Veterinary Internal Medicine in San Jose, CA

Occasional vomiting or diarrhea in pets can result from something as simple as eating something they shouldn't have. But when gastrointestinal symptoms persist, recur, or worsen over time, they often signal an underlying condition that needs investigation. Acute vomiting and diarrhea that resolve within a day or two are common and usually not alarming — but symptoms lasting more than a few days, or those accompanied by blood, lethargy, or loss of appetite, warrant closer evaluation.

Chronic gastrointestinal symptoms — defined as vomiting or diarrhea that recurs weekly or persists for more than a few weeks — may indicate inflammatory bowel disease, food sensitivities, chronic enteropathy, parasites, bacterial overgrowth, or organ disease affecting the digestive system. Our diagnostic approach typically begins with bloodwork and urinalysis to evaluate organ function, followed by ultrasound or other imaging if needed. Identifying the specific cause allows us to build a targeted treatment plan rather than relying on symptomatic management alone.

If your pet is experiencing repeated episodes of vomiting or diarrhea, persistent loose stools, or gastrointestinal symptoms that haven't improved with initial treatment, an internal medicine evaluation can help move toward a more definitive answer.

Inflammatory bowel disease (IBD) is one of the most common causes of chronic gastrointestinal symptoms in dogs and cats. IBD involves chronic inflammation of the intestinal wall, which interferes with nutrient absorption and normal digestive function. Symptoms include chronic vomiting, diarrhea, weight loss, and changes in appetite. While IBD cannot always be cured, it can often be managed effectively with dietary modification, anti-inflammatory medications, and supportive care — once an accurate diagnosis has been established.

Food sensitivity or food allergy is another frequent contributor to chronic GI symptoms. Unlike a true food allergy, food sensitivity does not involve the immune system in the same way, but the clinical signs — intermittent vomiting, soft stools, flatulence, and waxing and waning appetite — can overlap significantly. Diagnosis typically involves a structured elimination diet trial lasting eight to twelve weeks, during which the pet eats a single protein source or hydrolyzed diet and symptoms are carefully monitored.

Chronic enteropathy is a broader term for ongoing intestinal inflammation that doesn't fit neatly into a single diagnostic category. Some cases are responsive to dietary changes alone, while others require a combination of diet, medications, and probiotics. Our goal is to identify what's driving your pet's chronic digestive issues through a stepwise diagnostic process, so that the treatment plan is built on a clear understanding of the underlying condition rather than assumptions.

Chronic kidney disease (CKD) is one of the most common conditions affecting older cats and is also seen in dogs, particularly as they age. The kidneys filter waste from the blood and regulate fluid balance, so when kidney function declines, toxins build up and the body's electrolyte and fluid balance is disrupted. Early signs can be subtle — increased thirst and urination, mild weight loss, and a gradual decrease in appetite — which is why routine bloodwork and urinalysis are important, especially in pets over seven years old.

Urinary tract disease encompasses infections, bladder stones, and inflammation of the bladder or urethra. Signs include straining to urinate, frequent small volumes of urine, blood in the urine, and accidents outside the litter box. Some urinary conditions — particularly blockages in male cats — are medical emergencies that require immediate attention. For others, a systematic evaluation including urinalysis, culture, and imaging helps identify the specific problem and guide appropriate treatment.

Once diagnosed, kidney disease and chronic urinary conditions require ongoing monitoring. Regular bloodwork, urine checks, blood pressure measurement, and dietary adjustments form the backbone of long-term management. Our team works closely with pet owners to establish monitoring schedules and adjust treatment as conditions evolve, helping to maintain quality of life for as long as possible.

The liver plays a central role in metabolism, detoxification, bile production, and protein synthesis — so when it's not functioning properly, the effects can be widespread. Liver disease in pets can develop acutely (often from toxin exposure or infection) or chronically (from immune-mediated hepatitis, copper storage disease, or idiopathic causes). Symptoms may include vomiting, diarrhea, increased thirst and urination, jaundice (yellowing of the skin or gums), lethargy, and abdominal distension from fluid accumulation.

Diagnosing liver disease involves a combination of blood tests — including liver enzyme panels, bile acid testing, and coagulation profiles — along with ultrasound imaging to evaluate liver size, texture, and blood flow. In many cases, liver enzyme elevations on routine bloodwork are the first clue that something is happening, and ultrasound helps determine whether the changes are structural or diffuse. In select cases, a liver biopsy or fine-needle aspirate may be recommended to obtain a definitive diagnosis.

Treatment depends on the underlying cause. Some liver conditions respond well to dietary management and medications, while others require immunosuppressive therapy or long-term supportive care. Early detection is particularly valuable in liver disease because the liver has a remarkable capacity to regenerate — but only when damage is identified before it becomes too advanced.

Endocrine disorders involve dysfunction of the glands that produce hormones regulating metabolism, growth, reproduction, and stress response. Diabetes mellitus — characterized by insufficient insulin production or insulin resistance — is one of the most common endocrine conditions in dogs and cats. Signs include increased thirst, increased urination, weight loss despite a good appetite, and lethargy. Diagnosis is confirmed through blood glucose testing and urinalysis, and management typically involves insulin injections, dietary changes, and regular monitoring.

Cushing's disease (hyperadrenocorticism) results from excess cortisol production, most commonly from a pituitary gland tumor. Dogs are more frequently affected than cats. Common signs include increased thirst and urination, a pot-bellied appearance, hair loss, panting, and muscle weakness. Addison's disease (hypoadrenocorticism) is the opposite — insufficient cortisol production — and can present with vague, intermittent symptoms that are easy to miss until an adrenal crisis occurs. Both conditions are diagnosed through specific blood tests and managed with medications that regulate cortisol levels.

Thyroid disease is extremely common in older cats (hyperthyroidism) and occurs in middle-aged to older dogs (hypothyroidism). Hyperthyroidism in cats causes weight loss, increased appetite, hyperactivity, and a rapid heart rate. Hypothyroidism in dogs causes weight gain, lethargy, skin changes, and cold intolerance. Both conditions are straightforward to diagnose with blood testing and respond well to treatment — medication for hyperthyroidism and daily thyroid supplementation for hypothyroidism. Regular monitoring ensures that treatment remains balanced and effective over time.

Unexplained weight loss in pets is always worth investigating. Unlike intentional weight loss through a controlled diet, unexplained weight loss suggests that something is interfering with your pet's ability to absorb nutrients, maintain muscle mass, or regulate metabolism. Dogs and cats can lose weight gradually over weeks or months before the change becomes visually apparent — by the time it's noticeable, the underlying process may have been developing for some time.

The differential causes are broad and include chronic gastrointestinal disease (IBD, food sensitivity, parasites), kidney disease, liver disease, diabetes, hyperthyroidism (especially in cats), cancer, dental disease affecting the ability to chew, and malabsorption syndromes. A systematic diagnostic workup typically begins with comprehensive bloodwork and urinalysis, which can reveal metabolic and organ-related causes. If those are inconclusive, imaging with X-rays or ultrasound follows to evaluate internal organs more closely.

In some cases, weight loss is accompanied by other symptoms — increased thirst, changes in appetite, vomiting, or diarrhea — that help narrow the focus. In other situations, weight loss may be the only noticeable sign. Either way, prompt evaluation gives the best chance of identifying and addressing the cause early.

It's not unusual for a pet to skip a meal occasionally — stress, warm weather, or a change in routine can temporarily reduce appetite. But when a dog or cat consistently eats less than normal, refuses food for more than a day, or shows a gradual decline in interest in food over weeks, it may indicate an underlying health issue that needs attention. Learn what to watch for when your dog is not eating or your cat is not eating.

Chronic loss of appetite (inappetence) can be associated with gastrointestinal disease, dental pain, liver or kidney dysfunction, pancreatitis, infections, cancer, medication side effects, or chronic pain. In cats specifically, prolonged periods without eating can increase the risk of hepatic lipidosis (fatty liver disease), making it important not to dismiss a decreased appetite as trivial. Acute, complete refusal to eat — especially when accompanied by vomiting, lethargy, or abdominal discomfort — may signal a more urgent problem.

Our evaluation of a pet with loss of appetite typically includes a thorough history, physical examination, and baseline bloodwork to screen for metabolic causes. Imaging, oral examination, and additional testing are pursued based on initial findings. The goal is to identify whether the appetite loss is a symptom of a treatable condition, and to address the cause rather than simply encouraging the pet to eat without understanding why they don't want to.

An occasional cough in a dog or cat is not necessarily cause for concern — pets can cough from inhaling dust, drinking water too quickly, or mild upper airway irritation. But a cough that persists for more than a week, recurs frequently, or is accompanied by exercise intolerance, labored breathing, or lethargy warrants veterinary evaluation. Our guide to coughing in dogs explains common causes and warning signs. Chronic coughing can indicate conditions ranging from tracheal collapse and chronic bronchitis to heart disease, lung infection, or even parasites like heartworm.

The diagnostic approach to chronic coughing typically begins with chest X-rays to evaluate the lungs, airways, and heart size. Bloodwork — including heartworm testing and general screening — provides additional information. In some cases, a tracheal wash or bronchoscopy may be recommended to collect samples from the airways for cytology and culture. Cardiac evaluation, including echocardiography, may be pursued if heart disease is suspected.

Treatment depends entirely on the underlying cause. Tracheal collapse may be managed with weight management, anti-inflammatory medications, and cough suppressants. Chronic bronchitis may require bronchodilators and environmental management. Heartworm disease requires a treatment protocol, and heart disease may involve medications to support cardiac function. Identifying the right diagnosis is the essential first step toward effective treatment.

Laboratory testing is a cornerstone of internal medicine. A comprehensive blood panel evaluates organ function (liver enzymes, kidney values, blood glucose, electrolytes), red and white blood cell counts, and protein levels — giving a broad overview of your pet's metabolic health. Lab testing is often the starting point for investigating vague or non-specific symptoms like lethargy, weight loss, increased thirst, or decreased appetite.

Urinalysis complements bloodwork by providing information about kidney function (urine concentration), metabolic health (glucose and protein levels), and urinary tract health (evidence of infection, crystals, or blood). In many cases, bloodwork and urinalysis together provide enough information to establish a preliminary diagnosis or identify the direction for further investigation.

Cytology — the microscopic examination of cells collected from masses, fluid samples, or surface lesions — helps differentiate between inflammatory, infectious, and neoplastic (cancerous) processes. It is a quick, minimally invasive tool that can provide answers in many situations. Additional testing, such as thyroid levels, cortisol testing, bile acids, and infectious disease panels, is ordered based on clinical suspicion and initial results. Our approach is systematic: each test result guides the next step, ensuring a thorough and efficient diagnostic process.

Imaging plays an essential role in internal medicine because physical examination and bloodwork alone can only tell part of the story. X-rays are valuable for evaluating the chest (lungs, heart size, airway structure), detecting bone changes, and identifying radio-dense foreign objects or bladder stones. They are fast, widely available, and often the first imaging step for respiratory symptoms or acute injury.

Ultrasound provides detailed soft-tissue evaluation that X-rays cannot match. It uses sound waves to create real-time images of the liver, kidneys, spleen, bladder, gastrointestinal tract, and other abdominal structures — revealing organ size, texture, blood flow, masses, and fluid accumulations without any radiation exposure. Ultrasound is particularly valuable when bloodwork shows abnormalities that need structural correlation, when symptoms are vague or chronic, and when guiding minimally invasive procedures like fine-needle aspirates.

In many internal medicine cases, X-rays and ultrasound are complementary — each providing information the other cannot. Your veterinarian recommends the combination of imaging that makes the most sense for your pet's specific situation. Both are non-invasive, well-tolerated, and can typically be performed during a single visit. The images and findings are reviewed in the context of your pet's overall clinical picture to guide diagnosis and treatment decisions.