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Dr. Carl
Dr. Carl, Veterinarian
Category: Horse Veterinary
Satisfied Customers: 42
Experience:  Raised on horse breeding ranch; former farrier; Veterinary Pathologist
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why does my horse act lethargic and continue to lose weight

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why does my horse act lethargic and continue to lose weight whn I am feeding her a high fat diet?

Hi camelot,

Could be lots of reasons, can you please answer some questions for me?

How old is your mare?

What are you feeding her currently?

Does she get dewormed periodically?

Have her teeth ever been floated?

Is she in any pain? Lame?

How much weight has she lost?

Is she kept in a stall? Paddock? Pasture?

Do you ride her? Drive her? Run barrels? Foxhunt?

Could she be pregnant?

Is she kept with other mares and geldings or is she by herself?



Dr. Carl


Customer: replied 8 years ago.
She is a 7 1/2 years old pure arabian mare and has been a mother once. I am feeding her Purina Ultium (1) -12 oz jar and (2) M-G 12 - 8 Super horse Pellets twice a day. She was wormed in April and June 2009. Her teeth were floated in April, her feet are trimmed ( no shoes) becasue she is not trained to ride and she is current on all shots. She does not appear to be in pain but she walks slowing and doesn't run. She is not pregnant and is pastured with another mare and two minature donkeys. She stays aloof from them and I would estimate that she has lost 10 - 15 % of her weight since she arrived here last September.

OK, thanks,

I am going to make a few assumptions:

there is plenty of good grass for her to graze all day long


she is not being chased off by the other horses and donkeys and isn't the victim of being at the bottom of the "pecking order"


the other mare and donkeys are all doing well

please let me know if these assumptions are correct.


Is her slowing gait due to incoordination? or lack of energy?


Has your veterinarian run any diagnostic tests on her such as a cell count and serum chemisty panel?


What diseases are in your area that other horse owners are dealing with?

West nile?



Thanks for the info,





Customer: replied 8 years ago.
We are located in Central Texas which has been under severe drought conditions for the past month. She receives all the coastal hay she wants. The other animals are healthy; although the other horse is the Alpha and will bully her. I have recently put her in an adjoining pasture. Her gate and stiff walk seems to be due more to a lack of energy. We have no known case of West Nile (or other contagous diseases in this part of Texas) and she has received a vaccine shot for it. The mobile vet that was here in April, updated her shots and floated her teeth but did not do any diagnostic tests or bloodwork. He recommended increasing her fat intake and food quantity. We have an equine hospital within 25 miles; but, not having a horse trailer, I am trying to avoid that route. I can take her there if you feel that is the only option left.

Ok thanks for the additional information.

Has her weight loss occurred since the drought began?


Has she done any better since she has been seperated from the other horses?


You are currently giving her some pretty "hot" feed. Has she responded at all? Gained any weight on this mix? How long has she been on this hot feed mix?

Does she bolt her food down or take her time and pick at it?


What do her droppings look like? Nice, firm , bright green balls? Tannish brown and mushy? Dark brown to black and liquidy?



Customer: replied 8 years ago.
Her weight loss started last winter and has continued since. She has always taken a "long" time eating her grain and there has been no change since I put her on the hot food in April. Her dropping are bright green. I bathed her yesterday and I noticed hair coming off in my hand when i wiped the excess water off her. I looked up the clinical signs of EPM and she shows the muscle atrophy of the hind quarters, excessive sweating (although our temps have been over 100 degress for the past three weeks) and fatigue or narcolespy for extended periods.

If she has been on that hot feed since April and yet she is still losing weight than I certainly think you need to have her checked out more thoroughly. A 10-15% loss of body weight is pretty profound.

If EPM is a problem in central Texas than it certainly should be considered as a possibility, but there are many other causes for chronic weight loss. Diagnosing EPM can be difficult because the most available tests only tell you if the horse has been exposed to the disease, not if they are actually suffering from it. That being said, I think a serum test is warranted.

Internal parasites (worms) are extremely common; however, it sounds like you have a good and frequent deworming program so that is less likely.

Likewise, bad teeth that either hurt her mouth or do not allow her to chew and swallow her food effectively are a common problem, but it sounds like your mare's teeth were just checked and floated in April. Have them checked again when you can, just to be certain.

A chronic smoldering infection that is difficult to detect is a possibility, in which case a blood count may be helpful as would antibiotics.

Stomach ulcers are a possibility, and hot feed can be associated with them.

Cancer is always a possibility that has to be considered in chronic weight loss cases.

Nutritional deficiencies may also be an issue. Even though you are giving some pretty hot feed, certain vitamins, such as vitamin E, may be deficient or not present in enough quantity. Vitamin E deficiency is an antioxidant that offsets the damage caused by oxygen free radicals. Deficiency causes atrophy of certain types of muscle fibers (called Type I muscle fibers) and deficiency can result in muscle atrophy, weight loss, difficulty standing and even muscle twitching. Vitamin E supplements can be useful in treatment.

I know I just threw a whole lot of information at you but I want you to be well prepared for discussing your next move with your veterinarian. Because she has lost all that weight, I really think a more extensive work-up by your veterinarian is warrented. Please let me know if I have been helpful and also what you discover with your mare. I am really hoping it is something common and easily treated.

Dr. Carl

p.s. I have been around Arabians all my life, in particular Crabbet Arabians from the Indian Magic bloodline.

Customer: replied 8 years ago.
What do you think is causing the Hair loss when I bathed her yesterday? Is this a symptom of the same problem? Thanks, Jim.

Hi Jim,

I certainly think the hair loss could be related to the weight loss. Since she has lost 10-15% of her body weight, she must be looking a bit unkempt and unthrifty right now. Hair loss goes along with that. Whatever is dragging her down is probably also not allowing the nutrients she takes in for food to go towards her hair coat. If you lived in Montana and had had a severe winter where all the horses are "haired-out" with a nice shaggy coat, than the hair loss might be due to seasonal hair loss, but it sounds like you are dealing with something a bit different.

Oftentimes a high fever can end up manifensting itself as hair loss later on. If she has had a high fever in the recent past, this might be the only indicator.

Hormone imbalances also go along with hair-loss. A good work-up, to include a blood count and serum chemistry profile can help with figuring it out. Please keep me advised and abreast of how she's doing. Sincerely,


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