Ask Horse Journal: 06/03

Injection-Site Abscess
My horse received her spring check-up/shots, and for the first time I had the vet give the intranasal strangles vaccine. Since she sometimes gets reactions, we give her injections in the chest or rump instead of the neck.

At the same time, the vet treated a cut on her front leg with an antibiotic flush and put her on penicillin twice a day for five days, as he wanted to make sure the leg wound didn’t get infected. I began the penicillin shots with her neck, rump, and then the chest.

The next day after her chest injection, the left side of her chest swelled, and she had a fever of 101.5. The vet said she probably got a reaction or an abscess was developing. After several days the swelling pretty much was gone, and then about two weeks later the barn called to let me know her chest was severely swollen. The vet said she had an abscess.

He instructed me to soak it twice a day with hot Epson-salts water, and apply icthammol. Two weeks later the abscess came to a head. During this time she ran a fever, as high as 103.5. She was on antibiotics and bute for 10 days. Most of the chest was hard as a rock, and the abscess head area was the size of a baseball and soft.

The vet lanced it, and instructed me to irrigate with iodine and water, continuing the icthammol on the area away from the incision. The swelling is gone, but there’s still a lump under the skin, and every several days I massage her chest and push out some pus. The vet wants to wait to see what happens instead of cutting into her chest. This is fine with me, as she’s eating and moving fairly normally. I ride her (per the vet’s instructions) on the trail at a walk each day. She is also turned out daily.

Can I do anything to heal this more quickly’ I’m happy with my vet, but I’d like to be able to do anything extra to speed things along.

-Sally Gorman

It sounds like you are doing everything right already. An abscess is the body’s way of dealing with a foreign invader — either an infectious organism or sliver of wood, piece of dead tissue, etc. — and keeping it from gaining access to the rest of the body. The abscess reaction involves a thick wall of tissue around the area where the problem is located, like a wall of scar tissue, which then either seals around it into a “ball” if the problem is already internal or begins to thicken and tighten on all sides while pushing the material in the center toward the skin.

An abscess is one time where you really don’t want to interfere with the inflammatory process. The inflammation keeps blood coming to the area and stimulates the abscess wall. Inflammatory enzymes inside the abscess keep the contents liquified and ease the way through the tissues to the skin. The walking also helps with any excessive edema in the area and encourages movement of the contents toward the skin.

The only risk at this point is that since there is still pus in the area you don’t want the opening at skin level to close down prematurely. This can happen if the wall of the abscess begins to close around it 360 degrees. Be sure your vet knows you’re still getting pus. Keep an eye on the size of the lump. If the opening closes down significantly and the lump or any heat in the area increases, let your vet know. He may want to open it up a little more and may tell you to resume either flushing or the hot Epsom salt packs.


White Hair
I have a 20-year-old buckskin and the only way you can see his age is because of the white hair in his face. Is there anything I can do about it’

-Claudia Szidat
New York

Short of dying it — which we don’t recommend! — probably not. Many horses develop white/gray hairs as a normal consequence of aging, just like people do. There are also many horses that have white mixed through their coat in various locations from an early age so it is not necessarily making your horse look old to other people. There are cases where copper supplementation seems to help eliminate white hairs mixed through the coat, but it’s unlikely to be copper-related if only restricted to his face.


My horse has developed anhidrosis. He won’t sweat. He has to be hosed down daily. He’s on electrolytes, but they don’t seem to help. He’s otherwise healthy, although he likes to eat his salt block. What can I do’

-Name Withheld

Anhidrosis — a horse’s inability to sweat — is a mystifying ailment whose cause is unknown. It’s most common in hot, humid conditions, but it can occur anywhere. For many horses, it disappears during the cooler months of the year. One veteran Florida racetrack vet has been quoted as saying the best cure is October 15.

A further mystifying study shows that up to 25% of horses in training under these southern, hot/humid conditions were anhidrotic to a degree, but only 15% of nonpregnant mares and only 4% of 217 pregnant mares. Of 401 weanlings to two-year-olds, only 2% were anhidrotic. Stallions (much smaller sample size, 18) were similar to nonpregnant mares at 11%. There is almost certainly a hormonal and/or stress component here, although exactly what no one knows.

Microscopic examination of the sweat glands from anhidrotic horses shows they are atrophied/inactive. Electrolyte supplementation usually doesn’t resolve anhidrosis. Some anhidrotic horses are hypothyroid but far from all. Sweat glands do have thyroid hormone receptors on them so either a problem with low thyroid hormones, or with the thyroid hormone receptors, could be involved too. The major factor controlling sweating though is the sympathetic nervous system and the neurotransmitters epinephrine and norepinephrine.

A product called One AC is reported to work for many anhidrotic horses. The developer’s theory is that the ingredients support production of the neurotransmitter, dopamine, which is involved in transmission of sympathetic (epinephrine, norepinephrine) nerve impulses.

The tyrosine in One AC is the precursor of dopamine but is also the precursor of thyroid hormones or could be working directly through the adrenal glands, since tyrosine is also the precursor of epinephrine and norepinephrine, the sympathetic nervous system transmitters that mediate sweating, which are manufactured by the adrenals. Both vitamin C and tyrosine are present in high concentrations in the adrenals, while vitamin B12 and folate are needed for the synthesis of epi/norepi.

The mixture of Chinese adaptogenic herbs in the product APF (Advanced Protection Formula) has helped in some cases of anhidrosis. It was developed to help protect against the adverse effects of stress and to assist in adapting to stress.


Suspensory Strain
My husband’s four-year-old strong, healthy and stout Morgan gelding sustained a strain to a suspensory ligament on a foreleg.

The injury occurred about two weeks ago. We had gone for a two-hour ride, and the horse was fine. The next morning he was quite lame. The lameness gradually disappeared within three days. Some swelling remains at the fetlock, which we bandage. Aside from slight short striding, there is no lameness now.

The veterinarian wants him off work for two to three weeks. I don’t want to rush him back into service too quickly and risk re-injury. Do you recommend any particular boot to help prevent such injury in the future’

-Sharon Lambert

From your description of your horse’s build and his level of conditioning, it sounds to us like this was an injury roughly the equivalent of an accidental human ankle twisting rather than anything related to poor conformation, excessive speed, or poor conditioning for the work level. We don’t think boots are likely to be able to prevent something like this.

We agree with your veterinarian that you absolutely must allow sufficient time for healing to occur. Ligaments heal slowly. If he’s showing any soreness at all, he shouldn’t be worked. Even after he appears to be comfortable, the lesion may not be completely healed. A diagnostic ultrasound is your best guide to the location and severity of the problem, as well as level of healing.

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