SummaryA meta-analysis was conducted to understand quantitative aspects of calcium (Ca) and phosphorus (P) absorption in adult dogs and cats. 34 studies in dogs and 14 studies in cats met the criteria for inclusion in the meta-analysis. Intake and faecal excretion values of Ca and P were subjected to a modified Lucas test and subsequent regression analyses. According to the current scientific consensus, Ca true digestibility (absorption) should increase at low Ca intake and decrease at high Ca intake. If true, this should result in a nonlinear relationship between the percentage of Ca excreted and dietary Ca intake. The present metaanalysis showed a highly significant linear relationship (p < 0.0001) between Ca intake and Ca excretion suggesting a lack of systematic quantitative adaptation in true Ca digestibility. This finding suggests either that the time period covered by standard digestion trials is too short to induce adaptation mechanisms or that dogs and cats at maintenance will not efficiently alter quantitative Ca absorption percentage according to the amount ingested. If the latter is true, a dietary Ca supply differing greatly from the recommended dietary intake might impair the health of cats and dogs when fed long term. The data plots for P intake and faecal excretion were less uniform suggesting other factors not just dietary intake influence faecal P excretion. In adult cats, the dietary Ca:P ratio strongly influenced the true digestibility of P, whereas this effect was less marked in adult dogs. Faecal P excretion was significantly correlated to faecal Ca excretion in both species (p < 0.0001), and surprisingly, the level of P intake did not appear to be an important determinant of true digestibility of P.

According to a previous meta-analysis, adult dogs do not notably increase calcium absorption from the gastrointestinal tract when calcium intake is decreased. This results in a negative calcium balance even with a moderate calcium reduction. In this study we wanted to verify (i) whether a negative calcium balance occurs at a calcium intake equivalent to NRC (2006) (Nutrient requirements of dogs and cats, 2006, The National Academies Press, Washington, DC) minimal requirements, and if so (ii) whether the negative calcium balance will persist for up to 6 months on a low-calcium diet. After a pre-feeding period of at least 18 weeks with calcium intake slightly exceeding maintenance requirements (200 mg/kg body weight ), 12 dogs (6 Beagles, 6 Foxhound crossbreds) were fed a low-calcium diet for 28 weeks. One dog was removed from the trial for reasons unrelated to the study at week 23. Calcium intake amounted to 60 mg/kg body weight corresponding to the minimal requirement for maintenance in dogs (NRC, 2006 (Nutrient requirements of dogs and cats, 2006, The National Academies Press, Washington, DC)). Digestion trials were carried out at week 7, 14, 21 and 28 of the low calcium feeding period. At these time points, and at week 18 of the pre-trial, blood samples were taken and analysed for calcium, ionised calcium, phosphorus, parathyroid hormone, vitamin D, serum crosslaps and bone alkaline phosphatase. Apparent calcium digestibility was negative throughout the study, suggesting a negative calcium balance. There was no systematic decrease in faecal calcium excretion. Serum calcium, ionised calcium and phosphorus remained within the reference range. Serum crosslaps increased continuously from baseline to week 28 of trial, with averages increasing from 0.102 ng/ml to 0.279 ng/ml, suggesting osteoclastic activity, indicative of calcium mobilisation from the skeleton. The study supports the theory of a lack of adaptation of intestinal calcium absorption from diets with relatively low calcium content in dogs. This agrees with clinical findings in dogs eating low-calcium diet.

Inadequate supply with such nutrients during the growth phase can lead to severe developmental disorders, especially in large breed puppies. Therefore, a thorough review of self-made rations for puppies carried out by specialised veterinarians appears to be of utmost importance to avoid permanent damage during growth.

Two groups of Warmblood foals from the Bavarian federal stud participated in the study beginning from the age of approximately 6 months. The foals were offered a late 1st cut of haylage, oats and foal starter feed. For 2 months after weaning, group 'R' (15 foals) received an amount of oats to provide a total digestible energy supply meeting the recommendations of the German Society of Nutrition Physiology (GfE), whereas the other group 'A' (16 foals) was offered a higher amount of oats (surplus of approximately 1.3 kg/animal/day). Concentrates were fed individually twice daily; total daily haylage intake of all foals together was recorded. In both groups, individual concentrate intake, body weight (BW), body condition score (BCS) and several growth parameters were documented. Both groups showed an absolutely parallel development of the measured growth parameters and of BW and BCS. BW and BCS increased above the recommendations of GfE and Hois. The amount of concentrates offered was not ingested completely in both groups. The average metabolisable energy (ME) intake from concentrates amounted to 30.3 and 32.1 MJ ME/animal/day (group 'R') and 38.7 and 38.2 MJ ME/animal/day (group 'A') for the 7th and 8th month respectively. The mean haylage intake of all foals together equalled 26.2 MJ ME/animal/day. The parallel development of all documented growth parameters in both groups leads to the assumption that higher concentrate intake must have caused lower intake of haylage and vice versa, thus resulting in an overall comparable energy intake for each foal, independently of energy source. The calculated average daily energy intake for all foals together amounted to 60.5 and 61.4 MJ ME/animal for the 7th and 8th month. The mean crude protein intake in both groups together amounted to 640 and 647 g/animal/day for the 7th and 8th month.

A dog was referred for nutrition consultation after surgical removal of struvite uroliths from the bladder. Inspection of the dog's current ration revealed a pronounced vitamin-A deficiency together with a marked deficiency of protein, phosphorus and magnesium. Therefore, a supersaturation of the urine with ammonium, magnesium and phosphate, the three constituents of struvite, as a cause of struvite calculi formation appears rather unlikely. Vitamin-A deficiency can promote urinary infections and consequently struvite stone formation because of the lack of the protective effect of vitamin A on the epithelia of the urinary tract. Not only common causes for struvite urolith formation, including urinary supersaturation with stone-forming constituents and urinary tract infection, but also less common causes, including vitamin-A deficiency, which was the presumed trigger in the present case study, have to be taken into consideration. Dietetic measures appear to be a useful tool in such cases to prevent uroliths from reoccurring.

Zusammenfassung Ziel dieser Studie war, die Auswirkungen eines unterschiedlichen Energieangebots auf das Wachstum von Warmblutfohlen zu untersuchen, um die Versorgungsempfehlungen der Gesellschaft für Ernährungsphysiologie (6) zu überprüfen. Material und Methoden: Zwei Gruppen von Fohlen erhielten vom 1. bis 6. Lebensmonat unterschiedliche Kraftfuttermengen. Die Rationen entsprachen im Energiegehalt den Vorgaben der GfE (6) bzw. überschritten diese um ca. 20%. Das Energieangebot der Gruppe „Norm“ (n = 15) zielte für die Gesamtration auf 73 MJ DE (verdauliche Energie)/Tier/Tag ab, für die Gruppe „Zulage“ (n = 16) auf 87 MJ DE/Tier/Tag. Die angebotene Menge an Fohlenaufzuchtfutter war gleich, die Hafermenge unterschiedlich. Fohlen beider Gruppen erhielten 1,0, 1,2, 2,0, 2,0 und 2,35 kg Aufzuchtfutter/Tier/Tag im 2.–6. Monat sowie 0,6, 0,7, 0,5, 0,8 und 0,45 kg Hafer (Gruppe „Norm“) bzw. 1,8, 2,0, 1,75, 2,0 und 1,75 kg (Gruppe „Zulage“). Die Fütterung erfolgte zweimal täglich. Als Raufutter diente ein später erster Schnitt Heulage, zudem hatten die Tiere täglich Weidegang. Kraftfutteraufnahme, Körpermasse, Body Condition Score (BCS) und verschiedene Körpermaße wurden registriert. Die Gesamtaufnahme an Heulage aller Tiere wurde dokumentiert. Ergebnisse: Die durchschnittliche tägliche Kraftfutteraufnahme lag zwischen 0,4 („Norm“) und 0,5 kg („Zulage“) im 2. Monat und zwischen 2,8 („Norm“) und 3,7 kg („Zulage“) im 6. Monat. Die Gruppen unterschieden sich in keinem der erhobenen Parameter. Erst im Alter von ca. 180 Tagen nahmen die Fohlen das Kraftfutter vollständig auf. Schlussfolgerung: Der Energiebedarf der Fohlen dürfte um 10–20% unter den Empfehlungen (6) liegen.

Zusammenfassung Ziel der Studie war, den Energiebedarf von Warmblutfohlen zu überprüfen, die durch einen Betriebswechsel beim Absetzen erhöhtem Stress ausgesetzt sind. Material und Methoden: Neun Hengstfohlen, die als Absetzer von verschiedenen Züchtern gekauft und gemeinsam aufgestallt wurden, nahmen an der Studie vom Absetzen im Alter von etwa 6 Monaten bis zu einem Alter von etwa 1 Jahr teil. Das Absetzen erfolgte im heimischen Betrieb oder nach gemeinsamem Transport von Stute und Fohlen bei Ankunft im neuen Bestand. Die Fohlen erhielten Heulage (später erster Schnitt), Hafer und Fohlenaufzuchtfutter. Um eine individuelle Kraftfutterzuteilung zu ermöglichen, wurden die Fohlen zweimal täglich separat angebunden. Erhoben wurden die Gesamtaufnahme der Heulage aller Fohlen gemeinsam pro Tag, die tägliche individuelle Kraftfutteraufnahme sowie in 4-wöchigen Abständen Körpermasse und Body Condition Score (BCS). Ergebnisse: Die tägliche Energieaufnahme der Fohlen betrug 74 MJ verdauliche Energie (68 MJ umsetzbare Energie) pro Tier. Die Fohlen wurden mit vergleichsweise niedrigem BCS von 4,2 ± 0,4 (Skala von 1 bis 9) und einer durchschnittlichen Körpermasse von 285 ± 30 kg aufgestallt. Sie erreichten am Ende der Studie im Alter von 319 ± 22 Tagen eine Körpermasse von 326 ± 24 kg und einen BCS von 4,2 ± 0,4. Die Energieaufnahme der Fohlen war höher und ihre Gewichtsentwicklung langsamer als in einer parallel laufenden Studie mit Fohlen, die im Gestüt geboren und aufgewachsen und dementsprechend beim Absetzen weniger Stress ausgesetzt waren. Schlussfolgerung und klinische Relevanz: Fohlen mit relativ niedriger Körpermasse und BCS und erheblichem Stress zum Zeitpunkt des Absetzens benötigen deutlich mehr Energie als Fohlen, die beim Absetzen in ihrer gewohnten Umgebung verbleiben und dadurch weniger Stressoren unterliegen.

The dog is used as a model for human skeletal research, with the assumption that calcium (Ca) and phosphorus (P) metabolism are similar between species. A prior meta‐analysis of Ca intake and faecal excretion suggested that adult dogs are unable to adapt their Ca digestibility to Ca intake, meaning dogs lack the ability to increase Ca digestibility when dietary Ca is low. We wanted to test this hypothesis in vivo with diets reflective of normal feeding. Apparent Ca digestibility and selected Ca metabolism and safety markers were determined at baseline and every 6 weeks for 6 months of low Ca feeding (~60 mg Ca/kg BW^0.75 = Minimum Requirement (MR), Ca/P=0.6) in 11 adult dogs. During low Ca feeding there was no decrease in faecal Ca excretion and apparent Ca digestibility was negative. Markers of bone resorption increased. This study confirmed the results of the meta‐analysis: dogs fed Ca at MR exhibit negative apparent Ca digestibility and increased bone resorption suggesting that Ca regulation in the dog does not utilize changes in Ca digestibility. These data show that Ca homeostasis of the dog differs from human, and thus the dog should not be used as a model animal for human skeletal research.