Diseases #19
Hypertrophic Osteodystrophy is a debilitating disease seen most commonly in large breed, young dogs. It is characterized by a non-inflammatory bone growth or periosteal reaction in the metaphysis of long bones. It is seen commonly in Great Pyrenees, Great Danes and Newfoundlands.
In HOD, swelling and bone deposition cause widening of the metaphysis (This is sandwiched between the epiphyseal and diaphyseal part of the long bone). Periostitis may occur and this is extremely painful. The periosteum is the outer layer of the bone.
The most common sign seen associated with the disease is the development of bilateral lameness of the forelimbs with hot, painful swellings of the wrist joint. Dogs will usually run a high fever about 105.0F- 107.0F. They may have nausea, diarrhea and be dehydrated.
Radiographs of the affected joints are always taken. A CBC and Chemistry profile are performed to rule out systemic disease.
Diagnosis of HOD is made by historical findings plus the presentation of a young, large breed dog with bilateral lameness of the forelimbs with swellings around the wrist. Radiographs will confirm the diagnosis.
Many dogs may spontaneously clear or improve after several bouts of the condition. Any bone deformities will not correct on their own. Regardless, it is extremely painful. Most dogs are put on an appropriate dose of Rimadyl® a non-steroidal anti-inflammatory drug. If used frequently, the dogs liver enzymes need to be evaluated frequently. Some animals are put on antibiotics. It is crucial that the home environment be comfortable. A thick comfortable bed and protection from slippery tile or wood floors and stairs is recommended.
The prognosis for this disease varies with the individual and degree of inflammation and lameness that remains after the condition is resolved. Many animals get over it with only minor issues.
Idiopathic Thrombocytopenia (ITP) is a serious immune-mediated disease in the dog. It is caused by self produced auto antibodies against the bodies platelets. Platelets are needed in the coagulation process.
Platelets are crucial for primary hemostasis. They originate in the bone marrow from cells known as megakaryocytes. In the absence of platelets, severe internal bleeding can occur with skin bruising known as petequia or ecchymosis. Life can not continue without platelets. It is this lack of platelets that produce associated clinical signs.
Clinical signs associated with ITP are due to a decrease in active platelet numbers. Internal bleeding and signs can occur anywhere. Weakness & lethargy are commonly seen. Bleeding may be noticed in the oral cavity as well as blood passed in the feces. Animals bruise easily and that may be noticed over the animals body surface. Visible bleeding may also occur in the eyes.
A CBC and Chemistry profile are always performed. The platelet count is the most important piece of data. Normal dogs have a platelet count of about 225,000. Whenever that level reaches 20,000 bleeding will occur. Other conditions such as parasitic (babesiosis, heartworm and ehrlichiosis) can cause a secondary ITP. A tick born profile would than be recommended plus an occult heartworm test.
Diagnosis is made by the history and physical exam plus the presence of associated clinical signs. A diagnosis is confirmed by a platelet count of below 20,000.
Regardless of the cause of the ITP, almost all dogs will require a whole blood transfusion. This contains red cells and platelets. A low platelet count is life threatening. If the cause of the ITP is infectious, antibiotics will be given. If it is caused by a parasitic blood infection, the appropriate therapy is applied. If the ITP is immune-mediated, animals will be treated with corticosteroids and azothioprine. Other supportive measures such as intravenous fluids and feeding support are important.
Although ITP is a severe life threatening disease, the majority of dogs do well and lead normal happy lives. Those dogs that respond to therapy the quickest often have the best prognosis. The goal is to wean the animal off of all medications. In the case of infectious or parasitic causes, the platelet count should return to normal after appropriate primary treatment. Immune-mediated causes have a good prognosis also. An attempt is made to wean the animals off of corticosteroids and or azathioprine. Some dogs may relapse and require the same treatment. Prognosis for those animals is good as long as the owners are ultra vigilant about any changes in the dogs day to day life plus frequent medical visits for examination and multiple repeats of a CBC.
Inflammatory Bowel Disease (IBD) is often lumped into a host of different diseases. This presentation will attempt to put the issue into a more focal context. IBD is usually associated with an immune-mediated response to "something" in the body or digestive tract. That "something" might be a bacteria, virus, food allergy or parasite. The actual cause is unknown. It is a disease associated with the digestive system and is usually seen in middle to older dogs and cats.
IBD is a chronic disease process of the intestinal tract. The autoimmune reaction causes a thickening of the bowel mucosal tissues. This alters its absorptive and motility properties. This whole reaction is an intense local inflammatory response that disturbs the normal intestinal physiology. Clinical signs seen are all based on this precept.
The most common clinical signs noted are: the presence of loosely formed stools (even diarrhea), whole blood in the stool, associated weight loss and poor coat condition, fever, lethargy and tenesmus (straining to defecate).
A CBC and Chemistry profile are drawn to assess the animal's body wellness. An inflammatory response may be noted on the CBC plus albumin may be low due to the digestive losses of it and other proteins. Radiographs utilizing contrast media, such as barium, or an ultrasound may show a thickening of the intestine in question. Fecal exams are done to rule out intestinal parasites. On a laparotomy, a biopsy of the intestine may be required for a definitive diagnosis.
Diagnosis can many times be difficult because strict IBD can mimic many other disease processes or causes of intestinal upset. A diagnosis can be at least tentative by historical findings in a middle aged or older dog or cat, clinical signs and supporting blood work and radiographs. An intestinal biopsy would be diagnostic. Most people do not go that far so one can many times only suspect IBD and treat it.
Treatment of IBD rests on trying to treat the primary cause and provide supportive care. The goal of any therapy is to allow the animal to gain weight. The immune-mediated situation is usually taken care of by corticosteroids. Many patients also benefit from the oral administration of budesonide; a non-systemic glucocorticoid that acts locally without any negative side effects elsewhere. Dogs are also put on numerous types of broad spectrum antibiotics to take care of bacterial overload. Good possibilities are fenbendazole (Panacur®) and metronidazole (Flagyl®). Sulfasalazine is often used if the clinical signs are in the colon. Dietary changes may help. Chicken and rice diets or facsimile or a hypoallergenic diet may be tried if a food allergy is suspect by blood testing. Carafate may be given to coat and protect the intestinal mucosal surface. Animals that are dehydrated will require fluids.
The prognosis for most patients is good but IBD can not be cured but only controlled and it is highly likely that there will be relapses at times in both dogs and cats. Over time, an individual will respond better to one therapeutic regimen over another. If there is a relapse and glucocorticoids have already been used, azathioprine (Imuran®) should be attempted in the dog but NEVER in cats due to toxic metabolites produced in a cats liver. This is due to the lack of an enzyme named gluconyl transferase.
The inguinal area of the dog or cat is the groin area. An inguinal hernia is one where abdominal contents pass through the inguinal ring and canal and become entrapped. Inguinal hernias can be congenital or acquired.
1. Congenital: This type of hernia is one that the animal is born with where genetics play a role. The majority of these are seen in young animals being vaccinated or examined for the first time. Most can occur on one side or the other and contain omentum (abdominal fat). These are uncomplicated hernias.
2. Acquired: This type of hernia is produced by blunt trauma, pregnancy or obesity. Many of these are complicated. Regardless of the cause of the acquired hernia, intestinal loops, uterine horns and other viscera can be entrapped in the inguinal hernia. This is a life threatening problem.
In an uncomplicated inguinal hernia, the only clinical sign is a small protrusion or swelling in the groin area on one or both sides of the body. In a complicated inguinal hernia, fever, inflammation and a painful groin area, vomiting and anorexia are seen.
In all cases of inguinal hernias, radiographs are taken to figure out what is enclosed or entrapped in the hernia. Intestinal loops are gas containing and easy to see. Many cases of uterine horn displacement are in dogs along with their pregnancy and visibly seen. The issue is how long the organs have been displaced. Often that is not known so a complete CBC and Chemistry are done to assess general body condition. An ultrasound may also be performed.
Diagnosis is made by the presence of a soft, fluctuant swelling over the inguinal area in dogs or cats. Deciding whether it is uncomplicated or complicated is determined on lab work performed.
Treatment is always surgical. It can be approached several ways. In uncomplicated hernias, an incision is made over the hernia and the contents (usually omentum) are pushed back into the abdomen and the hernia is closed. In complicated cases, it may also require a caudal mid line abdominal incision to pull the intestinal loops and or uterine body out of the hernia. Tissue than is assessed for viability. Many times, the intestinal loops are twisted and blood supply is curtailed. These require a resection and anastomosis (putting back together). Regardless of the inguinal hernia contents, it is CRUCIAL that the caudal part (posterior) of the ring NOT BE CLOSED. This is where the femoral vessels pass through to the hindlimbs. Doing so, will choke off arterial and return blood flow from the hindlimb to the heart via the caudal vena cava.
The prognosis for the majority of inguinal hernia repairs is excellent. The more complicated ones where the animal is septic or extremely ill from distended intestinal loops or uterine horns, have a more guarded prognosis until the effects of surgery and antibiotic therapy take hold.
The spinal cord is a very protected piece of anatomy. Damage to it would impair normal body functioning. So that dogs and cats can have flexible movement of the spine there are spaces between the vertebrae that are filled with spongy cartilaginous material known as an intervertebral disk. If this disk degenerates over time or there is trauma that causes a protrusion of disk material away from its natural position (a disk hernia) clinical signs will develop.
In type 1, the actual outer layer of the disk can become extremely hard. Animals jump off of sofas and beds all the time. This force, over time, will allow the contents of the disk to prolapse onto the spinal cord.
In type 2, the entire disk becomes hard and as the animal ages it decomposes and prolapses into the spinal cord area.
In either case, this puts extreme pressure on the spinal nerve roots. Depending on where the prolapse occurs will determine the location and type of clinical signs seen. Disk disease is extremely common in Cocker Spaniels, Dachshunds, Miniature Schnauzers and Beagles. Obese animals are also more prone to disk disease than trim animals.
The most important clinical sign seen is excruciating pain over the spinal column in question and or nerve innervated areas. Animals may become lame or paralyzed if the disk protrusion is severe. There may be flaccid paralysis where the hindlimbs can not move and the musculature is limp or a spastic paralysis where the animal can not move in its hindquarters and the hindlegs are held in spastic extension under the animals abdomen.
In most animals there is referred pain. This is pain that is felt away from the site of the clinical lesion or trauma. An example would be an animal that has a lumbar disk protrusion. Just touching its abdomen will be excruciating painful.
Most animals will barely move. They try to position themselves so maximum weight is taken off of the injured disk area. They are incapable of getting into a comfortable sleeping position. Because they hurt so much, they will be off their food and many times find it too painful to get into a position to urinate or defectate. Dogs will also demonstrate kyphosis. This is an arching of the lumbar vertebrae that gives a hunched up look to the animal. I often showed a client a normal spine and than a radiograph of their pet showing the big difference in spinal curvature.
The most important thing to do is radiograph or ultrasound the animal. In some cases, the space between the verebrae is decreased suggesting a disk herniation. In other cases nothing is seen on a lateral or VD view. Specialists may perform a myelogram or MRI since the spinal cord can not be visualized on a straight radiograph.
A diagnosis is based on historical findings, neurologic exam, clinical signs and especially if the results of a myelogram are available. Breed association also is important to recognize.
The most important job to perform is alleviate the pressure of the herniated disk on the spinal nerve roots causing the clinical signs. The area must be decompressed rapidly otherwise permanent clinical signs such as lameness or paralysis will become permanent. In less severe cases this will mean medical management that includes the use of glucocorticoids that will decrease the inflammation over the spinal root area. In more severe cases, a laminectomy is surgically performed by a specialist that removes a part of the vertebral "roof" attempting to alleviate pressures. Sometimes, this does not work.
Regardless of treatment, it is crucial that obese animals lose weight or the animal can re-injure the area again, which is never good. Animals must be confined and not allowed to catch frisbees or other types of activity. Walks should be limited. If away from the home, animals should be confined in a room or put in a crate or cat carrier. If an animal wants to sit next to you on a sofa, do not pick the animal up by its elbows facing you!! This puts tremendous strain on the spine. Using both hands support the dogs chest and abdomen underneath and gently pick the animal up. Animals will often not eat because it hurts too much to get into an eating position (prehension). Always elevate food and water bowls with a stack of newspapers or books so the animal can walk up to the bowls without having to stoop down.
Animals that are completely paralyzed may have a satisfying life if fitted with a special mobile cart on wheels that is strapped to the animals body. I have used such devices and it is great to see an animal not think about going over a curb with the device on. A recommended supplier of carts and other support products is K9 Carts.
The prognosis for intervertebral disk disease is guarded in almost all cases. Yes, clinically they may do well after treatment and lose weight at the same time. However, no back or disk issue is ever 100% cured. It can cause disease again in the future. A big part of preventing re-injury is by following instructions written in the treatment block. Prognosis is also extremely guarded in those animals that are urinary or fecal incontinent. They will have to be supported to go outside to urinate or defecate.