Diseases #30
Rocky Mountain Spotted Fever is one of the most common diseases in the United States transmitted by ticks. It is caused by an organism known as a rickettsia. This organism is a hybrid between a bacteria and a virus. It is rod shaped like a lot of bacteria but it reproduces only inside the cell; like all viruses. The causitive agent of Rocky Mountain Spotted Fever is Rickettsia rickettsii.
The rickettsial organism lives in the tick and is transmitted to dogs and people by the bite of an infected dog tick known as Dermacentor sp. Cats can get the disease but it is basically self limiting and rarely causes any clinical issues. The organism also can live in a carrier state in many wildlife.
Clinical signs of canine Rocky Mountain Spotted Fever are: fever, depression, anorexia, fluid accumulation in the limbs, bloody urine, ataxia amongst others. What makes it difficult to pick up is that these signs are seen in a multitude of diseases in dogs.
A basic CBC and Chemistry profile must be done plus a urinalysis when clinical signs are seen. Many dogs may see their white cell counts go up and down like a yoyo. A chemistry profile may show liver or kidney involvement with rise in their particular enzymes.
There are antibody tests that can diagnose the immune response to the organism. The usual course is to draw two blood samples about 2-3 weeks apart and compare antibody levels. In an active infection, the second antibody titer will be much higher. There are other tests where a skin lesion is biopsied and in the lab checked for the tick protein antigen present in the skin.
Since clinical signs mimic many other disease processes, the history is extremely important. If it is tick season, that is important. In many parts of the country, April through July are prime tick periods. In Florida ticks are present year round. If the animal is a hunting dog such as a Coonhound or Retriever, that is important! A little Yorkshire Terrier that is carried around all day by its owner has a much lower risk of getting the disease than a hunting dog! A tentative diagnosis can be made with historical findings and clinical signs. It can be confirmed by either the antigen or antibody tests specific for the rickettsial organism.
Doxycycline and Baytril® (enrofloxacin) are the two most commonly used drugs to treat the disease. Treatment must last for about 3 weeks. If the dog is anemic with low platelet levels, a whole blood transfusion and other hematinics may be administered. Treatment must begin as soon as possible. If left untreated or treatment is delayed, it is always fatal.
The prognosis for rapidly diagnosed and treated dogs is very good. The key is to prevent the infection in the first place. Owners should detick their pets and themselves to prevent infection. Ticks usually need to stay on the host for a minimal of 6 or so hours for the rickettsial organism to be transmitted to a dog or human. In late winter, all dogs should be put on an appropriate tick product. There are collars such as Preventic® and Seresto®. Topical products such as Frontline® are effective against ticks, amongst others. If ticks are an environmental concern in the home, a professional should be hired to rid the home of ticks. You will normally see them climbing the walls of the home in an infested house. Ticks reside in tall, thick grasses. Make sure your lawn is cut frequently and you avoid wooded areas during tick season.
Roundworms or ascarids are an extremely common intestinal parasite in dogs and cats; particularly the youngsters. In the dog, the culprits are: Toxascaris leonina and Toxocara canis. In the cat, the culprits are: Toxocara cati and Toxascaris leonina.
It is extremely easy for a young animal to pick up roundworms. The common way is the oral fecal route. Feces contaminated with the eggs are ingested by the pet. The life cycle starts anew. Many puppies or kittens are infected while still in utero. The small larvae penetrate the unborn animals and infect them. While nursing, they can also pick up the parasite. The larvae in the intestine not only forms eggs to be secreted in the stool but can also pass through the intestines to the lungs and be coughed up. These are than swallowed and the infection starts all over again.
Most puppies and kittens with roundworms will have an unkempt appearance about them. Their coat has lost its luster and they are smaller than normal for their age. A potbelly is noticed by its owners. Many puppies will regurgitate worms that are visible in the erupted contents. This usually freaks out most people. The worm may be also present in the stools. Medical offices get calls all the time from people that have seen roundworms in the vomitus or stool. If they look like spaghetti, they are roundworms!
Roundworms produce tons of eggs and are easily recognized by fecal flotation in any veterinary lab.
Diagnosis is made by a positive fecal floatation test showing characteristic roundworm eggs. Seeing them in the vomit or stool is also diagnostic.
The most common preparations used to treat roundworms are: pyrantel (Strongid-T®), fenbendazole (Panacur®) and Piperazine. The latter is often not used that much since it may not be as effective as the others.
The new topical flea and or heartworm products also take care of roundworms. Effective products are: milbemycin (Interceptor®), Ivermectin with pyrantel (Heart-Gard® Plus) and Selemectin (Revolution®)
Puppies and kittens should have multiple fecal exams during their early months of life. They should be treated as often as necessary and than placed on an appropriate topical or oral product containing antihelmintics.
Roundworm treatment has an excellent prognosis. Once animals are dewormed, they look so much better and gain tremendous amounts of weight.
Prevention is important. Canine bowel movements should be cleaned up from the yard and properly thrown away in the trash. Cat litter boxes should be emptied and sanitized frequently. Female animals that will be used for breeding should have a fecal sample examined by the veterinarian to make sure the breeding dog or cat is free of intestinal parasites. This insures she has the calories for fetal development and lactation plus the larvae will not be passed on to her unborn or new born infants.
All dogs should be kept away from beaches. The hookworm and roundworm larvae can be transmitted to humans. It penetrates the skin and causes pathology. Roundworms will cause visceral larval migrans and hookworms will cause cutaneous larval migrans. These are serious diseases in humans. Beach sand is like an incubator. The eggs hatch rapidly and the larvae can easily penetrate the skin while people are lying on the beach.
Sarcoptic Mange is a very common skin condition seen in companion animals. It is a zoonotic disease and can easily be transmitted from animals to humans. It causes an intense pruritus and is caused by the mite, Sarcoptes scabiei.
The mange mite lives and causes it damage in the hair follicle of the dog or cat. This causes an intense pruritus and hair loss in the animal; particularly around the face and forelimbs. It is transmitted from pet to pet by direct contact with an infested animal. Contaminated bedding will also cause sarcoptic mange if other animals or people come in contact with it.
The most common sign is an intense pruritus (itch). This can start over the forelimbs and head region but spread to other areas of the body. Localized hair loss and a crusty scale with pustules is common. In cases of long duration the skin will thicken and become hyperpigmented. MIte infestation causes the presence of many grooves where bacteria can hide. This often produces a secondary pyoderma (see above).
Deep skin scrapings will demonstrate the characteristic ovoid appearance of the mite under a microscope.
Diagnosis is made by historical findings plus associated clinical signs. A positive skin scraping for the mite is diagnostic. There are cases where the mite can not be found on multiple scrapings but highly suspected. Most of these are tentative diagnosis's and treated.
Treatment of the mite can be by the use of dips or topical mediations. A dip can be applied to the animal. The most common one is Mitaban® (amitraz). This dip is repeated every 2 weeks but must dry on the animal. It has a foul odor. Lime Sulfur dip has also been used on cats but it too has a very unpleasant odor. More modern treatment methods include many of the topical flea preparations available. Revolution® (selamectin), Interceptor® (milbemycin), Frontline® Plus (fipronil) and oral ivermectins have been used. The latter, is an off label use of the product.
If a secondary pyoderma is present, it is treated with an appropriate antibiotic such as Clavamox® or Baytril®. If there are other animals in the home with the diagnosed dog, they too should be treated. Any bedding should be treated with an insecticide and thoroughly cleaned and disinfected.
The prognosis for the treatment of acute sarcoptic mange is very good. Chronic cases or those that are difficult to eradicate receive a more guarded prognosis.
Prevention is important. Keep dogs and cats indoors and away from infested pets. Avoid any areas where animals are in close quarters such as dog parks. In those situations you have no clue what is brewing on someone elses pet. Stay away!
Although the disease is self limiting in people, any suspect lesions should be investigated by a physician.
Sebaceous cysts are small, common growths seen usually in older dogs. The cause is a clogging of a hair follicle or a sebaceous gland pore by bacteria, dirt, cellular debris or sebum.
Sebum is the oily substance produced by sebaceous glands that give the animals coat that beautiful luster. In excess production, sebum will clog the system resulting in the cyst. This may also lead to seborhea oleosa (next disease to the right). Whatever the cause, sebacous cysts usually do not bother the animal.
Sebaceous cysts rarely bother animals unless they rupture, crack in cold weather or drain. They can than irritate the pet. The animal responds by licking at the wound. This does not allow the cyst to heal.
A biopsy will give the cellular diagnosis of a sebaceous cyst.
A tentative diagnosis is made by the presence of small raised cysts on an animals body; usually in a middle aged animal and up. They may be found anywhere on an animals body.
Cysts will do one of three things over time:
1. They will just sit there with no change in appearance or size.
2. They can be absorbed into the body at anytime and be gone.
3. They can open up to the outside, drain, heal and slough off during normal epithelial turnover.
I usually recommend that these growths be left alone. An exception are those pets like Poodles that get groomed frequently. Groomers can easily run over these cysts with clippers; causing infections and skin irritations. They than should be dealt with when presented. If an animal will be under an anesthetic for a dental procedure, I will remove them at that time. Unless the lesions look cancerous, continue to drain or bother the animal putting a pet under an anesthetic or sedative is too great a risk for the removal of a sebaceous cyst. However, if the cyst is removed, under any circumstance, it should be sent to a pathologist for a pathological diagnosis.
The prognosis for sebaceous cysts is excellent. The problem is, is that if they are removed, more will pop up later in different parts of the body.
Seborrhea oleasa is a member of the Seborrhea Complex. It is caused by an excessive production of sebum. Sebum is the normal waxy material that gives the normal luster to a dog or cats hair coat. Seborrhea oleasa is commonly caused by:
1. Endocrine Diseases: Hypothyroidism and Cushing's Syndrome are common causes.
2. Bacterial: Bacterial pyodermas can lead to this condition.
3. Parasitic Mites: Demodectic and Sarcoptic mange can cause this problem.
4. Cancer: Many cutaneous neoplasias such as cutaneous lymphosarcoma can produce a secondary seborrhea oleosa.
5. Fungal/Yeast Infections: The big guy on the block here is Malassezia yeast. They frequently cause seborhhea oleosa.
Seborrhea oleosa is often seen together with Seborrhea sicca, a dry type of seborrhea.
In Seborrhea oleosa, excessive sebum is produced. This excessive sebum accumulates and clogs hair follicles. The dog or cat has a literal coat of sebum over its body. Sebum production is greatest along the flanks, ears and lumbar back area. This buildup causes the animal to scratch at itself. This produces dander, inflamed papules and other lesions. This irritation often sets up a bacterial pyoderma or yeast infection.
Pets will often have a foul odor about them. Sebum is an oil and oils can become rancid as they are broken down. Yeast infections can cause a sweet, foul odor to the skin. Bacteria can metabolize oils and produce oil metabolites. One of the chief complaints people made to me was that "horrible stinky odor that my dog has plus all the furniture stinks". I understood clients on that one. I often could diagnose the condition before I even walked into the exam room!
Many times there will be skin folds present; which are full of sebum with bacteria and or yeast. This is a huge problem in English Bulldogs and others with natural folds of skin over the body. There will also be present: raised papules, dander and general skin inflammation.
A CBC and Chemistry profile are always performed. Both of these tests will often lead the doctor to order further tests based on those results. Skin scrapings are always done to eliminate mites. Fungal cultures are done to rule out a dermatomycosis (including ringworm). ACTH Stimulation Tests are done if suspecting Cushing's Syndrome. T4 and FT4 are performed if suspecting hypothyroidism. Surgical biopsies may be done.
Diagnosis is made by a history obtained from the owner plus the presentation of clinical signs. The primary cause is figured out by concurrent lab work test results. A surgical biopsy may lead to a diagnosis or confirm one that was tentative.
Treatment is initially geared to treating the primary cause of the Seborrhea lesions. Yeast infections are treated with Ketoconazole. Bacterial pyodermas are treated with antibiotics such as Clavamox® or Baytril® for long periods of time. Endocrine disorders such as Cushing's Syndrome are treated with Lysodren® or Trilostane®. Hypothroidism is treated by oral T4 administration.
Pruritus is usually controlled by Atarax® (hydroxyzine). This is a prescription antihistamine that alleviates some of the clinical signs associated with itch. One has to be careful about using corticosteroids. They will provide relief but can suppress the animal's immune system making it much harder to treat a bacterial, fungal or yeast infection. Giving corticosteroids to a suspect Cushing's Syndrome patient can make the condition worse! If the patient is a diabetic, steroids will really throw off the blood glucose and play havoc with an insulin dose.
Topical shampoos are crucial in providing some relief from clinical signs plus return the skin to a more normal condition. Shampoos containing chlorhexidine and or combinations of chlorhexidine and ketoconazole are very effective, if used properly. Some of the best products for this purpose are made by Virbac®. The best shampoo interval is twice the first two weeks, than once weekly for months on end. Do not use warm water. Use cool tap water or water from an outdoor hose. Warm water will make the animal scratch even more! Repeating the shampooing will keep sebum production under control; as long as the primary disease condition is being treated.
If a cause of seborrhea can not be determined, the condition is treated with antibiotics, ketoconazole and shampoos. Oral cyclosporine (Atopica®) may help some of those patients.
The prognosis for seborrhea oleosa depends upon the primary cause of the medical condition. The prognosis for idiopathic seborrhea oleosa is more guarded since a cause can not be found. Supportive medical care will at least keep those conditions under control in most situations.