Depending on breed and gender, body weight can vary widely among adult rabbits. Small breeds like the Netherland dwarf can weigh as little as 1 kg while large to giant breeds can exceed 5 to 7 kg. Many pet rabbits are mixed breeds that fall somewhere in the middle weighing between 2 to 5 kg (Reusch 2010, Vennen 2009) (Fig 1).
Normal conformation can also vary widely among breeds. Dwarf rabbits tend to have small, stocky bodies while giant breeds display a high, curved top line over the rump referred to as a “mandolin shape” by fanciers. Some breeds like the Belgian hare have a relatively long, lean shape (Vella 2012).
Evaluating body condition
Body condition scoring is a technique used to assess body condition in many species. Although no official scoring system exists for rabbits (MSU), evaluation of rabbit body condition can be adapted from methods used in cats, dogs, and large animals (Reusch 2010) (Box 1) (Fig 2).
|Box 1. Evaluating body condition in the rabbit (Reusch 2010, PFMA 2009)|
|Body region||Finding with an ideal body condition|
|Palpate the ribs just behind the elbow||The ribs should only be covered by a light layer of fat, and should be easily palpable with light pressure|
|Bony prominences||The hips, shoulder blades, and spine should be palpable with moderate pressure|
|Dewlap||The dewlap, a large skin fold over the throat, can increase greatly in size in overweight rabbits, however this large dewlap can persist after weight loss|
|Rump area||Flat, although normal conformation varies with breed|
First record the rabbit’s body weight on an accurate scale that changes in increments of 1 gram or less. As body weight increases in the rabbit, excess subcutaneous fat tends to be deposited in the axillary and inguinal regions as well as the dewlap. The dewlap is a large skin fold beneath the chin, usually only visible in female rabbits. The dewlap can become quite large in older breeding does (Fig 3). Excessive abdominal fat can make palpation of internal organs difficult. The rump also becomes increasingly round and then convex as body condition moves from “plump” to “obese”.
Additional abnormal physical examination findings in the overweight rabbit may include:
- Scruffy hair coat
- Skin fold pyoderma
- Urine or fecal staining
Pododermatitis is particularly common in Rex rabbits due to the thin layer of fur present on the on plantar surf of their feet. British giant and French lops are more likely to develop skin fold pyoderma beneath dewlap or around the perineum (Vennen 2009).
Obesity in rabbits
Obesity is a common problem in pet rabbits. Diets high in pellets and restriction of exercise are common underlying causes of weight gain (Vennen 2009). Chronic conditions, like arthritis, as well as old age can also contribute to obesity (Shrubsole 2013).
Obesity can lead to significant morbidity and mortality in rabbits (Shrubsole 2013). Obesity raises the risk of complications from anesthesia. The mesometrium can also serve as a major fat depot, making identification and ligation of blood vessels much more challenging during ovariohysterectomy. Overweight does are also at increased risk for pregnancy toxemia, and overweight rabbits are also at increased risk for pododermatitis or “sore hocks”. Fat can also collect in the skin folds around the perineum, making grooming more difficult. The rabbit may be unable to acquire nutrient-rich cecotrophs and fecal staining can develop (Vennen 2009). Finally, hepatic lipidosis can also develop rapidly if the obese rabbit becomes anorectic.
When owners and veterinary staff evaluate a pet’s body condition, the two groups can come away with very different impressions. In an pet obesity survey sponsored by the Pet Food Manufacturer’s Association, 80% of dog, cat, and rabbit owners believed that their pet was the perfect weight, although no more than one-third were able to correctly identify a photograph showing an animal with an ideal body condition (PFMA 2009).
The challenges involved in correctly evaluating body condition are compounded by the presence of a long or thick coat in many rabbit breeds. Veterinary staff must use the physical examination as an opportunity to teach owners how to physically evaluate their pet’s body condition score.
Owners can then monitor their pet’s body condition on a monthly basis, and if the rabbit is overweight, regular (every 2-4 weeks) weigh-ins on a clinic scale may also be indicated. Giving the owner something concrete to do can be much more successful for weight control when compared to verbal instructions alone (White 2011).