Although naturally occurring hypothyroidism is very rare in cats, iatrogenic hypothyroidism is a recognized complication of treatment for hyperthyroidism. However, confirming the diagnosis of hypothyroidism in cats is not generally straightforward. The potential for false-negative and false-positive results exists with all thyroid function tests, especially in older cats that may have concurrent nonthyroidal illness. Therefore, all thyroid function test results must be interpreted in light of the cat's history, clinical signs, and other laboratory findings. If a low to low-normal serum thyroxine (T4) value is found in a cat that has been treated for hyperthyroidism, repeating the total T4 analysis, determining free T4 and thyroid stimulating hormone (TSH) concentrations, or performing a TSH stimulation test or thyroid scintigraphy may be needed to confirm the diagnosis.
Inflammatory bowel disease (IBD) is a common gastrointestinal disorder of dogs. Current management strategies for this disease typically involve assessing the patient for resolution of clinical signs. Biologic markers that can be used to objectively assess the natural progression and predict the course of clinical disease, including response to treatment, are needed. Over the past 5 to 10 years, there has been an ongoing search for a cost-effective, minimally invasive laboratory parameter that can detect disease activity and aid in monitoring treatment. This article reviews the biomarkers currently available for evaluating dogs with IBD.
Heatstroke is a complex disease process that, in its most severe form, can result in multiorgan dysfunction and death. Heatstroke stems from the failure of the body’s thermoregulatory mechanisms, resulting in cellular damage and death. The organ systems most commonly affected in this disease process include the gastrointestinal tract and the coagulation, renal, cardiac, pulmonary, and central nervous systems. Heatstroke is diagnosed based on the patient history, physical examination, and clinicopathologic findings. Treatment should be instituted immediately to improve patient outcome and includes active cooling, fluid resuscitation, and supportive care. Patients with altered mental status, hypoglycemia, prolonged prothrombin time, and prolonged activated partial thromboplastin time at admission have increased mortality rates. Additional negative prognostic indicators include elevated serum creatinine level, delayed admission to the hospital, seizures, and obesity.
Feline inflammatory bowel disease is a diagnosis of exclusion and a common cause of chronic gastrointestinal signs suhc as weight loss, variation in appetite, vomiting, diarrhea, and lethargy. Patients with intestinal small cell lymphosarcoma can present identical clinical signs, and differentiating between these two conditions can be a challenge. A companion article discusses the value of performing immunohistochemistry and polymerase chain reaction testing on intestinal biopsy samples for this purpose.
Hyperadrenocorticism (HAC) is a common endocrinopathy in dogs. With better recognition of the disease, more cases are being presented to clinicians for management. Mitotane, a 3- to 4-decade-old therapy, remains a viable and useful option for management of this disease. Thorough education and understanding of the drug are important, however, as the learning curve of how to manage its effects can be significant. Trilostane, a newer option for management of HAC, offers a simplified protocol and, often, smoother and faster control of the disease. It also requires a comfortable knowledge of expected outcome and possible adverse effects. With either drug, careful monitoring and client communication are crucial.
Hepatic encephalopathy (HE) is a manifestation of clinical signs that may result from a variety of liver diseases. In small animals, HE is most commonly a result of portosystemic shunting. The pathogenesis is not completely understood, although it is likely multifactorial. Theories of pathogenesis include altered ammonia metabolism and glutamine and glutamate transmission, an increase in gamma-aminobutyric acid agonists and benzodiazepine-like substances, alterations of the serotonergic system and amino acid metabolism, elevated taurine levels, contributions from inflammatory mediators, and toxic effects of manganese. An understanding of the underlying mechanisms that result in HE may lead to new treatments in the future.
Systemic hypertension is an increasingly diagnosed disorder in dogs and cats and frequently occurs secondary to chronic kidney disease. Prevention of damage to organs such as the kidneys, brain, heart, and eyes is one of the primary concerns in the management of veterinary patients with hypertension. This article reviews the guidelines for antihypertensive therapy in patients with, or at risk for, kidney disease, including the initiation of treatment and currently recommended medications.
Hepatic encephalopathy (HE) is a neurologic syndrome resulting from the synergistic action of multiple pathologic factors, which are discussed in a companion article. Early recognition of the clinical signs can improve treatment outcome, as well as reduce the incidence of risk factors. Multimodal treatment of HE is usually indicated. Studies on the pathogenesis and treatment of HE in people may shed new light on further treatment modalities in small animal patients.
Thyroid hormones have many effects on cardiovascular function, and deficiency or excess of thyroid hormones can result in cardiac dysfunction. Abnormalities of the cardiovascular system are often identified during examination of hyperthyroid and hypothyroid patients. This article addresses the effects of thyroid hormones on the cardiovascular system and the clinical relevance of the cardiovascular response to thyroid dysfunction. In addition, treatment recommendations are presented.
The iliopsoas muscle is formed by the psoas major and iliacus muscles. Due to its length and diameter, the iliopsoas muscle is an important flexor and stabilizer of the hip joint and the vertebral column. Traumatic acute and chronic myopathies of the iliopsoas muscle are commonly diagnosed by digital palpation during the orthopedic examination. Clinical presentations range from gait abnormalities, lameness, and decreased hip joint extension to irreversible fibrotic contracture of the muscle. Rehabilitation of canine patients has to take into account the inciting cause, the severity of pathology and the presence of muscular imbalances.
When used in veterinary medicine, central venous catheters are typically inserted through the external jugular vein, with their caudal extension within the cranial vena cava. Radiographic or fluoroscopic guidance is recommended to assist in correctly placing these catheters. This article provides radiologic examples of common central venous catheter malpositions and complications.
Shock, defined as the state where oxygen delivery to tissues is inadequate for the demand, is a common condition in veterinary patients and has a high mortality rate if left untreated. The key to a successful outcome for any patient in shock involves having a clear understanding of the pathophysiology and compensatory mechanisms associated with shock. This understanding allows more efficient identification of patients in shock based on clinical signs and timely initiation of appropriate therapies based on the type and stage of shock identified.
Nutrition plays a key role in the management of gastrointestinal disease, and some patients may be managed by dietary therapy alone. Dietary ingredients can have a negative or positive effect on the bowel. Negative factors in a diet may include toxins, allergens, toxic dietary excesses, or nutritional deficiencies. Diet also has a direct effect on intestinal physiology, affecting motility, cell renewal rate, intestinal microbiome, enzyme production, ammonia production, and volatile fatty acid content. This article discusses dietary therapy of acute gastroenteritis, chronic gastroenteropathies, and feline constipation.
