# Can Dogs Have Down Syndrome? Conditions That Look Similar No, dogs cannot have Down syndrome. Down syndrome in people is caused by an extra copy of chromosome 21 (trisomy 21), and the canine genome is organized differently, with 39 pairs of chromosomes instead of the 23 pairs found in humans. The dogs that owners describe as a "dog with down syndrome" almost always have a different, diagnosable condition, and several of those conditions are treatable. This article is educational and is not a substitute for veterinary diagnosis or treatment. If you have searched "can dogs have down syndrome" after noticing a puppy that seems developmentally different, a dog with an unusual face, stunted growth, a wobbly gait, or a coat that never matured, the answer is not a dead end. It is a redirect. The features that make people think of Down syndrome in a dog point toward a specific short list of congenital and endocrine disorders, and a veterinarian can work through that list with blood tests, imaging, and, in some breeds, genetic testing. ## The Direct Answer: Why a Dog Cannot Have Down Syndrome Down syndrome is a chromosomal condition. In humans it results from trisomy 21, meaning three copies of chromosome 21 instead of the usual two. That extra chromosome changes how dozens of genes are expressed during development, producing the recognizable pattern of facial features, intellectual disability, congenital heart defects, and other health issues. Dogs do not have a chromosome 21 that corresponds to the human chromosome 21 in the way people assume. The domestic dog has 38 pairs of autosomes plus the sex chromosomes, for a total of 39 pairs, or 78 chromosomes. Human cells carry 46 chromosomes in 23 pairs. The numbering systems are not interchangeable, and a canine "trisomy 21" is not a recognized clinical entity. This is the core of the answer to "can dogs have down syndrome." It is not that the condition is rare in dogs. It is that the specific chromosomal error that defines Down syndrome in people has not been described in dogs, because the underlying chromosome does not exist in the same form. ### What People Mean When They Say "Down Syndrome Dog" Owners rarely use the phrase in a technical sense. A "down syndrome dog" is usually a dog that has some combination of: - A broad or flattened face, wide-set eyes, or a short muzzle - Small adult size or disproportionate dwarfism - A coat that stays puppy-like, thin, or patchy - Slow learning, reduced alertness, or unusual social behavior - A stiff or unsteady walk - Delayed growth compared with littermates That cluster of signs is real. It just is not Down syndrome. It is a phenotype, a set of observable features, and a phenotype can have many causes. The rest of this article covers the causes a veterinarian actually considers. ## Why the Chromosome Question Matters for Owners Some owners ask whether a dog can be "a little bit Down syndrome" or have a mild form. The framing is understandable but the biology does not work that way. Down syndrome is defined by a specific chromosomal event, and without that event there is no mild version. What does happen is that different diseases produce overlapping appearances. A dog with congenital [hypothyroidism in dogs](/knowledge/veterinary-medicine/endocrine-diseases/hypothyroidism-in-dogs) may look sluggish and stunted. A dog with pituitary dwarfism may have a puppy coat and a shortened stature. A dog with congenital hydrocephalus may have a domed head and a wide stance. To an owner, all three can look like the same vague thing. To a veterinarian, they are three different diagnoses with three different treatments. The practical takeaway is that the label matters less than the workup. If a dog looks unusual, the useful question is not "is this Down syndrome" but "what is this, and can it be treated." ## The Look-Alike Conditions Veterinarians Actually Diagnose The conditions below are the main differentials for a dog that owners suspect has Down syndrome. Each has a distinct cause, a distinct set of findings, and a distinct management plan. ### Congenital Hypothyroidism in Dogs Congenital hypothyroidism is a rare and often underdiagnosed disorder in dogs and cats, and the true incidence is unknown [1]. It occurs when the thyroid gland cannot produce adequate thyroid hormone from birth or early in life. Because thyroid hormone drives skeletal maturation, brain development, and coat growth, the consequences show up across the whole body. The hallmark signs are mental impairment and skeletal developmental abnormalities that produce disproportionate dwarfism [1]. A goiter, an enlarged thyroid gland, may or may not be present. Affected puppies often appear dull, grow slowly, keep a soft puppy coat, and develop a body shape that looks off compared with littermates. The causes are several. Documented causes in dogs include deficiency of or unresponsiveness to thyrotropin-releasing hormone (TRH) or thyroid-stimulating hormone (TSH), thyroid dysgenesis, dyshormonogenesis, and iodine deficiency [1]. In plain terms, the problem can sit in the brain's control of the thyroid, in the thyroid gland itself, or in the raw material the gland needs. One well-characterized form is a defect in iodide transport. In a family of Shih-Tzu dogs, researchers identified congenital dyshormonogenic hypothyroidism with goiter caused by a mutation in the SLC5A5 gene, which encodes the sodium/iodide symporter [2]. The two affected dogs in that report were also diagnosed with dilated cardiomyopathy, and one had only a moderate growth delay as the sole sign of hypothyroidism [2]. That last detail is a warning: congenital hypothyroidism does not always announce itself loudly. Another form involves an iodide organification defect. A 10-month-old dwarfed male puppy born to large-breed parents of normal stature had congenital goiter, and testing confirmed hypothyroidism due to failure to form organic iodine [3]. With thyroid hormone replacement, that dog gained more than 450 percent in body weight and 600 percent in shoulder height over eight months of treatment, and relapsed when treatment was withdrawn [3]. That outcome captures both the stakes and the reversibility of the condition when it is caught and managed. Skeletal changes can also cause neurologic signs. A four-year-old affenpinscher with congenital hypothyroidism developed hindlimb weakness that progressed to tetraparesis, and imaging showed diffuse skeletal immaturity with open growth plates and epiphyseal dysplasia in the long bones and vertebrae [4]. The dog had a fracture of the fourth cervical vertebra with displacement into the spinal canal, a consequence of the abnormal bone development caused by the hormone deficiency [4]. Transverse myelopathy is uncommon in these dogs, but it can happen through disc protrusion or endplate displacement [4]. Treatment for congenital hypothyroidism is thyroid hormone replacement, and adequate replacement therapy produces a successful outcome in most cases, especially when started early in life, because permanent developmental abnormalities can be prevented [1]. ### Pituitary Dwarfism and Combined Pituitary Hormone Deficiency Pituitary dwarfism is the condition most likely to be mistaken for a Down syndrome-like appearance in dogs, particularly in German Shepherds and related breeds. It is an autosomal recessive inherited abnormality in German Shepherds [5]. The pituitary gland fails to develop or function properly, so it does not secrete the normal complement of hormones. The result is combined pituitary hormone deficiency, or CPHD. The physical picture is growth retardation and stagnant development of the hair coat [5]. Affected dogs stay small and keep an immature coat. Testing with a combined pituitary stimulation protocol confirmed deficient growth hormone, low basal TSH and prolactin that did not respond to stimulation, and relatively low luteinizing hormone with a blunted response [5]. In males, follicle-stimulating hormone stayed below the detection limit throughout testing, while females had slightly low baseline levels with only a small increase after stimulation [5]. In the same study, basal and stimulated ACTH concentrations did not differ from controls, meaning cortisol production was preserved in those dogs [5]. The genetics have been mapped in detail. Dwarfism in German Shepherds localizes to a region on chromosome 9 that contains LHX3, a gene coding for a transcription factor essential for pituitary development [6]. Affected dogs have a deletion of one of six 7-base-pair repeats in intron 5 of LHX3, which shortens the intron and disrupts normal splicing [6]. The aberrant splicing produces RNA molecules that either skip exon 5 or retain intron 5, and the same splicing defects were found in pituitary tissue from affected dogs [6]. Other genes were ruled out along the way, which is useful context because it shows how specific the diagnosis has become. The LHX4 gene was excluded as a candidate for pituitary dwarfism in German Shepherds [7]. The PROP1 gene was also excluded [8]. The Pit-1 gene (POU1F1) was characterized and excluded as the primary cause in German Shepherds [9]. The leukemia inhibitory factor receptor gene was excluded as well [10]. The disease in German Shepherds traces to LHX3. Pituitary dwarfism is not limited to German Shepherds. Karelian Bear Dogs develop a similar dwarfism with abnormal coats, and researchers mapped that form to a homozygous intronic variant in the POU1F1 gene, establishing a second canine model for CPHD [11]. The variant segregated completely in Karelian Bear Dogs with a carrier frequency of about 8 percent, and carriers were found at low frequency only in Lapponian Herders, a related breed [11]. There is an important structural complication in these dogs. Some dogs with CPHD caused by an LHX3 mutation develop neurologic signs localized to the cervical spine [12]. Imaging in affected Czechoslovakian wolfdogs and a German Shepherd found abnormal positioning of the dens axis, incomplete ossification of the suture lines between the ossification centers of the atlas, and atlanto-axial instability with dynamic compression of the spinal cord [12]. The malformations and abnormal motion at the first and second cervical vertebrae were confirmed at necropsy and histology [12]. This mirrors findings in human CPHD patients with LHX3 mutations, where atlanto-axial abnormalities have also been described [12]. Hormone deficiencies can also evolve over time. A nine-week-old female White Swiss Shepherd was diagnosed with pituitary dwarfism due to an LHX3 mutation, and over the following two years developed persistent lymphocytosis and eosinophilia [13]. Testing confirmed pituitary hypocortisolism, meaning ACTH deficiency had emerged even though ACTH secretion is usually preserved in these dogs [13]. The dog improved on physiologic doses of prednisolone [13]. This case matters because it shows that a dwarf dog can develop new hormone deficiencies later, and screening for ACTH deficiency is worthwhile when compatible signs appear [13]. Diagnosis of growth hormone deficiency can be supported by stimulation testing. In a study of ghrelin stimulation, the growth hormone response was significantly lower in dwarf dogs than in healthy dogs, and no dwarf dog exceeded a plasma growth hormone concentration of 5 micrograms per liter at any time point, though three healthy dogs also stayed below that level, so false negatives are possible [14]. A growth hormone response above that threshold excludes growth hormone deficiency [14]. Treatment options exist. Three German Shepherds with pituitary dwarfism were treated with proligestone, which produced an adult hair coat, increased body weight, and elevated insulin-like growth factor-1 concentrations [15]. Two of the dogs also received thyroid supplementation during proligestone therapy [15]. Adverse effects including cystic endometrial hyperplasia and acromegaly occurred in two cases, and no side effects were reported in the third [15]. ### Congenital Hydrocephalus Congenital hydrocephalus is an accumulation of cerebrospinal fluid within the ventricular system of the brain. It is one of the most common reasons a puppy has a domed head, wide-set eyes, and a slow or clumsy demeanor, which is why it lands on the list of conditions that look like Down syndrome. The relationship between pressure and signs is more complicated than owners expect. Dogs with internal hydrocephalus do not necessarily have high intraventricular pressure [16]. In a study of 53 dogs, high intraventricular pressure was associated with obtundation, head tilt, and nystagmus [16]. Pain was associated with syringomyelia, a fluid cavity within the spinal cord [16]. The number of affected ventricles was associated with both high pressure and syringomyelia, and periventricular edema and a signal void sign were also associated with both [16]. The probability of syringomyelia was lower when there was disruption of the internal capsule and higher with a larger ventricle-to-brain ratio [16]. Treatment for congenital internal hydrocephalus often involves ventriculoperitoneal shunting, in which a catheter drains fluid from the ventricles into the abdominal cavity. This is the standard treatment, but obstruction of the ventricular catheter is a frequent and serious complication [17]. In a retrospective study of 100 dogs treated with shunting between 2001 and 2022, obstruction occurred in 9 of the 100 dogs, with onset ranging from 8 to 210 days after surgery and a median of 38 days [17]. Overshunting is another complication. In a study of 75 dogs and 7 cats, overshunting had a prevalence of 18 percent [18]. Each increase of 0.05 in the ventricle-to-brain ratio raised the risk of overshunting, and biventricular hydrocephalus carried the highest risk compared with tri- or tetraventricular hydrocephalus [18]. Overshunting caused hemispheric collapse, subdural hemorrhage, and peracute neurologic deterioration in 15 animals, and subdural hematoma was surgically removed in 8 dogs and 2 cats with prompt postoperative improvement [18]. ### Portosystemic Shunt A portosystemic shunt is an abnormal blood vessel that lets blood from the intestines bypass the liver. The liver normally filters toxins and metabolites absorbed from the gut, and when blood skips the liver, those substances reach the brain. The result is hepatic encephalopathy, which can cause dullness, pacing, head pressing, seizures, and stunted growth. Portosystemic shunts are congenital in many affected dogs and are diagnosed through blood work showing abnormal liver values and bile acids, plus imaging to identify the vessel. They are included here because a puppy with a shunt can look small, slow, and developmentally behind, which is the same vague picture that prompts the Down syndrome question. The distinction matters because shunts are treated differently from hormone deficiencies, often with surgery or medical management of the encephalopathy. ### Growth Hormone Deficiency Growth hormone deficiency can occur as part of combined pituitary hormone deficiency, as described above, or in a more isolated form. When growth hormone is the main missing hormone, the dog stays small while other pituitary functions may be relatively preserved. The ghrelin stimulation study is relevant here because it tested the growth hormone axis directly [14]. The finding that dwarf dogs had a blunted growth hormone response, with the caveat that some healthy dogs also responded poorly, tells you that a single stimulation test is not perfect and results need to be interpreted alongside the whole clinical picture [14]. ## Comparing the Look-Alike Conditions | Condition | Core problem | Typical signs | Key diagnostic step | Main treatment | |--|--|--|--|--| | Congenital hypothyroidism | Thyroid hormone deficiency from birth | Disproportionate dwarfism, mental dullness, puppy coat, possible goiter | Thyroid hormone levels, imaging of growth plates | Thyroid hormone replacement [1] | | Pituitary dwarfism (CPHD) | Pituitary fails to secrete multiple hormones | Growth retardation, stagnant coat, possible cervical spine instability | Hormone stimulation testing, genetic testing for LHX3 or POU1F1 [6][11] | Hormone support, proligestone in reported cases [15] | | Congenital hydrocephalus | Excess cerebrospinal fluid in the ventricles | Domed head, obtundation, head tilt, nystagmus | MRI, intraventricular pressure assessment [16] | Ventriculoperitoneal shunt [17] | | Portosystemic shunt | Blood bypasses the liver | Small size, dullness, neurologic signs from encephalopathy | Liver values, bile acids, imaging | Surgical or medical management | | Growth hormone deficiency | Insufficient growth hormone | Small stature, delayed growth | Growth hormone stimulation testing [14] | Hormone support | ## How a Veterinarian Works These Up The workup for a dog that looks like it might have Down syndrome is systematic. It starts with a full history, including the dog's age at the onset of signs, whether littermates are affected, and whether the dog has been spayed or neutered. Breed matters because pituitary dwarfism is strongly associated with German Shepherds and Karelian Bear Dogs, and congenital hypothyroidism has been documented in Shih-Tzus and other breeds [6][11][2]. The physical exam looks for specific findings. A veterinarian assesses body proportions, coat quality, mentation, gait, and cranial nerve function. A domed head, wide stance, or abnormal eye position raises suspicion for hydrocephalus. A stiff neck or pain on neck manipulation raises suspicion for atlanto-axial instability, which is documented in dogs with pituitary dwarfism [12]. Blood work is the next layer. A complete blood count and chemistry panel can reveal anemia, low blood glucose, or abnormal liver values that point toward a shunt. Thyroid testing measures thyroid hormone concentrations, and low total and free T4 supports hypothyroidism [4]. Because thyroid disease can be secondary to pituitary failure, the veterinarian may also test for TSH and other pituitary hormones. Hormone stimulation testing evaluates the pituitary directly. The combined pituitary stimulation test with releasing hormones assesses multiple hormone axes at once and confirmed hyposomatotropism along with low TSH and prolactin in German Shepherd dwarfs [5]. Growth hormone stimulation with ghrelin is another option, with the caveat about false negatives [14]. If ACTH deficiency is suspected, an ACTH stimulation test or CRH stimulation test can confirm it [13]. Imaging answers structural questions. Computed tomography and magnetic resonance imaging of the skull and cranial neck can identify pituitary abnormalities, hydrocephalus, and atlanto-axial malformation [12][16]. In the hydrocephalus studies, MRI findings such as periventricular edema and signal void sign were associated with high intraventricular pressure and syringomyelia, which helps guide treatment decisions [16]. Genetic testing is available for some conditions. The LHX3 mutation responsible for pituitary dwarfism in German Shepherds can be identified, and the POU1F1 variant responsible for dwarfism in Karelian Bear Dogs is also known [6][11]. These tests are most useful in at-risk breeds and in breeding decisions. ## What Care Looks Like After Diagnosis Care depends entirely on which condition is found. For congenital hypothyroidism, the treatment is thyroid hormone replacement, and adequate replacement therapy produces a successful outcome in most cases, particularly when started early, because permanent developmental abnormalities can be prevented [1]. The dog needs periodic monitoring to keep hormone levels in the right range, and the dose is adjusted over time as the dog grows. The dramatic recovery documented in one treated dog, with major gains in weight and height, shows what early and consistent treatment can achieve [3]. For pituitary dwarfism, management is more complex because multiple hormones may be deficient. Proligestone has been used to improve coat and body condition, with thyroid supplementation added in some cases [15]. Glucocorticoid replacement is indicated when ACTH deficiency is confirmed, and physiologic doses of prednisolone improved activity levels in one reported dog [13]. Because hormone deficiencies can emerge over time, ongoing monitoring is part of the plan [13]. For congenital hydrocephalus, ventriculoperitoneal shunting is the standard treatment, and owners should know that catheter obstruction is a real risk, occurring in about 9 percent of dogs in one series, typically within the first weeks to months after surgery [17]. Overshunting is another risk, and it can cause serious neurologic deterioration that may require surgical correction [18]. Follow-up imaging and neurologic checks are part of postoperative care. For portosystemic shunts, treatment may be surgical ligation of the abnormal vessel or medical management with dietary protein modification and medications to reduce toxin absorption. The choice depends on the shunt's anatomy and the dog's stability. For growth hormone deficiency, treatment aims to replace what is missing and support growth, though the response varies and the ghrelin study showed that testing has limits [14]. Across all of these conditions, the common thread is that early recognition changes outcomes. A puppy that is falling behind its littermates, a dog with a coat that never matured, or a dog with progressive neurologic signs deserves a veterinary workup rather than a wait-and-see approach. ## Myths and Misconceptions About Canine Down Syndrome Several ideas about Down syndrome in dogs circulate widely and are worth addressing directly. The first myth is that a dog can be diagnosed with Down syndrome by appearance alone. No veterinarian can diagnose a chromosomal condition by looking at a dog, and in dogs the condition does not exist to be diagnosed. Appearance is a starting point for a workup, not a diagnosis. The second myth is that a "down syndrome dog" is always severely disabled. Some of the look-alike conditions are compatible with a good quality of life, especially with treatment. Congenital hypothyroidism in particular can respond well to replacement therapy [1]. The third myth is that these conditions are always inherited. Some are inherited, such as pituitary dwarfism in German Shepherds, which is autosomal recessive [5]. Others, including some cases of congenital hypothyroidism, result from developmental errors or enzyme defects that are not necessarily passed from parent to offspring in a simple pattern [2][3]. The fourth myth is that a dog with these features should not be bred. For conditions with a known genetic basis, such as the LHX3 mutation in German Shepherds or the POU1F1 variant in Karelian Bear Dogs, breeding decisions should account for carrier status [6][11]. A veterinarian or veterinary geneticist can advise on testing. The fifth myth is that treatment is not worth pursuing. The evidence says otherwise. Treated congenital hypothyroidism can produce dramatic improvement [3]. Proligestone improved coat and body condition in dwarf dogs [15]. Shunting helps many dogs with hydrocephalus, even though complications occur [17][18]. The right answer depends on the specific diagnosis and the individual dog. ## What Is Still Uncertain Several questions remain open. The true incidence of congenital hypothyroidism in dogs is unknown, and the disorder is considered underdiagnosed [1]. That means the number of affected dogs is likely higher than reported cases suggest. The full range of genetic causes of pituitary dwarfism is not completely mapped. LHX3 explains the German Shepherd form and POU1F1 explains the Karelian Bear Dog form, but other breeds and other mutations may exist [6][11]. Several genes have been excluded, which narrows the search but does not close it [7][8][9][10]. The long-term course of hormone deficiencies in dwarf dogs is still being characterized. The White Swiss Shepherd that developed ACTH deficiency two years after diagnosis suggests that corticotrope function can decline over time, but how often this happens is not known [13]. The optimal management of hydrocephalus complications continues to evolve. Risk factors for catheter obstruction were not identified in one large study, leaving questions about how to prevent it [17]. Overshunting risk factors are better understood, but treatment decisions still require clinical judgment [18]. ## Limitations and When to Contact a Veterinarian Individual cases vary, and only a veterinarian who examines your dog can determine what is going on. Contact a veterinarian promptly if your dog or puppy shows any of the following: - Growth that stalls or falls well behind littermates - A coat that stays soft, thin, or puppy-like past the normal shedding age - A domed head, wide-set eyes, or an unusually broad face - Progressive weakness, wobbliness, or difficulty walking - Neck pain, reluctance to move the head, or a stiff neck - Episodes of dullness, pacing, head pressing, or seizures - Collapse, difficulty breathing, or sudden deterioration Some of these signs indicate emergencies. Seizures, collapse, and sudden weakness require immediate veterinary attention. Others, such as slow growth or a persistent puppy coat, warrant a scheduled appointment and a diagnostic plan. If your dog has already been diagnosed with one of the conditions in this article, ask your veterinarian what monitoring schedule is appropriate, what signs would indicate a complication, and what to do if those signs appear. Conditions like hydrocephalus and pituitary dwarfism can change over time, and regular rechecks catch problems earlier. ## Frequently Asked Questions ### Can dogs have Down syndrome? No. Down syndrome is caused by trisomy 21 in humans, and dogs have 39 chromosome pairs rather than the 23 pairs found in people, so the specific chromosomal condition has not been described in dogs. A dog that looks like it has Down syndrome has a different condition that requires veterinary evaluation. ### What does a dog with Down syndrome look like? Owners who use the phrase usually describe a dog with a broad or flattened face, wide-set eyes, small stature, a puppy-like coat, and slow or unusual behavior. That appearance is a phenotype, and it can be caused by congenital hypothyroidism, pituitary dwarfism, congenital hydrocephalus, portosystemic shunt, or growth hormone deficiency. ### Can a dog have a mild form of Down syndrome? No. Down syndrome is defined by a specific chromosomal event, and without that event there is no mild version. A dog with subtle signs may have a mild expression of a different condition, which is why veterinary testing matters more than the label. ### What is the most common condition mistaken for Down syndrome in dogs? Pituitary dwarfism and congenital hypothyroidism are the two conditions most often behind the "down syndrome dog" description. Pituitary dwarfism is well documented in German Shepherds and Karelian Bear Dogs, while congenital hypothyroidism has been reported in several breeds including Shih-Tzus [6][11][2]. ### Is congenital hypothyroidism in dogs treatable? Yes. Congenital hypothyroidism is treated with thyroid hormone replacement, and adequate therapy produces a successful outcome in most cases, especially when started early in life, because permanent developmental abnormalities can be prevented [1]. One treated dog gained more than 450 percent in body weight and 600 percent in shoulder height over eight months [3]. ### Can pituitary dwarfism in dogs be treated? Yes, though management is more involved because multiple hormones may be deficient. Proligestone therapy improved coat, body weight, and insulin-like growth factor-1 levels in three German Shepherds, with thyroid supplementation added in two cases [15]. Glucocorticoid replacement is used when ACTH deficiency is confirmed [13]. ### Do dogs with these conditions live normal lives? Many do, with appropriate treatment and monitoring. The outcome depends on the specific diagnosis, how early treatment starts, and whether complications develop. Dogs with hydrocephalus may need shunt surgery and monitoring for obstruction or overshunting, while dogs with hormone deficiencies need ongoing replacement therapy and periodic testing [17][18][1]. ### Should I breed a dog that looks like it has Down syndrome? You should not breed a dog with an undiagnosed congenital condition. Some of these conditions have a known genetic basis, including the LHX3 mutation in German Shepherds and the POU1F1 variant in Karelian Bear Dogs, and carrier testing is available [6][11]. Talk with your veterinarian before making any breeding decision. ## Related Articles - [Hypothyroidism in Dogs: Symptoms, Diagnosis & Treatment](/knowledge/veterinary-medicine/endocrine-diseases/hypothyroidism-in-dogs) - [Dog Shaking Head Up And Down](/knowledge/veterinary-medicine/clinical-methods/dog-shaking-head-up-and-down) - [Dog Seizures Put Down](/knowledge/veterinary-medicine/emergency-care/dog-seizures-put-down) - [What Does A Tick Look Like On A Dog](/knowledge/veterinary-medicine/parasitic-diseases/what-does-a-tick-look-like-on-a-dog) - [Dog Seizure What Does It Look Like](/knowledge/veterinary-medicine/emergency-care/dog-seizure-what-does-it-look-like) - [Can A Dog Have Herpes](/knowledge/veterinary-medicine/clinical-methods/can-a-dog-have-herpes) - [Can Cats Have Down Syndrome? What Those Features Really Mean](/knowledge/veterinary-medicine/symptom-guides/can-cats-have-down-syndrome) - [Dog Coughing Up Blood: Causes and When It Is an Emergency](/knowledge/veterinary-medicine/symptom-guides/dog-coughing-up-blood-causes-and-emergency-care) ## Sources 1. [Congenital hypothyroidism of dogs and cats: a review.](https://pubmed.ncbi.nlm.nih.gov/21541884/) 2. [Congenital dyshormonogenic hypothyroidism with goiter caused by a sodium/iodide symporter (SLC5A5) mutation in a family of Shih-Tzu dogs.](https://pubmed.ncbi.nlm.nih.gov/29777899/) 3. [Congenital hypothyroidism in a dog due to an iodide organification defect.](https://pubmed.ncbi.nlm.nih.gov/6881664/) 4. [Tetraparesis due to vertebral physeal fracture in an adult dog with congenital hypothyroidism.](https://pubmed.ncbi.nlm.nih.gov/9282344/) 5. [Combined pituitary hormone deficiency in german shepherd dogs with dwarfism.](https://pubmed.ncbi.nlm.nih.gov/11064220/) 6. 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