The use of MSM as a veterinary medicine-particularly for horses, cats and dogs-is vital and longstanding. There are hundreds of case reports detailing the use of MSM in treating canine arthritis alone. In this chapter, we will share veterinary cases that have been shared with us, cases that have been reported in the veterinary literature and in United States patents on MSM, and some cases that were collected by the late John W. Metcalf, DVM. Most of the cases presented here were not published in peer-reviewed journals. Some appear only in the private letters of Dr. Metcalf or in the MSM Patents. We recognize the inherent limitations in this type of reporting and welcome publication of controlled clinical trials in peer-reviewed veterinary journals. In the meantime, however, these are the most instructive cases available to us. From 1983 until his retirement, Dr. Metcalf, an expert on lameness in horses, used MSM in his practice with impressive results. He found that MSM provided often dramatic resolution of various causes of lameness, including bicipital bursitis, laminitis, myositis, suspected back pain not involving the spinal cord, peptic ulcers, diarrhea problems in young foals, and epiphysitis. Dr. Metcalf even reported stimulation of reproductive capacity in geriatric mares. Published research in veterinary journals suggests several pharmacological uses of MSM, including moderating allergic reactions from pollens; moderating gastrointestinal tract upset from many causes, including diet and oral drugs; and improving absorption of other nutrients affected by pain and inflammation.

CANINE ARTHRITIS

 After noting desirable benefits of MSM on himself, Dr. Metcalf tried MSM with his 11-year-old black Labrador retriever. She had severe arthritis, particularly involving the hips, and had been maintained on 400 mg of phenylbutazone per day. Her condition has been so sever, she frequently required help getting to her feet. Dr. Metcalf started adding a heaping teaspoon (6 to 7 grams BID) of MSM to her food and discontinued the phenylbutazone. For about a month, there appeared to be no benefit. Then she gradually improved, and eventually got to her feet regularly without help. A similar protocol was applied to four other dogs with similar histories. The consensus of their owners was that MSM ‘turned back the clock” on all five animals to their healthy state of three to four years prior to treatment. MSM was evaluated as an additive to the diet of older dogs of various breeds, each suffering from some form of arthritis and in some cases demonstrating other disorders. In all cases, MSM was mixed with the animal’s food immediately prior to feeding. In a similar case, a 15-year-old, spayed German shepherd, weighing 36 kg, demonstrated ataxia and virtual immobility with pain and joint stiffness. The

animal was not responsive to cortisone or phenylbutazone. She was given 0.5 grams of MSM, BID for seven days, without apparent benefit. The dosage was raised to S grams per day BID, and within 10 days the dog became freely mobile without evident discomfort or demonstrated ataxia. A male, black Labrador retriever, weighing 27 kg, demonstrated severe musculoskeletal compromise of the hindquarters with urinary incontinence. This animal, although owned by a veterinarian, had failed to respond to several therapeutic regimens over the previous 12 months. MSM was given to this dog in his food at a dose of 5 grams BID for one month. This dog derived no apparent benefit from MSM. A 14-year-old spayed German shepherd demonstrated severe arthritis of the back and legs. The dog was mobile but walked with obvious difficulty and discomfort. The animal was refractory to both cortisone and phenylbutazone. MSM was provided in the diet at a level of 5 grams twice daily. There was gradual improvement in mobility over the first month. During the third month following MSM supplementation of the diet, the dog demonstrated neither musculoskeletal restriction nor discomfort. A female mixed-breed

terrier, weighing 20 kg, demonstrated severe restriction in mobility and obvious discomfort with movement. The animal had responded to neither cortisone nor phenylbutazone and her condition was deteriorating rapidly. MSM was included in the dog’s diet at 4 grams BID. After one week, the dog appeared to be free of pain. This dog received MSM for over six months and remained apparently healthy and frisky, requiring no medication.

 HIP DYSPLASIA

 This case was related by DF of Colorado. A large, male German shepherd dog, approximately 8 years old, had always been exceptionally active and “up.” However, he gradually developed hip dysplasia, and his pain became evident by the antalgic carriage of his hindquarters. He ceased grooming his hindquarters and would snap at anyone attempting to touch him there. He lost his ability to jump in and out of vehicles and was reticent to walk or run any more than necessary.

His caregivers began giving him 1-2 teaspoons (5 to 10 grams) of MSM mixed with his food on a daily basis. Within just a few days, he showed improvement. After approximately three weeks of treatment, the changes in the dog’s behavior and attitude were dramatic. He was reportedly bouncing and frolicking ‘like a puppy” and clearly experienced relief. Nevertheless, the problem was not completely eliminated; the dog has good and bad days, but his caregivers are convinced that MSM clearly benefited him, and manifestations of his hip dysplasia are notably less severe.

POOR HOOF HEALTH IN HORSES

 In a report from a veterinary clinic in England, the authors identify a link between poor hoof health and non-grazing or stabling among horses and attribute the connection to a lack of naturally occurring MSM in lush pastureland. Horses and foals, when stabled and fed processed, low-protein, or milk replacer feedstuffs, are most liable to be sulfur-deficient. The authors stated: “Results have been quite revealing to the expressed delight of owners, farriers and ourselves alike. MSM visibly demonstrated rapid resolution in both hoof quality and growth.

This reversal to normality was manifest not only from within the coronary band (i.e., the growth

center for the hoof) but also showed a dramatic improvement in quality within the hoof wall closer to the bearing surface (i.e., where the shoe is fitted}. The reason for this latter curious and unprecedented finding is unknown. One suggestion is that MSM somehow increases moisturization in the hoof wall. “Taking into account all of the few dozen, and often on-going, cases where MSM feed supplementation has been applied, we have found (almost} without failure that MSM evokes effective hoof resolution. This was brought about far sooner than had been achieved, for example, in past experiences with biotin. Incidentally, at present biotin is the most utilized hoof growth supplement.” These authors reported that horses given daily doses of MSM returned to their sporting, riding, and shoeing activity quicker than the authors had imagined possible. They suggest that other minerals (e.g., zinc, calcium) can be administered concomitantly. Specifically, the authors recommend 2.5 to 10 grams of MSM per day in feed, which is approximately 5 to 10 times what they estimate the animal would obtain naturally from grazing in lush pastureland. A large 1,100-pound (500 kg} horse has an average MSM intake per feeding of 0.5 to 1.0 gram. The authors recommend preventive feeding of MSM to stabled horses and foals “against a fair chance of developing poor hooves later in life.”