Immunoglobulin concentrations in feline colostrum and milk, and the requirement of colostrum for passive transfer of immunity to neonatal kittens

The purpose of this study was to clarify whether cats have a colostral and milk phase of lactation differentiated by concentrations of immunoglobulins, and whether colostrum ingestion by newborn kittens is essential for optimal transfer of passive immunity. Milk from specific pathogen-free queens was analyzed for IgG and IgA concentrations from parturition through 6 weeks of lactation. Serum IgG and IgA concentrations from birth through 8 weeks of age were determined for colostrum-fed kittens, colostrum-deprived kittens that were fed a milk replacer, and colostrum-deprived kittens that were fostered onto queens in the milk phase of lactation. The total IgG and IgA concentrations in milk were significantly higher on the day of parturition than on day 7 of lactation, indicating cats do have a colostral phase of lactation. The predominant immunoglobulin in both colostrum and milk was IgG. The serum IgG concentrations in colostrum-deprived kittens fostered on queens in the milk phase of lactation were similar to colostrum-deprived kittens fed a milk replacer, and the concentrations were significantly lower than in colostrum-fed kittens for the first 4 weeks of life. The serum IgA concentrations in both colostrum-deprived groups were significantly lower than colostrum-fed kittens on day 2 after parturition, but were similar thereafter. Colostrum-deprived kittens fostered onto queens in the milk phase of lactation had failure of passive transfer of maternal antibodies. Protective concentrations of immunoglobulins can be restored in kittens with failure of passive transfer of immunity by parenteral administration of adult cat serum, but not by fostering on queens in mid-lactation.     

Evaluation of surrogate markers for passive transfer of immunity in kittens

OBJECTIVE: To identify surrogate markers of passive transfer of immunity in kittens. DESIGN: Prospective clinical trial. ANIMALS: 55 kittens from 12 specific-pathogen-free queens. PROCEDURE: Kittens were allocated at birth into colostrum-fed (n = 27) and colostrum-deprived (28) groups. Blood was collected at birth and on days 1, 2, 4, 7, 14, 28, and 56. Serum samples were analyzed for activities of alkaline phosphatase (ALP), alanine aminotransferase, aspartate aminotransferase, creatine kinase, lactate dehydrogenase, gamma-glutamyltransferase, amylase, and lipase and for concentrations of albumin, total protein, bilirubin, urea nitrogen, creatinine, cholesterol, glucose, calcium, phosphorus, and triglycerides by use of an automated analyzer. Total serum solids concentrations were estimated by use of refractometry. Serum IgG concentrations were quantified by use of radial immunodiffusion. RESULTS: All kittens were agammaglobulinemic at birth. Colostrum-fed kittens had significantly higher IgG concentrations than did colostrum-deprived kittens from 1 though 28 days of age. Transient significant differences in serum biochemical variables between the colostrum-deprived and colostrum-fed groups were substantially resolved by day 4. Passive transfer of immunity could be reliably determined at 1 day of age and to a lesser extent at 2 days of age only by measurement of serum activity of ALP. CONCLUSIONS AND CLINICAL RELEVANCE: Adequacy of passive transfer in kittens initially correlated with serum activity of ALP, but quantification of serum IgG concentration was necessary after 2 days of age.     

Evaluation of treatment of colostrum-deprived kittens with equine IgG

OBJECTIVE: To evaluate equine IgG as a treatment for kittens with failure of passive transfer of immunity (FPT). ANIMALS: 13 specific pathogen-free queens and their 77 kittens. PROCEDURE: Kittens were randomized at birth into 9 treatment groups. One group contained colostrum-fed (nursing) kittens; the other groups contained colostrum-deprived kittens that were administered supplemental feline or equine IgG PO or SC during the first 12 hours after birth. Blood samples were collected at serial time points from birth to 56 days of age for determination of serum IgG concentrations. The capacity of equine IgG to opsonize bacteria for phagocytosis by feline neutrophils was determined via flow cytometry. RESULTS: Kittens that received feline or equine IgG SC had significantly higher serum IgG concentrations than those of kittens that received the supplements PO. In kittens that were administered supplemental IgG SC, serum IgG concentrations were considered adequate for protection against infection. The half-life of IgG in kittens treated with equine IgG was shorter than that in kittens treated with feline IgG. Feline IgG significantly enhanced the phagocytosis of bacteria by feline neutrophils, but equine IgG did not. CONCLUSIONS AND CLINICAL RELEVANCE: Serum concentrations of equine IgG that are considered protective against infection are easily attained in kittens, but the failure of these antibodies to promote bacterial phagocytosis in vitro suggests that equine IgG may be an inappropriate treatment for FPT in kittens.     

Effect of age on reference intervals of serum biochemical values in kittens

OBJECTIVE: To determine the effect of age on reference intervals of serum biochemical values in kittens. DESIGN: Prospective clinical trial. ANIMALS: 55 kittens from 12 specific-pathogen-free queens. PROCEDURE: Kittens were allocated at birth into colostrum-fed (n = 27) and colostrum-deprived (28) groups. Blood was collected at birth and on days 1, 2, 4, 7, 14, 28, and 56. Serum samples were analyzed for activities of alkaline phosphatase, alanine aminotransferase, aspartate aminotransferase, creatine kinase, lactate dehydrogenase, gamma-glutamyltransferase, amylase, and lipase and for concentrations of albumin, total protein, bilirubin, urea nitrogen, creatinine, cholesterol, glucose, calcium, phosphorus, and triglycerides by use of an automated analyzer. Total serum solids concentrations were determined by use of refractometry. Serum IgG concentrations were quantified by use of radial immunodiffusion. RESULTS: For several analytes, reference intervals changed rapidly, most notably during the first few days of life. Reference intervals for alkaline phosphatase, creatine kinase, lactate dehydrogenase, and triglycerides were higher from birth to 8 weeks than adult reference intervals. Aspartate aminotransferase, bilirubin, urea nitrogen, and creatinine were higher than in adults at birth but were similar to or lower than adult reference intervals by 8 weeks. Compared with adult reference intervals, reference intervals for calcium and phosphorus concentrations were higher and for albumin and total protein concentrations were lower throughout the study period. CONCLUSIONS AND CLINICAL RELEVANCE: Important differences exist between reference intervals for serum biochemical values of neonatal and adult cats. Age-appropriate reference intervals should be used for accurate assessment of serum biochemical test results in cats.     

Neutrophil function and plasma opsonic capacity in colostrum-fed and colostrum-deprived neonatal kittens

OBJECTIVE: To determine whether passive transfer of IgG in neonatal kittens affects plasma opsonic capacity and neutrophil phagocytic and oxidative burst responses to bacteria in vitro. ANIMALS: 22 kittens from 6 specific pathogen-free queens. PROCEDURE: Kittens were randomized at birth into the following treatment groups: colostrum-fed, colostrum-deprived, or colostrum-deprived supplemented with feline or equine IgG. Blood samples were collected at intervals from birth to 56 days of age. Plasma IgG concentrations were determined by radial immunodiffusion assay. Neutrophil function was assessed by a flow cytometry assay providing simultaneous measurement of bacteria-induced phagocytosis and oxidative burst. The opsonic capacity of kitten plasma was determined in an opsonophagocytosis assay with bacteria incubated in untreated or heat-inactivated plasma. RESULTS: Among treatment groups, there were no significant differences in neutrophil phagocytic and oxidative burst responses to bacteria or opsonic capacity of plasma. In all samples of plasma, inactivation of complement and other heat-labile opsonins significantly reduced the opsonic capacity. Plasma IgG concentrations in kittens did not correlate with neutrophil function or plasma opsonic capacity before or after inactivation of complement. CONCLUSIONS AND CLINICAL RELEVANCE: The plasma opsonic capacity and neutrophil phagocytic and oxidative burst responses in vitro of kittens receiving passive transfer of IgG via colostrum intake or IgG supplementation and those deprived of colostrum were similar. The alternate complement pathway or other heat-labile opsonins may be more important than IgG in bacterial opsonization and phagocytosis.     

Feline neonatal isoerythrolysis in two litters

The clinical, pathological and serological findings for feline neonatal isoerythrolysis (FNI) in two litters are described. In each litter one of four kittens died shortly after birth, two showed varying degrees of depression, jaundice and haemoglobinuria and one remained healthy (clinically unaffected). Three of the kittens with jaundice died and the necropsy findings included variable degrees of erythrophagocytosis in the spleen and liver and many casts containing haemoglobin in the tubules and collecting ducts of the kidney. Blood typing and haemocompatibility testing were performed on the surviving kittens, queens and sires. Both queens and the healthy kittens were Type B while both sires and the surviving affected kitten were Type A. In both litters the queens sera haemolysed the sires erythrocytes but did not affect the erythrocytes of the healthy kittens. The erythrocytes of the surviving affected kitten were haemolysed by the serum of its queen. The pathogenesis and treatment of FNI are discussed.     

Oral and intravenous immunoglobulin therapy in neonatal foals

Newborn foals, deprived of colostrum and its rich supply of immunoglobulin G (IgG), were supplemented both orally and intravenously with purified equine immunoglobulin G (Lyphomune^®). Data were obtained from 18 foals given oral administration of IgG at Colorado State University and 26 foals given IgG intravenously at the Jockey Club de Sao Paulo in Brazil.Oral administration of 10-gm doses of Lyphomune^® in 18 colostrum-deprived Arabian foals, at various intervals within the first 24 hours after birth, resulted in increased serum concentrations of IgG. Administration of one 10-gm dose of Lyphomune^® immediately following birth provided a mean serum IgG level of 125 mg/dl after two hours. The recommended dosage of two 10-gm doses per 15 kg of body weight produced mean IgG serum concentrations of approximately 400 mg/dl by 14 hours. It was determined that an early bolus of IgG was most effective, although administration at any period during the first 24 hours would increase IgG levels significantly and in direct relationship to grams of Lyphomune^® administered.After the 24-hour study period, colostrum from each respective mare was provided by bottle feeding (200 ml) to 10 of the foals that were then allowed to nurse their dams normally. Significant increases in circulating IgG were observed in nine of these ten animals at four and eight hours after colostrum administration. No interfering effect was noted when colostrum and Lyphomune^® were given to the same foal.Intravenous administration of 10-gm doses of Lyphomune^® in Thoroughbred foals, immediately after birth, resulted in serum concentrations of IgG of 200–300 mg/dl six hours later. A second intravenous dose, at six hours after the initial dose, resulted in an additional average increase of 184 mg/dl. Four of six foals administered 10 gm of Lyphomune^® for each 15 kg of body weight reached serum concentrations greater than 400 mg/dl. It was demonstrated that Lyphomune^® was able to increase circulating levels of IgG, by either oral or intravenous administration, to levels considered protective in the newborn foal.     

Absorption of an alternate source of immunoglobulin in pups.

Newborn pups from 4 large litters were alloted to 6 groups to determine effect of time and route of administration on absorption of an alternate source of immunoglobulin. Selective absorption of specific classes of immunoglobulins was also investigated. The alternate source of immunoglobulin consisted of pooled serum that was administered either PO or SC. Control groups were either left with the dam (group C1) or fed milk replacer (group C2). Blood samples were collected from pups at birth and 24 hours. Immunoglobulin (IgA, IgG, IgM) concentrations were determined by use of radial immunodiffusion on samples of pooled serum, colostrum, and pups' serum (birth and 24 hours). Serum IgA concentration was less than the sensitivity of the procedure and was not included in the statistical analysis. Pups fed 8 ml of pooled serum at birth and 12 hours later (group T1) absorbed more (P less than 0.05) IgG and IgM than did group-C2 pups, but less (P less than 0.05) than did group-C1 pups. Pups fed 8 ml of pooled serum at 12 hours only had significant (P less than 0.05) increase of IgG concentration, but no absorption of IgM (P greater than 0.05) at 24 hours, compared with control pups (group C2). Pups administered 8 ml of pooled serum SC at birth (group SC1) had similar (P greater than 0.05) absorption of IgG and higher (P less than 0.05) absorption of IgM than did pups of group T1.(ABSTRACT TRUNCATED AT 250 WORDS)     

Lyophilized hyperimmune equine serum as a source of antibodies for neonatal foals

In a study with 15 neonatal foals (5 per treatment group), foals were fed within 4 hours of birth as follows: 250 ml of colostrum, 250 ml of lyophilized serum reconstituted at 5 times the original concentration, or 250 ml of a mixture (1:1) of colostrum and lyophilized serum. Foal serum samples were tested for immunoglobulin (Ig)G concentration and titrated for anti-equine rhinovirus 1 and anti-equine influenza A1 and A2 antibodies at 0 and 24 hours after foals were born. Except in a foal which had suckled the dam before treatment, there was no evidence of IgG or specific viral antibodies in the samples taken at birth. There were no significant differences found in the serum IgG concentrations and antibody titers among the 3 treatment groups. Seemingly, IgG was absorbed efficiently from both serum and colostrum, so that the use of reconstituted lyophilized serum as a prophylactic measure of conferring passive immunity to a newborn foal deserves serious consideration.     

Chronic ingestion of high concentrations of cholecalciferol in cats

OBJECTIVE: To determine whether ingestion of 63 times the recommended amount of vitamin D3 (cholecalciferol) results in renal calcification or damage in cats. ANIMALS: 20 four-month-old kittens, 17 queens, and 20 kittens born to these queens. PROCEDURE: 4-month-old kittens and queens were given a purified diet with 846 microg of cholecalciferol/kg of diet (high vitamin D3 diet) or 118 microg of cholecalciferol/kg of diet (control diet) for 18 months. Kittens born to queens were weaned onto the same diet given to dams. RESULTS: There were no apparent adverse effects of the high vitamin D3 diet. Plasma cholecalciferol and 25-hydroxycholecalciferol (25-OHD3) concentrations of queens and 4-month-old kittens given the high vitamin D3 diet significantly increased with time. At 6 months, plasma cholecalciferol concentrations in these kittens and queens were 140.0+/-7.3 nmol/L and 423.6+/-26.6 nmol/L, respectively (10 times initial values). Corresponding 25-OHD3 concentration in queens was 587.5+/-59.4 nmol/L (2.5-fold increase over initial values). At 3 months of age, kittens born to queens given the high vitamin D3 diet had an increase in serum BUN and calcium concentrations and a decrease in RBC and serum total protein, albumin, and hemoglobin concentrations. By 18 months, these kittens had an increase in plasma cholecalciferol (276.0+/-22.2 nmol/L) and 25-OHD3 (1,071.9+/-115.3 nmol/L) concentrations. However, all indices of renal function and the appearance of renal tissue on histologic evaluation were normal. CONCLUSIONS AND CLINICAL RELEVANCE: These results indicate that cats are resistant to cholecalciferol toxicosis when the diet is otherwise complete and balanced.     

Teratogenic effects of chronic ingestion of high levels of vitamin A in cats

High concentrations of retinoids occur in some commercial cat food formulations as a result of the use of animal liver as an ingredient. Our objective was to study the teratogenic potential of dietary vitamin A in cats. We investigated the incidence of birth defects in kittens of queens given diets with retinyl acetate concentrations of 6000, 306000, or 606000 retinol equivalents (RE)/kg diet (control, 306K, or 606K groups, respectively) for approximately 3 years [1 RE=1 micro g retinol=3.3 International Units (IU)]. Each group comprised 12-15 age-matched, nulliparous domestic short-haired queens that were exposed to toms. There were a total of 396 kittens born in 97 litters. Pregnancy rate, number of kittens per gestation and gestations per year were not significantly different among treatment groups. A total of 2, 5 and 11 malformed kittens occurred in the control, 306K and 606K groups, respectively. Malformations included cleft palate, cranioschisis, foreshortened mandible, stenotic colon, enlarged heart and agenesis of the spinal cord and small intestine, which are typical foetal defects consistent with ingestion of excess retinoids in other species. This study demonstrated that a concentration of 306000 RE/kg diet has a potential for causing birth defects in the kittens.     

Transmission of feline leukaemia virus in the milk of a non-viraemic cat

The possibility of the transmission of feline leukaemia virus (FeLV) from latently infected cats was studied. Five female cats with latent infections were examined for evidence of transmission of the virus to their kittens. One of the cats infected members of four consecutive litters of kittens which subsequently became persistently viraemic and transmitted the virus to other susceptible kittens by contact. Shortly after birth its kittens were apparently FeLV-free since neither viral antigen nor infectious virus was detected in their blood and no virus was found in cell cultures made from aspirates of bone marrow. The kittens became viraemic from 45 days of age onwards at a time when their passively acquired colostral FeLV neutralising antibodies were no longer detectable. Transmission of the virus occurred via the milk since both FeLV antigen and infectious virus were found in milk samples taken six weeks after kittening and the virus was transmitted to a fostered kitten. Eleven weeks after the birth of the fourth litter the cat became viraemic. The intermittent presence of FeLV antigens detected by the Leukassay F test, but not infectious virus, in the plasma of this cat over the previous months and a low level of serum neutralising antibodies distinguished it from four other latently infected queens which did not transmit infection to their kittens. These factors may indicate a risk of milk transmission and reactivation of latent virus.     

Age-related changes in protein concentrations in serum and respiratory tract lavage fluid obtained from cats.

Total protein concentrations was determined in serum, bronchoalveolar lavage (BAL) fluid, and nasal flush fluid obtained from specific-pathogen-free cats from birth to maturity and from adult conventionally raised cats. Protein components were analyzed by immunoelectrophoresis and isoelectric focusing. Albumin, and alpha-, beta-, and gamma-globulins were among the proteins identified in BAL fluid, and their isoelectric point ranged from 3.1 to 5.1. gamma-Globulin was not detected in serum or BAL fluid of newborn kittens before they had ingested colostrum. By day 3 after ingestion of colostrum, IgG was detected in high concentration in serum and was the predominant immunoglobulin in serum and BAL fluid of older cats. Nasal flush fluid from cats greater than 6 months old contained albumin, and alpha-, beta-, and gamma-globulins, with IgA being the predominant immunoglobulin. Total protein concentration in nasal flush fluid increased progressively with increasing age, and albumin was the predominant protein. Protein concentration was significantly (P less than 0.01) higher in BAL fluid from conventionally raised adult cats than in that from specific-pathogen-free cats.     

Attempted transmission of Toxoplasma gondii infection from pregnant cats to their kittens

Sixteen 1- to 7-week-old pregnant specific-pathogen free cats were inoculated orally with Toxoplasma gondii cysts. Fetuses and neonatal kittens were examined for toxoplasma infection by inoculating suspensions of their tissues into mice. Toxoplasma gondii was not isolated from 23 fetuses and 16 newborn kittens from 13 queens. Six (3 litters) of the 15 kittens from the 3 remaining queens were killed on the day of or a day after birth, and the remaining 9 kittens were housed with their mothers for 7 to 33 days. None of the 9 kittens from the 2 litters examined between 0 and 33 days of age was infected with T gondii. In the other litter, T gondii was isolated from 3 kittens killed at 9, 16, and 22 days of age but not from 3 littermates killed on days 1, 1, and 22. Internal organs from the 3 kittens with proved toxoplasma infectivity in mice were examined histologically. Multifocal granulomatous encephalitis, hepatitis, nephritis, myocarditis, myositis, and interstitial pneumonia were found in all 3 kittens. Toxoplasma forms were demonstrated histologically in the tissues of 2 of these kittens. The mode of toxoplasma infection in newborn kittens was not determined but did not appear to be either transplacental or via fecal contamination from oocysts excreted by the mother cat. Evidence obtained in these experiments suggests that transplacental toxoplasma infection in the cat is not an important epidemiologic factor in perpetuation of the disease in the feline population.     

Increase of serum gamma-glutamyltransferase in neonatal Standardbred foals

Serial blood samples were obtained from 16 Standardbred foals from time of birth to postpartum day 28. Sera were obtained and analyzed for gamma-glutamyltransferase (GGT), aspartate transaminase, and immunoglobulin (Ig) G. Presuckle colostrum from the respective mares of these foals was analyzed for GGT activity. Mean serum aspartate transaminase activities were significantly increased above presuckle values by postpartum hour 48 (P less than 0.01) and increased gradually over the first 14 days. Mean serum IgG concentrations were significantly greater than presuckle values by 5 hours after foals first suckled (P less than 0.01) and remained significantly increased during the 28-day sampling period. Serum GGT activity did not differ significantly over the period sampled. The SD were large, since there was a large degree of interindividual variation. Serum GGT activity in the foals was significantly increased over that in the mares throughout the period of the study. The profile of serum GGT activity over time in each foal did not show a pattern of change. There was no postsuckle increase in serum GGT activity nor a correlation between serum GGT activities and IgG concentrations at 24 hours after foals first suckled. Evidence was not obtained to support a colostric source of GGT involved in the increase of serum GGT activity in foals. Serum GGT activity seems to be increased in foals due to endogenous sources.     

Serum immunoglobulin G concentrations in calves fed fresh colostrum or a colostrum supplement

This study compared serum immunoglobulin G (IgG) concentrations in calves fed colostrum with those of calves fed a colostrum supplement containing spray-dried serum. Twenty-four Holstein calves were randomly assigned to I of 2 treatment groups (fresh colostrum or colostrum supplement). Each calf was fed 4 L of colostrum (n, = 12) or 4 L of colostrum supplement (n2 = 12) via oroesophageal intubation at 3 hours of age. The concentration of the colostrum supplement fed to calves was twice the manufacturer's recommendation. The median and range values for colostral IgG concentration were 6,430 mg/dL and 1,400-17,000 mg/ dL, respectively. Median serum IgG concentrations at 2 days of age differed significantly (P = .001) between calves receiving fresh colostrum (3,350 mg/dL) and the colostrum supplement (643 mg/dL). Eight percent of calves force fed colostrum had serum IgG concentrations < 1,000 mg/dL, whereas 75% of calves force-fed supplement had IgG concentrations below this threshold. The calculated population relative risks for mortality associated with passive transfer for calves force-fed colostrum and calves force-fed colostrum supplement were 1.09 and 1.90, respectively. Force-fed fresh colostrum is superior to the colostrum supplement studied, but the colostrum supplement has similar efficacy to routine colostrum administration practices.     

Effects of passive transfer of immunity on results of diagnostic tests for antibodies against feline immunodeficiency virus in kittens born to vaccinated queens

OBJECTIVE: To determine whether passive transfer of immunity affects results of diagnostic tests for antibodies against FIV in kittens born to vaccinated queens. DESIGN: Experimental trial. ANIMALS: 12 specific-pathogen-free queens and their 55 kittens. PROCEDURE: Queens were vaccinated with a whole-virus FIV vaccine prior to breeding. Serum was obtained from the queens on the day of parturition and from the kittens on days 2 and 7, then weekly until results of tests for antibodies against FIV were negative for 2 consecutive weeks. Milk was collected from the queens daily for the first week and then weekly. Serum and milk were tested for antibodies against FIV with 2 commercial assays. RESULTS: Antibodies against FIV were detected in serum obtained from the queens on the day of parturition and in the milk throughout lactation. All kittens tested positive for antibodies against FIV at 2 days of age. At 8 weeks of age, 30 (55%) kittens tested positive with 1 of the commercial assays, and 35 (64%) tested positive with the other. All kittens tested negative for antibodies against FIV by 12 weeks of age. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that kittens readily absorb antibodies against FIV in colostrum from vaccinated queens and that these antibodies may interfere with results of commercially available tests for FIV infection past the age of weaning. Currently licensed diagnostic tests for FIV infection are unable to distinguish among kittens with antibodies against FIV as a result of infection, passive transfer from infected queens, and passive transfer from vaccinated queens.     

Serum IgG Concentrations after Intravenous Serum Transfusion in a Randomized Clinical Trial in Dairy Calves with Inadequate Transfer of Colostral Immunoglobulins

Background: Plasma transfusions have been used clinically in the management of neonates with failure of passive transfer. No studies have evaluated the effect of IV serum transfusions on serum IgG concentrations in dairy calves with inadequate transfer of passive immunity.
Hypothesis: A commercially available serum product will increase serum immunoglobulin concentration in calves with inadequate transfer of colostral immunoglobulins.
Animals: Thirty-two Jersey and Jersey-Holstein cross calves with inadequate colostral transfer of immunoglobulins (serum total protein <5.0 g/L).
Methods: Thirty-two calves were randomly assigned to either control (n = 15) or treated (n = 17) groups. Treated calves received 0.5 L of a pooled serum product IV. Serum IgG concentrations before and after serum transfusion were determined by radial immunodiffusion.
Results: Serum protein concentrations increased from time 0 to 72 hours in both control and transfused calves and the difference was significant between the control and treatment groups ( P < .001). Mean pre- and posttreatment serum IgG concentrations in control and transfused calves did not differ significantly. Median serum IgG concentrations decreased from 0 to 72 hours by 70 mg/dL in control calves and increased over the same time interval in transfused calves by 210 mg/dL. The difference was significant between groups ( P < .001). The percentage of calves that had failure of immunoglobulin transfer 72 hours after serum transfusion was 82.4%.
Conclusions and Clinical Importance: Serum administration at the dosage reported did not provide adequate serum IgG concentrations in neonatal calves with inadequate transfer of colostral immunoglobulins.     

Feline calicivirus infection in kittens borne by cats persistently infected with the virus

On the basis of repeated isolation of feline calicivirus (FCV) from oropharyngeal swabs four to eight months after exposure to FCV strain 255, four carrier queen cats were identified. These cats gave birth to 16 kittens. Litters were individually housed with their mothers until nine weeks of age and were monitored virologically and serologically from birth until 15 weeks old. All kittens became infected between three and nine weeks old and shed FCV consistently for periods of three to 11 weeks. Clinical signs of FCV were observed in 11 kittens but none developed severe respiratory disease. At the time of initial infection maternal antibody titres in the kittens ranged from 1:4 to 1:24. Within one to three weeks of infection titres began to rise. The results indicated that kittens of queen cats persistently infected with FCV frequently experience mild or subclinical immunising infections.     

Variations in the concentrations of the immunoglobulins IgG1, IgG2, IgM and IgA in sheep. 2. Changes in the blood of lambs of different breeds and crossbreeds during the course of the rearing period

The sera of 188 lambs from seven breed groups were analyzed for the concentrations of IgG1, IgG2, IgM and IgA by radial immunodiffusion using monospecific antibodies. From each lamb, 14 blood samples were drawn before and 5 samples after weaning. The following results were obtained: 1. Immunoglobulins could not be detected in sera drawn before the first intake of colostrum. 2. In normally suckling lambs, the peak concentrations of maternal immunoglobulins are attained at 0-18 hrs after birth. They can be assessed in a single blood sample drawn between 18 and 24 hrs. 3. The half-life times of maternal immunoglobulin in lamb sera are 11 days for IgG1, 7 days for IgG2, 6 days for IgM and 18 hours for IgA. 4. The absolute peak heights relate to the amounts of colostrum ingested before 12-18 hrs after birth. 5. The decline of maternal immunoglobulins in lamb sera over-laps with the onset of lamb immunoglobulin synthesis. Renewed rises of concentrations are observed for IgG2 after week 2, for IgM after week 3 and for IgG1 after week 7. The concentrations of IgA remain at the low levels characteristic for the serum of grown sheep. 6. The role of immunoglobulin synthesis in suckling lambs is only briefly and to a small extent reduced after weaning.