Brittney Lechner
RVT, BS, VTS (Nutrition)
Brittney is a registered veterinary technologist with VTS certification in nutrition. After graduating from Purdue University’s veterinary technology program in 2012, she moved to California to begin working for Royal Canin. She obtained board certification in nutrition in 2021 and currently works for Zoetis Diagnostics in San Diego. She is committed to sharing her passion for nutrition with her fellow technicians in the field and pet owners across the United States. In her free time, she enjoys hiking, spending time with her family and fiancé, baking, and exploring national parks.
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Nutrition plays a vital role in veterinary patients’ longevity and disease prevention/management. Knowing a patient’s stage of life (growth, young to middle-aged, or senior) and the nutrients of concern for each stage helps veterinary nurses effectively communicate those needs to the client.
Take-Home Points
- Nutrition plays a vital role in longevity, regardless of the pet’s age or health status.
- During the growth phase, young pets should be fed diets that provide high energy, high-quality protein, phosphorus/calcium at appropriate ratios, docosahexaenoic acid, and microbiome/immune support.
- During the maintenance phase, young to middle-aged pets should be fed diets that provide the appropriate energy density (calories), high-quality protein, microbiome support, eicosapentaenoic and docosahexaenoic acids, and other optimizing nutrients.
- During the senior phase, older pets should be fed diets that provide high-quality protein and appropriate calories and mineral ratios and that reduce inflammation.
When it comes to the longevity of animal patients, nutrition plays such a critical role that the profession now recognizes it as the fifth vital assessment. Thus, at every veterinary visit, patients should undergo not only temperature, pulse, respiration, and pain assessments but also a nutrition assessment.1 Nutrition tailored to life stage ensures that the food going into the bowl is appropriate for each patient’s current physiologic needs and contains nutrients at an optimal level for that patient’s life stage.2
Life-stage nutrition is not a one-size-fits-all science, but age is the main determinant. For example, the nutritional needs of a 6-week-old Maine Coon kitten differ greatly from those of a 6-year-old Maine Coon adult. Veterinary nurses should understand that nutrient needs (nutrients of concern) vary between life stages and what those nutrients do so that they can communicate those needs to clients and recommend appropriate feeding practices.
Maintaining the patient at a healthy weight, regardless of life stage, is a major piece of the nutrition plan. Excess body weight leads to other serious medical issues and can shorten a pet’s lifespan.3 Patients’ body condition score (BCS) should be assessed at each visit, and clients should be taught how to evaluate BCS themselves.
3 Main Life Stages of Dogs and Cats
The 3 main life stages of dogs and cats are growth (from weaning to maturation, which can be 12 to 18 months, depending on the breed or estimated target weight), young adult to middle-aged (approximately 1 to 1.5 through 7 years of age), and senior (approximately 7 years of age to the end of life).4-6
Growth
Growth is a critical stage of life, when proper nutrition is imperative. Puppies and kittens require twice the energy of adult dogs and cats, in the form of calories or kilocalories.4 Calculating energy requirements is key, even during the growth stage. Feeding too much or too little can lead to detrimental health effects. Different breeds of puppies and kittens mature at different rates; therefore, these differences should be identified early on.4
A well-balanced, high-quality puppy/kitten food should be complete and should not require additional supplementation. It should contain the following:
- Energy: A diet formulated for growth should provide energy at higher density than that of an adult diet.
- Protein: High-quality, highly digestible protein is essential for tissue growth.
- Balanced ratios: The protein-to-energy ratio should be tailored to the size and breed of the patient, especially for large/giant-breed puppies.
- Taurine: This amino acid must be provided in feline diets because cats, as obligate carnivores, cannot synthesize enough on their own.7
- Vitamins and minerals: Vitamin C, vitamin E, vitamin A (in the form of β-carotene), selenium, and zinc can support the developing immune system and help reduce the number of free radicals.4 Phosphorus and calcium are essential minerals for skeletal development; the ratio between them is critical, and excesses or deficiencies of either can be detrimental.4
- Essential fatty acids: Docosahexaenoic acid (DHA) is needed for growth, and it plays a vital role in retinal and neurologic development. DHA is derived from α-linolenic acid; however, the conversion is not an efficient process for dogs and cats. Therefore, DHA should be added into formulas for growing cats and dogs.4
- Prebiotics: Specific fibers should be considered to help support a healthy microbiome, which can lead to lifelong positive health effects.8
TABLE 1 lists the main nutrients of concern for growing puppies and kittens.
Young Adult to Middle Age
For healthy dogs and cats in the young adult to middle-age group, the diet should focus on nutrients that will prevent disease and maximize longevity.2
Because obesity can lead to endocrine diseases (e.g., diabetes) and inflammatory conditions (e.g., osteoarthritis), preventing obesity becomes relevant at this stage. Clients should focus on maintaining their pet at an ideal BCS, as obesity is easier to prevent than treat.9 If the pet is above ideal body weight, a weight-loss diet and plan should be implemented.
For patients already at an ideal BCS, there are other diets that can help optimize the nutrition plan (e.g., dental diets, breed-specific diets, joint diets). Within reason, the diets can be tailored to the patient’s current needs (e.g., breed [size] considerations, possible future health concerns). Taking a proactive nutrition approach by ensuring that the patient is being fed the appropriate nutrients of concern will benefit the patient throughout life.
For cats specifically, urinary health should be considered. Cats can be susceptible to feline lower urinary tract disease and thus need access to fresh water; moist foods can help lower the concentration of the urine. Over-the-counter diets are available that help create a balanced urinary pH and have adjusted mineral content to prevent stone/crystal formation.10
TABLE 2 lists the main nutrients of concern for young and middle-aged adult dogs and cats.
Senior
For healthy senior pets, the best nutritional approach is proactive. As pets age, many body systems begin to change as well. Aging affects the skin, gastrointestinal tract, renal system, and immune system, among others. Aging can lead to oxidative stress of the cells; therefore, the nutrients provided in the diet should support cell function and processes. Focuses should be on maintaining ideal body weight; maintaining muscle; providing immune, cognitive, and joint support; and minimizing/eliminating pain. Comorbidities such as obesity and joint disease are common in senior patients; therefore, a full nutritional assessment should be completed, taking all disease processes into consideration. Most senior diets have adjusted levels of minerals (e.g., phosphorus) to preserve kidney function.11 If the patient is not healthy, therapeutic diets are typically recommended.
TABLE 3 lists the main nutrients of concern for dogs and cats in the senior life stage.
Client Talking Points
There are many possible physiologic states within each age group, but regardless of the pet’s age, the following script can be used as a starting point for a nutrition discussion:
“Thank you for bringing ________ in today. ________ is ____ years old and is in the ________ life stage. I’m going to share what nutrients are most important for pets in this stage of life. We will then talk about the diet you’re currently feeding, identify any gaps, and work together to ensure you’re on the right path. How does that sound?”
The following specifics can be provided, with elaboration and/or pauses between sentences to allow the client to ask questions.
Growth Stage
Coco is a 4-month-old, intact female, 6.8-kg (15-lb) French bulldog. Begin the client conversation by explaining that proper nutrition is essential while Coco is growing.
Start with:
“The needs of growing puppies differ greatly from those of adult dogs. Here are some of the nutrients that should be included in Coco’s diet to help her develop properly. They are already included in high-quality diets designed for growth.”
Main points:
“Coco needs adequate calories and high-quality protein for tissue growth.”
“The calcium and phosphorus ratio must be balanced to support bone development at the right pace.”
“Puppies require DHA, an essential fatty acid, to help their eyes and other organs develop properly.”
“Because puppies are born with immature immune systems, vitamins A and C will help support her immune system.”
“Fiber helps support a healthy microbiome from the start and can help prevent problems such as diarrhea.”
End with:
“Let’s talk about the diet you are currently feeding and see if there are any gaps. How does that sound?”
Young Adult to Middle-Aged Stage
Miles is a 3-year-old, neutered male domestic shorthair cat and weighs 4.5 kg (10 lb). Begin the conversation by commenting on maintaining Miles’ current weight.
Start with:
“Miles is currently at an ideal body weight—great job! The following nutrition plan will help maintain it.”
Main points:
“High-quality protein and the right amount of calories will help maintain Miles’ weight.”
“As Miles ages, specific nutrients will help support his gut, immune system, and joints.”
“Fiber and essential fatty acids will help support his gut. Fiber can be provided in the form of beet pulp, and it can help prevent hair balls.”
“Vitamins, such as vitamin C, will help support his immune system as he ages.”
“EPA and DHA are essential fatty acids that will help reduce inflammation and support his joints as they age.”
“I see that his teeth have a little bit of tartar forming. We can slow that process with proper nutrition aimed at supporting dental health.”
End with:
“Let’s talk about the diet you’re currently feeding and see if there are any nutrient gaps. How does that sound?”
Senior Stage
Ruben is a healthy, 11-year-old neutered male boxer mix and weighs 17 kg (38 lb). Begin the conversation by commenting on Ruben’s life stage and his changing nutritional needs.
Start with:
“Ruben is considered a senior, so it’s important we discuss how to support him nutritionally.”
Main points:
“Since Ruben is already at a healthy weight, we need to keep the calories in his food consistent to prevent weight gain.”
“Ruben needs high-quality protein to maintain his muscles and fiber to be sure his gut stays healthy.”
“Omega-3 fatty acids and joint supplements containing glucosamine and chondroitin will help support his joints.”
“We also want to support his immune system and brain health with vitamins such as vitamins E and C and l-carnitine.”
“As he ages, his kidney function might become compromised. We will want to evaluate his kidney function through routine blood work and might need to make dietary changes based on those results.”
End with:
“Let’s talk about what you are currently feeding him and see if there are any nutrient gaps. How does that sound?”
Summary
No matter the age of each patient, nutrition is a major piece of patient care. Different nutrients are required during each life stage. Optimal nutrition ensures that there are no nutrient gaps so that all body systems can function properly. The veterinary nurse plays a vital role in nutrition management and by understanding the nutrients of concern at each stage can help effectively communicate those needs to clients.
- Identify the patient’s life stage and which nutrients are of concern for that life stage.
- Communicate to the client how those nutrients help the individual patient, and identify any nutrient gaps.
- If nutrient gaps are identified, work with the veterinarian to identify an appropriate diet and create a nutrition plan.
References
- Nutritional assessment guidelines. World Small Animal Veterinary Association. June 2011. Accessed June 15, 2025. https://wsava.org/wp-content/uploads/2020/01/WSAVA-Nutrition-Assessment-Guidelines-2011-JSAP.pdf
- Debraekeleer J, Gross KL, Zicker SC. Introduction to feeding normal dogs. In: Hand MS, Thatcher CD, Remillard RL, Roudebush P, Novotny BJ, eds. Small Animal Clinical Nutrition. 5th ed. Mark Morris Institute; 2010:251-255.
- Salt C, Morris PJ, Wilson D, Lund EM, German AJ. Association between life span and body condition in neutered client-owned dogs. J Vet Intern Med. 2019;33(1):89-99. doi:10.1111/jvim.15367
- Case LP, Daristotle L, Hayek MG, Raasch MF. Growth. In: Case LP, Daristotle L, Hayek MG, Raasch MF, eds. Canine and Feline Nutrition: A Resource for Companion Animal Professionals. 3rd ed. Elsevier Mosby; 2011:221-237.
- Case LP, Daristotle L, Hayek MG, Raasch MF. Adult maintenance. In: Case LP, Daristotle L, Hayek MG, Raasch MF, eds. Canine and Feline Nutrition: A Resource for Companion Animal Professionals. 3rd ed. Elsevier Mosby; 2011:239-242.
- Case LP, Daristotle L, Hayek MG, Raasch MF. Geriatrics. In: Case LP, Daristotle L, Hayek MG, Raasch MF, eds. Canine and Feline Nutrition: A Resource for Companion Animal Professionals. 3rd ed. Elsevier Mosby; 2011:261-275.
- Jewell DE, Schoenherr WD, Debraekeleer J, et al. Macronutrients. In: Hand MS, Thatcher CD, Remillard RL, Roudebush P, Novotny BJ, eds. Small Animal Clinical Nutrition. 5th ed. Mark Morris Institute; 2010:93.
- Saar R. The microbiome and nutrition. Todays Vet Nurse.
2023;6(1):16-22. - Prevention of obesity. American Animal Hospital Association. June 22, 2021. Accessed July 7, 2025. https://www.aaha.org/resources/2021-aaha-nutrition-and-weight-management-guidelines/prevention-of-obesity
- Gross KL, Becvarova I, Armstrong PJ, Debraekeleer J. Feeding young adult cats: before middle age. In: Hand MS, Thatcher CD, Remillard RL, Roudebush P, Novotny BJ, eds. Small Animal Clinical Nutrition. 5th ed. Mark Morris Institute; 2010:373-387.
- Debraekeleer J, Gross KL, Zicker SC. Feeding mature adult dogs: middle aged and older. Hand MS, Thatcher CD, Remillard RL, Roudebush P, Novotny BJ, eds. Small Animal Clinical Nutrition. 5th ed. Mark Morris Institute; 2010:273-280.
- Debraekeleer J, Gross KL, Zicker SC. Feeding young adult dogs: before middle age. In: Hand MS, Thatcher CD, Remillard RL, Roudebush P, Novotny BJ, eds. Small Animal Clinical Nutrition. 5th ed. Mark Morris Institute; 2010:257-272.
- Gross KL, Becvarova I, Debraekeleer J. Feeding mature adult cats: middle aged and older. In: Hand MS, Thatcher CD, Remillard RL, Roudebush P, Novotny BJ, eds. Small Animal Clinical Nutrition. 5th edition. Mark Morris Institute; 2010:389-400.
- Canadian Academy of Veterinary Nutrition (CAVN), Abood SK, Llera R, Downing R. Nutrition for dogs with cognitive dysfunction syndrome (CDS). VCA Animal Hospitals. Accessed June 20, 2025. https://vcahospitals.com/know-your-pet/nutrition-for-dogs-with-cognitive-dysfunction-syndrome-cds



