W

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Weight Loss

AUTHORS: BRADLEY. GREEN, HELIO AUTRAN. DE MORAIS

EDITOR: ETIENNE. CÔTÉ

BASIC INFORMATION image

DEFINITION

Decrease in body mass; may be intended (as in the treatment of obesity) or an unintended consequence of disease

SYNONYMS

Cachexia, emaciation

EPIDEMIOLOGY

SPECIES, AGE, SEX: Dog or cat, any age, either sex

CLINICAL PRESENTATION

DISEASE FORMS/SUBTYPES

With or without localizing gastrointestinal (GI) signs

HISTORY, CHIEF COMPLAINT

• Thin appearance, lethargy, decreased appetite
• It is important to determine:
○ Quantity, quality, and appropriateness of the diet
○ Appetite (increased or decreased)
○ Daily activity/caloric expenditure
○ Presence of physiologic conditions that may increase energy requirements (e.g., growth, pregnancy, lactation)
○ Presence of localizing GI signs (dysphagia, regurgitation, vomiting, diarrhea)

PHYSICAL EXAM FINDINGS

Poor body condition (or decrease in weight in comparison to historic body weight) +/− poor haircoat, muscle atrophy

ETIOLOGY AND PATHOPHYSIOLOGY

• Body weight is affected by caloric intake, absorptive capacity, metabolic demand, and nutrient losses.
• Weight loss may result from (1) inadequate quantity or quality of diet, (2) inability to prehend or swallow food, (3) regurgitation or vomiting of ingesta, (4) anorexia (loss of desire to eat), (5) inability to digest or absorb ingested nutrients, (6) inability to utilize absorbed nutrients (e.g., diabetes mellitus), (7) increased metabolic rate, (8) increased catabolism, (9) loss of nutrients.

DIAGNOSIS image

DIAGNOSTIC OVERVIEW

Weight loss is a nonspecific clinical sign. When it is confirmed to not be deliberate (i.e., no weight-loss diet), a broad systemic evaluation beginning with fecal flotation and routine blood and urine tests is indicated. The diagnostic approach is then adapted to results of these tests, the history, and the physical exam.

DIFFERENTIAL DIAGNOSIS

• Weight loss with localizing GI signs:
○ Inability to prehend or masticate food:
▪ Dental disease
▪ Head trauma
▪ Temporomandibular joint disease
▪ Masticatory myositis
○ Dysphagia:
▪ Neuromuscular disorders
▪ Oropharyngeal neoplasia
▪ Nasopharyngeal polyp
○ Regurgitation:
▪ Esophageal disorders
○ Vomiting (see p. 1175)
○ Small-bowel diarrhea (see p. 305; e.g., protein-losing enteropathies)
○ Large-bowel diarrhea:
▪ Does not cause weight loss
• Weight loss due to anorexia/decreased appetite:
○ All GI causes of vomiting
○ Systemic diseases leading to anorexia
○ All systemic causes of vomiting
○ Neoplasia (anywhere)
○ Chronic infections:
▪ Viral: feline leukemia virus (FeLV), feline immunodeficiency virus (FIV), feline infectious peritonitis (FIP)
▪ Mycotic: blastomycosis, histoplasmosis, cryptococcosis, coccidioidomycosis
▪ Bacterial: endocarditis, chronic pneumonia, rickettsial infections (e.g., chronic ehrlichiosis), mycobacterial infections
▪ Protozoal: leishmaniasis, hepatozoonosis
○ Chronic pancreatitis
• Weight loss despite normal to increased appetite:
○ Unrecognized vomiting or regurgitation
○ Dietary:
▪ Inadequate quantity
▪ Poor-quality diet
○ Increased energy demand:
▪ Pregnancy
▪ Lactation
▪ Increased exercise
▪ Growth
○ Increased metabolic rate or increased catabolism:
▪ Hyperthyroidism (cats)
▪ Congestive heart failure
▪ Chronic inflammation
○ Inability to utilize nutrients:
▪ Diabetes mellitus
○ Nutrient loss:
▪ Protein-losing nephropathies (see p. 926):
□ Rarely, protein-losing enteropathies cause weight loss without diarrhea

INITIAL DATABASE

• CBC, biochemistry panel, urinalysis
• FeLV/FIV testing (cats)
• T4 (cats >5 years old)
• Fecal flotation

ADVANCED OR CONFIRMATORY TESTING

• Trypsinlike immunoreactivity (TLI), if there is small-bowel diarrhea, to rule out exocrine pancreatic insufficiency (EPI)
• Fecal α1-protease inhibitor activity if PLE is suspected but no diarrhea
• Abdominal ultrasound to identify GI tract thickening or layer loss, neoplasms, granulomas, pancreatitis
• Upper GI endoscopy to rule out esophageal or gastric foreign body, ulcerations, or luminal neoplasms
• GI biopsies via endoscopy or exploratory laparotomy
• Bile acids to rule out liver failure (portosystemic shunt)
• Urine protein/creatinine (UPC) ratio to rule out protein-losing nephropathy
• Adrenocorticotropic hormone (ACTH) stimulation test to rule out hypoadrenocorticism
• Infectious disease testing when indicated

TREATMENT image

TREATMENT OVERVIEW

Treat underlying disease and provide nutritional support.

ACUTE GENERAL TREATMENT

• Improve appetite/symptomatic therapy:
○ Diet change
• Antacids (H2 blockers [famotidine, ranitidine] or proton pump inhibitors [omeprazole])
• Antinausea medications (metoclopramide, ondansetron, maropitant) unless contraindicated
• Appetite stimulants (mirtazapine [dogs], cyproheptadine [cats])
• Increase caloric intake.

CHRONIC TREATMENT

Treat underlying disease and maintain adequate caloric intake.

NUTRITION/DIET

• Enteral nutrition is preferred in animals that have a functioning GI tract.
• Assisted feeding through a nasoesophageal, esophagostomy, gastrostomy, or jejunostomy tube may be required (see p. 1267).
• Parenteral nutrition may be necessary in animals that cannot tolerate enteral feeding or if enteral feeding alone cannot meet caloric requirements.
• Caloric requirements are estimated by calculating resting energy requirements (RER) and illness energy requirements (IER):
○ RER (in kilocalories) can be calculated as:
▪ 70 × (body weight [BW] in kilograms)0.75
○ IER is calculated by multiplying RER by an illness factor (1.2 to 1.4 for dogs; 1.1 to 1.2 for cats).

BEHAVIOR/EXERCISE

Exercise should not be encouraged until weight is controlled.

POSSIBLE COMPLICATIONS

• Refeeding syndrome if anorexia is chronic and/or severe
• Aspiration pneumonia in patients that are regurgitating, vomiting, or being force-fed

RECOMMENDED MONITORING

• Body weight
• Other testing based on underlying cause

PROGNOSIS AND OUTCOME image

Weight stabilization occurs in the majority of surviving patients through treatment of the underlying disease and appropriate nutrition.

PEARLS & CONSIDERATIONS image

COMMENTS

• If the patient has other clinical signs (e.g., vomiting, diarrhea, fever, etc.), the diagnostic approach should not focus on the weight loss alone.
• In the initial stages of therapy, changes in body weight often reflect changes in fluid dynamics.

PREVENTION

Dependent upon the underlying cause

CLIENT EDUCATION

Weight loss is caused by a wide array of diseases; many are treatable. Obtaining a diagnosis often requires extensive testing.

SUGGESTED READING

Remillard RL, Armstrong PJ, Davenport DJ. Assisted feeding in hospitalized animals. In: Hand MS, Thatcher CD, Remillard RL, et al, editors. Small animal clinical nutrition. ed 4. Topeka, KS: Mark Morris Institute; 2000:351-399.

Sanderson S, Bartges JW. Management of anorexia. In: Bonagura JD, editor. Current veterinary therapy XIII. Philadelphia: WB Saunders; 2000:69-74.

West Nile Virus Infection

AUTHOR: MILLICENT. EIDSON

EDITOR: DOUGLASS K. MACINTIRE

1ST EDITION AUTHOR: KATHRYN. TAYLOR

BASIC INFORMATIONimage

DEFINITION

Mosquito-borne virus that affects humans and animals but rarely causes clinically significant illness in dogs and cats

EPIDEMIOLOGY

SPECIES, AGE, SEX: Wild birds are the principal hosts of West Nile virus. More than 150 species of birds have been infected in North America. Horses and humans, particularly if older, may also develop clinical signs of infection. Dogs and cats appear to be more resistant to clinical illness, with lower morbidity and mortality.

RISK FACTORS: Infection in dogs and cats has been associated with being stray, residing exclusively outdoors, and not receiving heartworm medication. In humans, advanced age, alcohol abuse, diabetes mellitus, immunosuppression, requirement of mechanical ventilation, history of stroke, and being homozygous for a defective allele have been associated with increased risk of encephalitis, death, or a poor prognosis. In some studies, horses were at greater risk of death or euthanasia if they were older, had not received West Nile vaccination, or had collapsed or become recumbent.

CONTAGION & ZOONOSIS: Exposure to domestic animals is not considered a risk factor for acquisition or amplification of West Nile virus.

GEOGRAPHY AND SEASONALITY: Infections are more common during warm seasons in manmade and natural environmental conditions supportive of the transmitting mosquito species.

CLINICAL PRESENTATION

DISEASE FORMS/SUBTYPES: Most infections with West Nile virus are subclinical.

HISTORY, CHIEF COMPLAINT: Dogs or cats with clinical West Nile virus infection could present with signs related to joint, cardiac, or neurologic infection, as well as sudden death.

PHYSICAL EXAM FINDINGS: Lethargy, anorexia, weight loss, lameness, depression, neurologic involvement (central neurologic deficits), and myocarditis (e.g., cardiac arrhythmia on auscultation, pulse deficits) may be expected in advanced cases. The physical exam is likely often normal, and the infection is not suspected (nor necessarily of clinical concern).

ETIOLOGY AND PATHOPHYSIOLOGY

• West Nile virus is a mosquito-borne disease. The natural hosts are wild passerine birds (e.g., robins, sparrows, finches, blackbirds, warblers), which predominantly experience latent infection. However, high mortality has been reported in crows and blue jays. Mosquitoes (primarily Culex spp. in the United States) feed on infected birds and are vectors, transmitting disease to other animals and to people.

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Jul 24, 2016 | Posted by in SMALL ANIMAL | Comments Off on W

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