Limping - Pano

Help! My dog is limping!

Panosteitis & HOD

by Patricia Long and Lisa Allen, Molly Bass, Laurie Brandt, Sue Brightman, Cathy Burlile, Kathryn Butterfield-Davis, Sue Clawson, Toni Davies, Sue German, Melissa (Green) Zebley, Ruth Reynolds, Wanda Tait, Bob Torstenson, S.F.V. Edited by Dr. Kathy Berge, DVM

Limping can be caused by several problems associated with bones and bone growth. The most common is panosteitis or "pano." This is also referred to as growing pains and wandering leg lameness. Pano is characterized by shifting leg lameness; one leg will heal, then another may be affected. There are no long-term ill-effects from pano.

Pano is associated with large breed dogs and usually occurs in dogs 5 to 12 months of age, although it has been found in dogs as old as 5 years. It most commonly affects males by a ratio of 4:1. Females are most often affected around their first heat. It is possible that the condition is partially genetic since so many German Shepherd Dogs are prone to it. However, many other factors have been associated with pano: diet, viral diseases, autoimmune problems, hyperestrogen, and vascular problems. In other words, no one knows what causes it.

Pano is a process in which the fatty marrow inside the long bones degenerates and is replaced by bone cells. As the blood flow inside the bone becomes congested, the tissue covering the inside of the bone (endosteum) and the tissue covering the outside of the bone (periosteum) can also become involved. Eventually the new bone cells are resorbed, and the marrow is restored. This buildup of bone cells can sometimes be seen as darker patches on the bone in a radiograph. Once a bone has been affected, it is unlikely to be affected again - but remember, each leg has 3 long bones.

The dog normally limps on the affected limb and only rarely holds the limb to prevent any weight from being placed on it. It is often easily diagnosed with an x-ray; the lesion shows as the tell-tale dark patch on the bone. Pressure applied on the bone elicits a pain response. Currently, treatment consists of reduction of the percentage of protein in the dog's diet and pain management through the use of buffered aspirin, Ascriptin, or Rimadyl, or steroids in severe cases. Restricting the dog's activity has not been shown to have an effect on the healing process.

Like many problems, pano may be difficult to diagnose. The dark patches may not appear on the x-rays. The lameness may not shift to another leg. It can be extremely frustrating with many bouts of radiographs. Assuming that the limping is caused by pano can help delay diagnosis of other more severe problems. Never assume that limping is caused by pano without having it properly diagnosed.

The best thing that an owner of a growing pup can do is to choose a high quality dog food, or a carefully planned natural diet, which does not have too much calcium, nor too high a percentage of protein. Recent studies show that the balance of calcium and phosphorus is the most important dietary consideration for a growing puppy followed closely by the amounts of protein and fat. Most breeders recommend a maximum of 26% protein and others like to see the pup switched to an adult formula by the age of 4 months. Diet may be the single most important aspect of puppy development (especially when coupled with exercise) under an owner's control. Listen carefully to your breeder's recommendations, they usually know what suits their lines best.

The on-line Berner-L has a wealth of experience with panosteitis.

Laurie Brandt's Crusader was treated with aspirin and Adequan injections to help increase the fluid in the joints. His protein intake was reduced to 14% until he was 2 years old, after which it was increased to 20%. He responded well to the treatment. [Ed Note: Adequan is used for joint problems, and its use for pano seems questionable.]

Melissa Green's Aylen went lame in one leg at 10 months. One vet took radiographs and diagnosed an injured cruciate ligament. A second vet, a board certified radiologist using the same radiographs, diagnosed pano. The lameness went away in a little over a week. Over the next several months Aylen would occasionally go lame in another leg, and then recover in a little over a week.

Molly Bass advises vitamin C supplements, which many list members recommend for growing puppies. There is no scientific evidence to show that this will help, but there are a great deal of experiences to show that it may indeed benefit the joints [Ed. Note: see Steve Dudley's post in digest 131 on vitamin C, although I'm not sure it would help specifically with pano, which is not a joint disease]. Molly advises list members who have dogs with pano to reduce protein and fat intake by switching to an adult food, reduce all exercise to a minimum, give vitamin C or Ester-C - 1000 mg/day, and give Ascriptin 1x - 3x daily for pain.

Sue German's Strykker was troubled with pano and the only thing that helped him was steroids. Codi received Ascriptin and rubdowns with Absorbine liniment, which was palliative at best. But when Garth had pano, Sue used a formula from Marina Zacharias for 2 months that worked very well. The formula contained boneset, blue vervain, comfrey, fenugreek, goldenseal, nettle, mullein, rose hip, and sarsaparilla. Sue says that what's really interesting is that Star, so far, has had no symptoms of pano and she's been on the BARF diet since Sue got her. She also has been growing steadily with no big growth spurts like the boys.

Toni Davies had an 11.5 month old female with pano.

Sue Clawson suggested that crating an affected dog has not been seen to help. She advised Ascriptin as being easier on the dog's stomach than buffered aspirin. Sue hasn't seen any cases of pano in her dogs since she switched to Sensible Choice Large & Giant Breed Puppy food, which is 36% protein, low fat, and a precise balance of calcium and phosphorus.

Bob Torstenson's Sasha was examined for the possibility of OCD. That was ruled out, and pano was tentatively diagnosed. Since it was already getting better, it was decided not to subject her to x-rays. It was all right about the time of her first heat cycle.

Pat Long told of a young German Shepherd Dog with severe back leg lameness which looked like a horrible case of hip dysplasia. It was diagnosed as pano and within 4 months all signs of problems vanished.

Wanda Tait's Brigitte was initially diagnosed with HOD. Devastated, Wanda took Brigitte for a second opinion. Pano was conclusively diagnosed and treatment consisted of rest, reduced plane of nutrition, and an aspirin every other day. Brigitte is still happily bounding along.

Kathryn Butterfield-Davis switched a 3 month old litter of Lab puppies from Nature's Recipe Puppy to a Lamb, Rice & Potato (LR&P) adult dog food. Six of the 10 pups whose owners kept them on the LR&P kibble developed almost debilitating pano. Two of the owners overexercised their pups and the pups could hardly get up. All the puppy owners who had their pups on the LR&P food were told to switch to a quality Lamb & Rice only dog food. Within a day, the pups vastly improved. Kathryn suspects that the LR&P contains parts of the potato with the alkaloid solanine, which aggravates arthritis. Kathryn also felt that, since this was an incredibly fast-growing litter and with so many affected puppies, genetics probably played a large role in the development of pano.

Lisa Allen posted a summary from Canine Orthopedics by Robert Brooks, DVM, M.S. He defines pano as a spontaneous, self-limiting inflammatory disease of the long bones that commonly appears in young, fast-growing dogs. Prognosis is excellent, but lameness may shift to other limbs and be intermittent for several months. He lists contributory causes: transient vascular abnormalities, allergies, metabolic disorders, stress, autoimmune reactions following viral or bacterial infections, first estrus in females, and it has been associated with von Willebrand's disease.

S.F.V.'s 2 year old Simca was recently diagnosed with pano. The limping is sporadic and is triggered by exercise. The vet's recommended treatment is aspirin or Rimadyl.

Ruth Reynolds had pups in 2 litters that experienced symptoms of shifting leg lameness. When she switched their food from a 26% chicken-based protein to a 25% turkey-based protein, and supplemented with vitamin C (1000 mg/day) the problems abated within 2-3 days. One of the pups underwent 3 weeks of steroid treatment before Ruth was notified. Once the dietary change was made, it took about 3 weeks for the pup to recover.

HOD, or hypertrophic osteodystrophy, is another of the growth related problems. It is an inflammation of the growth plates, which is the knobby section at the end of the bones. It is characterized by lameness, "walking on egg shells," and can be accompanied by depression, weight loss, and fever. The joints may be swollen and feel hot. It occurs most often in young (2 to 8 months of age) large breed dogs, and occurs equally in both males and females. It usually appears on x-rays as soft tissue swelling in the area of the growth plates.

There is no known cause and, like almost all of the growth-related bone problems, diet is thought to play a part. It has not been shown to be genetic but heredity cannot be ruled out.

There is no known treatment other than pain management. Ascriptin or buffered aspirin is usually prescribed. Mild cases usually resolve with no lasting ill effects. However, in the rare case of severe HOD, permanent damage to the bone joints can result in limb deformities.

Experience with HOD on the berner list is thankfully limited. Cathy Burlile posted a discussion of HOD from Dr. Fred S. Jacobs DVM (CA, USA) in which he recommended an aggressive treatment with diminishing doses of cortisone-type drugs in order to avoid the limb deformities caused by the severe cases. He also uses a drug called Dyprone to help reduce any fever. Sue Brightman posted a summary of the October 1995 Alpenhorn article by Elena Smith in which a similar course of bed rest and diminishing doses of prednisone are recommended for treatment.

References: Small Animal Orthopedics, Marvin L. Olmstead, Mosby 1995. Veterinary Medical Terminology, Dawn E. Christenson, W. B. Saunders 1997. The Merck Veterinary Manual, 7th Ed, Merck & Co. 1991. Saunders Manual of Small Animal Practice, W. B. Saunders 1994.

The Berner List, http://www.berner.org, digests number: 112, 124, 133, 160, 167, 280, 282, 285, 305, 359, 554, 655, 682, 704