, but can feel it radiating from inside the hoof. The heat is present in winter also. On bad days I give him a little bute.

    (View Answer)

    If your horse is "ouchy" on all four feet and you consistently feel heat emanating from the hoof, it is likely that something is amiss.

    Heat, along with pain, is usually a sign of inflammation. Inflammation is the body's way of reacting to an abnormal insult. Common causes of heat and pain in the foot include abscesses and laminitis (founder).

    It is unlikely, although not impossible, that your horse has abscesses in all four feet. 

    I recommend that you have a veterinarian perform a complete lameness workup. I am extremely suspicious of low grade laminitis, although there are other possibilities. Radiographs may be necessary to evaluate the foot completely. Sometimes there is little radiographic evidence of rotation or sinking in low grade chronic laminitis. You didn't mention how old your horse is, but testing for PPID may be indicated. Brian MacNamara, DVM, MRCVS, New Bolton Center, University of Pennsylvania, College of Veterinary Medicine

  4. If a horse has an active EPM infection and is not treated, what is the predicted outcome? Does the horse become progressively worse? After years without treatment, how mobile woud the horse be? I have a senior mare with long back, weak coupling, low neck (very downhill balance). For over ten years, she has exhibited occasional narcoleptic-like episodes, toe-dragging when she backs up, falling when cantering through sharp turns on lunge line or during turnout, and intermittent hind quarter lameness. All the above were reported to her vet as I observed them but a neurological deficit was not discussed nor a neurological exam done. The behavior was attributed to her conformation. After barn help reported to me recently that she fell in the aisle and in her stall, I requested a neuro exam. Unfortunately, I was ignorant about the procedure for a thorough exam at the time. I have since researched this and feel that the exam she received was superficial. Her past history was reviewed with the attending vet. He rated her neuro response "no more than a 1" out of 5. EPM ELISA test was run with results as follows: SAG1 = 16 SAG2 = 16 SAG6 = 64. The test was done by a lab that sells an EPM treatment. They recommended treating (with their product) anything over 4. I can find nothing about SAG5 and 6 except what is published on the company's web site and their Elisa test for SAG1 was found to have more false results than other test types in studies run by university researchers and others. That said, I question the reliability of the result as diagnostic for EPM. With the exception of the two falls a couple of months ago, in circumstances that I didn't witness, her gait and coordination deficits have been in existence for years. If this has been due to EPM, should she not have become much worse?

    (View Answer)

    Equine Protozoal Myelitis is a difficult disease to diagnose and treat. None of the diagnostic tests are 100% informative. Usually, spinal fluid analysis is required to maximize the chance of an accurate diagnosis. Oftentimes, veterinarians will recommend treatment based on clinical signs and monitor response to treatment to determine if the horse actually has EPM.

    Progression of the disease can be very variable. Untreated horses may stay relatively asymptomatic for years and then suddenly show signs if stressed (surgery, fever, episode of colic, long ship, etc.) .

    Oftentimes they will spontaneously improve without treatment after the stressor is removed. Other horses will deteriorate rapidly, sometimes to recumbency.

    A thorough neurological exam, preferably by a trained equine neurologist, is recommended to obtain a correct diagnosis. There are other neurologic conditions with very similar symptoms. Laboratory testing and radiographs are often helpful in making a definitive diagnosis. It is always preferable to have a definitive diagnosis before instituting treatment whenever possible. Sometimes, however, a definitive answer is not obtainable and in those instances initiating treatment and monitoring response is not unreasonable. Brian MacNamara, DVM, MRCVS, New Bolton Center, University of Pennsylvania, College of Veterinary Medicine

  5. My horse has been recovering for the last three years from a partially torn suspensory, colic surgery and ulcers. He now looks the best he ever has in three years and it’s time to get him in shape again. His past career he was used as a reiner, but switched to Cowboy Dressage three years ago. I have started walking and a little trotting, but I can’t seem to get him to walk out other than a pokey little walk. He will also trot a little. I've had his hocks injected about one month ago and two months ago he had Osphos. I don't know if he’s being lazy or something else could be wrong?

    (View Answer)

    From what you describe, you should start with a comprehensive physical and lameness exam by your first opinion practitioner. His reluctance to walk energetically may be due to one of his prior medical conditions or an entirely new problem. Without a detailed examination it would be impossible to determine if the condition you describe is attributable to a medical problem or laziness.

    As a very general observation, it would seem unlikely, though not impossible, that a three year old, resolved suspensory desmitis would affect his ability to walk. You don't mention if the suspensory ligament disease was a in a forelimb or hindlimb, but unless he is still very active, any lameness would most likely be seen at the trot. 

    Prior colic surgery could possibly be implicated if there are significant adhesions in the abdomen. There would be a slight possibility that an adhesion could be causing pain when he moves. It would be helpful to know how he moves when not under tack.

    Although pain or lameness from multiple locations could potentially cause signs as you describe, I would pay particular attention to the forefeet and back as these areas are often implicated in horses with similar complaints, especially if it only occurs when ridden.

    You mention that his hocks were injected and he was treated with Osphos. If your primary practitioner diagnosed an arthritic condition warranting intra articular therapy of the hock and he did not respond to treatment in that location, it would be wise to confirm the diagnosis with intra articular local anesthesia. If the biphosphonate Osphos was administered to treat lesions in the navicular bone, digital nerve blocks should be attempted to confirm this as a source of lameness.

    The bottom line, however, is that you must start with a complete examination by your veterinarian to determine if the problem is physical. Brian MacNamara, DVM, MRCVS, New Bolton Center, University of Pennsylvania, College of Veterinary Medicine

  6. I have an 8-year-old Quarter horse gelding on trial. The pre-purchase vet check discovered a rounded coffin bone and the lameness test on the right front leg was as 1 on a scale of 5. The horse has been always been barefoot and is new to jumping. Would shoeing help his foot or is there a bigger problem on the horizon? 

    (View Answer)

    Your question raises a few issues with regard to pre-purchase examinations and lameness evaluation. 

    First, I will assume that the "rounding" of the coffin bone (third phalanx) is present in the right forelimb, the one on which the horse exhibits lameness. Second, I am also assuming that "rounding" refers to some form of modelling of P3 that is significantly different from the left forelimb. Now, it needs to be determined if the changes in the right forelimb coffin bone are, in fact, the cause of the lameness. You didn't mention if the horse responded to a hoof test examination, which might indicate if the foot is painful. 

    The general purpose of a pre-purchase examination is to determine the horse's condition at that specific point in time. It is not meant to be diagnostic or predictive. In order to diagnose the cause of the lameness, further examination will be required: diagnostic nerve blocks, additional imaging (radiographs, ultrasound, MRI, scintigraphy, etc. ) may be required. Until an accurate diagnosis is made, it is impossible to give any meaningful advice as to the long term soundness of the horse. This can be an involved, and often frustrating, process that is well beyond the scope of a pre-purchase examination. Usually it becomes incumbent upon the seller and his or her veterinarian to diagnose the cause of the lameness. You can always go back and see the horse again in a few weeks after a diagnosis is obtained and whatever corrective measures are initiated. Brian MacNamara, DVM, MRCVS, New Bolton Center, University of Pennsylvania, College of Veterinary Medicine