Practice tips for the retriever patient (Proceedings)

In any dog there can be times when an activity stresses the dog's metabolic processes to extremes. There are two types of patients in these cases. One is the underconditioned dog participating in activity in an environment that it is not conditioned to handle. The other is the conditioned dog that engages in an activity that it is not prepared to handle. Examples of these cases include overheating, hypoglycemia, and exertional rhabdomyolysis.

Overheating is also called hyperthermia, heat prostration, and heat stroke. There is an inability of the body to regulate its temperature. The heat produced by the body is greater than the body's heat dissipation. The causes of hyperthermia include lack of conditioning, lack of acclimatization, high humidity, high temperature, too much exercise too soon, obesity, and previous overheating episodes. The clinical signs of overheating are panting, extreme hyperventilation, hypersalivation, altered mentation (glassy eyed), ataxia, muscle weakness, vomiting, diarrhea, weakness and collapse. All of the body's systems can be damaged. Other problems associated with hyperthermia are disseminated intravascular coagulation (DIC), adult respiratory distress syndrome (ARDS) severe electrolyte abnormalities. Basically the internal tissues can be cooked.

Overheating in the field is a scary situation, and time is of the essence. It is best to educate the clients that have athletic or working dogs on how to handle dogs with hyperthermia. They must understand that the most important thing to do is to get to the veterinarian. The longer the body is exposed to high temperatures the more damage is done. Too many dogs have suffered brain damage or have died because of futile attempts to treat in the field. The cause of death wasn't the initial heat exhaustion itself, but the secondary damage to the kidneys resulting in kidney failure. In a lot of these cases the dog would have been much better served if the top priority had been to initiate the trip to the veterinarian. The cooling down treatments could have been performed during the trip to the veterinarian and therapy could have been provided at an earlier stage of the emergency. Immediate treatment for this condition is a cool water bath or spray, ice applied to the abdomen, and/or blow a vehicle air conditioner or fan on the dog's body. Cool the body to around 103 degrees and the stop. If cooling measures are continued after this, the body's temperature will continue to drop. This will result in a hypothermic state.

Once the veterinarian receives the case, start to cool the dog down, insert an intravenous (IV) catheter and begin to determine the dog's status. Corticosteroids (dexamethasone) given IV at a shock dose of 1 mg per pound have shown to be of benefit in most cases. It is important to monitor the kidney function of the dog. It is common for a dog to recover from the hyperthermic event and then succumb to kidney failure.

Some dogs have a metabolic abnormality that is exposed by exercise or performance anticipation. There are two scenarios associated with these problems. One scenario is where a dog has a medical condition that is caused by exercise. The other scenario is where a dog has a sub-clinical metabolic issue that will be exhibited when the dog exercises. Clinically it is important to define which is relevant because the treatment and prognosis is vastly different for the two different issues.

Medical conditions caused by exercise are now starting to be identified. It is not clear if we are now just starting to identify problems that have been there fro a long time or if these conditions are now starting to appear because the work level of dogs has recently started to increase. Currently the most common example of an exercise induced medical problem is in Labrador Retrievers. Exercise induced collapse (EIC) is a condition in certain Labrador retrievers where after about 5-15 minutes of exercise these dogs start to loose control of their rear limbs. Some of the dogs will progress to the point that their body will totally collapse. There have been instances where the dog will get so bad that death is the end result. In most cases, if the handler stops the work at the first sign of an episode and then rests the dog for 10 – 15 minutes, the dog will return to normal. At this time there is no definitive treatment for this condition. It is very important that the veterinary clinician rule out other medical conditions before actually diagnosing a Labrador Retriever with this problem because it has recently been shown that other medical conditions that can be treated will exhibit clinical signs similar to EIC. Two other conditions that have been reported to occur on a rare occasion are exercise induced seizures and phosphofructokinase deficiency.

Many exercise-related problems can be linked to a subclinical medical problem. The clinical issue is not exhibited when the dog isn't exercising. When metabolic stress is introduced in the form of work or competition the metabolic problem becomes evident. In these cases the only way to diagnose the problem is to perform a performance workup. A performance workup includes data and blood samples taken at three different times related to inactivity and activity. When the problem is associated with a certain activity samples are taken in relation to the activity. Set up a time where the dog can perform the specific activity. Twenty-four hours prior to initiating the activity the resting physiological parameters are taken and fasting blood samples are drawn. A complete-blood count (CBC) and a blood chemistry are performed on the blood samples. Creatine kinase, cortisol and Insulin values should also be analyzed. The next day the dog is taken to location of the activity and is introduced to the activity. Once the dog is excited and is anticipating performing the activity the Pre-activity samples are taken. The dog is allowed to perform the task for a period of time that allows the body to be affected by the work but not long enough to elicit the pathological response. The activity is stopped and the post-activity samples are taken. The affects of event-anticipation and work can then can assessed. Many times the subclinical problem will be exposed and treatment can be initiated accordingly.

For the clinician, exercise induced medical problems can very challenging and rewarding to work up and diagnose. Usually once the correct diagnose is made the treatment will resolve the issue. The trick is finding a way to make the correct diagnosis. It makes managing these cases much easier.