Genetic diversity, growth and heart function of Auckland Island pigs, a potential source for organ xenotransplantation.

One of the prerequisites for successful organ xenotransplantation is a reasonable size match between the porcine organ and the recipient's organ to be replaced. Therefore, the selection of a suitable genetic background of source pigs is important. In this study, we investigated body and organ growth, cardiac function, and genetic diversity of a colony of Auckland Island pigs established at the Center for Innovative Medical Models (CiMM), LMU Munich. Male and female Auckland Island pig kidney cells (selected to be free of porcine endogenous retrovirus C) were imported from New Zealand, and founder animals were established by somatic cell nuclear transfer (SCNT). Morphologically, Auckland Island pigs have smaller body stature compared to many domestic pig breeds, rendering their organ dimensions well-suited for human transplantation. Furthermore, echocardiography assessments of Auckland Island pig hearts indicated normal structure and functioning across various age groups throughout the study. Single nucleotide polymorphism (SNP) analysis revealed higher runs of homozygosity (ROH) in Auckland Island pigs compared to other domestic pig breeds and demonstrated that the entire locus coding the swine leukocyte antigens (SLAs) was homozygous. Based on these findings, Auckland Island pigs represent a promising genetic background for organ xenotransplantation.

High Intake of Sodium Chloride for 28 Days Causes No Effect on Serum FGF23 Concentrations in Cats.

BACKGROUND: FGF23 is an acknowledged parameter to assess kidney health. As chronic kidney failure is one of the most common diseases in aging cats, dietary influences on renal health warrant investigation. The purpose of this study was therefore to investigate potential correlations between dietary sodium chloride and FGF23. METHODS: In a total of two trials, 11 cats were included. In the first trial, the cats were fed a complete and balanced control diet; in the second trial, sodium chloride was added (8 g/kg/DM)). Blood, urinary, feed, and faecal samples were analysed for major minerals. FGF23 and creatinine were measured in blood and urine samples. RESULTS: Serum phosphate and FGF23 were unaffected by high sodium chloride intake, thus showing no correlation between serum FGF23 and sodium concentrations. Apparent phosphorus digestibility was significantly increased, however, by high sodium chloride intake, whereas apparent digestibility of calcium was unaffected. The present study confirms differences in FGF23 and sodium chloride interaction in cats compared with other species. Further research regarding the correlation between sodium chloride and phosphate homeostasis is warranted.

PLASMA VITAMIN AND MINERAL CONCENTRATIONS IN CAPTIVE GREATER FLAMINGOS (PHOENICOPTERUS ROSEUS) AS INFLUENCED BY DIET CHANGE.

The greater flamingo (Phoenicopterus roseus) is often maintained in managed care. Although values for plasma concentrations of minerals and vitamins have been published for this species, limited studies investigate the effects of diet changes on these values. Plasma concentrations of selected vitamins (A [and the provitamin A carotenoid ß-carotene] and E), minerals (Ca, Cu, Fe, K, Mg, Mn, Na, inorganic P, Se, and Zn), and total protein (TP) were measured in a zoo collection of greater flamingos in November 2018 (n = 48) and in November 2019 (n = 52), 30 d after a change from the summer diet, which was the same in both years, to different winter diets. Chloride, cholesterol, and triglycerides were only measured once in 2019. The nutrient profiles of the two complete diets (labeled and analyzed) differed considerably, especially for the canthaxanthin concentration. The plasma concentrations of ß-carotene (P < 0.0001), Cu (P < 0.0001), Fe (P < 0.0001), Mg (P < 0.0001), and Se (P < 0.0001) were significantly higher and vitamin E (P < 0.0001), Ca (P = 0.0014), Mn (P < 0.0001), Na (P = 0.0005), and TP (P < 0.0001) were significantly lower in 2018 than in 2019. Four minerals (Cu, Fe, Mg, and Zn) were measured using both spectrophotometry and inductively coupled plasma mass spectrometry, and all of these minerals showed significant (P < 0.05) differences between the two methods. Based on the results of the study, both the influence of diet and the detection method used for circulating nutrients must be considered when interpreting the plasma vitamin and mineral concentrations in greater flamingos.

From Nutritional Adequacy to Hygiene Quality: A Detailed Assessment of Commercial Raw Pet-Food for Dogs and Cats.

Raw meat-based diets (RMBDs) are widely used as unconventional diets for dogs and cats at different life stages, despite concerns regarding nutritional adequacy and microbial contamination. The aim of this study was to evaluate both the nutritional and hygiene quality profile of RMBDs purchased in Germany. For this purpose, crude nutrients were assessed in 44 RMBDs and compared to declared values. In addition, selected minerals were determined in 31 RMBDs labelled as complete and compared to the minimum requirement (MR) for intended species and life stages. Aerobic colony count (ACC) and Enterobacteriaceae were used to assess the hygiene quality of 37 commercial RMBDs, while the presence of Salmonella spp. was examined in 10 products. Fat and protein content exceeded tolerated deviation from declared values in 33% and 45% of RMBDs, respectively. Each RMBD showed at least one concern regarding nutrient content. The RMBDs had high fat contents (mean 69, range 33−95 g/Mcal) that were negatively correlated with protein (r = −0.74, p < 0.0001). Considerable contaminations by ACC and Enterobacteriaceae were found (2.61 × 108 ± 3.63 × 108 and 3.61 × 106 ± 8.39 x106 CFU/g, respectively). A higher count of Enterobacteriaceae was detected in a frozen RMBDs made of poultry or carcasses from different animals, compared to the thawed counterpart (p = 0.003), as well as compared to other sources, such as beef, horse, and lamb, regardless of the storage condition. Salmonella spp. were found in 2/10 RMBDs. This study confirmed that feeding commercial RMBDs might pose a risk to pet health.

Faecal dry matter excretion per se affects faecal calcium and phosphorus losses in dogs.

The study aimed to investigate the effect of faecal dry matter (DM) excretion on faecal losses of calcium (Ca) and phosphorus (P) without potentially confounding factors. Dogs were fed two levels of the same basal diet (cooked pork, rice, gelatine; 8.5 ± 0.7 and 12.6 ± 1.2 g DM/kg BW). Mineral supplements were added separately for identical Ca and P supply independent of DM intake (Ca 226 and P ~170 mg/kg BW). Digestion trials (10 days adaptation, 5 days quantitative faecal collection) were carried out. Digestibility of DM averaged 87% in both trials. Faecal DM and mineral excretion increased highly significant (DM 1.1 ± 0.3 to 1.7 ± 0.2 g/kg BW, p = 0.00005; Ca 185 ± 34 and 233 ± 22 mg/kg BW, p = 0.00119; P 99 ± 23 to 127 ± 12 mg/kg BW, p = 0.00212), revealing a highly significant correlation. Apparent digestibility of Ca was positive in the first trial and negative in the second leading to a slightly negative Ca retention in the latter one. The results suggest that in dogs (i) factors influencing Ca and P absorption can only be compared if faecal DM excretion is identical and (ii) Ca requirements may be affected by DM intake and digestibility.

A pilot study on dietary and faecal calcium/phosphorus ratios in different types of captive ruminating herbivores.

Quantitative differences in calcium and phosphorus metabolism between domestic species exist and can be visualised using data on calcium and phosphorus intake and faecal excretion. The parameter for analysing the results was defined as Δ = dietary calcium/phosphorus (Ca/P) ratio - faecal Ca/P ratio. In previous studies, hindgut fermenters had significantly higher Δ values than ruminants (sheep, cattle, goats), which was explained by the high calcium digestibilities in hindgut fermenters in contrast to highly efficient phosphorus recycling in ruminants. The first hypothesis of the present study was that different types of ruminants (grazer, browser, intermediate feeder) would show differences in Δ as a proxy for quantitative calcium and phosphorus metabolism. The second hypothesis was that camelids as functional, but not taxonomic ruminants would show Δ values similar to ruminants. We used herbivorous zoo animals (17 species, hindgut and foregut fermenters), which were kept on their regular diet without variation for 1 week. Then, faecal samples were obtained from the individual animals. Feed items and faecal samples were analysed for calcium and phosphorus, and dietary and faecal Ca/P ratios as well as Δ were calculated. A comparison of the species groups (one-way ANOVA on ranks, p < 0.05) showed that zoo hindgut fermenters had significantly higher Δ values (0.67 ± 0.34) than camelids and zoo ruminants (-1.07 ± 0.35 and -1.87 ± 1.56). There was no significant difference between camelids, grazers (-1.49 ± 1.31), browsers (-1.63 ± 0.88) and intermediate feeders (-2.11 ± 1.76). The ruminant species from this study had markedly lower Δ than domestic ruminants from literature data. Especially intermediate feeders had low Δ, possibly due to more efficient phosphorus recycling than the domestic ruminants.

The Source Matters-Effects of High Phosphate Intake from Eight Different Sources in Dogs.

Elevated serum phosphate concentrations are an established risk factor for cardiovascular disease and mortality in chronic kidney disease in various species. Independent associations of other parameters of phosphorus metabolism, such as phosphorus intake from different sources and serum concentrations of phosphorus, as well as parameters involved in the regulation, such as parathyroid hormone (PTH) or markers of bone turnover, have been studied in less detail. Therefore, the serum kinetics of phosphate, PTH, and the bone resorption marker bone-specific alkaline phosphatase (BAP) were investigated after 18 days of feeding a control diet and diets supplemented with eight different organic and inorganic phosphate sources aiming at 1.8% phosphorus per dry matter and calcium to phosphorus ratio between 1.3 and 1.7 to 1. Eight healthy beagle dogs (f/m, 2-4 years, 12.9 ± 1.4 kg body weight) were available for the trial. Highly significant differences in the serum kinetics of phosphorus, PTH, and BAP with the highest postprandial levels after feeding highly water-soluble sodium and potassium phosphates were found. We conclude that the use of certain inorganic phosphates in pet food is potentially harmful and should be restricted.

[Phosphate intake with complete food and diets for chronic kidney disease available on the German market]. / Phosphataufnahme durch auf dem deutschen Markt befindliche Alleinfutter und Nierendiäten für Hunde und Katzen.

OBJECTIVE: Complete foods and renal diets for dogs and cats available on the German market were analyzed for their concentrations of total phosphorus as well as highly soluble and therefore highly available phosphorus due to the possible effects of this element on the animal's health. MATERIAL AND METHODS: A total of 133 complete foods for healthy dogs and cats, 8 snacks and 43 diets for patients with chronic kidney disease were analyzed for total phosphorus and the fraction of phosphorus soluble in water after 1 minute (Psol1). RESULTS: In the tested compound food, the amount of phosphorus in relation to the recommended daily allowance ranged from 90 to 740 %. More than 90 % of the products supplied twice the required amounts; in 6 dog feeds the nutritional maximum wasexceeded. For almost 75 % of the products, the recommended daily allowance for phosphorus was already met vollby Psol1. More than 50 % of the tested renal diets contained more than twice the recommended amounts for healthy individuals and with this also exceeded the legal limits. Even in the renal diets, the amount of Psol1 alone exceeded the recommended daily allowance for this element. CONCLUSION: This work demonstrates that compound food and renal diets available on the German market may contain a multiple of the recommended or legally permitted phosphorus concentrations. Therefore, a considerable number of products may be expected to not meet the expectations of customers and veterinarians.

Effects of dietary phosphates from organic and inorganic sources on parameters of phosphorus homeostasis in healthy adult dogs.

BACKGROUND: The impact of dietary phosphorus (P) excess, especially on renal and cardiovascular health, has been investigated in several species, but little is known in dogs. OBJECTIVE: The aim of this study was to examine effects of different P sources on concentration and postprandial kinetics of selected parameters of P homeostasis in dogs. METHODS: Eight beagles received one control diet (P 0.5% dry matter [DM]) and three high P diets (poultry meal, NaH2PO4, and KH2PO4; P 1.7% DM) for 18d. Urine samples were collected pre- and postprandially while faeces were collected quantitatively for 5d and analysed for minerals. On day 18, blood was sampled 1h pre- and 0.5, 1, 1.5, 2, 3, 5 and 7h postprandially. RESULTS: Pi (KH2PO4, NaH2PO4) but not organic P caused an increased apparent P digestibility and significantly influenced kinetics of serum FGF23, parathyroid hormone, P, CrossLaps and bonespecific alkaline phosphatase, demonstrating a disrupted calcium (Ca) and P homeostasis with potential harm for renal, cardiovascular and skeletal health. CONCLUSIONS: Results of feeding Pi to dogs indicate distinct disturbances of Ca and P metabolism, in contrast to organic sources. The use of Pi in food can therefore not be considered as safe. Further research, especially on dose and long-term effects, is warranted.

Case of suspected theobromine poisoning in dairy cattle.

High-yielding dairy cows collapsed and died displaying signs of a disturbed central nervous system (muscle tremor, convulsion) and a considerably reduced body condition score. An intense diagnostic screening did not allow to confirm a definite diagnosis. Therefore, further analyses including an evaluation of feeds and feeding were initiated. The herd was fed a total mixed ration (TMR) based on corn and grass silage of moderate nutritive value supplemented with various amounts of chocolate chips. In retrospect, the amount of chocolate chips added to the respective TMR batches could not be quantified. These chips were purchased from a company producing bakery and chocolate products for human consumption and added to the silage and therefore to the TMR in order to increase the energy intake of the animals. Because the TMR, which was fed during the time of the incidence, was no longer available, a sample of a later batch of silage was examined. The amount of chocolate chips was quantified (0.44% per fresh matter), and a theobromine analysis was performed in the chocolate chips of the available batch (69.7 mg/100 g fresh matter). Because of the possible link between chocolate intake and observed signs, an immediate cessation of using the chocolate chips was recommended in addition to an optimisation of the TMR, that is an increase of the energy density. Even though the theobromine intake during the time of the incidence is unknown and information about toxicity of theobromine in ruminants is limited, we suspect that the feeding of chocolate in this case caused all signs including the sudden death of the cows. Further reasons are that no differential diagnoses were established and the problems at the farm stopped after removing the chocolate from the TMR.

Effect of Dietary Sodium Modulation on Pig Adrenal Steroidogenesis and Transcriptome Profiles.

Primary aldosteronism is a frequent form of endocrine hypertension caused by aldosterone overproduction from the adrenal cortex. Regulation of aldosterone biosynthesis has been studied in rodents despite differences in adrenal physiology with humans. We, therefore, investigated pig adrenal steroidogenesis, morphology, and transcriptome profiles of the zona glomerulosa (zG) and zona fasciculata in response to activation of the renin-angiotensin-aldosterone system by dietary sodium restriction. Six-week-old pigs were fed a low- or high-sodium diet for 14 days (3 pigs per group, 0.4 g sodium/kg feed versus 6.8 g sodium/kg). Plasma aldosterone concentrations displayed a 43-fold increase (P=0.011) after 14 days of sodium restriction (day 14 versus day 0). Low dietary sodium caused a 2-fold increase in thickness of the zG (P<0.001) and an almost 3-fold upregulation of CYP11B (P<0.05) compared with high dietary sodium. Strong immunostaining of the KCNJ5 (G protein-activated inward rectifier potassium channel 4), which is frequently mutated in primary aldosteronism, was demonstrated in the zG. mRNA sequencing transcriptome analysis identified significantly altered expression of genes modulated by the renin-angiotensin-aldosterone system in the zG (n=1172) and zona fasciculata (n=280). These genes included many with a known role in the regulation of aldosterone synthesis and adrenal function. The most highly enriched biological pathways in the zG were related to cholesterol biosynthesis, steroid metabolism, cell cycle, and potassium channels. This study provides mechanistic insights into the physiology and pathophysiology of aldosterone production in a species closely related to humans and shows the suitability of pigs as a translational animal model for human adrenal steroidogenesis.

Effect of feeding a daily oral care chew on the composition of plaque microbiota in dogs.

The objective of this study was to investigate the influence of daily feeding of an oral care chew on the composition of canine supragingival plaque microbiota. Twelve beagle dogs were recruited to the randomized cross-over study. The dogs were fed one of two dietary regimes, both consisting of a commercially available wet and dry diet mix, either with or without daily supplementation with an oral care chew. After each 28-day test phase, supragingival plaque samples were collected and processed via Illumina sequencing to determine the microbiota composition. A comparative analysis of bacterial species associated with health and periodontal disease, identified from prior clinical studies, revealed differences between the dietary regimes. Consumption of the daily oral care chew, resulted in a significant increase in proportion of 6 health associated taxa but only 3 disease associated taxa compared to no chew. In contrast, 8 disease and 1 health associated taxa showed increased proportions for no chew versus the oral care chew. Daily feeding of the oral care chew tested in this study has therefore been shown to increase the proportion of health associated bacteria, over bacteria associated with periodontal disease, in supragingival plaque compared to no chew. By influencing plaque microbiota towards a bias for health associated bacteria, feeding of the oral care chew provides a means to reduce the prevalence of bacterial species shown to be associated with periodontal disease in dogs.

Calcium and phosphorus metabolism in peripartal dogs.

Recommended allowances for calcium and phosphorus are mostly based on factorial calculations partly set at the level determined adequate for giant breeds (Nutrient requirements of dogs and cats. Washington, DC, USA: The National Academies Press. 2006). Information about appropriateness of supply with both minerals during the peripartal phase is limited. From other species is known that bone mineral stores are used in addition to oral intake of calcium and phosphorus in periods of higher needs such as gestation and lactation. The aim of this study was to determine parameters of calcium and phosphorus homeostasis in female dogs receiving the recommended amount of these minerals according to NRC (Nutrient requirements of dogs and cats. Washington, DC, USA: The National Academies Press. 2006) during the peripartal phase. In five Beagles and four Foxhound crossbreds, all primiparous with a litter size of 1-8 puppies, apparent digestibility of calcium and phosphorus as well as serum parameters of mineral metabolism (total and ionised calcium, phosphorus, parathyroid hormone, bone specific alkaline phosphatase, crosslaps) was determined in the period of 12-9 days before and 4-9 days after parturition. The apparent digestibility of calcium was relatively low and did not differ significantly between both peripartal phases, whereas the apparent digestibility of phosphorus increased during lactation. Serum concentrations of calcium (total as well as ionised), phosphorus and parathyroid hormone did not differ between gestation and lactation. The bone resorption marker serum crosslaps increased in lactating dogs but most individual values were within the reference range for adult female dogs at maintenance. On the other hand, the bone formation marker bone specific alkaline phosphatase decreased from prepartal to postpartal phase with values clearly above reference range in both phases. Based on the results especially of the bone markers, which stayed within the reference range during the peripartal phase without indicating predominant bone resorption, we hypothesise that the applied recommended daily allowances defined for peripartal dogs are appropriate.

Effects of Calf Horn as Chews on the Behavior of Laboratory Dogs.

It is increasingly required that non-human animals in laboratories are provided with adequate enrichment to promote the welfare of the animals. In a previous publication we showed that laboratory dogs intensively used the horn of calf hooves as chewing objects. In this report, we describe the effect of calf horn on selected behaviors of 62 laboratory dogs (60 beagles, two Foxhound crossbreds) in three research facilities (A, B, C). In addition, we assessed the dogs' tooth condition and fecal consistency. The selected behaviors: "aggressive behavior," "mounting," "tussle," "coprophagy," "manipulation" of the equipment and "abnormal behavior" did not change. In facilities A and C, the dogs receiving horn showed a significant reduction in staying near the fence of the kennel and observing the outside area. By analyzing the overall behavior in facility B, we found that "exploration" increased with horn, whereas "inactivity," "social play" and "other social behavior" decreased. In conclusion, the results indicate that horn of calf hooves offers alternative stimulation. We found positive effects on tartar/plaque reduction and fecal consistency which should be confirmed in further studies.

Factorial calculation of calcium and phosphorus requirements of growing dogs.

Calcium and phosphorus requirements for growing dogs can be calculated by different methods. The current standard feeding recommendations are based on experimental data derived from young giant breed puppies. In order to determine the absolute requirement, an extrapolation via metabolisable energy requirement is recommended. Another approach is to calculate the requirement factorially, taking into account the endogenous losses and the amount of calcium and phosphorus retained due to tissue accretion during growth as well as the expected availability of these nutrients. The working hypothesis was that both methods are valid and lead to comparable results in young puppies of a high mature body weight (BW). Yet, deviations for other age and mature BW groups were expected. Thus, the aim of the present study was to compare the results of both methods using exemplary puppies of different age and mature BW groups. The hypotheses could be verified for calcium. The extrapolated requirements overestimate the factorial requirements by up to 59.7% for puppies <60kg mature BW and/or >6 months of age. In case of phosphorus requirement, the deviations between both methods are overall very high in all stages. Taking into account the potentially harmful effects of calcium and phosphorus excess, the feeding recommendations based on the extrapolation should be reconsidered.

Pharmacokinetics of low-dose and high-dose buprenorphine in cats after rectal administration of different formulations.

OBJECTIVES: A prospective experimental study was performed in nine young healthy cats to investigate a pharmacokinetic profile and the clinical relevance of rectally administered buprenorphine. Rectal pH value was measured in all nine cats. METHODS: Blood was collected 15, 30, 60, 90, 120, 240 and 480 mins and 24 h after the rectal administration of a suppository and a gel at doses between 0.02 mg/kg and 0.1 mg/kg buprenorphine to determine the plasma concentration of buprenorphine. Rectal pH was measured with pH paper. RESULTS: Upon pharmacokinetic non-compartment analysis of high-dose buprenorphine (0.1 mg/kg), average maximal plasma concentration was found to be 1.13 ng/ml, time to maximal plasma concentration was 45 mins and area under the plasma concentration-time curve was 94.19 ng*min/ml, representing low but potential bioavailability. Mean residual time was 152.2 mins and the half-life was 92.6 mins. A wide range of plasma concentrations within the cohort was measured and two of the cats had to be excluded from statistical analysis owing to incomplete uptake. Vital parameters of all cats were considered to be normal but three of the cats showed mydriasis up to 8 h after application. After the administration of a low-dose suppository or a rectal gel (0.02 mg/kg) within pilot studies, no buprenorphine was detected in cat plasma. Rectal pH in all cats was between 7.7 and 8. CONCLUSIONS AND RELEVANCE: The rectal application of buprenorphine at a dose of 0.1 mg/kg revealed a potential but weak uptake in cats. Regarding effective concentrations in previous pharmacokinetic investigations, rectal administration is currently not recommended for good provision of opioid analgesia in cats. Pharmacological investigations of formulation and galenics in order to improve the rectal bioavailability of buprenorphine remain to be clarified before further dose-finding and pharmacokinetic/pharmacodynamic studies are performed.

A pilot study on in vitro solubility of phosphorus from mineral sources, feed ingredients and compound feed for pigs, poultry, dogs and cats.

Excess phosphorus (P) as seen in cat foods can have a negative effect on health (Dobenecker, Webel, Reese, & Kienzle, ; Pastoor, Klooster, Mathot, & Beynen, ). P surpluses may affect the environment, and economics in food producing animals, whereas marginal supply may impair performance and health. P can only be absorbed if it is soluble. Solubility of feed P in water and weak acid solution-as a precondition for absorption-was investigated in feed for dogs, cats, pigs and poultry. Different P containing mineral compounds (Ca(H2 PO4 )2 , CaHPO4 •2H2 O, Ca4 Na(PO4 )3 , KH2 PO4 , K4 P2 O7 , NaH2 PO4 , Na5 P3 O10 (29 samples), as well as eight different ingredients such as wheat or meat, 64 compound feeds for pig and poultry, eight complete dry and 13 complete moist dog foods, 25 complete moist cat foods and 29 experimental diets were analysed for P solubility. Finely ground feeds were soaked in water or hydrochloric acid (0.4%) for 1 and 90 min. The samples were centrifuged and the supernatant was analysed for P (photometric vanadate molybdate method after wet ashing). The solubility of P from inorganic sources reflected the solubility of the main compound of the feed grade material. "organic" ingredients, such as fish meal or meat, showed a lower P solubility than inorganic sources. Most ingredients from animal origin (exception fish meal) had a higher P solubility than those from plant origin. When inorganic and "organic" P sources were mixed, the P solubility of the mixture reflected the P solubility and percentages of its compounds. In chicken, turkey and pig compound feed the percentage of acid soluble P increased with increasing P content. Pet moist food showed high percentages of water-soluble P. The results show that the method is suitable to obtain data on water and acid solubility of P in feed and ingredients.

Renal phosphorus excretion in adult healthy cats after the intake of high phosphorus diets with either calcium monophosphate or sodium monophosphate.

Renal and faecal phosphorus excretion of adult healthy European shorthaired cats after the intake of high phosphorus diets (meat/rice based) with either calcium monophosphate (HP-CaP) or sodium monophosphate (HP-NaP) as main phosphorus source was compared. The control diets (CON-CaP and CON-NaP, respectively) did not contain any added phosphorus. Calcium/phosphorus ratio was adjusted to 1.3/1 by adding calcium carbonate. Twenty-three cats were available for the trials. All cats were fed the control diets for 29 days; then, the HP diets were tested for 29 days against controls in a crossover design. Faeces and urine were collected in the last 10 days of each trial. Phosphorus in food, faeces and urine was measured by photometry after wet digestion. Phosphorus intake amounted to 84 ± 10 mg/kg body weight (BW) in CON-NaP (n = 13) and to 74 ± 7 in CON-CaP (n = 12). In the HP groups, the intake was 255 ± 34 mg/kg BW (HP-NaP; n = 13) and 216 ± 20 mg/kg BW (HP-CaP; n = 12). The sodium monophosphate in group HP-NaP led to a higher renal phosphorus excretion (83 ± 15 mg/kg BW) than the calcium monophosphate (25 ± 5 mg/kg BW; p < 0.05), even though the apparent phosphorus digestibility was higher in HP-CaP than in HP-NaP (p < 0.05). Faecal calcium excretion was strictly correlated to faecal phosphorus excretion (r2  = 0.98). The same was true for calcium and phosphorus balance (r2  = 0.89). In group HP-NaP, seven of 13 cats showed glucosuria. By contrast, in HP-CaP glucosuria was not observed. Highly water-soluble inorganic phosphorus sources such as sodium phosphate are likely to lead to phosphaturia and may present a risk for renal health of cats.

Effects of low phosphorus intake on serum calcium, phosphorus, alkaline phosphatase activity and parathyroid hormone in growing dogs.

A sufficient and balanced supply of calcium and phosphorus is important mainly for the skeletal health of dogs, especially during growth. Numerous reports and research results are quoted, which focus mainly on the effects of both deficient or excessive calcium supplies. The important role that phosphorus plays in the disruption to skeletal development is also explored. The aims of this study were to evaluate the effects of a low phosphorus supply on selected serum parameters of calcium and phosphorus metabolism in both medium and large breed growing dogs, alongside the effects on the apparent digestibility and retention of these minerals as well as the musculoskeletal development, which were published before. Beagle and Foxhound-crossbred puppies (n = 53) between the age of 6 and 24 weeks were either fed a balanced (control) or a low phosphorus diet, the latter one providing about one-third of P amount fed to the control group. In regular intervals, blood samples were obtained to measure serum levels of phosphorus, calcium, alkaline phosphatase activity (ALP) and parathyroid hormone (PTH). Functional Additive Mixed Models were used to analyse these serum concentrations per group and per diet. In the puppies being fed the low phosphorus diet, a distinct decline of serum phosphate concentration was detected with a more pronounced and prolonged effect in the smaller Beagles. At the same time, serum calcium concentration altered in the opposite direction, implying that the product of calcium multiplied by phosphorus was regulated more closely than the calcium to phosphorus ratio. The PTH concentrations were reduced and ALP activity increased at certain time points during the low phosphorus feeding compared to the puppies being fed the control diet. In the latter group, an effect of time or maturation could be demonstrated in relation to the serum phosphate concentration.