Puppy growth charts
Growth charts for children are nothing new, but recent work has resulted in the concept being developed for dogs, and they are now an essential part of the veterinarian’s toolkit.
The Waltham Centre has developed charts as a tool for veterinary healthcare teams to help assess whether a puppy’s growth is correct for its age.
Growth charts can be an integral part of routine checks for puppies and will help ensure that they are receiving the correct nutrition as they develop.
Ten growth charts are currently available for dogs, organized by gender (male vs. female) and by estimated adult size.
Generic growth charts are not suitable for giant breeds (>40kg), so the veterinarian should construct a unique chart for individual dogs in this category.
Puppy and kitten consultations are a daily occurrence for the veterinary team, and they tend to be enjoyable for all concerned, but they are also hugely important when it comes to getting a new pet off to the best possible start. At least part of the consultation should involve a discussion on how to ensure the most appropriate diet for the new arrival – so before talking about growth charts, it is important to first review why conversations about nutrition are so important to incorporate into these initial visits.
Why talk about nutrition?
Socialization and habituation
Visits to the clinic every few weeks for weight checks can be a great way to not only monitor the growth of the patient, but also to socialize a new puppy. Pets may learn to have positive associations with the clinic if they get praise and treats for things like going on the scale or allowing a brief physical exam for assessment of body condition score (BCS).
New puppies and kittens will visit the clinic a lot in their first year – for vaccine appointments, testing for heartworm and other parasites, and spay and neuter surgery. These are all great opportunities to check in with the pet owner and to assess how well their new family member is growing, and to see whether they have questions about what they are feeding (Figure 1).
The Association for Pet Obesity Prevention reported in 2018 that nearly 60% of pet dogs and cats in the US were overweight or obese 1. Weight loss plans can be tough! Owners may take some convincing before they are even ready to broach the topic of weight loss, and helping a pet achieve an ideal body condition score when they have maybe 15 or 20% (or even more) excess body fat can take time. Veterinary healthcare teams need to be comfortable having these difficult conversations and initiating a weight loss plan, but another approach to the obesity epidemic is to focus on prevention. What better time to prevent obesity than when the pet is still young and healthy? If the team can talk about the risks of obesity at this stage, and provide eager owners with tools to prevent their new pets from getting too heavy, it may be possible to reduce the number of animals that become overweight or obese. If pet parents are trained on matters such as ideal weight gain, body condition scoring, portion control and “smart” treats, they will be more receptive to early recommendations if their pet starts to put on too much weight.
Owners want to talk about nutrition with their pet’s veterinary healthcare team, and having these conversations early on in a pet’s life demonstrates a proactive approach and conveys the message that the veterinary clinic is the best source of good information when it comes to nutrition. In this way, when pet parents get dietary recommendations from their breeder, friend, pet store employee, or other well-meaning person, they will hopefully bring that recommendation back to the clinic to double check before following it.
Owner interest and readiness to learn
There is a reason why everyone loves puppy or kitten appointments – aside from the chance to cuddle a healthy and adorable patient. New pet parents are just as excited as the veterinary healthcare team and often look forward to showing off their cute new family member. These owners are also likely to be more determined to do everything they can to keep their pet healthy and are often motivated to listen to advice on how to provide the best nutrition. Suggestions like weighing food with a gram scale or avoiding high calorie treats may seem daunting to owners of sick pets, as they may be overwhelmed with many other treatment recommendations, and nutrition gets bumped to the bottom. New pet parents can be more eager and receptive to these types of suggestions, and if they learn that behavior early on, it can be much easier to keep it up for the duration of the pet’s life. Furthermore, research investigating communication with clients in a veterinary setting has found that pet owners want to be in a partnership with the veterinarian 2. By having nutrition conversations earlier on, we can establish this partnership with our clients and have a stronger veterinary-client relationship.
With all of that in mind, it is time to look at an exciting tool that every veterinary healthcare team should have in their nutrition toolkit – Growth Charts.
What are growth charts?
Growth charts may be more familiar to any pet owners that also have children, as they are a tool used by pediatricians and nurses to track the growth of infants and youngsters. They consist of percentile curves using a series of measurements (height, weight, body mass index (BMI) and age) 3, and have been used in human medicine since 1977 as a tool to assess whether a child’s growth is adequate. In a similar way, growth charts for dogs have now been developed by the Waltham Centre, an institute for science and research owned by Mars Petcare 4. These charts were developed based on data from tens of thousands of healthy dogs and they now provide a tool for veterinary healthcare teams to help assess whether a puppy’s growth is on track for its age.
However, one additional factor that had to be considered during the development of the Puppy Growth Charts is that there is a huge variety in dog breeds – so one size does not fit all for a growth curve. There are therefore currently ten growth charts available for dogs – organized by sex (male vs. female) and by estimated adult size (<6.5 kg, 6.5-9 kg, 9-15 kg, 15-30 kg, and 30-40 kg) 5.
What information is needed?
In order to use a growth chart for a puppy, the following information is required:
- Sex of the puppy – there are separate charts available for males and females
- Estimated adult weight of the puppy; this can be determined either by using the weight of the parents (note that this assumes the parents are in ideal body condition) or via the breed standard
- Age of the puppy in weeks
- Weight of the puppy in kilograms
Once these details are to hand, the correct growth chart can be printed off, and the puppy’s weight and age plotted. For downloadable PDFs of all 10 growth curves available, visit: https://www.waltham.com/resources/puppy-growth-charts.
Growth charts were developed based on data from tens of thousands of healthy dogs and they now provide a tool for veterinary healthcare teams to help assess whether a puppy’s growth is on track for its age.
How often should you measure?
In order to interpret the data most accurately, frequent measurements are needed, especially early in the puppy’s life. This allows determination of what percentile curve the puppy is starting out on within the first couple of months of life, which gives a better idea of what the target weight should be at any given age. At a minimum, puppies should be weighed every two weeks, but the best option is to weigh them weekly. Make sure that these weights are recorded at the same time of day, as time of last meal, bowel movements and hydration status can all cause the weight to fluctuate during the day.
Bringing a puppy in for weekly weight checks may not be possible for some owners with busy schedules or who live further away, so the following home-based options can be considered:
- Bathroom scales: if the owner can safely lift the puppy, they can weigh themselves with the puppy and then subtract their own weight.
- Luggage scales: small puppies can be put into a pet carrier and weighed on luggage scales – again subtract the weight of the empty carrier from the gross weight.
- Pet scales: these can be purchased online and will range in cost depending on the size of the scales.
If the owner is able to do some weekly weights at home, ideally the puppy should still attend the clinic for an assessment every four weeks (which will often line up with booster vaccine appointments), allowing the veterinary healthcare team to both ensure the puppy is growing well and to perform a BCS assessment.
Putting the growth curve to work
Once a growth chart for a patient has been started, it is important to use it properly! The chart will give a fairly accurate prediction of the expected growth rate of a puppy once the percentile curve they are growing on is established. A recent study compared healthy dogs and dogs with abnormal body condition to their growth chart data 6 and found that departure from the original percentile line was very rare in healthy dogs, but dogs who were obese by the age of three years showed more rapid growth, and the majority had crossed two or more percentile lines during their growth period. The chart should therefore be used to check that a puppy is growing according to the percentile curve that they started with, and they should avoid crossing a percentile line. If a puppy approaches a line above their curve, they are growing too quickly, and energy intake should be reduced, whereas if they approach a line below their curve, they are growing too slowly, and energy intake should be increased.
What else should be done at weight checks?
The weight checks do not simply include a visit to the scales and a recording of weight on the growth chart. The veterinary healthcare team can use this opportunity to check in on a few other important topics:
- Diet history: ask what food the puppy is eating and how much. The owners may have switched foods since the last visit, or adjusted the portion size on their own.
- BCS: the body condition score system is not yet validated in puppies, but it can still be useful in conjunction with weight and the growth chart to determine if the puppy is over- or under-weight. It can also help get the puppy accustomed to having this assessment performed, and the owner may be encouraged to do a regular BCS at home.
- Activity: ask about the puppy’s activity levels – are they starting obedience classes or going for more walks? An increase in activity may warrant an increase in energy intake.
Limitations of growth charts
- Giant breed dogs (i.e., those exceeding an adult body weight of 40 kg): the growth charts currently available stop at 40 kg, as researchers found that giant breed dogs have variable breed-dependent growth, which prevents the creation of standard curves 5. For a giant breed patient, the veterinarian can still follow all of the suggestions above, but should create a unique chart to track weight and age. This allows monitoring of the growth patterns and the energy intake can be adjusted if a large increase in weight is noted, or if the pet gains less weight than expected.
- Mixed breed dogs: the growth charts can be used for mixed breeds, but the challenge here is that identifying the target adult weight of a puppy may be difficult if the breed makeup is uncertain. The author’s recommendation is to make a “best guess” and use the first few recorded weights to help decide whereabouts the puppy might fall on a growth curve. Another option is to suggest genetic testing if the owner is interested to know what their pet’s make-up involves.
- Cats: there are currently no growth charts published for cats, but as with the comments above for giant breeds, it is possible to make a chart for each patient using its individual data and following the same guidelines.
Case example – Remus
Remus is a male Shepherd X Collie mix puppy (Figure 2) adopted from a shelter by his new owner, and who started to feed him a commercial puppy food designed for German Shepherds. Remus had his weight recorded at his first clinic visit when he was 10 weeks old, and his owner had his 8-week weight from the adoption shelter. Given that he is a mixed breed dog, it was more challenging to determine what his adult weight would be, but the 30-40 kg chart was chosen as the best match for him.
His weight at 10 weeks was 6 kg, and this was plotted on the growth curve. His owner decided to feed him a commercial food formulated for puppies, specifically Royal Canin Puppy Large dry food. This food provides 366.7 kcal per 100 grams, or 352 kcal per cup. Remus’ energy requirement was estimated to be 805 calories per day (RER multiplied by a DER factor of 3 since he was under 4 months of age *) 7 (2 X RER is typically used for a puppy over 4 months of age, whilst neutered adult dogs usually require between 1.4-1.6 X RER, although this can be higher or lower depending on activity levels). Remus was prescribed a daily ration of 2 ¼ cups (792 calories).
* RER = resting energy requirement; DER = daily energy requirement
His follow-up weights at 14 and 18 weeks were 12 kg and 16 kg respectively (Figure 3) which corresponded to the 50th percentile trend. His food amount was increased to 3 ¼ cups (1,144 calories) at this latter point. Remus was next seen at 6 months of age for a heartworm test and to weigh for oral preventative medicines. His weight at this visit was 25 kg which, according to the growth chart, was slightly higher than predicted by his growth curve (Figure 4). At this time, he was being fed a total of 4 ½ cups (1,584 calories) per day, so a 10% reduction in calorie intake was recommended (i.e., 389 grams (1,426 calories)). His owner was also instructed to weigh his food on a gram scale for better precision 8, and since she was concerned that he would beg more if his food amount was reduced, she began to feed him with a food puzzle (Figure 5).
Remus then came in for follow up assessments at 28 and 30 weeks; his weight at 28 weeks was 26 kg and since it seemed to be trending closer to the curve (Figure 6), no change in food amount was recommended. At 30 weeks, his weight was back on the 50th percentile curve, with him weighing in at 27 kg. Remus’ owner decided to purchase a scale to use at home so she could weigh him more frequently and adjust his food intake up or down if needed (Figure 7). His weight on his first birthday was reported to be 32 kg, which according to the growth chart was exactly where he was predicted to end up!
Ultimately, our goal as veterinarians is to set pet owners up for success, and the best time to start this is at the early stages of puppy and kittenhood. Having conversations around nutrition, selecting an appropriate food, and advising on proper portion control are all part of the veterinary team’s responsibility, along with monitoring weight and body condition, and advising on the use of low calorie treats and a gram scale to weigh food. Introduction of all these measures at an early stage can help to educate owners on how to ensure their pet is healthy and allow them to live a long and happy life.
Association for Pet Obesity Prevention. https://petobesityprevention.org/ Accessed October 8, 2021.
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Centers for Disease Control and Prevention. Growth charts – 2000 CDC Growth Charts – United States 2016. www.cdc.gov/growthcharts/cdc_charts.htm Accessed October 8, 2021
Puppy growth charts | Waltham Petcare Science Institute. www.waltham.com/resources/puppy-growth-charts Accessed October 8, 2021.
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