CNS hypomyelination in Rat Terrier dogs with congenital goiter and a mutation in the thyroid peroxidase gene

Arrested physical development and neurologic abnormalities were identified in 3 of 5 Rat Terrier puppies at 9 weeks of age. Bilaterally firm symmetrical masses were palpated in the region of the thyroid glands. Low serum total (T4) and free thyroxine (FT4, by equilibrium dialysis) and markedly elevated thyroid stimulating hormone (TSH) concentrations supported the diagnosis of hypothyroidism. At necropsy, the thyroid gland was grossly enlarged and histologically exhibited severe, diffuse hyperplasia of the follicular epithelium. Gross examination of the central nervous system revealed a myelin deficiency, most evident in the corpus callosum. Regional distribution of hypomyelination was confirmed histologically, affecting the corpus callosum and, to a lesser degree, the corona radiata, the longitudinal fibers of the pons, the pyramids, and the lateral funiculi of the spinal cord. Myelin reduction was paralleled by axon reduction, suggesting that hypomyelination was a consequence of reduced axonal formation. A homozygous nonsense mutation in the thyroid peroxidase gene was identified in the affected puppies. The dam and a clinically normal litter mate were heterozygous for this mutation, confirming simple autosomal recessive inheritance of the disease trait. The same mutation, causing congenital hypothyroidism with a goiter was previously described in the Toy Fox Terrier breed. Given the ongoing practice of introducing the Toy Fox Terrier genetic background into some Rat Terrier breeding programs to obtain a smaller stature and the apparent relative incidence of the disorder in the 2 breeds, it is likely that this mutation crossed into the Rat Terrier breed from Toy Fox Terriers fairly recently.     

Canine wobbler syndrome: A study of the Dobermann pinscher in New Zealand

The aim of this study was to investigate the prevalence of wobbler disease within a Dobermann pinscher population from three geographical locations in New Zealand. The study population consisted of 138 adults (aged 1–13 years) and 32 puppies (aged 6 weeks to 11 months). Data collected for each dog included age, sex, geographic location, if a choker chain was used or not and, in adults, the following body measurements: dimensions of head length, head circumference, width between shoulders, neck length, height at withers and withers to rump length. In addition, lateral radiographs were taken of the caudal cervical vertebrae of each dog and the radiological abnormalities associated with wobbler disease scored, so that each dog could be assigned to one of three radiological groupings. Based upon a neurological examination, each animal was also placed into one of three neurological groupings. The relationship between radiological and neurological groupings and the independent variables was initially compared using a univariate and subsequently a multivariate analysis.

It was found that 48.8% of the dogs investigated had some abnormal radiological sign associated with wobbler disease, and 32.0% of them showed neurological signs. Dogs with radiological signs of the disease were 5.56 times more likely to have neurological signs. Statistical analysis of the data indicated that more severe radiological and neurological abnormalities occurred in the older dogs. In addition, dogs located in Hawke's Bay region had less chance of showing radiological changes than dogs from the other two regions, Hamilton and Wellington. Twelve of the 32 puppies were examined for radiological and neurological changes over the first year of their life. No abnormalities were detected in puppies under 12 weeks of age, but 28% (n=9) of the 32 puppies over 3 months of age did show some radiological changes. Only 9%(n=3) of puppies showed any neurological signs. Although several pedigree lines were investigated, the lineage data were incomplete, and therefore there was no conclusive evidence that wobbler disease was an inherited trait.

This study showed that, although the radiological signs of wobbler disease were present throughout a wide age range, the associated neurological changes tended to appear at a later age. In both instances, the severity of these changes increased with age.     

Canine wobbler syndrome: a study of the Dobermann pinscher in New Zealand

The aim of this study was to investigate the prevalence of wobbler disease within a Dobermann pinscher population from three geographical locations in New Zealand. The study population consisted of 138 adults (aged 1-13 years) and 32 puppies (aged 6 weeks to 11 months). Data collected for each dog included age, sex, geographic location, if a choker chain was used or not and, in adults, the following body measurements: dimensions of head length, head circumference, width between shoulders, neck length, height at withers and withers to rump length. In addition, lateral radiographs were taken of the caudal cervical vertebrae of each dog and the radiological abnormalities associated with wobbler disease scored, so that each dog could be assigned to one of three radiological groupings. Based upon a neurological examination, each animal was also placed into one of three neurological groupings. The relationship between radiological and neurological groupings and the independent variables was initially compared using a univariate and subsequently a multivariate analysis. It was found that 48.8% of the dogs investigated had some abnormal radiological sign associated with wobbler disease, and 32.0% of them showed neurological signs. Dogs with radiological signs of the disease were 5.56 times more likely to have neurological signs. Statistical analysis of the data indicated that more severe radiological and neurological abnormalities occurred in the older dogs. In addition, dogs located in Hawke's Bay region had less chance of showing radiological changes than dogs from the other two regions, Hamilton and Wellington. Twelve of the 32 puppies were examined for radiological and neurological changes over the first year of their life. No abnormalities were detected in puppies under 12 weeks of age, but 28% (n=9) of the 32 puppies over 3 months of age did show some radiological changes. Only 9% (n=3) of puppies showed any neurological signs. Although several pedigree lines were investigated, the lineage data were incomplete, and therefore there was no conclusive evidence that wobbler disease was an inherited trait. This study showed that, although the radiological signs of wobbler disease were present throughout a wide age range, the associated neurological changes tended to appear at a later age. In both instances, the severity of these changes increased with age.     

Congenital hypothyroidism in Scottish Deerhound puppies

Two Scottish Deerhound puppies had clinical and pathological features consistent with the diagnosis of congenital non-goitrous hypothyroidism. They were from separate litters, but were the progeny of the same sire and dam. The puppies were smaller, had shorter limbs and shorter, broader heads than their littermates. They also had histories of weakness, difficulty in walking and somnolence. A characteristic radiographic feature was the absence of epiphyseal growth centres. Both had depressed serum thyroxine (T4) levels and one did not respond to exogenous thyroid stimulating hormone. On necropsy, the thyroid glands were small, the follicles varied in size and contained little or no colloid. The adenohypophysis contained many cells with markedly vacuolated cytoplasm. It is suggested that the clinicopathological pattern is the result of a primary thyroid abnormality. Possible mechanisms include either primary thyroid hypoplasia or an unresponsiveness to thyroid stimulating hormone.     

Congenital hypothyroidism with goiter in toy fox terriers

Congenital hypothyroidism with goiter was observed to segregate as a simple autosomal recessive trait in Toy Fox Terriers (TFTs). Neonatal affected pups exhibited inactivity, abnormal hair coat, stenotic ear canals, and delayed eye opening. Palpable ventrolateral cervical swellings were evident by 1 week of age. Serum thyroid hormone and thyroid-stimulating hormone concentrations were low and high, respectively. Histologic examination of the cervical masses disclosed cuboidal to columnar follicular epithelial cell hyperplasia with widely varying follicular size, shape, and amount of colloid. Oral thyroid hormone replacement therapy restored near-normal growth and development. At 8 weeks of age, radioiodine uptake and perchlorate discharge testing indicated an iodine organification defect. Biochemical analysis of thyroid tissue from affected dogs demonstrated enzymatic iodine oxidation deficiency and lack of sodium dodecyl sulfate-resistant thyroglobulin dimers, suggesting thyroid peroxidase deficiency. A nonsense mutation in the thyroid peroxidase gene of affected dogs was discovered and demonstrated to segregate with the disease. A DNA-based carrier test was developed and currently is used by TFT breeders to prevent this disorder.     

Goitrous hypothyroidism associated with treatment with trimethoprim-sulfamethoxazole in a young dog

CASE DESCRIPTION: A 16-week-old female Boxer that had been treated for 5 weeks with trimethoprim-sulfamethoxazole and chloramphenicol because of aspiration pneumonia was evaluated for bilaterally symmetric masses in the subcutaneous tissues of the ventral neck, in the region of the larynx. CLINICAL FINDINGS: Fine-needle aspirates were obtained from the neck masses; cytologic examination revealed well-differentiated thyroid epithelial tissue. A blood sample was collected for serum biochemical and thyroid function analyses. Mild hyperphosphatemia, severe hypercholesterolemia, mild hyperkalemia, and a mild increase in creatine kinase activity were identified. Serum concentration of total thyroxine was less than the lower reference limit, and that of thyroid-stimulating hormone was greater than the upper reference limit. Findings were consistent with a diagnosis of clinical hypothyroidism in a skeletally immature dog. TREATMENT AND OUTCOME: Treatment with trimethoprim-sulfamethoxazole was discontinued. The dog was reevaluated 3 weeks later, at which time the neck masses were markedly decreased in size. Serum concentrations of cholesterol and potassium were lower; serum concentrations of total thyroxine and thyroid-stimulating hormone were near or within respective reference ranges. Age-appropriate increases in serum phosphorus concentration and serum alkaline phosphatase activity were also detected. CLINICAL RELEVANCE: To the authors' knowledge, this is the first report of antimicrobial-induced goiter in a dog. Cytologic examination of fine-needle aspirates and interpretation of data from serum biochemical and thyroid function analyses were needed to obtain a definitive diagnosis. Practitioners should include goiter among the differential diagnoses for ventral neck swellings in young dogs receiving potentiated sulfonamide antimicrobials.     

Pathological characteristics of thyroid glands from Japanese Black Cattle living in the restricted area of the Fukushima Daiichi Nuclear Power Plant accident

To study the effect of ionizing radiation on thyroid glands, 66 Japanese Black cattle residing in the restricted area of the Fukushima Daiichi Nuclear Power Plant in 2013–2017 were pathologically examined. There were no clinical symptoms of thyroid disease in these cattle. Three cases of goiter and seven of atrophy were found in two among the four farms examined. Cases of goiter exhibited normal morphological structure without mass or nodule formation in thyroid glands. Cellular atypia or capsular invasion of the follicular epithelium was absent. The estimated integrated dose of external radiation in goiter cases ranged from maximum 797 mSv to minimum 24 mSv. All lobules in the seven atrophic thyroid glands were affected, but pathological findings, such as inflammatory cell infiltration or stromal fibrosis, were not observed. The estimated integrated dose of external radiation in atrophic thyroids ranged from maximum 589 mSv to minimum 8 mSv. Immunohistochemical analysis of anti‐nitroguanosine and the TUNEL method in goiter and atrophic thyroid glands did not reveal any positive findings. The present study indicates that there was no significant relationship between a radiation effect and pathological findings in any thyroid glands.     

Observations on exocrine pancreatic insufficiency in a family of English setter dogs

The aim of this paper is to report serum trypsin-like immunoreactivity (TLI) concentrations in the progeny of a pair of English setters. These dogs had a history of producing puppies with a high prevalence of exocrine pancreatic insufficiency (EPI) secondary to either congenital deficiency or early onset juvenile atrophy of pancreatic acinar cells. Serum TLI concentrations in the clinically healthy parents of the puppies with EPI were normal, as were serum TLI concentrations in the unaffected puppies. However, serum TLI concentrations were extremely low (less than 1 μg/litre) in three puppies at eight to 12 weeks of age when clinical signs of EPI were present. In addition, one of the three puppies, with low TLI concentrations at eight weeks of age, had serum TLI concentrations of 0.7 μg/litre at two weeks of age even though no clinical signs were evident at that time. These results suggest that serum TLI assay may be a useful diagnostic aid in identifying puppies at a very early age with this unusual form of EPI.     

Contamination of dog hair with eggs of Toxocara canis

Toxocara canis, the common intestinal nematode of dogs and foxes, is the parasite responsible for human toxocarosis. It has recently been shown that dogs may harbour eggs of the parasite in their fur. To further investigate this claim a population of 100 stray dogs was examined to establish the prevalence and intensity of adult toxocaral worm infection in the intestines and eggs harboured in the hair. A novel method of washing the eggs from the hair was used. Sixty-seven percent of dogs were found to have T. canis eggs on their hair with a mean egg retrieval of nearly 584 eggs per gram from positive dogs. The age of the dog was found to be the only significant factor to influence the prevalence and intensity of eggs, with 95% of all the eggs recovered found on puppies. Thirty-nine percent of dogs were found to have adult T. canis worms in their intestine, although a significantly higher percentage of puppies (80%) were infected with worms than adults (22.5%). Puppies also had more worms per infection than adults and have a strong positive correlation between egg and worms numbers whereas adults did not. These studies show that stray dogs, particularly puppies, potentially harbour considerable numbers of eggs on their hair, at densities far higher than those reported in the soil or the general environment.     

Goiter in a cockatiel (Nymphicus hollandicus)

Goiter in a 2-year-old male cockatiel with respiratory distress was characterized by bilateral enlargement of the thyroid glands. Microscopic lesions included features of both hyperplastic goiter and colloid goiter. There also was localized hemosiderosis due to hemorrhage in subcapsular space and in thyroid follicle lumens.     

Effects of host maturity and prior exposure history on the production of Neospora caninum oocysts by dogs

To investigate whether dogs shed Neospora caninum oocysts more than once, five dogs with a previous history of shedding oocysts were fed infected bovine tissues. Two of three dogs shed oocysts when they were re-exposed 18-20 months after the first challenge; two other dogs re-exposed earlier, only 8 months after the primary exposure, did not produce oocysts. These results suggest that dogs may become refractory to shedding N. caninum oocysts for a period approximately between 8 and 18 months after a primary infection; however, this possibility requires statistical validation by testing of more dogs. The development of a high antibody titer did not ensure that a dog would completely resist shedding oocysts after consuming an infected meal. Oocyst production was also compared between puppies and adult dogs with primary infections. Twelve puppies (three from the present study and nine from a previous study) shed significantly more oocysts (mean: 166,400) compared with five adult dogs following primary exposure (mean: 2900), indicating that a dog's age can influence N. caninum oocyst production (P=0.02).     

Postnatal changes in bacterial populations in the gastrointestinal tract of dogs

OBJECTIVE: To describe postnatal changes in the populations of bacteria in the gastrointestinal tract (GIT) of dogs. ANIMALS: 110 Beagles ranging from neonatal to adult dogs. PROCEDURE: Contents of the stomach and proximal and distal portions of the colon and contents and mucosa of the mid region of the small intestine were collected from puppies at 1 day after birth and subsequent suckling; puppies at 21, 42, and 63 days after birth; and adult female dogs (ie, dams of the puppies) for enumeration of bacterial populations. RESULTS: The entire GIT was colonized at day 1 by all groups of bacteria studied; aerotolerant forms were dominant. During subsequent postnatal development, there were changes in the relative proportions of the various groups of bacteria with anaerobic groups increasing in absolute and relative numbers. CONCLUSIONS AND CLINICAL RELEVANCE: Establishment of bacterial populations in the GIT of dogs is a gradual process that begins immediately after birth. Age-related changes in the relative proportions of bacterial groups coincided with changes in diet and physiologic processes of the host and can influence nutritional state and disease resistance of developing dogs. Differences among regions of the GIT suggest that fecal samples may have limited use for understanding the populations of bacteria and the age and diet-related changes in various regions of the GIT.     

Changes in factor VIII activity and von Willebrand factor antigen concentration with age in dogs.

The factor VIII activity of 38 German shepherd puppies, 6-12 weeks old, submitted for diagnosis of haemophilia A was measured. Eight of these puppies had values higher than would be expected for haemophiliacs, but less than the reference range for adult dogs. A further sequential study of 21 puppies (6-26 weeks of age) indicated that the factor VIII activity of puppies is generally less than that of adult dogs until about 14 weeks of age. Changes in the concentration of von Willebrand factor antigen in the puppies were irregular. These variations are probably not sufficient to interfere with accurate diagnosis of haemophilia A in most affected young dogs, but may interfere with the detection of heterozygotes in young bitches.     

Congenital Hypothyroid Dwarfism in a Family of Giant Schnauzers

Congenital hypothyroid dwarfism was diagnosed in a family of Giant Schnauzers. Three female and two male puppies from different litters were evaluated for dwarfism, lethargy, somnolence, gait abnormalities, and constipation. On physical examination, disproportionate dwarfism (n = 5), macroglossia (n = 3), hypothermia (n = 3), delayed dental eruption (n = 3), ataxia (n = 2), and abdominal distension (n = 1) were identified. Results of initial laboratory tests showed anemia (n = 4), hypercholesterolemia (n = 4), hypercalcemia (n = 2), and transudative abdominal effusion (n = 1). Radiographic skeletal surveys disclosed epiphyseal dysgenesis and delayed skeletal maturation (n = 5). A diagnosis of hypothyroidism was established on the basis of low basal serum thyroxine concentrations that failed to increase following the administration of TSH (n = 5) and markedly reduced to absent thyroid image when evaluated with gamma camera imaging of the thyroid gland (n = 4). In the two dogs that were most thoroughly evaluated, the results of thyroid histology, prolonged TSH testing, and repeat thyroid imaging, after three daily injections of TSH, were all consistent with secondary or tertiary, rather than primary, hypothyroidism. When TSH was administered over a period of 3 consecutive days (5 IU/day, subcutaneously), serum thyroid hormone response became normal and resulted in a normal thyroid image in the two dogs re-evaluated with gamma camera imaging. Daily treatment with oral levothyroxine (20 micrograms/kg) resulted in complete remission in puppies (n = 4) treated prior to 4 months of age. The other puppy failed to attain normal breed standards for height.(ABSTRACT TRUNCATED AT 250 WORDS)     

Development of hypertrophic osteodystrophy and antibody response in a litter of vaccinated Weimaraner puppies

Two different vaccination protocols were compared with regard to the development of hypertrophic osteodystrophy (HOD) (also termed metaphyseal osteopathy) and effectiveness of immunisation in a litter of 10 Weimaraner puppies. Five puppies (group 1) were vaccinated with a modified live canine parvovirus vaccine (CPV) and then two weeks later with a trivalent vaccine containing modified live canine distemper virus and adenovirus type 2 combined with a Leptospira bacterin (DHL). The CPV and DHL vaccine protocols were administered a further two times, at two-week intervals. Group 2 was vaccinated with three consecutive multivalent vaccines containing modified live canine distemper virus, canine parvovirus, parainfluenza and adenovirus type 2 combined with a Leptospira bacterin, at four-week intervals. All puppies were first vaccinated at the age of eight weeks. Three dogs in group 1 developed HOD, while all five dogs in group 2 developed HOD during the study period. Dogs in group 2 had more episodes of HOD than those in group 1. Dogs in group 1 developed higher antibody titres to canine distemper virus and parvovirus compared with those in group 2. Only two out of the 10 dogs developed protective antibody titres to parvovirus. The results of this study suggest that the two different vaccination protocols affected the pattern of appearance of HOD and immunisation in this litter of Weimaraner puppies. The results obtained and the previously reported data suggest that a larger controlled study is needed to further elucidate the effect of different vaccination protocols on HOD and immunisation in Weimaraner puppies.     

Six-month prophylactic efficacy of moxidectin sustained release (SR) injectable for dogs against experimental heartworm infection in growing puppies

The purpose of this study was to assess the efficacy of moxidectin sustained release injectable for dogs (moxidectin SR, Fort Dodge Animal Health) in protecting growing puppies from experimental infection with the heartworm, Dirofilaria immitis, six months after treatment. The study involved 27 puppies, approximately 12 weeks of age at the beginning of the study, with nine puppies in each of three size classes. The small breed class included eight Pekingese and one purpose-bred small breed mongrel; the medium breed class included nine purpose-bred mongrels, and the large breed class included nine puppies with an anticipated adult weight >or=30-35 kg. Both genders were included with no attempt made to have equal numbers of male and female puppies. Puppies were blocked by weight within each size class and randomly assigned to three treatment groups of nine dogs. On Day 0, pups in two groups were injected subcutaneously with moxidectin SR, dosed to deliver 0.17 mg moxidectin/kg b.w. The third group was injected with sterile saline. Personnel making observations were blinded to the treatment status of the animals. Following treatment, puppies were observed for signs of adverse local and systemic reactions. Puppy weights and serum moxidectin levels were also monitored. On Day 180, puppies in all treatment groups were inoculated subcutaneously with 50 third-stage larvae of D. immitis. On Days 348 and 349, puppies were euthanatized and necropsied. Hearts and lungs were examined for adult heartworms. All animals in the saline control group were infected with an arithmetic mean of 39.22 adult heartworms each. Seventeen of 18 dogs in the moxidectin SR-treated groups were uninfected. One treated puppy was infected with a single adult heartworm. This infected individual was from the large breed size class and had the second highest percent increase in body weight. Based on arithmetic means, the heartworm recovery from all treated puppies represents a 99.86% reduction relative to the saline control. There were no adverse local or systemic reactions to treatment in any animal.     

Active use of coyotes (Canis latrans) to detect Bovine Tuberculosis in northeastern Michigan, USA

Seroconversion after early vaccination at four weeks against canine parvovirus (CPV) using a high antigen titre vaccine was evaluated in 121 puppies from three breeds of dogs housed in kennels representative of the private practitioner's environment. The trial included 52 German shepherd pups, 25 Rottweiler pups and 44 Boerboel pups. From each group 11, 4, and 18 puppies acted as control dogs, respectively. Depending on the different groups, puppies were vaccinated at 4, 6, 9 and 12 weeks. The experimental group differed from the control group in that they received the high titre vaccine at 4 weeks of age, whereas the control group was not vaccinated at 4 weeks. Blood was collected from all pups prior to vaccination to measure maternally derived colostral antibody. The results indicated that vaccination at 4 weeks of age in pups with high maternally derived antibody levels, results in seroconversion rates that may lead to a reduction in the window of susceptibility with respect to CPV infection. The implications of the findings with respect to dogs in heavily contaminated environments are discussed.     

Collie eye anomaly in the rough collie in Norway

The results of eye examinations of 741 rough collies for collie eye anomaly (CEA) are described. Of the examined dogs, 40-8 per cent had CEA, including, in most cases, chorioretinal dysplasia (CRD). 7-7 per cent had coloboma of the optic disc while 3–5 per cent had complications of CEA, either retinal detachment or intraocular bleeding. There was no sex difference nor was the frequency of the disease influenced by coat colour. After estimating the total frequencies of the different manifestations of the disease, the dogs were divided into two groups according to the age at first examination. In the group of dogs examined between seven weeks and three months old, 48-9 per cent had CEA, compared to a frequency of 25-6 per cent in the group of dogs examined after three months of age. All the puppies with coloboma also showed signs of CRD, while among the older dogs 11 of the 66 CEA cases reported showed signs of coloboma without CRD. Twenty-two dogs which had been examined as puppies and given the diagnosis CEA with minor chorioretinal changes were re-examined at an older age. Of these dogs, 15 had ophthalmoscopi-cally normal fundi at re-examination while seven were unchanged from the first examination.     

Serum immunoglobulin E concentrations in West Highland White Terrier puppies do not predict development of atopic dermatitis

Sera from 154 West Highland White Terrier puppies between 6 and 12 weeks of age were assayed for total IgE using a sandwich ELISA method. Development of clinical signs of atopic dermatitis in these dogs was monitored by use of an annual owner questionnaire, until the dog reached 3 years of age. Of 114 evaluated dogs, skin disease severe enough to warrant veterinary examination was reported in 52 (46%) during the three study years. A diagnosis of atopic dermatitis was made by the attending veterinarian in 28 dogs (25%). Certain litters had an especially high prevalence of apparently atopic dogs, consistent with the genetic predisposition towards atopy in this breed, but clear evidence of consistent heritability was not present. The median IgE concentration in 154 puppies at 6–12 weeks of age was 0.9 units mL⁻¹, with a skewed distribution. Significant ( P < 0.01) variation in serum IgE concentrations was observed between litters, with median serum IgE concentrations for a litter ranging from 0 to 27.7 units mL⁻¹. The median serum IgE concentration in puppies that later developed clinical signs of atopic dermatitis was not significantly different from that of puppies that remained healthy. There were no apparent correlations or significant differences found between serum IgE concentration as a puppy, parental history of skin disease, and subsequent emergence of clinical signs of atopic dermatitis. We conclude that early total serum IgE determinations seem to have little usefulness in predicting the later onset of atopic dermatitis in this breed.     

Serial plasma lactate concentrations in 68 puppies aged 4 to 80 days

Objective: To determine a reference range for venous blood lactate concentrations in healthy neonatal dogs. Design: A prospective cohort study. Setting: All work was conducted at the College of Veterinary Medicine, Texas A&M University. Animals: Clinically healthy dogs: 68 puppies and 30 adults. Measurements and main results: A blood sample was collected from each puppy into lithium heparin via jugular venipuncture at 4, 10, 16, 28, 70, and 80 days of age. A single venous sample was collected from each adult dog. Lactate concentration in each sample was measured immediately using an automated analyzer. Two hundred seventy‐seven blood samples were analyzed. Blood lactate concentrations of adult dogs were 1.80±0.84 mmol/L (mean±SD). Mean blood lactate concentrations of puppies were significantly higher at 4, 10, 16, and 28 days of age compared with those of adult dogs. The reference range for lactate concentration for puppies at 4 days of age was 1.07–6.59, and for the puppies from 10 to 28 days of age was 0.80–4.60. Conclusions: Assessment of perfusion can be challenging in neonates due to normal physiologic variation and small size. Measurement of lactate is rapid, minimally invasive, and has potential to be a useful marker of perfusion in neonatal dogs. However, lactate concentrations of neonatal dogs in this study were significantly higher than those of adult dogs. Reference ranges for venous lactate concentrations in adult dogs should not be used for puppies younger than 70 days of age.