Experienced and professional animal trainer provide their insights in answering this question :
A. Is likely to be an stomach upset but to be sure is not been intoxicated we might need to know what kind of leaves is been eating to rule out the leaves aren’t toxic for dogs. Your vet will give him the best medication to stop that sickness.

How to Identify Common Pet Problems ?

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If your dog has an upset stomach, they may also use leaves and grass as a way to make themselves vomit and get rid of whatever is causing them gastrointestinal pain. Leaves and grass are not technically harmful, but, in large amounts, they can cause a blockage, especially in puppies.
Generally, the ingestion of leaves and grass cause the expulsion of stomach acid, causing them to vomit. It is not a serious event as long as the owners are careful. If the dog eats grass in small quantities, it vomits and then it starts being lively in all its functions, there will be no problem.
Sometimes, a dog with an upset stomach will eat grass or leaves to make themselves vomit and feel better. This isn`t always a bad thing. However, if a dog is eating leaves and vomiting frequently, it could signal a gastrointestinal issue or other underlying medical conditions that might require vet attention.
In fact, many shrubs, trees, and flowers commonly found in the garden and in the wild are dangerous if your dog eats them. Some can cause discomfort, some will make your dog miserable, and some can even be fatal if ingested.
Dogs need roughage in their diets and grass is a good source of fiber. A lack of roughage affects the dog`s ability to digest food and pass stool, so grass may actually help their bodily functions run more smoothly.
Bacterial Infection:

Uh oh…are those wet leaves harboring bacteria? (Answer: Probably, yes.) Old, rotting leaves are the perfect environment for dangerous bacteria like staph to thrive. If your dog has a cut somewhere on their body, that bacteria can easily make its way in!

Unsupervised dogs are more likely than adults to consume things outdoors that may cause gastrointestinal upset and diarrhea. Things like feces of other animals, dead animals/road kill, stagnant water, and even foreign objects, like leaves and wood chips, may all cause diarrhea in dogs.
While most leaves that fall from trees are safe for your dog, be wary of areas with heavy pesticide use, as these chemicals can be harmful for your dog if ingested. Graham says that even if leaves come from a “safe” plant, eating too many can cause intestinal blockages, which can be serious.
While this behavior can be stomach-turning to many pet parents it`s actually a natural scavenging behavior in our canine companions. Puppies can be particularly keen on eating things they find including leaves, trash, stones and dead animals.
Contact your veterinarian if you notice your dog consistently eating plants or if you notice any symptoms that might be indicative of poisoning. Symptoms of poisoning may include vomiting, diarrhea, tremors or seizures and loss of consciousness. Reasons why your dog is eating plants include: They enjoy the taste.
English Ivy, both leaves and berries (Hedera helix) Mistletoe (Viscum album) Oleander (Nerium oleander) Thorn apple or jimsonweed (Datura stramonium)
Affected dogs show signs 30 minutes to 4 hours after ingesting the poison. Initially affected dogs become anxious and have an elevated body temperature. Panting is usually seen. Progressively they become worse and staggery.
Eating grass is a way for dogs to clear their system. Dogs instinctively know that eating grass will settle a GI upset. The tale-tale sign of an upset digestive system is when your dog keeps licking lips and swallowing and eating grass or your dog eating grass frantically and panting.
According to the National Highway Safety Administration, a road with wet leaves can be just as slippery as an icy road. The water droplets atop the leaves make it difficult for tires to find traction, and the car may go into a skid. Leaves, wet or dry, can also mask potholes and other obstacles on the road.
The virus lives in grass, soil, puddles, mud, snow, leaves, sidewalks, etc.. Humans can bring the virus home and the virus could be living at dog parks, people parks, rest areas, dog washes, kennels, private yards, beaches, hiking trails, … there is no end to where parvo virus can live and wait.
If your pet has ingested a poison, try to rinse or wipe out the mouth with a damp towel/flannel. Do not give your pet anything to eat or drink before speaking with the Animal Poisons Helpline or a vet.
Adding them to the daily diet provides your body with essential nutrients such as vitamins, minerals, fibre, antioxidants, etc. The antioxidants present in leaves can make a strong immune system. A regular intake of leaves can protect your skin and keep your body hydrated longer.
In fact, bay leaves are considered to be toxic to dogs due to the presence of a substance called eugenol plus a number of other essential oils. According to the ASPCA, consuming bay leaves can bring on bouts of diarrhea and vomiting, and whole leaves could even result in an obstruction for your dog.
Some of the signs of parvovirus include lethargy; loss of appetite; abdominal pain and bloating; fever or low body temperature (hypothermia); vomiting; and severe, often bloody, diarrhea. Persistent vomiting and diarrhea can cause rapid dehydration, and damage to the intestines and immune system can cause septic shock.
A bland diet for 24 to 48 hours may help to resolve your pup`s issue. Plain-cooked white rice with a little chicken and some canned plain pumpkin (not pumpkin pie filling) may help to make your pup`s tummy feel better. Once your pooch feels better, gradually reintroduce their regular food.
If your dog has diarrhea but is acting fine and isn`t displaying any other symptoms, the issue is contained in the GI. This means it`s more than likely that your dog ate something that isn`t agreeing with them or has a parasite infection.
If your dog eats grass often, even if she throws up from it, there probably isn`t much of a concern. They may be responding to a psychological need to do so. However, you should have her checked for parasites regularly, just to be sure he/she isn`t picking up anything from consuming grass.
Unfortunately for some dogs, the time of the pretty falling autumn leaves will also bring itching, dry skin and allergic reactions. Dogs that are vulnerable to fall allergies usually have reactions to plants like goldenrod, lamb`s quarters, and other nasty plants that release irritating pollen.
Puppies usually stop eating everything once they have been through their teething stage. At about 6 months old, your puppy will have gotten their adult teeth, and will feel less of a need to chew on everything.

Relevant Questions and Answers :

the most relevant questions and answers related to your specific issue

Q. My 5 month old 60 lb Labrador ate some leaves while we were doing yard work on Saturday and started vomiting off and on since. What could it be
ANSWER : A. Is likely to be an stomach upset but to be sure is not been intoxicated we might need to know what kind of leaves is been eating to rule out the leaves aren’t toxic for dogs. Your vet will give him the best medication to stop that sickness.

Q. My Beagle listens to me, but cries & whines when I’m gone & doesn’t listen to my parents. I adopted him just a couple days ago. Any tips for my folks?
ANSWER : A. I really highly doubt that your Beagle listens to you and has formed a connection with you in just a couple of days. It takes months to build up any kind of serious connection with your dog. You need to work on communication with your dog through training them to understand different cues. For instance the Leave-It cue:

You have to work on bonding with your dog through mental stimulation. Training is very important. Luring each new behavior from scratch, and training using treats is how you form a strong bond with your new dog. No scolding is ever necessary… work on being calm, and positive, all the time.

If your dog is crying/whining when you leave, this may be separation anxiety. You’re going to have to separation train this dog from scratch. This dog needs to learn that separation can be a good thing! Tell your “folks” to NOT scold the dog when he is crying/whining after you leave, because that will make your dog MORE anxious when you leave next time. Your dog will be dwelling on the negative if your parents fuel your dogs negative feelings towards you leaving. FUN things should happen when you leave. Your parents should pull out the treats and start doing some basic obedience training with your dog. Your parents should stuff a Kong filled with awesome treats (peanut butter) and give it to him so he feels happy when you leave.

I have some excellent separation anxiety exercises you can work on. If you’d like, you can purchase a consultation with me, and I will go over how to separation train from scratch. It will make your dog comfortable being alone, guaranteed.

Read Full Q/A … : I Don't Like My Mother

Q. My dog has been throwing up a clear liquid (a little slimey) but otherwise acts fine. Could something be wrong?
ANSWER : A. How long has he been doing this? Ongoing vomiting (>2 weeks) warrants a vet visit, but if it’s a one-off, or happens very infrequently then it could be due to something he ate disagreeing with him. Is he is bright, alert and happy in himself I would monitor him, start keeping a vomit journal (seriously) of when he vomits, how much, what the vomit was like, what he was doing before and any other notes. This will be really useful for your vet if it requires further investigatoon. You can also try bland food – boiled chicken and white rice – in small amounts on his vomit days to give his tummy a rest. Withhold for 8h after a vomit and reintroduce the bland diet in small, frequent meals.

Q. 2yr old unfixed male Swiss Mtn dog Started a new behavior of barking loudly in my face. No does not work. He does this if I go to the barn what’s up
ANSWER : A. Fear barking should be treated delicately. You should use high value treats (chicken, cheese sticks, hotdog bits, diced ham, cooked fish, turkey pepperoni, turkey bacon – all cut into tiny little bits.. or peanut butter in a squeeze tube, etc) and with the high value treats you should begin feeding them as soon as your dog becomes uncomfortable. Try keeping your dog under threshold. If going to the bark makes your dog bark (out of fear of the barn), then slowly work on his attention just outside of where he would bark. Slowly move closer feeding him treats the entire way. If at any point he begins barking, back up and work under threshold.

If this is separation anxiety, you should be working slowly at leaving your dog behind. First, make it seem like you’re leaving, “coat/shoes/keys/hat” and open the door, but close the door and don’t leave. Toss your dog a few treats without looking at him or talking to him. Slowly work on exiting for short amounts of time, returning to toss treats

Read Full Q/A … : Vetinfo

Q. I have a 9 week old kitten. At what age do they start spraying? We have a 12 yr old cat that has sprayed a door, I think. Could it be the kitten?
ANSWER : A. It is not unusual for an established house cat to start acting out once there is a change in his environment. In this case, the new kitten could be a stressor for the older cat as he tries to get used to the new change of an added house member. To answer your question, cats generally do not start spraying until the are around 5-6 months old.

Q. My 5 month old dog woke up today very lethargic and not very hungry. His feces smells very bad and it has an orange colored mucus in it. only 5 lbs
ANSWER : A. This could be many things, however first I’d ask you (if we could talk) if your puppy is vaccinated against parvo? That’s a serious viral disease that produces very bad-smelling bloody diarrhea. If he’s not vaccinated against parvo, please take him in to see a vet right away.

Otherwise, if he is vaccinated against parvo, he could have intestinal parasites, he could have eaten something that’s upset his GI tract, or he could have a bacterial infection, for starters. The orange color you mentioned has me especially concerned – I’m worried it could be blood. Regardless – he’s not eating, and he’s lethargic, so he likely feels pretty awful. I recommend you take him to see a vet right away who can figure out what’s going on and treat it appropriately.

Read Full Q/A … : Causes of Blood in Dog Stool

Q. My dog ran away 3 days ago , he came back later and immediately threw up all his food. He hasn’t eaten and is still throwing up since then.
ANSWER : A. I’m really glad to hear your dog came back! If you dog is vomiting I would recommend having him examined by a veterinarian because his vomiting could be caused by a gastrointestinal disturbance. He could have eaten something that upset his stomach, including an intestinal parasite or he could have even consumed something toxic. It would helpful for a veterinarian to evaluate for any injuries he could have sustained while being out of the home and for any abnormalities that could be causing his sickness. Stress could also be playing a role in his stomach upset since he was out of the home for several days.

Q. My cat of 15 years male was diagnose with hyperthyroidism started coughing tonight for about 10 minutes an then stopped.
ANSWER : A. If your cat is vomiting there could be several underlying causes. I guess the first thing I would want to check is the thyroid level, since I have definitely seen cats that were at one point “controlled” on a specific dose of medication no longer be controlled, and the dosage has to be adjusted. This is why we always recommend rechecking thyroid levels yearly, even in hyperthyroid cats that are clinically doing well.

If the thyroid levels have recently been checked and are stable, then I’d start looking for other causes, such as GI disease. Other possibilities include kidney disease, which can definitely cause vomiting and typically goes along with hyperthyroidism (as well as just being a geriatric cat). Always a good idea to check liver values as well, as liver disease is a common problem in older cats too.

So since your cat is hyperthyroid the first step to diagnosing causes of vomiting is running full blood work – complete blood count, chemistry panel, and urinalysis – to look for some of the things I mentioned above. If nothing turns up, imaging with x-rays or ultrasound or both will likely provide a lot more information. Good luck.