IN THIS NEWSLETTER:
It's hard to believe that the year is half over - where has the time gone? Fall is just right around the corner, and many of you will be seeing the annual influx of hunting dogs being brought in to your hospital for their "annual trip to the vet". With that in mind, I thought this might be a good forum to introduce and discuss a topic that many of us are not familiar with, and certainly one which we were not taught about in school.
Limbertail is a poorly understood condition seen in many breeds of hunting dogs that is just now generating some interest in the academic environment to stimulate further research on it's etiology and treatment. Dr. Jan Steiss at Auburn, in conjunction with their Sports Medicine program, has initiated a research project aimed at characterizing the abnormalities involved in limbertail to help us gain a better understanding of this condition. Dr. Steiss is measuring serum enzyme levels and conducting nerve conduction tests as well as taking muscle biopsies from selected dogs to evaluate affected muscles.
Although limbertail is a term familiar to people who work with hunting dogs (i.e., owners, trainers, field trial participants), many veterinarians are not familiar with this syndrome. Typically, limbertail affects young adult Pointers whereby they temporarily lose control of their tail. A dog which would normally have an erect tail carriage when running or on point, now carries the tail much lower than normal and seems unable to lift the tail past the level of the dorsal midline. The tail commonly extends straight out from the level of the back for a variable distance (from three or four inches out to the mid-portion of the tail), then drops to point towards the ground. While this may not seem of earth-shattering importance to many of us, such a tail carriage effectively eliminates an affected animal from competition and is of major concern to owners and handlers who have a considerable amount of time and money invested in these athletes.
Like any type of lameness, limbertail probably has multiple etiologies. Many theories have been proposed, mostly by laymen associated with the field trial/training community based on personal observations and prejudices.
Dr. Steiss recently mailed out a questionnaire to 418 owners and trainers of hunting dogs and received 111 useable replies. Five breeds were identified as being most commonly affected: in descending order (1) English Pointer, (2) English Setter, (3) Brittany Spaniel, (4) Labrador retriever and , (5) German Short-Haired Pointers. From the survey, certain conditions seemed to be common among affected dogs. These described that limbertail seemed to occur primarily after a hard workout the previous day, or cold, wet weather the previous night, or cage transport. My conversations with handlers and trainers seem to correlate with this; additionally, two other items have been recurrently described to me. Dogs most commonly affected are those that are under-conditioned and then subjected to a strenuous workout, and housing of dogs in a barrel (a common housing method for hunting dogs). In the Labrador, it is often associated with hard workouts or very cold water.
Dr. Steiss' current work is focusing on a primary muscle problem. So far, no evidence has accumulated to suggest a neuropathy. Treatment at this time seems to be mainly symptomatic, with most affected dogs tending to recover within 2 weeks. Various treatments have been tried (expressing the anal glands, vitamin supplements, aspirin or other NSAID's, antibiotics and corticosteroids, as well as anabolic steroid injections). No one treatment has proven more efficacious than another. It seems that prevention is probably the best medicine at this stage, and counselling owners to get their dog in good physical condition before hunting season is probably the best recommendation we can make at this time. Proper housing of animals being transported should also help.
Dr. Steiss has asked our office to cooperate with her in identifying
and sampling affected dogs. If you have an owner with a dog affected with
limbertail who would like to be a part of this study, all tests are non-invasive
and simply require blood sampling within 24 - 48 hours after the onset
of limbertail. Please contact me at the office if you would like more information
With the start of our second year here in Tulsa, we thought that we would try a new method of getting some of the newer and more interesting information out to you which may not be widely known about. As of now, we anticipate sending out a newsletter on a quarterly basis, depending upon the response. If you enjoy this, please let us know. If it is a waste of your time, let us know also. We plan to make it brief and hopefully informative. I would also like to personally thank everyone for their support and encouragement over the last year.
Megacolon in cats is a condition characterized by dilatation of the colon and rectum with chronic inability to pass feces. Numerous studies have been done to try and define the etiology of the condition, but no definitive cause has been established. Some authors have tried to link the condition to a disease in humans known as Hirschsprung's disease, in which there is an abnormality involving absence or loss of ganglion cells in a segment of the colon, creating an immotile colonic region. This does not appear to be the case in the cat, and most cases are termed idiopathic megacolon. A mechanical obstruction of the pelvic canal can also produce chronic obstipation, and radiographs of the pelvis should be taken to diagnose and rule out old pelvic fractures.
A diagnosis of megacolon can be made by palpation of an enlarged colon, radiographs (with or without barium contrast) demonstrating dilatation of the colon with fecal material, and digital rectal examination to rule out rectal stricture or neoplasia.
Idiopathic megacolon is usually seen in middle aged to older cats, and initially the history is of tenesmus and difficulty passing stools. At this stage, oral cathartics, enemas, and manual evacuation of the feces is usually effective in temporarily removing the stool. Treatment in the early stages can include dietary management with high fiber diets, including bulk agents such as bran or methylcellulose, and laxatives such as docusate sodium (50 to 200 mg q 8 h). Osmotic agents such as lactulose can also be used to induce loose feces (1 cc/kg q 8h).
One of the newer treatment options we have available for cats with megacolon is a drug called cisapride (Propulsid). Cisapride is more effective than metoclopramide in increasing motility in the g.i. tract and does not cross the blood brain barrier (no CNS side effects). Although there is very little "hard" scientific data available as of yet on the efficacy of this drug, anecdotal response has been positive. The doses being used are from 0.5 - 5.0 mg/cat BID to TID. Note, these are total doses, NOT per kilogram dose. Some cats that initially respond to cisapride may eventually become refractory to the drug, even at doses as high as 7.5 mg/cat BID to TID.
In cats where cisapride is not effective, subtotal colectomy has been well-established as an effective method of treatment. Subtotal colectomy involves removal of the colon from just in front of the pelvic brim to the level of the ileocolic valve. If the colon is dilated throughout its length up to and involving the ileocolic region, this segment is removed and an ileocolonic/ileorectal anastomosis performed. If at all possible, it seems preferable to retain the ileocolic valve and perform a colocolonic or colorectal anastomosis. Clients need to be cautioned that the cat will experience loose stools postoperatively due to a decrease in water absorption. This usually improves as the small bowel "takes over" and adapts to the water absorptive function of the excised portion of the large bowel. This adaptation usually takes place over about six weeks. Complications with this procedure are not common, but can be severe, and good presurgical client communication is essential.
If you have questions about a case of megacolon in a cat, please do not hesitate to contact our office. Office hours are Monday through Friday, from 8:00 am to 5:00 pm.