Submitted by: Patricia Shea, DVM
Aging cats prefer warm food.
Eyre R, Trehiou, M, et al.
In both humans and cats, aging changes can be associated with decreased food intake, and full or partial inappetence in older individuals of both species can further contribute to metabolic changes, sarcopenia, and nutrient deficiencies already present with aging in and of itself. This study aimed to evaluate whether the feeding preferences and food intake of cats over seven years old were influenced by the temperature of a meal.
Animals included in the study were 32 healthy domestic shorthair cats, all of whom were spayed or neutered. The average age of the cats was 11.11 years (range, eight to 14 years old), with an average weight of 4.4 kg (range, 3.5-5.6 kg); there were 14 males and 18 females. The subjects were group-housed in rooms with 12-16 cats per room in a pet health nutrition research facility, and all were acclimated to the housing situation, the food consistency (chunks in gravy), and the testing procedures prior to commencement of the study. Each cat was individually fed in a private feeding station. A chunk in gravy product was fed at three different temperatures: 6°C, typical of refrigerated food; 21°C, common room temperature; and 37°C, approximating mammalian body temperature.
Study cats took part in three separate two-day, two-bowl difference tests. The most preferred food temperature in all two-bowl food comparisons was 37°C, while the least preferred food temperature was 6°C. In all three of the two-bowl difference tests, significantly more food served at 37°C was consumed than food served at another temperature, although the difference between the amounts eaten of the 37°C meal and the 21°C meal was less significant than in the 37°C – 6°C pairing and the 21°C-6°C pairing. This is consistent with prior research findings, that cats prefer food served at blood temperature (37°-40°C), approximately the temperature at which they would consume fresh prey.
Other changes in food palatability and acceptability can occur with variations in meal temperature. The viscosity of the gravy, when separated from the chunks, did not change with the serving temperature of the food. However, there were significant changes in the volatile profile with the serving temperature of the meal. As the serving temperature of the meal increases, there are marked increases in acids, especially hexanoic acid (known to be a palatability enhancer for dogs) and sulfur-containing compounds. The latter is very important in meat flavors. Terpenes, which are aromatic compounds responsible for many plant scents, including orange peel, decrease significantly when wet cat food is heated. Orange oil has been utilized as an off-putting flavor in other feeding studies of cats and has been shown to reduce short-term food intake in this species. Aldehydes also decrease when product temperature is increased; these substances, especially hexanal, are associated with oxidation of lipids and consequent rancidity, which may have a negative effect on food palatability. Based on these findings, heating food, which changes its volatile profile in the headspace directly above the meal, is likely to enhance the attractiveness of the food.
Research in humans has demonstrated that aging is associated with a gradual decline in smell and taste. These aging changes are likely to occur in cats as well and could explain why older cats prefer warmed food. Heating wet food to near body temperature is an easy step that owners at home and professional staff caring for cats in boarding, shelter, and veterinary settings can take to increase interest in food and food consumption by cats in both health and disease. Offering this consideration is especially crucial in supporting food intake in those animals with fussy or picky appetites, and/or who are not consuming enough food to maintain healthy body weight and muscle mass.
J Am Vet Med Assoc 2022; 260:S24-S28.
Outcome of appendicular or scapular osteosarcoma treated by limb amputation in cats: 67 cases (1997-2018).
Nakano Y, Kagawa Y, et al.
Osteosarcoma, a tumor of malignant mesenchymal spindle cells which produce osteoid, and other primary bone tumors are rare in cats. Literature published in the late 20th Century reported low metastasis rates for osteosarcoma, which is the most common of feline primary bone tumors. Previous studies of cats with this tumor treated with limb amputation alone reported significantly longer survival times due to low metastasis rates.
Varieties of osteosarcoma include osteosarcoma of medullary origin, parosteal osteosarcoma, fracture-associated osteosarcoma, and extraskeletal osteosarcoma. Medullary origin osteosarcoma can occur in either the axial or appendicular skeleton; appendicular osteosarcoma is slightly more common than that of the axial skeleton and is seen more often in the hindlimbs than in the forelimbs. The distal femur, proximal tibia, humerus, and digits are the most frequent sites of occurrence of osteosarcoma of medullary origin.
This retrospective cohort study included 67 cats with appendicular or scapular osteosarcoma treated with limb amputation. The osteosarcoma diagnosis was confirmed histologically by a pathology service at one of several reference laboratories. Following surgery, questionnaires were sent to the veterinary clinics where the limb amputation was performed to investigate the patients’ outcomes. Data gathered included body weight, tumor location, presence of lameness, radiographic abnormalities, distant metastasis at the time of amputation, use of other treatments (surgery, radiotherapy, chemotherapy, NSAIDs), date of tumor recurrence, lymph node metastasis, date and cause of death, and other potentially pertinent information. The outcome of this study demonstrated that metastasis of osteosarcoma in the cat may not be as rare as previously thought.
The median age of the cats was 11 years (range, 8-13 years). Five were intact males, 33 were neutered males, six were intact females, and 23 were spayed females. The body weight of the animals ranged from 3.5-5.3 kg, with a median of 4.5 kg. Most cats (n = 53) were mixed breed; six were American Shorthair, two were Norwegian Forest Cats, one was a Scottish Fold, and five were of unknown breed. Lameness prior to amputation was evident in 91% (60/66), and radiographic abnormalities before amputation were present in 64/65 (98%). Five of the cats had distant metastasis, one to bone and the other four pulmonary, at the time of limb amputation, and one had axillary lymph node metastasis at the time of surgery.
The median follow-up time was 324 days (range, from 151-566 days). Six cats had local recurrence of their tumor during follow-up, five of which had an amputation site close to the tumor. Lymph node metastasis occurred in two cats following surgery. The rate of distant metastasis after limb amputation was a significant 41.9% (26/62 cats); if the five cats with distant metastasis discovered prior to limb amputation are included, this rate increases to a total of 31/67 cats, or 46.3%–almost half—experiencing distant metastasis of their osteosarcoma. The median time from amputation to distant metastasis in 26 cats with post-amputation metastasis was 235 days (range 120-265 days). No significant association was found between the age of the patient and the presence of distant metastasis.
Tumor location in the study cats represented a variety of sites. Seven cats had humeral osteosarcoma, and a different seven had this tumor in the radius or ulna. Four cats had osteosarcoma of the carpus, ten in the scapula, 22 in the femur, 12 in the tibia or fibula, seven in the metatarsus or phalanges of the hindlimb, and none in the metacarpus or phalanges of the forelimb, or in the tarsus. One patient is represented twice in this count because they had lesions in both the femur and the tibia.
The location of the tumor was significantly associated with the finding of distant metastasis. Humeral osteosarcoma was more likely to be associated with distant metastasis than osteosarcoma in other bones. Six out of seven (85.7%) of the patients with osteosarcoma of the humerus had distant metastases, while distant metastasis occurred in 41.7% (25/60) of the cats with non-humeral osteosarcoma. Similar findings are reported in humans and dogs: a proximal humeral tumor in canines is a negative prognostic factor for survival time and disease-free interval. Poorer metastasis-free survival is also noted in humans with osteosarcoma of the proximal humerus. The median overall survival time of all study cats was 527 days (range, from 284 to 1,678 days). In the patient population studied, neither age nor tumor location was associated with survival time.
The authors recommend that owners be informed that distant metastasis may occur in around 40% of cats with appendicular or scapular osteosarcoma undergoing limb amputation and that detailed follow-up studies, including imaging, are strongly recommended, especially in those diagnosed with osteosarcoma of the humerus. Post-operative adjuvant chemotherapy should also be seriously considered.