Use a consistent method and scale to measure body weight (BW), body condition score (BCS) and muscle condition score (MCS) to assess current status and changes over time. Although different scoring systems may have situation- specific merits, the panel recommends that practices choose, and all doctors and staff consistently use, one system and record the total points on which it is based (i.e., the denominator).

The BCS evaluates body fat [Figure 2]. Various BCS systems are used to evaluate dogs and cats (e.g., scales of 5, 6, 7 or 9).^11,12,13

The goal for most pets is a BCS of 2.5–3 of 5, or 4–5 of 9. (This may appear too thin to some pet owners, so client education is important.) These BCS goals are based on a limited number of studies in dogs and cats^14,15,16,17 as well as those from other species. Disease risk associations with higher BCS in adult animals appear to increase above 3.5 of 5 (6 of 9). Similar risk associations for other life stages in client-owned pets have not been reported, but may occur at low BCS based on studies of laboratory-housed animals, and in humans.^16,18 Additional research in dogs and cats is needed to more fully evaluate the effects of body condition on disease prevention.

The MCS differs from the BCS in that it evaluates muscle mass [Figure 3]. Evaluation of muscle mass includes visual examination and palpation over the temporal bones, scapulae, lumbar vertebrae and pelvic bones. Assessing muscle condition is important because muscle loss is greater in animals with most acute and chronic diseases (i.e., stressed starvation) compared to healthy animals deprived of food, when primarily fat is lost (i.e., simple starvation). Muscle loss adversely affects strength, immune function, wound healing and is independently associated with mortality in humans.^19,20

A simple MCS scale is currently undergoing development and validation.²¹ The authors' clinical experience suggests that early identification of subtle muscle loss, at the "mild muscle wasting" stage, is valuable for successful intervention.

Clinically, BCS and MCS are not directly related. An animal can be overweight but still have significant muscle loss. This can make an MCS of mild to moderate look relatively normal if not carefully evaluated. In these cases, although some of the areas of the body may appear relatively normal or even to have excessive fat stores (especially over the ribs or in the abdominal region), muscle wasting is readily felt over bony prominences. Palpation is required for accurately assessing BCS and MCS, especially in animals with medium- to long-hair coats.

Extended evaluation

Extended nutritional evaluation of animal, diet, feeding and environmental factors is indicated for animals identified to be at risk for any nutrition-related problems from the screening evaluation [Table 2]. Those items suggest that nutrition may play an important role in development of or management of the animal's underlying disease, or life stage. First, review and summarize the history, medical record and information obtained during the screening evaluation. Second, obtain additional data as appropriate, as described below. A more detailed list of potentially relevant historical factors may be found in various references.

Animal factors

• Changes in food intake or behavior (e.g., amount eaten, chewing, swallowing, nausea, vomiting).
• Condition of the integument. Nutrition-related abnormalities may include variable combinations of dry, easily plucked hair; thin, dry or scaly skin; and reduced resistance to venipuncture (due to loss of normal skin collagen density).
• Diagnostic work up.
  • Minimum database/laboratory testing as appropriate.
  • Specific testing might include a complete blood count (checking for anemia), urinalysis, biochemistry profile (including electrolytes, albumin), fecal culture or evaluation of other nutrient concentrations that may be low (or high) as a result of an unbalanced diet (e.g., taurine, vitamin B12, iron).
  • Additional workup as indicated (e.g., imaging, endoscopy).
• Current medical conditions and medications.
  • Assess effects of the disease and any treatment plan on pet's nutritional status (e.g., thyroid disease).
  • Some medications (e.g., diuretics) or procedures (e.g., significant intestinal resection, drain placement) can cause a loss or malabsorption of essential nutrients.

Diet factors

• Evaluate caloric density of current pet food, particularly if pet is below or above desired BCS, or if owner has to feed unusually large or small amounts to maintain desired BCS (may have to contact pet food manufacturer for this information).
• Evaluate other sources of nutrients: treats, table food, supplements, food used for administering medication, chew toys (e.g., rawhide).
• If disease conditions exist that may be the result of tainted or spoiled food, the diet should be submitted for testing.²² Questions about having food analyzed or tested for potential toxins may be referred to the state feed control official (www.aafco.org).
  • Evaluate commercial foods.
    • Specific type, formulation, flavor, when purchased, where purchased, storage conditions.
    • Label information must include the guaranteed analysis, ingredient list, AAFCO nutritional adequacy statement, food type, manufacturers' contact information. Beware of label's role as advertisement.²³
    • The AAFCO adequacy statement provides several important facts:
      • Whether the diet is complete and balanced, and if so, for what life stages. All diets should be complete and balanced. If it says "intermittent or supplemental use only," it is not complete and balanced. That may be acceptable if it is a veterinary therapeutic diet and is being used for a specific purpose (e.g., severe kidney disease).
      • Labels may include one of two statements regarding nutritional adequacy:
        1. "[Name] is formulated to meet the nutritional levels established by the AAFCO Dog (or Cat) Food Nutrient Profiles for [life stage(s)]."
           (Chemical analysis of food)
        2. "Animal feeding tests using AAFCO procedures substantiate [Name] provides complete and balanced nutrition for [life stage(s)]."
           (Feeding trial analysis of food)
      • Formulated foods are manufactured so the ingredients meet specified levels, without testing via feeding trials; interpret with caution. However, the use of feeding trials does not guarantee the food provides adequate nutrition under all conditions.
      • AAFCO provides nutrient profiles and regulates pet food labeling for growth, reproduction and adult maintenance, but not for senior/geriatric pets.
    • What is the manufacturer's reputation as a food maker? Have you had positive experiences with their products? What objective (not testimonial) information do they provide about their foods to assist evaluation?
    • The other information provided on the label is of little practical value in assisting nutritional assessment. Because pet owners sometimes base their purchasing decisions on the initial ingredients or on unregulated terms such as "organic," "holistic," "human grade" or "premium," veterinarians and veterinary technicians must help them make informed decisions.
    • Contact the food manufacturer with any questions or concerns. Consider asking the following questions, as appropriate:
      • Do you have a veterinary nutritionist or some equivalent on staff in your company? Are they available for consultation or questions?
      • Who formulates your diets, and what are their credentials?
      • Which of your diet(s) are tested using AAFCO feeding trials, and which by nutrient analysis?
      • What specific quality control measures do you use to assure the consistency and quality of your product line?
      • Where are your diets produced and manufactured? Can this plant be visited?
      • Will you provide a complete product nutrient analysis of your best-selling dog and cat food, including digestibility values?
      • What is the caloric value per can or cup of your diets?
      • What kinds of research on your products has been conducted, and are the results published in peerreviewed journals?
• Evaluate homemade diets.
  • Contact a board-certified veterinary nutritionist to evaluate or formulate a homemade diet [Table 3].
  • Ask client about the specific recipe, preparation, storage, recipe rotation or substitution.
  • Consider sources and amounts of protein, carbohydrates, fats, vitamins and minerals; bioavailability.
  • Consider specific needs of cats (e.g., amino acids, arachidonic acid, etc.).
• Evaluate any unconventional diet, whether commercial or homemade.
  • Evaluate additional risks of raw meat diets.^24,25,26 Pathogenic bacteria may cause gastroenteritis and can be shed in the feces for up to 1 week after ingestion of contaminated raw meat. If an animal that has been fed a raw-meat diet is hospitalized, evaluate the risk to hospital staff and other hospitalized animals. In addition, raw diets containing bones can be associated with dental damage and esophageal/gastrointestinal obstruction or perforation.
  • Evaluate risks of vegetarian diets, particularly with cats but also with dogs.

Feeding management and environmental factors

• Primary feeder of pet.
• Feeding management (e.g., location, frequency).
• Issues with multiple pets (competition for food, threats).
• Other food providers and sources.
• Extent of enrichment (e.g., toys, other pets, housing, food-delivery devices).
• Activity of pet at home.
  • Type (e.g., leash walks, backyard, free roaming/spontaneous).
  • Amount (times per day/week).
  • Energy level and amount of activity.
• Environmental stressors (e.g., recent changes in the home, uncontrollable outdoor stimuli, conflict over resources such as food or access to the owner, conflict between animals, etc.).^27,28,29
• Environment has a direct impact on nutrition. For example, both laboratory³⁰ and clinical³¹ studies of cats with lower urinary tract syndrome show that environment plays an important role in presentation of signs regardless of the diet fed. The role of environment in other "nutrient-sensitive" disorders in cats has been reviewed, and a recent study concluded that indoor confinement and physical inactivity rather than the proportion of dry food were risk factors in the development of type 2 DM in cats.³²
• In dogs, a range of clinical situations, including competitive eating, coprophagia and obesity have been associated with environmental as well as with animal and dietary factors.^33,34 Additionally, provision of food in dispensing toys may improve the welfare of indoorhoused pets,³⁵ so changes in feeding containers also may be more important than is generally perceived.