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Recently in the Horse health Category

Feeding a Laminitic Horse

Diets of horses with a history of laminitis (founder) should be kept to less than 12% non-structural carbohydrates.

What treats are ok for horses?

Q: I recently received a gift of two horses, a Percheron and a Quarter Horse. These two horses grew up eating anything, including banana and potato peels, even if they've started to decay. The original owner continues to bring these "treats" over for the horses. The horses are in good health, but are overweight. Is this good for them?

A: I'd suggest your neighbor bring more typical horse treats to the horses, such as apples, carrots, or manufactured horse treats. Anything novel or not normally found in the horses diet can cause problems. If the food is slightly decayed, the possibility of the horses ingesting mold or a mycotoxin is real and could be deadly, even in small amounts.

Equally important, the risk of laminitis and other metabolic issues is greater in over-weight horses (especially the breeds you have), so for the health of the horses, the treats should be eliminated. Once your horses weight is reduced, the treats, if given in small quantities, could be reintroduced.

If the well-intended original owner understands the risk, hopefully they'll be willing to bring different treats or stop all together.

By Krishona Martinson, PhD, University of Minnesota

Can I give rain barrel water to my horses?

Q: Rain barrels are commonly used to collect rainfall for use in watering ornamentals. What are your thoughts and concerns about using gutters and downspouts to catch rainwater in stock tanks with the goal of watering horses?

A: It is not recommend to use rain barrel water for human or pet consumption, or even for watering root crops and vegetables that will be consumed. There are potential issues with runoff from rooftops in terms of safe drinking water.

Atmospheric deposition of fine metals and particulates can be carried into roof runoff and possibly concentrated in the rain barrel water, as can petro-chemicals from shingles. New roofs can be especially prone to releasing particulates and chemicals into runoff, particularly when there hasn't been much rainfall for a while and the sun has been heating the rooftop.

In a setting where there may be birds roosting or resting on the rooftop, you can also get significant amounts of bird droppings in the runoff, and that can contain salmonella and other bacteria that can be potentially pathogenic (disease-causing).

By Barb Liukkonen, Water Resources Center, University of Minnesota

Is it safe to vaccinate my mare for strangles?

Q: My 22 year old mare had strangles two and a half years ago. I am wondering if it is safe to vaccinate her for strangles now.

A: Since your mare had strangles relatively recently, I would recommend having her antibody levels tested to see if they are still high. If they are 1,600 or higher, vaccination is unnecessary and use of vaccine could trigger an episode of purpura hemorrhagica.

Without testing, there is no way for sure to say if vaccination will be safe. Your veterinarian will be able to evaluate the antibody levels with a single blood test.

By Christie Ward, DVM, PhD, University of Minnesota

What is the ideal water temperature in winter?

Q: What is the ideal water temperature during the winter months?

A: Most adult horses weighing 1,000 pounds require a minimum of 10 to 12 gallons of water each day for their basic physiological needs. During winter months, water should be kept between 45 to 65°F to maximize consumption.

Waterers should be cleaned regularly, and clean, fresh water should always be available. If using a tank heater to warm water, inspect it carefully for worn wires or other damage, and check the water for electrical sensations or shocks. Snow or ice is not an adequate water source for horses.

By Marcia Hathaway, PhD, University of Minnesota

Can horses get diseases from deer?

Q: Do you know if horses can get any diseases from deer? With the amount of snow we had this winter, the deer are eating hay out of the round bale feeder.

A: Unlike cattle and bison, which can contract tumberculoss (TB) from deer, horses seem to be less susceptible. I have never personally seen a case of TB in a horse in approximately 20 years as a practicing veterinarian. The risk exists, but is very low. There have been extremely rare reports of meningeal worm (Paralaphostrongylus tenuis); a parasite in deer feces that can migrate into the central nervous system of animals grazing contaminated pastures. Meningeal worm is a significant problem for sheep, goats, and camelids, but horses are minimally susceptible.

Some horse owners do prefer to fence the deer out of hay piles, which is basically impossible to do at a round bale feeder, unless horse access is also restricted. If the deer herd is large, fencing can reduce the economic impact of hay loss associate with deer feeding, which is likely of greater concern.

By Christie Ward, DVM, PhD, University of Minnesota

Q: I want to get a second opinion but I don't want to make my veterinarian mad. Is this a good idea? How do I do it without hurting her feelings? My veterinarian is good at what she does but my horse has lots of issues.

A: Sometimes we all have gut feelings that indicate we are missing something. We probably need to listen to this voice; it is often recognizing subtle clues that we can't consciously identify. A second opinion is almost always a good idea in veterinary medicine as in human medicine. A fresh look or a new perspective often gives an answer or leads in a new direction that can solve the problem.

Most referral centers will ask if you want them to talk to your regular veterinarian or not, it is up to you. You can elect a middle ground where your veterinarian gets the information even if they did not know you were going to a specialist.

Ideally, however, your veterinarian is included and on board with the plan as that will enable the best care for your horse. You might try, "I have a feeling we are missing something and would like to expand our team. Do you have a recommendation for a specialist in this area?" If you meet reluctance, tell her how it impacts you, "I don't think I will sleep well until I pursue this and would like to do this with you as I trust you to help me sort out any conflicting advice and make sure I have all the medical history correct".

With your veterinarian involved, the horse benefits from the knowledge of his regular veterinarian along with the additional knowledge of the specialist, both before and after the appointment.

By Erin Malone, DVM, University of Minnesota

Q: I have two clients whose horses are having liver problems. Some of the light colored horses also have signs of sunburn. Their pastures are filled with alsike clover. Is the alsike clover causing this?

A: Clovers (i.e. red, alsike, and white clover) are usually considered a beneficial pasture forage. However, alsike (and other clovers) is considered toxic when infected with the mold Cymodothea trilolii that causes Black Blotch disease in clovers and legumes (i.e. alfalfa). When mold infected clovers are ingested by horses, photosensitivity (sunburn) and liver damage can occur.

To determine if your clover has Black Blotch disease, go to the lowest, wettest area of the pasture, and look at the underside of the leaves on the lower 6 inches of the clover. Look for black or brown "blotches"; like a felt tipped marker was blotted on to the leaves. Look for this on all clover species in the pasture.

If you find the "blotches", rotate the horses off the pasture to a shaded area to reduce the exposure to sun and potential sunburn, mow the pasture or cut it for hay; the mold can not live on dried hay. After the pasture has had a chance to regrow and dry out, you can begin grazing again.

There is research being done on rabbits in Canada demonstrating that alsike clover not infected with mold did not cause toxicity, whereas alsike clover infected with the mold did. However, this research has not been done with horses. In our experience, mold infected clover has been present in pastures of horses with photosensitivity, and we have not seen photosensitive horses in pastures of clover or alfalfa uninfected with the mold.

Because clovers tend to grow in thick bunches that promote moisture retention (most molds thrive in humid conditions), if the problems persist, you may want to consider reducing or eliminating the clover from your pasture. Broadleaf herbicides (i.e. 2-4,D) will moderately control clovers and could be used to thin stands. All herbicides do have grazing restrictions so it's important to read the herbicide label and follow all directions. Fertilizing a grass/clover pasture with nitrogen will also help the grasses better compete with the clovers. Grasses need "applied" nitrogen while legumes (i.e. clovers and alfalfa) can fix it from the environment. Not fertilizing a grass-legume mixed pasture will heavily favor the legume species and over time, the legumes will become the dominant species in the pasture. Mowing and other practices to increase air flow to the pasture should also be done to reduce the amount of moisture retained in the thick stands of clover.

By M. Murphy, DVM, PhD; and K. Martinson, PhD; University of Minnesota

Do mayflies carry Potomac horse fever (PHF)?

Q: There have been reported cases of Potomac Horse Fever (PHF) in my area (Isanti, MN). A local horse owner told me that mayflies are the vectors and that dead mayflies can still carry the disease. Is this true? Any information about PHF would be helpful.

A: Potomac horse fever (PHF), caused by Neorickettsia risticii, has been frequently diagnosed in case clusters in horses near waterways during the summer. The disease has been association with several vectors (hosts) including flukes living in water snails and aquatic insects including caddisflies, mayflies, damselflies, dragonflies, and stoneflies. The disease also appears to be carried in bats, birds and amphibians.

Clinical signs observed in horses with PHF include fever, anorexia (not eating), colic, depression, ileus (non-motile gastrointestinal tract), diarrhea, and laminitis (founder). Clinical signs and severity vary, but common to all cases is the manifestation of colitis (inflammation of the bowel). Clinical signs of the disease have been experimentally produced in horses 10-14 days after ingesting caddisflies.

In 2005, an outbreak of PHF was confirmed in Winona, MN and was linked to numerous dead mayflies that were positive for PHF. Horses are thought to accidentally ingest infected flukes from snails or infected insects while drinking and grazing, or from foraging or living in areas with high amounts of dead insect hosts. PHF cannot be spread horse to horse.

There is a killed vaccine for PHF, which may reduce the severity of illness but will not fully prevent infection. A veterinarian can perform tests on feces or blood to confirm PHF and most cases will respond to specific antibiotics and fluid therapy, however, some horses have died or have been euthanizes due to severe laminitis. The best treatment is prevention: reduce the contact your horse has with insect vectors by turning off lights in the evening that attract insects, turning off lights over outside water tanks, and removing dead insects from the barn. In MN, PHF is most often seen in isolated cases, but case clusters of PHF can occur given the wide distribution of rivers, lakes and ponds. Horse owners should ask their veterinarian about the frequency of PHF in their area to determine if the PHF vaccine is warranted. If so, the vaccine should be given in the late spring, and in high risk areas, boostered in late summer.

By Julia Wilson, DVM, University of Minnesota

Why is my thoroughbred collapsing?

Q: I have an off the track thoroughbred who collapses periodically. I have had him since November and he has gone down twice in the cross ties and once by the mounting block. He is 8 years old and approximately 17 hands. I recreated the situation and discovered that if I tighten the girth he goes down. He has not done this with me riding him. I do not think this is behavioral. I am just looking for directions and answers.

A: Some horses develop this odd form of collapse when they elevate their heads or when the girth is tightened without it being a specific medical issue. Sometimes muscle soreness is involved. The collapse could also be a result of sore withers, ribs fractured, or fainting from cardiac issues. I would recommend a complete physical for the horse. During the physical, I would also recommend you tightening the girth while the veterinarian watches to see if there are other areas that need exploration.

By Stephanie Valberg, DVM, PhD, University of Minnesota

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