Nutritional secondary hyperparathyroidism in six cats

Atraumatic Fractures in Multi-Morbid Older Adults: A Series of Five Cases and Review of Literature

Atraumatic fractures (ATFs) are a fragility fracture subtype with occasional medicolegal issues. ATFs are defined as fractures because of a "low-energy mechanism that is usually considered incapable of producing a fracture." They are an underreported disorder, with epidemiological variations. ATF phenomena were previously reported not only in older adults, but also in children, young adults, older adults, and animals. This study is a short retrospective case series exploring atraumatic fractures in a tertiary care university hospital. Over a period of two years, a total of seven ATF cases were identified. However, only five fulfilled the inclusion criteria. Local causes of pathologic fractures (e.g., metastasis) and elder abuse or neglect were excluded. Comparison of the cases' clinical profile, fracture profile, and management was done. All five cases were frail females with significant osteotoxic burdens from medications and multi-morbidities. ATF presentations included typical (as pain) and atypical (as painless, loud crack, and sudden giveaway) symptomatology. One ATF had a coincident unexplained aseptic fever. Three cases had more than one fracture (fracture cascade), confirmed and followed up by x-rays. All the cases were managed conservatively except for one case that underwent hip hemiarthroplasty. Plans of care included managing the osteotoxic multi-morbidities burden, focusing on the whole body, not only on the fracture or bone. The study provided insights about challenges in presentations of ATF (as the bone fracture acute phase reaction: osteogenic aseptic fever). Risk factors are classically assumed to be osteoporosis, but it is usually systemic and multifactorial. A high risk of fracture warning sign could help decrease ATF occurrence or fracture cascades. Four ATF categories were detected to help healthcare systems identify high-risk patients and raise awareness among medical staff, families, and caregivers. Future studies of the at-risk groups are needed to understand ATF knowledge gaps, challenges, and the best treatments.

Feline precision medicine using whole-exome sequencing identifies a novel frameshift mutation for vitamin D-dependent rickets type 2

OBJECTIVES

A 14-week-old female domestic longhair kitten presented with shifting lameness and disproportionately smaller size compared with a co-housed littermate.

METHODS

Hematology and serum biochemical testing were conducted to investigate causes for delayed growth, and radiographs of the appendicular skeleton were obtained.

RESULTS

The afflicted kitten had marked hypocalcemia, mild hypophosphatemia and substantial elevations in alkaline phosphatase activity, as well as pathognomonic radiographic findings consistent with rickets. Skeletal changes and hypocalcemia prompted testing of concentrations of parathyroid hormone (PTH) and vitamin D metabolites. Endocrine testing demonstrated significant increases in serum concentrations of PTH and 1,25-dihydroxycholecalciferol (calcitriol), supporting a diagnosis of vitamin D-dependent rickets type 2. Provision of analgesia, supraphysiologic doses of calcitriol and calcium carbonate supplementation achieved normalization of the serum calcium concentration and restoration of normal growth, although some skeletal abnormalities persisted. Once skeletally mature, ongoing calcitriol supplementation was not required. Whole-exome sequencing (WES) was conducted to identify the underlying DNA variant. A cytosine deletion at cat chromosome position B4:76777621 in VDR (ENSFCAT00000029466:c.106delC) was identified and predicted to cause a stop codon in exon 2 (p.Arg36Glufs*18), disrupting >90% of the receptor. The variant was unique and homozygous in this patient and absent in the sibling and approximately 400 other cats for which whole-genome and whole-exome data were available.

CONCLUSIONS AND RELEVANCE

A unique, heritable form of rickets was diagnosed in a domestic longhair cat. WES identified a novel frameshift mutation affecting the gene coding for the vitamin D3 receptor, determining the likely causal genetic variant. Precision medicine techniques, including whole-exome and whole-genome sequencing, can be a standard of care in cats to identify disease etiologies, and to target therapeutics and personalize treatment.

Nutritional secondary hyperparathyroidism in a kitten, supported by immunoenzymatic measurement of feline intact parathyroid hormone

A 6-mo-old, intact male, domestic shorthair cat was referred with a history of poor growth, reluctance to move, and deformation of the nasal profile. The kitten had been fed a diet composed almost exclusively of a complementary pet food and tuna, which was similar to an all-meat diet. We detected osteopenia and hypocalcemia associated with severe parathyroid hormone (PTH) and calcitriol increases; we measured PTH concentrations with an immunoenzymatic method that has been validated in cats. Dietary correction, consisting of a complete and balanced wet pet food formulated for growth, resulted in normalization of calcium and PTH concentrations within 2 mo.

Commercial vs Homemade Cat Diets: What you need to know

PRACTICAL RELEVANCE

A feeding plan recommendation for cats, both healthy and with disease, should include diet choice, amounts to feed and the feeding method. Diet choice can be complex owing to the abundance of products, sometimes with conflicting marketing messages, and the prevalence of information with no scientific basis. It is important to be aware of the specific challenges of both commercial and homemade diets. Moreover, a nutritional assessment is a prerequisite when recommending a diet to ensure that it is safe, appropriate for the cat's life stage and nutritious for long-term feeding.

COMMERCIAL VS HOMEMADE DIETS

There are a variety of commercial diets available, allowing considerable customisation. These products are regulated and can be tested to determine nutritional adequacy and safety, although as the industry is partly self-regulated, choice of manufacturer is important. Properly formulated homemade diets can be customised to the patient and are a good option when no commercial product that meets the patient's needs exists. Homemade diets can be an owner preference. A serious limitation is the lack of testing, potentially affecting safety and also resulting in a reliance on database information to determine nutritional adequacy. Generic homemade diet recipes (eg, sourced from the internet) have additional risks of deficiencies and imbalances, and are not recommended. Homemade diets should be devised by a veterinary nutrition specialist with consideration of both patient and owner factors.

CLINICAL CHALLENGES

Dietary misinformation, which is all too readily available on the internet, may result in owners making questionable feeding choices for their pets. A homemade diet may be requested by owners based on the perception that there are poor ingredients in commercial foods. The veterinary healthcare team needs to have good evidence-based information to present to owners about diet choice.

EVIDENCE BASE

Several decades of research on feline nutrition forms the basis for nutritional requirements and dietary recommendations. There are varying degrees of evidence regarding requirements for each nutrient, and a lack of data on the effects of different types of processing on nutrient needs.

Evaluation of the nutrients supplied by veterinary diets commercialized in Brazil for obese dogs undergoing a weight loss program

During a weight loss program, energy restriction is performed, which can result in nutrient intake below the minimum recommendations if a proper diet is not offered. A common recommendation for dogs undergoing energy restriction is to use a veterinary diet formulated for the management of obesity to potentially reduce the likelihood of nutritional deficiencies. The objective of this study was to perform bromatological and essential mineral analysis in veterinary diets for the management of canine obesity available in the Brazilian market and to analyse whether these diets provide the recommended amount of nutrients per kg of metabolic body weight (kg BW^0.75 ) for animals undergoing energy restriction. Samples of all veterinary diets for the management of canine obesity available in the Brazilian pet food market were analysed (n = 8). The nutrient supply per kg BW^0.75 was calculated and compared with the NRC recommended allowance and FEDIAF recommendations by descriptive statistics. For this purpose, the weight loss energy requirement equations of 70 kcal/target body weight^0.75 and 63 kcal/target body weight^0.75 were used, in which target body weight corresponds to 10%-40% of the initial body weight according to the body condition score. The manufacturers' intake recommendations were also evaluated and compared to the NRC and FEDIAF recommendations. Almost all of the diets (n = 7/8) had at least one nutrient below the NRC and FEDIAF recommendations when target weight of minus 10%, 20% or 30% was considered, and all diets had at least one nutrient deficiency when the target weight was minus 40%. When the energy intake was restricted a further 10%, all diets had at least one nutrient below recommendations at the minus 30% target weight. The nutrients for which the recommendations were not met were as follows: calcium, magnesium, potassium, selenium, sodium, protein and fat. When compared to the manufacturers' recommendations, nutrient deficiencies were observed in all of the diets when compared to the NRC and in 7/8 when compared to FEDIAF, and all diets had at least one deficiency when compared to both NRC and FEDIAF after an extra 10% calorie restriction. It was concluded that the majority of veterinary diets formulated for weight loss/obesity management in Brazil did not meet all the recommendations of the analysed nutrients, which reinforces that diets for weight loss should be used according to veterinary prescription and should ideally be prescribed by nutrition specialists that can better understand the limitations of the diet's composition.

Analytical Validation of a New Immunoenzymatic Method for the Measurement of Feline Parathyroid Hormone in Cats with Chronic Kidney Disease

Simple Summary

Parathyroid hormone (PTH) is involved in many metabolic diseases, such as chronic kidney disease (CKD) and calcium disorders, and its measurement could be of clinical utility. However, available methods for the measurement of feline PTH are limited and not widely accessible. The aim of this study was to perform the analytical validation of a new method for PTH measurement in cats. Thirty-eight cats affected with CKD were included. The analytical protocol provided an evaluation of the precision, accuracy, and storage stability at different temperatures. The method investigated showed good precision and accuracy and good stability for 1 week of storage at freezing temperatures. The method was validated in cats, allowing its future use in diagnostic procedures.

Abstract

The determination of parathyroid hormone (PTH) in cats could be of clinical utility in many metabolic disorders, such as renal diseases, hypercalcemia, or nutritional imbalances. However, the available methods for the measurement of feline PTH are limited, not widely available, and need radioimmunoassays. The aim of this study was to perform the analytical validation of a new immunoenzymatic method for the measurement of feline PTH. Thirty-eight cats affected with chronic kidney disease (CKD) were included. PTH was measured using a two-site immunoenzymatic method validated in humans and dogs (ST AIA-PACK^® Intact PTH, Tosoh Bioscience, Tessenderlo, Belgium). The analytical validation provided the evaluation of precision (intra-assay and inter-assay), accuracy (linearity under dilution (LUD) and spike recovery test (SRT)), and the storage stability of serum samples at 20 °C, 4 °C, and −20 °C. The method showed good precision (intra-assay CVs (coefficient of variations) 3.19–9.61%; inter-assay CVs 9.26–15.28%). In both the intra- and inter-assays, the highest imprecision was found with the low concentration pool (9.61% and 15.28%) and accuracy (LUD and SRT r² = 0.99, p < 0.001), while the stability was optimal up until 7 days at −20 °C (−7.7%). The method was successfully validated in cats, allowing its future use in diagnostic procedures.

Vitamin-mineral supplements do not guarantee the minimum recommendations and may imply risks of mercury poisoning in dogs and cats

Given the importance of using the vitamin-mineral supplements to guarantee the minimum nutritional recommendations for pets in homemade foods, and hypothesizing that these products may contribute to toxic metals contamination, the present study aimed to determine the concentrations of essential minerals and toxic metals in vitamin-mineral supplements available in the Brazilian market and calculate if the amount recommended by the manufacturer guarantees the minimum recommendations of NRC (2006) and FEDIAF (2020), as well as calculating the amount of toxic metals that animals would consume, according to the amounts recommended by the manufacturer. Seven vitamin-mineral supplements were analyzed. The determination of essential minerals and toxic metals was performed using ICP-OES. Comparisons were made with the minimum recommendations for essential minerals, and with the maximum tolerated levels of toxic metals established by the FDA (2011), descriptively. Most of the vitamin-mineral supplements, in the quantities recommended by the manufacturers, do not guarantee the minimum recommendations of NCR (2006) and FEDIAF (2020) for the following elements: calcium, potassium, magnesium, sodium, phosphorus, selenium, and zinc. Only one supplement had detectable selenium concentrations. Three supplements provided more than 0.02mg of mercury/kg of body weight, the safe upper limit used to establish the maximum tolerated level of this element. It is concluded that most vitamin-mineral supplements do not meet the minimum recommendations for most essential minerals and, if formulated by untrained professionals, even with supplementation, homemade foods may still be nutritionally deficient. Furthermore, some vitamin-mineral supplements analyzed may imply risks of mercury poisoning in pets.

The Role of Vitamin D in Small Animal Bone Metabolism

Dogs and cats have differences in vitamin D metabolism compared to other mammalian species, as they are unable to perform vitamin D cutaneous synthesis through sun exposure. Therefore, they are dependent on the dietary intake of this nutrient. The classic functions of vitamin D are to stimulate intestinal calcium and phosphate absorption, renal calcium and phosphate reabsorption and regulate bone mineral metabolism. Thus, it is an important nutrient for calcium and phosphorus homeostasis. This review highlights the evidence of the direct and indirect actions of vitamin D on bone mineral metabolism, the consequences of nutritional imbalances of this nutrient in small animals, as well as differences in vitamin D metabolism between different size dogs.

Unusual presentation of vitamin D3-dependent rickets type II in a kitten

Case summary

A 15-week-old kitten presented with a 1-month history of intermittent generalised tremors and abdominal distension. Hypocalcaemia associated with increased 1,25-vitamin D₃ was consistent with vitamin D₃-dependent rickets type II. The bone appearance on CT scan was most consistent with the changes typically seen with nutritional secondary hyperparathyroidism and less typical of the changes seen with rickets. Our patient had a positive response to high vitamin D₃ therapy as it remained normocalcaemic 16 months after diagnosis, supporting the diagnosis of rickets.

Relevance and novel information

This case report is an unusual and interesting presentation of rickets in a kitten. Despite the characteristic vitamin D₃ disturbance for rickets type II, the atypical radiographic changes have not been previously reported. In the literature, a positive response to treatment is not commonly seen or follow-up is short. Our case responded well to treatment and was followed for 16 months from the time of diagnosis. This emphasises that the pathophysiology of the condition is not well understood, and that different types of vitamin D₃-dependent rickets type II may exist. Although the genetic defects responsible for some cases of rickets type I have been identified, this has still not been determined for rickets type II.

Radiographic Evaluation of Keel Bone Damage in Laying Hens-Morphologic and Temporal Observations in a Longitudinal Study

The keel bone of commercially kept laying hens is known to be frequently affected by morphologic changes such as fractures and deformations with important implications for animal welfare. To detect morphologic changes, various methods such as palpation, computed tomography, and ultrasound are available, though radiography allows for the greatest level of detail in combination with the most ease of use. To explore the benefits of radiography in providing objective data on keel fractures from the age of 22–61 weeks within a single laying period, the keel bones of 75 Lohmann Brown and 75 Lohmann Selected Leghorns were radiographed every 3 to 5 weeks. Type, location, angulation, dislocation, callus formation, and healing process were assessed descriptively for each lesion. Ninety-nine percent of the animals showed at least one keel bone lesion during the study and 97% of the animals had at least one keel bone fracture. In 77% of the cases, the caudal third of the keel bone was affected. The fracture types were transverse and oblique (88%), comminuted, and butterfly. Further lesions were sclerosis, new bone formation and angulation. For each keel bone, an average of three fractures (3.09 ± 1.80) was detected at the end of the study. The described radiographic protocol for keel bone lesions was suitable for longitudinal, on-site examinations in conscious laying hens. Our results also indicate that keel bone fractures are more frequent than reported in earlier studies. The described radiographic examination protocol can be used to perform comparative studies of palpatory findings, or to assess the clinical significance of different fracture types which require a high level of detail.

The effects of crossbreeding, age, and sex on erythrocyte indices and biochemical variables in crossbred pet rabbits (Oryctolagus cuniculus)

BACKGROUND

A number of domestic rabbit (Oryctolagus cuniculus) breeds exist, and the pet rabbit population consists of a variety of pure- and crossbred animals. However, the reference intervals (RIs) for rabbits are limited by outdated methods and a single-breed source.

OBJECTIVE

This study aimed to establish more complete, updated erythrocytic and biochemical RIs for the crossbred pet rabbit population to improve routine diagnostic accuracy in clinical practice, and to examine the effects of crossbreeding on erythrocytic and biochemical parameters.

METHODS

Blood specimens were collected from 85 clinically healthy crossbred pet rabbits representing a wide range of breeds. RIs for the erythrocyte indices and 12 chemistry analytes were determined as recommended by the American Society for Veterinary Clinical Pathology guidelines. The results were compared with four widely used RIs. Age and sex differences for all variables were statistically analyzed.

RESULTS

The results diverged from the RIs for New Zealand white rabbits, indicating that not all RIs from this species are appropriate for use in exotic animal practices. Breed-associated variations were evident for aspartate amino transferase, alkaline phosphatase, and glucose, while crossbreed effects were found for total protein, albumin, blood urea nitrogen, creatinine, calcium, and phosphate. Statistically significant differences and clinical relevance among age groups were detected for hemoglobin, hematocrit, and creatinine.

CONCLUSIONS

Establishing RIs specifically for crossbred pet rabbits is desirable for clinicians treating pet rabbits of various breeds and ages. Age-specific RIs for this population warrants further investigation.

Nutritional inadequacies in commercial vegan foods for dogs and cats

The objective of this study was to evaluate the macronutrients composition, fatty acid and amino acid profiles, and essential minerals content of all vegan foods for dogs and cats available in the Brazilian market, and to compare results with FEDIAF (2019) and AAFCO (2019) recommendations. Four vegan pet foods were assessed (three for dogs and one for cats). The comparisons were made in a descriptive manner. All foods met the minimum recommendations for macronutrients. Arachidonic acid was not reported in any food label. Regarding the FEDIAF recommendations, one food for dogs had low calcium, another had low potassium and a third had low sodium. The cat food presented potassium content lower than recommended. The Ca:P ratio did not meet the minimum recommendation of FEDIAF (2019) and AAFCO (2019) in any of the dog’s foods analyzed, and the cat food also did not present the minimum recommendation based on FEDIAF (2019). Copper concentrations exceeded the legal limit in all foods. Zinc concentrations exceeded this limit in two foods (one for dogs and one for cats) and iron levels exceeded the legal limit in one dog food. One of the dog foods did not meet the minimum recommendation for methionine and the cat food did not meet the minimum recommendation for arginine. In addition, when the amount of nutrients consumed by animals with low energy requirements was simulated, in addition to the same non-conformities described above, it was observed that the cat food does not meet the minimum recommended of protein and taurine in unit/Kg^0.67. It was concluded that all foods analyzed had one or more nutrients below the recommended levels and some presented zinc and copper excess, therefore, these foods should not be recommended for dogs and cats, because dietary deficiencies found may lead to health risks for dogs and cats. Furthermore, manufacturers should review their formulations to ensure the nutritional adequacy of these foods.

Hole-in-the-head disease in discus fish, Symphysodon (Heckel, 1840): Is it a consequence of a dietary Ca/P imbalance?

Hole-in-the-head (HITH) disease-affected fish develop characteristic lesions in the skin above sensory pores of the head and the trunk. This study investigated whether an unfavourable Ca/P ratio in the diet could provoke lesions consistent with HITH disease in discus fish Symphysodon (Heckel, 1840) as a comparable condition to secondary hyperparathyroidism of tetrapod species. Two groups of five fish were fed a plain beef heart diet (Ca/P of 0.03), whereas two other groups were kept on commercial discus feed (Ca/P of 2.73). Each feeding group was submitted to two different water hardness regimes (35.66-71.39 mg/L CaCO₃ and 124.94-196.33 mg/L CaCO₃ , respectively). All fish were observed for the development of the characteristic lesions for 16 weeks. At the end of the study, histological, bacteriological and parasitological examinations were conducted and plasma Ca, P and Mg values were determined. Diplomonad flagellates were detected in two fish. Isolated bacteria of all groups mostly belonged to Aeromonadales and Pseudomonadales. No significant difference of plasma mineral values between the groups was observed. Compared to the results of other authors, Ca stayed mainly in the range and P exceeded the reference values. Histological examinations did not indicate HITH disease, and no fish developed signs of the disease during the study. Clinical trial registration number GZ 68.205/0135-WF/V/36/2014.

Vitamin D toxicity of dietary origin in cats fed a natural complementary kitten food

Case series summary

This case series describes two young sibling cats and an additional unrelated cat, from two separate households, that developed hypercalcaemia associated with hypervitaminosis D. Excessive vitamin D concentrations were identified in a natural complementary tinned kitten food that was fed to all three cats as part of their diet. In one of the cases, there was clinical evidence of soft tissue mineralisation. The hypercalcaemia and soft tissue mineralisation resolved following withdrawal of the affected food and medical management of the hypercalcaemia.

Relevance and novel information

This case series demonstrates the importance of obtaining a thorough dietary history in patients presenting with hypercalcaemia and the measurement of vitamin D metabolites when investigating such cases. Complementary foods may have the potential to induce nutritional toxicity even when fed with complete, nutritionally balanced diets.

[Evaluation of nutritional characteristics of commercial canned cat diets]

OBJECTIVE

To evaluate commercial complete canned cat foods according to their composition, labeling and nutritional characteristics.

MATERIALS AND METHODS

A total of 21 commercial complete canned compound feeds for adult cats were analyzed for crude nutrients, minerals, vitamins, selected amino acids and taurine. The analyzed parameters were compared to the internal set of standards of the European Pet Food Industry Federation (FEDIAF). The energy content was calculated and compared with the labeled recommendations regarding the amounts of diet that should be fed. Analyzed nutrients were compared with the labeled nutrients according to the regulations of the EU food and feed law (directive EU regulation 767/2009).

RESULTS

In many cases, the labeled feeding protocols did not match the calculated daily energy requirements. In eight complete foods, the recommended daily feed amounts were underestimated and four recommendations exceeded energy requirements of adult cats. In 12 complete foods, the calcium and phosphorus contents were threefold higher than the respective requirement. In 16 of 21 complete foods, substantial discrepancies were observed between the recommendations and the analyzed trace elements. In particular, selenium contents exceeded the selenium requirement more than threefold. The vitamin, arginine and taurine contents showed no significant discrepancies to the recommendations. With respect to the labeled nutrients, there were only minor deviations from the regulations of the European law.

CONCLUSION AND CLINICAL RELEVANCE

In general, healthy adult cats are adequately supplied with energy and nutrients when feeding commercial canned complete diets for cats. In cases of body weight loss or gain, the labelled feed amounts should be questioned. The high phosphorus contents are an issue of concern, because a high phosphorus intake can potentially increase the risk for urinary stones and particularly for older cats the risk for renal insufficiency. Furthermore, it is recommended to decrease the high selenium levels by the reduction of selenium-rich feed materials such as offal.

Feline hyperparathyroidism: pathophysiology, diagnosis and treatment of primary and secondary disease

PRACTICAL RELEVANCE

Hyperparathyroidism exists in primary and secondary forms. Primary hyperparathyroidism has typically been considered a disease that uncommonly affects cats, but this condition is more prevalent than previous diagnoses would suggest. Secondary hyperparathyroidism may be caused by either nutritional influences (ie, nutritional secondary hyperparathyroidism) or chronic kidney disease (ie, renal secondary hyperparathyroidism). Tertiary hyperparathyroidism has yet to be documented in veterinary medicine, but it is possible that this condition occurs in some cats following longstanding renal secondary hyperparathyroidism.

CLINICAL CHALLENGES

Diagnosis of this group of calcium metabolic disorders presents a number of challenges for the clinician. For example, clinical signs can be non-specific and, especially in the case of primary hyperparathyroidism, there is often a low index of suspicion for the disease; careful sample handling is required for testing of parathyroid hormone (PTH) and ionized calcium levels; and there is currently no feline-specific assay for PTH, which has implications for test sensitivity and interpretation of results.

AIMS

This article briefly outlines PTH and calcium physiology by way of introduction to a review of PTH measurement and interpretation. Various forms of feline hyperparathyroidism are then described, encompassing diagnosis and treatment options.

Evaluation of the owner's perception in the use of homemade diets for the nutritional management of dogs

Many dog owners see homemade diets as a way of increasing the bond with their pets, even though they may not have the convenience of commercial diets. Modifications of ingredients, quality and proportion might change the nutritional composition of the diet, generating nutritional imbalances. The present study evaluated how dog owners use and adhere to homemade diets prescribed by veterinary nutritionists over an extended period of time. Forty-six owners of dogs fed a homemade diet for at least 6 months were selected for the present study. Owners were invited to answer questions by first reading all possible answers and then selecting the one that best indicated their opinion. The results were evaluated through descriptive statistics. Thirty-five owners (76·1 %) found that the diets are easy to prepare. Fourteen owners (30·4 %) admitted to modifying the diets, 40 % did not adequately control the amount of provided ingredients, 73·9 % did not use the recommended amounts of soyabean oil and salt, and 34·8 % did not correctly use the vitamin, mineral or amino acid supplements. Twenty-six owners (56·5 %) reported that their dogs refused to eat at least one food item. All of these alterations make the nutritional composition of the diets unpredictable and likely nutritionally imbalanced. Although homemade diets could be a useful tool for the nutritional management of dogs with certain diseases, not all owners are able to appropriately use this type of diet and adhere to it for an extended period of time and this limitation needs to be considered when recommending the use of homemade diets.

Mineral metabolism in growing cats: changes in the values of blood parameters with age

The purpose of this study was to describe changes in calcium, phosphorus, magnesium, parathyroid hormone, calcitriol and calcidiol in cats from 3 to 15 months of age. Fourteen European shorthair healthy cats of both sexes (seven males, seven females) belonging to a research colony were studied from 3 to 15 months of age. Plasma concentrations of total calcium, ionised calcium, albumin, phosphorus, magnesium, intact parathyroid hormone (I-PTH), whole parathyroid hormone (W-PTH), calcidiol and calcitriol were measured at 3, 6, 9, 12 and 15 months of age. From 3 months of age to adulthood cats showed a decrease in calcium (both total and ionised), phosphorus and magnesium. No major changes in PTH were evident, although the ratio of W-PTH:I-PTH decreased significantly with age. A reciprocal change in vitamin D metabolites (decrease in calcitriol and increase in calcidiol) was identified during the growing process. Our results, showing changes in most parameters of mineral metabolism during growth, reinforce the need to use adequate age-related reference values for diagnostic purposes.

Evaluation of recipes for home-prepared diets for dogs and cats with chronic kidney disease

OBJECTIVE

To evaluate recipes of diets recommended for animals with chronic kidney disease (CKD), compare nutritional profiles for those recipes to requirements for adult dogs and cats, and assess their appropriateness for the management of CKD.

DESIGN

Evaluation study.

SAMPLE

Recipes of 67 home-prepared diets promoted for use in dogs (n = 39 recipes) and cats (28) with CKD.

PROCEDURES

Recipes were analyzed with computer software to determine calories, macronutrient calorie distribution, and micronutrient concentrations and were assessed for appropriateness for the management of CKD.

RESULTS

Assumptions were required for the analysis of every recipe, and no recipe met all National Research Council nutrient recommended allowances (RA) for adult animals. Compared with RAs, concentrations of crude protein or at least 1 amino acid were low in 30 of 39 (76.9%) canine recipes and 12 of 28 (42.9%) feline recipes. Choline was most commonly below the RA in both canine (37/39 [94.9%]) and feline (23/28 [82.1%]) recipes; selenium (34/39 [87.2%] canine and 9/28 [32.1 %] feline recipes), zinc (24/39 [61.5%] canine and 19/28 [67.9%] feline recipes), and calcium (22/39 [56.4%] canine and 7/28 [25.0%] feline recipes) concentrations were also frequently below recommendations. The median phosphorus concentration in canine and feline recipes was 0.58 and 0.69 g/1,000 kcal, respectively.

CONCLUSIONS AND CLINICAL RELEVANCE

Many problems with nutritional adequacy were detected, and use of the recipes could result in highly variable and often inappropriate diets. Many recipes would not meet nutritional and clinical needs of individual patients and should be used cautiously for long-term feeding.

Musculoskeletal oddities in the cat: an overview of some curious causes of lameness

PRACTICAL RELEVANCE

Cats, both young and old, can suffer a variety of weird and wonderful musculoskeletal conditions that are a cause of lameness. These include developmental, metabolic and nutritional bone diseases, ectopic mineralisation disorders, conditions that cause lameness or exercise intolerance and primarily or secondarily affect muscle, and lastly pad conditions.

CLINICAL CHALLENGES

These conditions are mostly rare and can be challenging to diagnose. The aim of this review is to bring these conditions to the attention of practitioners so that, if they are encountered, further research around the topic can be undertaken. Radiographic changes and diagnostic tests that can be used to try to confirm diagnoses are described.

EVIDENCE BASE

These unusual causes of lameness are the subject of multiple single case reports or small case series, many of which are relatively old. The evidence presented here is drawn from these articles. However, it is not possible within the scope of this review to discuss all the conditions in as much detail as they may warrant, or to make reference to every article relating to them.

Vitamin D-dependent non-type 1, non-type 2 rickets in a 3-month-old Cornish Rex kitten

CASE PRESENTATION AND ASSESSMENT: A 3-month-old female Cornish Rex kitten was found to have non-painful swelling of the carpal and tarsal regions when presented for routine neutering. The kitten was smaller in stature and less active than its siblings and, according to the owner, had a bunny-hopping gait, was reluctant to climb stairs and strained during defecation. Radiography of the affected limbs and a subsequent radiographic survey of the entire skeleton demonstrated features consistent with rickets. The three littermates were clinically and radiographically normal. As a nutritionally complete diet was being fed, it seemed most likely that the kitten had an inborn error related to vitamin D metabolism. Serum biochemistry demonstrated reduced total alkaline phosphatase activity and increased concentrations of parathyroid hormone. Concentrations of 1,25- and 25-hydroxycholecalciferol were markedly reduced, confirming the diagnosis of rickets.

TREATMENT

The kitten was treated with calcitriol, administered orally once daily, and improved rapidly both clinically and radiologically. Serial laboratory studies suggested that the error in vitamin D metabolism was transient, and, at the time of writing, as an adult, the cat appears to require no ongoing replacement calcitriol therapy.

CLINICAL RELEVANCE

This case emphasises the value of examining a full 'calcium profile' via a human or veterinary reference laboratory, and a favourable prognosis in some kittens with rickets makes such investigations worthwhile. Even when finances preclude detailed investigation, trial therapy using a nutritionally complete diet and physiological doses of calcitriol or cholecalciferol is inexpensive and can produce a good response.

Feline hypertrophic osteopathy: a collection of seven cases in Taiwan

Between October 2003 and May 2004, seven cats were diagnosed with severe and extensive hypertrophic osteopathy of the appendicular skeleton without detectable underlying causes. All cats showed similar clinical signs of pain with progressive lameness of the limbs. One cat died shortly after presentation, whereas conditions of the others resolved after medical treatment and a change in diet. Regression of the bone lesions was observed radiographically in all surviving six cases.

Feline spinal cord diseases

The objective of this article is to review the recent literature that reports on the most common diseases affecting the spinal cord of cats, and to draw some general conclusions that will be useful to formulate diagnosis and prognosis for feline spinal patients. The most common types of feline spinal cord diseases documented were inflammatory/infectious diseases, and feline infectious peritonitis was the most common disease, representing approximately 50% of all feline myelitis. Neoplasms were documented in approximately 25% of cases; lymphosarcoma was the most common tumor affecting the spinal cord of cats, with reported prevalence between 28% and 40%. Cats diagnosed with spinal lymphosarcoma were significantly younger (median age 4 years) than cats with other spinal cord tumors (median age 10 years). Cats with clinical signs of intervertebral disc disease had a median age of 8 years, and 67% had Hansen type I disc protrusions. The most commonly affected intervertebral disc was at the L4 to L5 intervertebral disc space. Fibrocartilaginous embolism-affected older cats (median age 10 years), seemed to predominate in the cervicothoracic intumescence, and clinical signs were markedly lateralized, especially when the cervical region was affected.

The paralyzed cat. Neuroanatomic diagnosis and specific spinal cord diseases

PRACTICAL RELEVANCE

Although gait disturbance is one of the most common neurological presentations in feline medicine, the clinical approach to the paralyzed cat can be challenging. After excluding orthopedic and cardiovascular diseases that may mimic a neurological condition, the clinician has to address a long list of different diseases that may affect the spinal cord and produce paresis.

CLINICAL CHALLENGES

In many cases a definitive cause of spinal weakness in cats is difficult to prove. Even when treatable diseases are identified, the prognosis is very much dependent on the severity of the clinical signs and their chronicity. This review sets out to describe the specific approach, diagnosis and management of cats with spinal cord disease and to outline the most common diseases responsible.

PATIENT GROUP

Patients of either gender and all ages and breeds can be affected by spinal cord disease.

EVIDENCE BASE

Many diseases affecting the spinal cord of cats, which include fibrocartilaginous embolic myelopathy, intervertebral disc disease, exogenous spinal cord trauma, spinal cord lymphosarcoma and feline infectious peritonitis, are well described in the literature. Many of these descriptions, however, have been based on case reports or series. While there have been several retrospective studies that describe the characteristics and incidence of these diseases in cats, there are no long term treatment trials or outcome studies to assist with prognostic determinations.

Unusual Case of Osteopenia Associated With Nutritional Calcium and Vitamin D Deficiency in an Adult Dog

A 6-year-old, spayed female rottweiler was presented for facial enlargement from swelling of the maxilla and mandible. The dog was fed a homemade diet deficient in calcium and vitamin D, suggesting that rubber jaw syndrome was a secondary nutritional disorder. Radiographic and tomodensitometric examinations revealed diffuse bone resorption in the skull. The plasma parathormone concentration was high, and serum 25-hydroxycholecalciferol concentration was low. Based on these findings, nutritional calcium and vitamin D deficiency associated with secondary hyperparathyroidism was diagnosed. Dietary correction resulted in clinical and biological improvement, with an increase in skull mineralization.

Pansteatitis and severe hypocalcaemia in a cat

A 13-year-old Siamese cat was presented for investigation of lethargy and progressive abdominal enlargement. Serum chemistry revealed severe reduction of total and ionised serum calcium. The omentum appeared hyperechoic with scattered hypoechoic foci on abdominal ultrasound examination. Elevated serum parathormone and low fractional excretion of calcium excluded a parathyroid disorder and renal loss of the electrolyte. During laparotomy the omentum appeared opaque, white and firm. Post-mortem examination revealed that the thoracic and subcutaneous fat was also affected. Histopathology confirmed the diagnosis of pansteatitis with diffuse calcium soaps formation. While, severe hypocalcaemia is occasionally seen in cats, the association with pansteatitis has not been reported previously. In man, a cause-and-effect relationship between calcium soaps and hypocalcaemia is recognised, though the association is rare.

Multiple myeloma in 16 cats: a retrospective study

BACKGROUND

There is limited published information regarding feline multiple myeloma. Diagnostic criteria are derived from canine studies and to our knowledge, have not been critically reviewed for cats.

OBJECTIVE

To evaluate the clinical and laboratory findings in cats with multiple myeloma and appraise diagnostic criteria.

METHODS

Retrospective evaluation of medical records was performed. Inclusion required an antemortem diagnosis of multiple myeloma using 2 of 4 criteria: 1) >or=20% plasma cells in the bone marrow, or >or=10% if atypical plasma cells; 2) paraproteinemia; 3) radiographically-evident osteolysis; 4) light chain proteinuria. Alternatively, a postmortem diagnosis was based on the findings of multiple plasma cell neoplasms, with marrow involvement.

RESULTS

Sixteen cats were diagnosed with multiple myeloma between 1996 and 2004, with a median age of 14.0 years; 9 of 16 (56%) were castrated males, and 7 of 16 (44%) were spayed females. Laboratory abnormalities included hyperglobulinemia (14/16, 87.5%), with 11/14 (78.5%) monoclonal and 3/14 (21.4%) biclonal gammopathies; hypoalbuminemia (4/16, 25%); light chain proteinuria, (4/9, 44.4%); hypocholesterolemia (11/16, 68.7%); hypercalcemia, (3/15, 20%); nonregenerative anemia, (11/16, 68.7%); regenerative anemia, (1/16, 6.2%); neutropenia (5/15, 33.3%); thrombocytopenia (8/16, 50%); and marrow plasmacytosis (14/15, 93.3%). Plasma cells were markedly immature, atypical, or both in 10 of 12 (83.3%) cats. Focal or multifocal osteolysis was noted in 6 of 12 (50%) cats for which radiographs were available for review; generalized osteopenia was found in 1 (8.3%) cat. Noncutaneous, extramedullary tumors were found in all cats assessed, 7/7 (100%), including spleen (6), liver (3), and lymph nodes (4). The disease in 1 of 2 cats with cutaneous tumors progressed to plasmacytic leukemia.

CONCLUSIONS

Common findings in feline multiple myeloma include atypical plasma cell morphology, hypocholesterolemia, anemia, bone lesions, and multi-organ involvement. Based on the results of this study, we advocate modifying diagnostic criteria in cats to include consideration of plasma cell morphology and visceral organ infiltration.

Hyperparathyroidism in dogs with hyperadrenocorticism

OBJECTIVES

To assess the effect of canine hyperadrenocorticism (HAC) on parathyroid hormone (PTH), phosphate and calcium concentrations.

METHODS

PTH concentrations and routine biochemical parameters were measured in 68 dogs with HAC. Ionised calcium was measured in 28 of these dogs. The results obtained were compared with an age- and weight-matched group of 20 hospital patients that did not show signs of HAC.

RESULTS

There were significant differences between the PTH, phosphate, alkaline phosphatase, creatinine and albumin concentrations between the two groups. Total and ionised calcium concentrations were not significantly different. Most of the dogs (92 per cent) with HAC had PTH concentrations that were greater than the reference range (10 to 60 pg/ml), and in 23 dogs they were greater than 180 pg/ml. There were significant positive correlations between the PTH and basal cortisol, post-adrenocorticotropic hormone (ACTH) cortisol and alkaline phosphatase concentrations, and also the phosphate and post-ACTH cortisol concentrations.

CLINICAL SIGNIFICANCE

Adrenal secondary hyperparathyroidism is a cause of increased PTH concentrations and may be associated with abnormalities in calcium and phosphate metabolism in dogs with HAC. The findings of this study could explain why canine HAC may cause clinical signs such as calcinosis cutis that are associated with altered calcium metabolism.

Nutritional secondary hyperparathyroidism in rabbits

The present study was designed to document the effect of a low (0.6%) calcium-high (1.2%) phosphorus (LCaHP) diet on the development of parathyroid gland hyperplasia in rabbits and to describe the dynamics of parathyroid function (PTH-Ca2+ curves) in rabbits with nutritional secondary hyperparathyroidism (N2HPT). Parathyroid gland weight, parathyroid cell proliferation (measured as percentage of cells in S-phase), and parathyroid calcium (CaRmRNA) and Vitamin D (VDRmRNA) receptor expression were measured in normal rabbits and in rabbits with N2HPT. The PTH-Ca2+ curve was studied in normal rabbits (Group I) and in rabbits with N2HPT at two stages: 2-3 weeks (Group IIA) and 5-6 weeks (Group IIB) after being fed LCaHP diet. An increase in parathyroid gland weight and percentage of cells in S-phase was detected in the course of N2HPT. After receiving a LCaHP diet for 6 weeks rabbits had decreased levels of CaRmRNA but VDRmRNA remained unchanged. A progressive increase in the concentrations of plasma PTH (Group IIA=167+/-14 pg/ml and Group IIB=377+/-54 pg/ml, P<0.05 versus Group I=27+/-3 pg/ml) was detected in the rabbits fed a LCaHP diet. This was accompanied by an increase in maximal and minimal PTH, reductions in plasma Ca2+ and calcitriol and elevations in plasma phosphate and creatinine. In conclusion, feeding a LCaHPD results in a rapid induction of N2HPT in rabbits. After 6 weeks on the LCaHPD rabbits develop parathyroid hyperplasia characterized by increases in PTH secretion, glandular weight and proliferation and by a decrease in CaRmRNA.

A Case of Nutritional Secondary Hyperparathyroidism in a Siberian Tiger Cub

A three-month-old female Siberian tiger cub with hindlimb ataxia was referred to the veterinary teaching hospital of Konkuk University. The patient was fed only beef without supplementation of calcium and vitamins after weaning. The tiger was presented with ataxia and back pain on digital palpation. In addition, abnormal gait, reluctance to move, and depressed withdrawal reflex were noted at the neurological examination. The overall osteodystrophic change of the lumbosacral vertebrae was observed on the lateral and ventrodorsal view of radiographic examination. And also PTH level was increased in hormonal assay when compared to that of cat reference range. Based on the results of examinations, nutritional secondary hyperparathyroidism was diagnosed. Clinical signs of this patient were improved after administration of vitamin D and calcium. This case demonstrates that nutritional hyperparathyroidism could be occurred in wild animals raised on a meat diet containing imbalanced calcium and phosphate.

Feline odontoclastic resorptive lesions an unsolved enigma in veterinary dentistry

This article presents a comprehensive review of the literature on feline odontoclastic resorptive lesions (FORLs), including etiopathogenesis, prevalence and predisposition, classification, histopathologic appearance, diagnosis, and treatment. Approximately one-third of all domestic cats may develop FORLs during their life span, and the risk of developing FORLs increases with age. Sophisticated dental treatments promise neither cure nor permanent improvement of affected teeth. Extraction is the current treatment of choice. Research on the etiology of FORLs has not been rewarding in recent years, and the causative factors contributing to the development of FORLs are still unknown.

Update on the diagnosis and treatment of disorders of calcium regulation

The availability of PTH, iCa, PTHrP, and 25OHD assays for evaluation of calcium abnormalities in companion animals has been well received [table: see text] by clinicians and diagnosticians. Use of these assays has heightened awareness that some of these disorders are more common than originally thought. Also, there is added insight of alterations of calcium homeostasis as a consequence of other illness or environmental factors such as diet. Animal counterparts of other disorders of calcium metabolism in people are likely to be identified, and use of these assays should play a significant role. As already emphasized, the foundation of using [table: see text] these assays is first assessing whether the calcium abnormality is of a parathyroid-dependent or parathyroid-independent classification.

Feline endocrinology update

This article highlights the advances in feline endocrinology, excluding diabetes mellitus and hyperadrenocorticism, which have recently been reviewed elsewhere. The goal will be to provide clinically relevant information regarding pathogenesis, diagnosis, and treatment options for these feline endocrine disorders.