What this tool helps you understand
Pet nutrition is not just about whether an ingredient sounds good on a bag or can. It is also about balance. Too little of an essential nutrient can create problems over time, and too much of certain nutrients can be just as harmful.
This tool is designed to help you explore both sides of that issue in plain language. Click on any nutrient in the list and you will see what may happen when intake is too low and what may happen when intake is too high. Each entry is written to help you better understand nutrient risk patterns in dogs and cats, including where species differences matter.
This is an educational reference, not a diagnostic tool. Nutrient imbalances can sometimes look similar to other health problems, and many pet food labels do not provide enough detail to tell the full story on their own. Still, this tool can help you ask better questions, think more critically about nutrition, and better understand why balance matters so much.
Green sections show potential concerns tied to too little of a nutrient. Red sections show potential concerns tied to too much.
Nutrient Risk Reference for Dogs and Cats
Browse the nutrient list below. Click any item to open it. Green shows what too little can do. Red shows what too much can do.
Important: This is an educational reference. Nutrient problems and disease can overlap. Do not use this tool to diagnose or treat a pet.
Visible items
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How to use it
Start with the list. Click a nutrient name to open the details. The species focus appears inside each entry. Green shows what too little can do. Red shows what too much can do.
No entries match your current category filter.
Species focus
Dogs and cats
Why it matters
Omega 3 precursor included in growth and reproduction recommendations.
If too little
Reduced omega 3 reserve and poorer support for healthy tissue development when the total omega 3 supply is inadequate.
If too much
Very high unsaturated fat loads can worsen oxidative stress if antioxidant support is poor and can upset stools in some pets.
Higher risk situations
Growth, reproduction, and heavily manipulated homemade diets.
Practical note
ALA is not the same thing as EPA and DHA.
Species focus
Cat focused
Why it matters
Omega 6 fatty acid that cats require preformed because they convert linoleic acid poorly.
If too little
Poor reproductive performance, poor skin and coat support, and impaired normal physiologic signaling in cats.
If too much
Very high intake can favor production of pro inflammatory mediators. Clear toxicity from complete foods is not usually described.
Higher risk situations
Cats on poorly formulated homemade or plant heavy diets.
Practical note
This is one more reason cats are not small dogs nutritionally.
Species focus
Dogs and cats
Why it matters
Needed for the urea cycle, ammonia disposal, immune function, and growth.
If too little
Can trigger ammonia buildup. Cats are especially vulnerable and may develop drooling, vomiting, ataxia, tremors, or severe neurologic signs after a deficient meal.
If too much
Toxicity from complete foods is uncommon. Excessive imbalance from supplementation can disturb amino acid balance and may worsen gastrointestinal tolerance.
Higher risk situations
Cats, rapidly growing animals, and poorly formulated homemade or vegetarian style diets.
Practical note
Arginine deficiency is one of the most dangerous amino acid mistakes in cats.
Species focus
Dogs and cats
Why it matters
Supports skin, coat, and several carboxylase enzyme systems.
If too little
Poor coat, dermatitis, and reduced growth or metabolic efficiency.
If too much
Clinically meaningful dietary toxicity is uncommon.
Higher risk situations
Raw egg white heavy feeding, because avidin binds biotin, and poorly formulated homemade diets.
Practical note
Biotin problems are uncommon in complete foods but can appear in homemade mistakes.
Species focus
Dogs and cats
Why it matters
Structural mineral for bone and teeth, also required for muscle contraction, nerve function, and blood clotting.
If too little
Poor bone mineralization, rickets or osteomalacia, secondary hyperparathyroidism, weakness, and skeletal deformity.
If too much
Developmental orthopedic disease risk, abnormal skeletal development, constipation, and interference with absorption of other minerals. Large breed puppies are especially sensitive.
Higher risk situations
Growth, especially large breed puppies, raw meaty diets without balance, boneless meat diets, and oversupplemented homemade diets.
Practical note
Calcium is one of the easiest nutrients to get dangerously wrong at home.
Species focus
Dogs and cats
Why it matters
Reflects whether two major skeletal minerals are in a workable relationship.
If too little
A low ratio usually means calcium is too low relative to phosphorus, which raises risk of bone demineralization and nutritional secondary hyperparathyroidism.
If too much
A high ratio often signals too much calcium relative to phosphorus, which can impair skeletal development and mineral balance, especially in growth.
Higher risk situations
Puppies, kittens, raw or homemade diets, and any diet built around meat without a full mineral plan.
Practical note
The ratio matters almost as much as the individual numbers.
Species focus
Dogs and cats
Why it matters
Partners with sodium in fluid and acid base balance and is part of stomach acid.
If too little
Weakness, poor growth, dehydration, and acid base disruption.
If too much
Usually tracks sodium chloride excess rather than a separate chloride problem. Can contribute to excessive thirst and acid base disturbance in susceptible animals.
Higher risk situations
Fluid loss states, restricted water access, and heavily supplemented homemade diets.
Practical note
Chloride is essential even though almost no retail label highlights it.
Species focus
Dogs and cats
Why it matters
Important for cell membranes, methyl donation, and fat export from the liver.
If too little
Fatty liver tendency, poor growth, and impaired lipid handling.
If too much
Large supplemental doses can cause gastrointestinal upset and are unnecessary when the diet is already balanced.
Higher risk situations
Rapid weight loss, poorly balanced homemade diets, and liver disease contexts.
Practical note
Choline sits at the border of vitamin and lipid biology, which is why it gets overlooked.
Species focus
Dogs and cats
Why it matters
Needed for cell division, methyl metabolism, and normal intestinal and neurologic function.
If too little
Weight loss, poor appetite, poor growth, anemia, and gastrointestinal disease signs. Deficiency is especially relevant in some intestinal and pancreatic disorders.
If too much
Dietary toxicity is uncommon.
Higher risk situations
Cats with intestinal disease, EPI, pancreatitis, chronic inappetence, and other GI disorders.
Practical note
Low B12 is often a disease clue, not just a feeding clue.
Species focus
Dogs and cats
Why it matters
Supports enzymes, connective tissue, pigment, iron metabolism, and antioxidant defense.
If too little
Anemia, poor coat and pigmentation, weak connective tissue support, and poor growth.
If too much
Liver copper accumulation, oxidative liver injury, and in severe cases hemolysis, especially in genetically predisposed dogs.
Higher risk situations
Bedlington Terriers and other copper sensitive breeds, liver disease patients, and oversupplemented diets.
Practical note
Copper status is one of the places where breed biology really matters.
Species focus
Dogs and cats
Why it matters
Long chain marine omega 3 fats that support development and healthy inflammatory regulation.
If too little
Lower support for neurologic and retinal development in growth and reduced anti inflammatory reserve.
If too much
Excessive fish oil style supplementation can cause gastrointestinal upset, softer stools, excess calories, and increased oxidative stress if vitamin E coverage is poor.
Higher risk situations
Puppies, kittens, pregnant or lactating animals, and pets on multiple supplements.
Practical note
Omega 3 supplementation should be matched to the whole diet, not added blindly.
Species focus
Dogs and cats
Why it matters
Provides concentrated energy, carries fat soluble vitamins, and supplies essential fatty acids.
If too little
Poor growth, low energy density, dry coat, reduced nutrient absorption, and reduced reproductive performance.
If too much
Excess calories, obesity risk, and in susceptible animals worsening of fat intolerance disorders. Total fat does not reveal fatty acid quality.
Higher risk situations
Growth, reproduction, working animals, pancreatitis prone dogs, and overweight pets.
Practical note
Fat quantity matters, but fatty acid quality and energy balance matter too.
Species focus
Dogs and cats
Why it matters
Needed for DNA synthesis, cell division, and normal blood cell production.
If too little
Poor growth, anemia, and reduced intestinal health or cell turnover.
If too much
Dietary toxicity is uncommon. Excess may cloud interpretation of some deficiency patterns rather than causing classic toxicosis.
Higher risk situations
Intestinal disease, growth, and poor homemade diet balance.
Practical note
Folate values can also be used clinically as part of GI workups.
Species focus
Dogs and cats
Why it matters
Supports protein synthesis, tissue repair, hemoglobin structure, and histamine production.
If too little
Poor growth, weight loss, reduced lean tissue, and in cats deficiency has been linked to cataract formation.
If too much
Clinically meaningful dietary toxicity is uncommon. Large imbalances can reduce diet quality and compete with other amino acids.
Higher risk situations
Cats and growing animals.
Practical note
This is essential but usually invisible to the retail buyer.
Species focus
Dogs and cats
Why it matters
Required for thyroid hormone production.
If too little
Goiter, hypothyroid type signs, poor growth, and developmental problems.
If too much
Can also disturb the thyroid and contribute to goiter or thyroid dysfunction. Both too little and too much can be problematic.
Higher risk situations
Homemade diets, excessive kelp use, and animals with thyroid issues.
Practical note
Iodine is a classic example of a U shaped nutrient. Too little or too much can both hurt.
Species focus
Dogs and cats
Why it matters
Required for hemoglobin, oxygen transport, and many enzymes.
If too little
Anemia, lethargy, weakness, poor growth, and reduced exercise tolerance.
If too much
Gastrointestinal irritation, vomiting, diarrhea, oxidative injury, liver damage, and in severe overdose shock or death.
Higher risk situations
Young animals, chronic blood loss, and households with human iron supplements.
Practical note
Iron is essential, but iron pills are real emergency toxicants.
Species focus
Dogs and cats
Why it matters
Branched chain amino acid important for muscle metabolism and tissue maintenance.
If too little
Poor growth, weight loss, muscle wasting, and reduced overall protein utilization.
If too much
Very high imbalance may interfere with other branched chain amino acids and reduce intake or performance. Clear toxicity from complete foods is uncommon.
Higher risk situations
Growth, recovery, and marginal protein diets.
Practical note
This usually becomes an issue when overall amino acid balance is poor.
Species focus
Dogs and cats
Why it matters
Branched chain amino acid that supports muscle protein synthesis and tissue repair.
If too little
Poor growth, reduced lean mass, impaired recovery, and lower overall protein quality.
If too much
Marked imbalance may depress appetite and disrupt the balance of the other branched chain amino acids. Clear toxicity from complete foods is uncommon.
Higher risk situations
Growth, seniors with muscle loss, and imbalanced home formulations.
Practical note
Leucine helps drive muscle protein synthesis, but only when the whole amino acid pattern is adequate.
Species focus
Dogs and cats
Why it matters
Essential omega 6 fatty acid needed for skin barrier function, coat quality, and normal reproduction.
If too little
Dry scaly coat, poor skin barrier, poor growth, and reproductive problems.
If too much
When omega 6 greatly outweighs omega 3 intake, inflammatory tone can tilt in an unfavorable direction even if frank toxicity is absent.
Higher risk situations
Low fat homemade diets and poorly balanced restricted diets.
Practical note
A nutrient can be technically present yet still be poorly balanced against omega 3 intake.
Species focus
Dogs and cats
Why it matters
Supports growth, collagen formation, muscle, and efficient use of dietary protein.
If too little
Poor growth, low lean body mass, poor tissue repair, and reduced protein quality.
If too much
Oversupply is not usually a problem in complete foods, but large excesses can create amino acid antagonism. In dogs, excess lysine can antagonize arginine.
Higher risk situations
Growing animals and unbalanced supplementation.
Practical note
Lysine is essential, but balance matters more than megadosing.
Species focus
Dogs and cats
Why it matters
Needed for hundreds of enzyme reactions, muscle function, and normal mineral metabolism.
If too little
Weakness, poor growth, neuromuscular irritability, and reduced metabolic efficiency.
If too much
Gastrointestinal upset can occur, and excessive mineral load may be unhelpful in susceptible urinary patients. Higher risk exists when kidney function is poor.
Higher risk situations
Cats with urinary concerns and pets with kidney compromise.
Practical note
Magnesium is essential. The question is balance, not fear.
Species focus
Dogs and cats
Why it matters
Supports cartilage, bone matrix, reproduction, and enzyme systems.
If too little
Poor growth, skeletal abnormalities, and reproductive problems.
If too much
Clinically important toxicity from complete foods is uncommon. Oversupply can interfere with other trace mineral handling.
Higher risk situations
Growth and poorly balanced homemade diets.
Practical note
Manganese is rarely discussed, but balance still matters.
Species focus
Dogs and cats
Why it matters
Sulfur amino acid needed for protein synthesis, methyl donation, coat health, and taurine production.
If too little
Poor growth, poor coat quality, reduced taurine synthesis in dogs, and weakened overall amino acid balance.
If too much
Oversupplementation can reduce palatability, acidify the body and urine excessively, and upset overall amino acid balance.
Higher risk situations
Dogs relying on methionine to help maintain taurine status, and any diet using narrow protein sources.
Practical note
Methionine matters on its own and as part of sulfur amino acid supply.
Species focus
Dogs and cats
Why it matters
Combined sulfur amino acid target used in pet food formulation because these nutrients work together.
If too little
Poor growth, poor coat, reduced protein quality, and in dogs reduced support for taurine synthesis.
If too much
Usually reflects oversupplementation rather than normal feeding. Can reduce diet acceptance and disturb acid base balance or amino acid balance.
Higher risk situations
Formulators using unconventional proteins or heavy amino acid supplementation.
Practical note
This is a formulation concept that helps reveal whether sulfur amino acid coverage is truly adequate.
Species focus
Dogs and cats
Why it matters
Supports energy metabolism and many enzyme systems.
If too little
Poor growth, weight loss, inflamed mouth, poor skin condition, and general failure to thrive.
If too much
Supplement oversupply can upset the gastrointestinal tract and stress the liver. Toxicity from balanced foods is uncommon.
Higher risk situations
Cats, because their metabolic handling makes dietary niacin especially important.
Practical note
Cats have unique niacin biology and cannot be treated like tiny omnivores.
Species focus
Dogs and cats
Why it matters
Part of coenzyme A, central to energy and fatty acid metabolism.
If too little
Poor growth, poor coat, gastrointestinal upset, and reduced metabolic efficiency.
If too much
Clinically meaningful dietary toxicity is uncommon. Large supplemental doses may cause mild gastrointestinal upset.
Higher risk situations
Poorly balanced homemade diets.
Practical note
This is usually a background adequacy issue rather than an obvious stand alone deficiency.
Species focus
Dogs and cats
Why it matters
Essential aromatic amino acid used for proteins and as a precursor for tyrosine.
If too little
Poor growth, reduced protein quality, and lower support for skin, coat, and pigment pathways.
If too much
Marked oversupplementation is uncommon in complete foods. Large imbalances can reduce tolerance and disturb amino acid balance.
Higher risk situations
Growth and narrow ingredient diets.
Practical note
This nutrient is most informative when interpreted together with tyrosine.
Species focus
Dogs and cats
Why it matters
Combined target that supports protein synthesis, pigment formation, and catecholamine pathways.
If too little
Poor growth, reduced coat pigment intensity, and lower overall protein quality.
If too much
Clinically important excess from complete foods is uncommon. Imbalances are more likely than true toxicosis.
Higher risk situations
Dark coated animals, growth, and incomplete homemade diets.
Practical note
A faded coat can be multifactorial, but amino acid balance belongs on the list.
Species focus
Dogs and cats
Why it matters
Works with calcium in bone, and is central to ATP, cell membranes, and metabolism.
If too little
Poor growth, weak bones, rickets or osteomalacia, and reduced overall cellular energy support.
If too much
Can distort calcium balance, burden mineral regulation, and be especially unhelpful in kidney disease. High phosphorus with low calcium is a classic homemade diet problem.
Higher risk situations
All meat diets, bone free raw diets, growth, and pets with kidney disease.
Practical note
Phosphorus is not the villain in every healthy pet, but imbalance is a real problem.
Species focus
Dogs and cats
Why it matters
Critical intracellular electrolyte for muscle, nerve, and acid base balance.
If too little
Weakness, poor appetite, neck ventroflexion in cats, and reduced muscle function.
If too much
Dangerous elevations can disturb heart rhythm and muscle function, especially when kidney handling is impaired. True dietary excess in healthy pets is uncommon.
Higher risk situations
Cats with kidney disease, pets with vomiting or diarrhea, and pets on certain medications.
Practical note
Potassium problems often reflect disease, but diet still matters.
Species focus
Dogs and cats
Why it matters
Provides amino acids for muscle, enzymes, hormones, immune proteins, tissue repair, and growth.
If too little
Poor growth, weight loss, muscle loss, dull coat, anemia, poor immune response, slower recovery from illness, and reproductive problems.
If too much
Healthy dogs and cats usually tolerate appropriately balanced protein well. Problems are more likely when overall diet balance, energy balance, kidney handling, or ingredient quality is poor.
Higher risk situations
Growth, reproduction, recovery, seniors with muscle loss, and any pet eating an unbalanced homemade diet.
Practical note
Quality, digestibility, amino acid balance, and protein to calorie ratio matter, not just crude percentage.
Species focus
Dogs and cats
Why it matters
Supports amino acid metabolism, neurotransmitter synthesis, and red blood cell function.
If too little
Poor growth, anemia, seizures, and impaired protein metabolism.
If too much
Very high supplemental exposure can injure nerves. Toxicity from balanced diets is uncommon.
Higher risk situations
High protein diet manipulation and unbalanced supplement use.
Practical note
B6 is water soluble, but that does not make megadosing wise.
Species focus
Dogs and cats
Why it matters
Needed for energy metabolism and many oxidation reduction reactions.
If too little
Poor growth, dermatitis, poor coat, and ocular or mucosal changes.
If too much
Clinically significant dietary toxicity is uncommon.
Higher risk situations
Rapid growth and poorly balanced homemade diets.
Practical note
Low risk of excess does not make deficiency irrelevant.
Species focus
Dogs and cats
Why it matters
Works with antioxidant systems such as glutathione peroxidase and supports muscle and thyroid biology.
If too little
Reduced antioxidant defense, poor growth, reduced fertility, and muscle weakness.
If too much
Supplement overdose can cause gastrointestinal upset and systemic toxicity. Chronic excess causes hair or coat issues and brittle nails or claws in some species.
Higher risk situations
Multiple supplement use, homemade diets, and products combining several antioxidant blends.
Practical note
Selenium has a narrow margin compared with many nutrients.
Species focus
Dogs and cats
Why it matters
Major extracellular electrolyte needed for nerve function, fluid balance, and nutrient transport.
If too little
Weakness, dehydration, poor growth, low blood pressure, and neurologic dysfunction in severe cases.
If too much
Thirst, sodium overload, worsened dehydration if water access is poor, and increased concern in some disease states.
Higher risk situations
Pets with fluid loss, restricted water access, or disease that alters sodium handling.
Practical note
Sodium should be interpreted in context, not as a stand alone villain.
Species focus
Cat focused
Why it matters
Essential for cats, supports the retina, heart, bile acid conjugation, and reproduction.
If too little
Dilated cardiomyopathy, central retinal degeneration, poor reproduction, poor kitten development, and other systemic problems in cats.
If too much
Dietary excess is generally well tolerated. Toxicity from complete foods is not well documented.
Higher risk situations
Cats, especially if fed dog food, vegetarian style diets, poorly formulated homemade diets, or marginal formulas.
Practical note
Cats require preformed taurine. Dogs can synthesize taurine, but low taurine status can still occur in some contexts.
Species focus
Dogs and cats
Why it matters
Water soluble vitamin essential for carbohydrate metabolism and nervous system function.
If too little
Neurologic signs including ataxia, head tilt, ventroflexion in cats, seizures, depression, and death in severe deficiency.
If too much
Dietary toxicity is uncommon because thiamine is water soluble. Problems are far more often due to deficiency than excess.
Higher risk situations
Cats, raw fish diets, sulfur dioxide preserved foods, and severely anorectic animals.
Practical note
Thiamine deficiency can become dramatic and life threatening.
Species focus
Dogs and cats
Why it matters
Supports proteins in muscle and the gut lining, including mucin production.
If too little
Poor growth, weight loss, reduced protein quality, and weaker support for the gastrointestinal lining.
If too much
Toxicity from complete foods is uncommon. Large supplemental imbalances may reduce tolerance or diet balance.
Higher risk situations
Growth, intestinal disease, and marginal protein diets.
Practical note
Threonine helps support the gut, not just muscle.
Species focus
Dogs and cats
Why it matters
Needed for protein synthesis and as a precursor for serotonin and niacin pathways.
If too little
Poor growth, lower intake, weight loss, and altered behavior or stress tolerance.
If too much
High supplemental intakes may upset the gastrointestinal tract or create neurochemical imbalance. Dietary toxicity from complete foods is uncommon.
Higher risk situations
Growth, stress, recovery, and heavily supplemented diets.
Practical note
Behavior and appetite can both be affected when tryptophan balance is off.
Species focus
Dogs and cats
Why it matters
Branched chain amino acid used in muscle metabolism and protein turnover.
If too little
Poor growth, reduced lean mass, and weaker overall protein quality.
If too much
Large imbalances can interfere with other branched chain amino acids. Clear dietary toxicity from complete foods is uncommon.
Higher risk situations
Growth and incomplete formulations.
Practical note
This is another amino acid that matters most as part of the full pattern.
Species focus
Dogs and cats
Why it matters
Supports vision, epithelial health, immunity, and development.
If too little
Poor vision, impaired immunity, poor skin and mucosal health, and growth or reproductive problems.
If too much
Hypervitaminosis A can cause bone and joint changes, pain, stiffness, constipation, and liver stress. Cats are especially susceptible with chronic oversupply from foods such as liver or cod liver oil.
Higher risk situations
Cats, high liver feeding, and owners stacking supplements.
Practical note
Vitamin A is essential, but it is not harmless just because it is a vitamin.
Species focus
Dogs and cats
Why it matters
Required for calcium and phosphorus absorption and normal bone mineralization.
If too little
Rickets, osteomalacia, weak bones, and poor mineral balance.
If too much
Hypercalcemia, soft tissue mineralization, kidney injury, vomiting, weakness, and potentially death.
Higher risk situations
Young animals, supplement mistakes, and pets exposed to vitamin D containing products.
Practical note
Dogs and cats rely heavily on dietary vitamin D because skin production is limited.
Species focus
Dogs and cats
Why it matters
Major lipid phase antioxidant that helps protect cell membranes and fatty acids from oxidation.
If too little
Oxidative injury, poor immune support, steatitis in cats, and muscle or reproductive problems.
If too much
Usually well tolerated, but excess supplementation can complicate balance with other fat soluble nutrients and may upset the gastrointestinal tract.
Higher risk situations
Fish oil supplementation, high polyunsaturated fat diets, and cats.
Practical note
The more unsaturated fat a diet uses, the more vitamin E adequacy matters.
Species focus
Dogs and cats
Why it matters
Needed for normal blood clotting.
If too little
Easy bruising, bleeding, prolonged clotting times, and serious hemorrhage in severe deficiency.
If too much
Natural food forms have low toxicity, but some synthetic forms such as menadione have a poorer safety profile and can damage red blood cells or the liver at high exposure.
Higher risk situations
Liver disease, fat malabsorption, long antibiotic courses, and exposure to certain toxins.
Practical note
Vitamin K problems often present as a bleeding issue, not a coat issue or growth issue.
Species focus
Dogs and cats
Why it matters
Supports circulation, temperature control, digestion, urinary health, and every major metabolic process.
If too little
Dehydration, lethargy, poor appetite, constipation, reduced skin elasticity, kidney stress, and in severe cases shock or death.
If too much
Usually reflects disease or inappropriate access patterns rather than nutrient toxicity itself. Rapid overconsumption can contribute to dilutional electrolyte problems in rare cases.
Higher risk situations
Cats with low thirst drive, animals with vomiting or diarrhea, seniors, and hot weather.
Practical note
Water is the most important nutrient. A bowl can be full while intake is still inadequate.
Species focus
Dogs and cats
Why it matters
Required for skin, keratinization, immunity, growth, and many enzyme systems.
If too little
Crusting skin disease, poor coat, poor growth, impaired immunity, and reproductive issues.
If too much
Vomiting, anemia, hemolysis, pancreatic injury, and interference with copper and iron metabolism.
Higher risk situations
Northern breeds with zinc responsive dermatosis, rapidly growing dogs, and pets swallowing zinc objects or supplements.
Practical note
Zinc deficiency can show up on the skin, while zinc toxicity can become a true emergency.
Reference framework used for this tool
- AAFCO nutrient profile and label guidance framework for dog and cat foods.
- FEDIAF nutritional guidelines for practical minimum and maximum nutrient recommendations.
- Merck Veterinary Manual nutrition and toxicology references for deficiency and excess patterns.
Framework date: March 30, 2026. Review periodically as evidence and guidance evolve.
Educational use only. This tool is not veterinary diagnosis or treatment advice and should not be used as the sole basis for supplement use, feeding changes, or medical decisions.
© 2026 Purrs McBarkin’, LLC. This tool and its content are the property of Purrs McBarkin’, LLC. All rights reserved.