Veterinary Help

Hypothyroidism is caused by a decrease in production of thyroid hormone by the thyroid gland. This usually occurs due to either atrophy of the thyroid gland where thyroid tissue is replaced by inactive tissue, or immune mediated inflammation where the immune system inappropriately destroys thyroid tissue. It is very uncommon for hypothyroidism to be due to a tumor or the thyroid gland or surrounding tissue.

This disease typically occurs in older, large breed dogs. Clinical signs are usually vague, affecting multiple organ systems and slow to develop. The changes that appear are often initially attributed to “old age” by owners. Affected dogs tend to be less active, less interested in their surroundings, intolerant of cold and prone to weight gain.

Changes in the skin and hair coat are often noted including dry flakey skin, thinning of hair, dry coat, loss of coat luster and an increase in skin infections. In rare cases some dogs will develop edema in the face causing puffy eyelids, forehead and cheeks.

Reproductive problems and decreased fertility can occur in both males and females if dogs are intact.

Hypothyroidism can also affect the nervous system. Neuropathy can occur leading to weakness, exercise intolerance, ataxia or paralysis. Changes to the vestibular nerve which controls the vestibular system in the ear can cause “stroke like” episodes where the dogs are having trouble righting themselves and are unable to stand. They may have drooping of one side of the face and drooling if the facial nerve is affected.

Congenital hypothyroidism, also called cretinism,is very rare in dogs and leads to failure of these pets to grow properly.

Diagnosis of hypothyroidism is made based on clinical signs and changes on blood work. The most commonly evaluated value is the total T4 which is a good screening test for hypothyroidism. In some cases where the total T4 level is low normal and hypothyroidism is still suspected it may be necessary to evaluate additional thyroid hormone levels.

Treatment is supplementation with a synthetic form of thyroid hormone, usually given twice daily in pill form. Side effects are rare but can include excitability, nervousness and panting if the dose is too high. Activity levels often increase after 1-2 weeks of therapy. Improvements in weight, skin condition and other clinical signs take longer to appear - often 4-8 weeks or longer. 4-8 weeks after starting dogs on supplement, a recheck of thyroid hormone levels is needed to ensure they are at the proper dose. Form there levels are typically checked every 6-12 months or as clinically indicated.

Idiopathic vestibular disease is also referred to as old dog vestibular disease or geriatric vestibular syndrome because it is typically seen in older dogs. Clinical signs are acute in onset and are often described as a stroke. This is due to disruption of the peripheral vestibular system that controls balance.

Signs seen with this disease are consistent with those expected in other peripheral vestibular diseases - peripheral meaning not involving the brain but the vestibulocochlear nerve in the ear. Patients may be unable to stand, fall to one side, tilt the head to one side or have an abnormal flicking of the eyes called nystagmus.

Diagnostics involve ruling out other potential causes of peripheral vestibular disease that can be treated. The most common being middle or inner ear infection. This involves an otoscopic exam - in some cases anesthesia is required. X-rays of the skull may be indicated to evaluate the inner ear. Lab work is evaluated to rule out hypothyroidism as a possible cause.

Treatment is supportive as the clinical signs will typically resolve on their own over a few days to several weeks. Some patients are nauseated so anti-emetics are indicated in these cases. Intravenous fluids can be given if the patient will not eat.

The feline immunodeficiency virus (FIV) is a retrovirus that is transmitted from cat to cat via direct inoculation. It is often referred to as a disease of unfriendly cats because bite wounds are the most common mode of transmission. Infection is for life as there is not cure. The virus can cause acute disease but many cats remain asymptomatic and healthy for years after infection.

The virus is spread most commonly by bite wounds and as a result intact male cats are most prone to infection. Outdoor cats are also at higher risk than indoor cats in stable populations. There appears to be wide variability in the ability of queens to pass the virus on to kittens though the placenta or milk depending on the mothers immunity, blood levels of virus and the strain of the virus.

Clinical signs after initial infection may include fever, low blood cell counts, and infection though this phase often goes unnoticed. Most infected cats are asymptomatic carries who will not show signs of illness for months to many years after infection.

Because the virus suppresses the immune system, infected cats are susceptible to secondary infections and cancer. It is complications of these secondary diseases that tend to be most problematic. These can include chronic skin disease, gastrointestinal disease, respiratory disease and dental disease (gingivitis, stomatitis, periodontitis). These cats may also have recurrent eye problems.

Diagnosis is by an antibody test called a serum ELISA test. This test looks for antibodies produced in response to the virus and can be quickly performed at most veterinary hospitals. While these tests are very reliable, a positive test needs to be confirmed with a Western Blot assay that can be run at most commercial laboratories. Cats that should be tested include any new cat or kitten prior to introducing into the household, any sick cat or any at risk cat (outdoors, fights). It is important to note that FIV antibodies are passed from mother to kittens and they will persist for up to 6 months. Therefore any positive test on a kitten under 6 months of age needs to be repeated after 6 months as the test will likely be negative after antibodies clear. The FIV vaccine will also interfere with testing as it will cause a positive antibody response. There is currently no way to differentiate an infected cat from a vaccinated cat.

Treatment for infected cats is supportive and involves environmental management as well. These cats do best when kept strictly indoors in a stable house hold. This prevents them from spreading the disease to cats outside, prevents fighting in the house and decreases these cats exposure to other infectious diseases. Routine dental care needed to help keep the mouth healthy and prevent serious periodontal infection. Any type of infection (urinary, respiratory, skin, dental, etc.) needs to be treated aggressively - more so than with an uninfected cat. These cats need to be examined every 6 months with full lab work and urinalysis every 6-12 months with the goal being to catch any problems early. They need year round flea and heartworm prevention and regular dewormings as well. These cats should also be spayed or neutered.

Feline Infectious Peritonitis (FIP) is a progressive and fatal disease of cats caused by a feline corona virus. Typically the feline enteric corona virus replicates in the intestines causing only mild gastrointestinal disease in young cats and kittens. Another form of the virus, FIP corona virus, is more tissue invasive and can cause severe disease in some cases. The enteric corona virus can mutate and become the more virulent FIP form of the virus. While advances in understanding the disease have been made, there is still much that is not well understood in the areas of which cats are infected and why, viral shedding, treatment and vaccination.

The enteric corona virus and the FIP form are shed most effectively in feces and oropharyngeal secretions. Infection is mainly oronasal through contact with infected stool. Infected cats may shed the virus prior to showing clinical signs and carrier cats do exist though their significance is uncertain. The virus can persist in the environment for weeks but is destroyed by most common disinfectants and detergents. Infection with the enteric corona virus is widespread with most infections being mild or asymptomatic. The factors which influence the development of the fatal forms of FIP are not completely understood and include the cats age at infection, the magnitude of the immune systems response, genetics, recent stress and the strain of the virus which has infected the cat. Affected cats are most often between 3 months and 3 years of age. There is also an increased incidence in geriatric cats. Stresses that may be associated with development of the disease include concurrent infections, surgery, pregnancy in a young cat or weaning and moving to a new environment.

There are 2 types of FIP syndromes, wet and dry. Initial clinical signs of both are similar and nonspecific including fever, lethargy, decreased appetite and possibly diarrhea. With time, cats typically lose weight and have a recurrent or persistent fever with resulting lethargy and lack of interest in food. The wet form is so called due to development of effusions in either the abdomen (ascites) or chest (pleural effusion). There can also be fluid buildup around the heart. These cats may have a distended abdomen or difficulty breathing. In the dry form, instead of effusions, granulomas develop in various organs. Almost any organ can be affected including the liver, spleen, lymph nodes, kidneys, nervous system or eyes. The clinical signs depend on the organs affected.

The only way to truly diagnose the disease is by histopathological exam of infected tissues from a biopsy or at necropsy. This being the case, FIP is not a quick diagnosis in the hospital setting as is the case with several other feline viruses. The effusions produced in wet FIP do aid in diagnosing this form of the disease as there are characteristic changes commonly seen in the fluid. There are also lab work changes that are common in FIP infection such as elevated white blood cell counts, elevated protein and liver levels but these changes are not specific for this disease. Viral titers can be used to detect exposure to the feline corona virus but exposure does not equal disease since may cats with positive titers will never develop FIP. Diagnosis is typically made based on clinical signs, consistencies on diagnostic tests and ruling out other diseases.

There is no treatment that addresses the virus directly. Since the disease process involves an abnormal immune response to the viral infection treatment focuses on suppressing the immune system. Steroids are often used for this as is the immunosuppressive drug cyclophosphamide. The disease is ultimately fatal even with immunosuppressive therapy. The best candidates for therapy are animals that are otherwise in good physical condition and still eating. These cats are the most likely to get an extended period of good quality of life from treatment.

In general, household cats in stable environments with no exposure to other cats outside the family are less likely to develop the disease compared to cats in a cattery or shelter. It is unclear at this time if the FIP vaccine that has been developed is prudent to give to household pets.

Chronic kidney (renal) failure is common in middle aged to older dogs and cats. It refers to primary kidney disease that has been ongoing for months to years. There are various underlying causes but the effect is irreversible damage to the kidneys though the condition may be managed by addressing underlying secondary problems.

Causes may be congenital or inherited and thus typically suspected when seen in younger animals, or acquired as is most common in older animals. Acquired chronic kidney failure results from any process that damages any component of the kidneys. The initiating factor is often unknown but inflammation is frequently present.

Clinical signs may be insidious in onset and not noted immediately. This includes slow weight loss, increased drinking and urination and loss of appetite. There may also be intermittent vomiting. If these signs are subtle or missed, the patient may present as if the process is acute (sudden onset of not eating, persistent vomiting and lethargy) even though the underlying disease has been present for some time. Other clinical signs include ulcers in the oral cavity, depressed mentation, seizures or blindness.

Initial diagnostics that indicate kidney failure are blood work that shows an elevation in the kidney values (BUN - blood urea nitrogen and creatinine which are typically cleared by normally functioning kidneys) along with a decreased ability to concentrate the urine. Other changes with chronic renal failure may include an increase in phosphorus, low potassium, elevated calcium. These changes result from the kidneys impaired ability to filter or retain these minerals as is normally done. The red blood cell count is also typically decreased as the kidneys are not able to produce normal amounts of erythropoietin - the hormone responsible for telling the bone marrow to produce red blood cells.

Since the damage to the kidneys is irreversible, the goal of therapy is to correct underlying dehydration, electrolyte imbalances, clear buildup of toxins and address any current disease processes that may further injure the kidneys. The additional diagnostics include a urine culture to help determine if a urinary tract infection is present and if so identify the bacteria to find the most effective antibiotic for treatment. X-rays of the abdomen will help identify kidney, ureteral or urinary bladder stones which can predispose to infection or further damage. They can also identify abnormalities in size or shape of the kidneys. Changes here can indicate a cyst or tumor. An abdominal ultrasound can evaluate the architecture of the kidneys. This allows better visualization of any cysts or tumors that may be present as well as any abnormal dilation of the kidneys. Blood pressure readings are indicated as hypertension is often seen with kidney failure and if untreated not only contributes to the patient not feeling well but can hasten kidney damage.

Treatment includes intravenous fluids if the patient is dehydrated, vomiting or not eating. This helps restore fluid and electrolyte balance. These patients are treated symptomatically for vomiting with medications to stem the vomiting and protect the gastrointestinal tract. Antibiotics are used if indicated. Hypertension is addressed with medication when it is present. Once the patient is eating and hydrated, long term oral medications can be instituted. These include a diet change to a prescription diet that has appropriate amounts of high quality protein as well as ideal concentrations of minerals and electrolytes. Patients may be placed on phosphorus binders to help keep phosphorus levels from rising and a potassium supplement if indicated. In cases of severe anemia, recombinant human erythropoietin is the treatment of choice though not without risk. It can cause seizures, allergic reactions and refractory anemia due to the animals immune system attacking the erythropoietin. At home, smaller dogs and cats an benefit from regular subcutaneous fluid therapy to help with hydration.

Chronic kidney failure patients can in some cases have a good quality of life for many months with good management, particularly if the disease process is caught in the early stages. This is one of the reasons it is important to regularly check screening blood work and urine samples on older pets.